--- **Functional** - Create random air traffic in your missions.
--
-- ===
--
-- The aim of the RAT class is to fill the empty DCS world with randomized air traffic and bring more life to your airports.
-- In particular, it is designed to spawn AI air units at random airports. These units will be assigned a random flight path to another random airport on the map.
-- Even the mission designer will not know where aircraft will be spawned and which route they follow.
--
-- ## Features:
--
--   * Very simple interface. Just one unit and two lines of Lua code needed to fill your map.
--   * High degree of randomization. Aircraft will spawn at random airports, have random routes and random destinations.
--   * Specific departure and/or destination airports can be chosen.
--   * Departure and destination airports can be restricted by coalition.
--   * Planes and helicopters supported. Helicopters can also be send to FARPs and ships.
--   * Units can also be spawned in air within pre-defined zones of the map.
--   * Aircraft will be removed when they arrive at their destination (or get stuck on the ground).
--   * When a unit is removed a new unit with a different flight plan is respawned.
--   * Aircraft can report their status during the route.
--   * All of the above can be customized by the user if necessary.
--   * All current (Caucasus, Nevada, Normandy, Persian Gulf) and future maps are supported.
--
-- The RAT class creates an entry in the F10 radio menu which allows to:
--
--   * Create new groups on-the-fly, i.e. at run time within the mission,
--   * Destroy specific groups (e.g. if they get stuck or damaged and block a runway),
--   * Request the status of all RAT aircraft or individual groups,
--   * Place markers at waypoints on the F10 map for each group.
--
-- Note that by its very nature, this class is suited best for civil or transport aircraft. However, it also works perfectly fine for military aircraft of any kind.
--
-- More of the documentation include some simple examples can be found further down this page.
--
-- ===
--
-- ## Additional Material:
--
-- * **Demo Missions:** [GitHub](https://github.com/FlightControl-Master/MOOSE_MISSIONS/tree/master/Functional/RAT)
-- * **YouTube videos:** [Random Air Traffic](https://www.youtube.com/playlist?list=PL7ZUrU4zZUl0u4Zxywtg-mx_ov4vi68CO)
-- * **Guides:** None
--
-- ===
--
-- ### Author: **funkyfranky**
--
-- ===
-- @module Functional.RAT
-- @image RAT.JPG

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--- RAT class
-- @type RAT
-- @field #string ClassName Name of the Class.
-- @field #string lid Log identifier.
-- @field #boolean Debug Turn debug messages on or off.
-- @field Wrapper.Group#GROUP templategroup Group serving as template for the RAT aircraft.
-- @field #string alias Alias for spawned group.
-- @field #boolean spawninitialized If RAT:Spawn() was already called this RAT object is set to true to prevent users to call it again.
-- @field #number spawndelay Delay time in seconds before first spawning happens.
-- @field #number spawninterval Interval between spawning units/groups. Note that we add a randomization of 50%.
-- @field #number coalition Coalition of spawn group template.
-- @field #number country Country of spawn group template.
-- @field #string category Category of aircarft: "plane" or "heli".
-- @field #number groupsize Number of aircraft in group.
-- @field #string friendly Possible departure/destination airport: all=blue+red+neutral, same=spawn+neutral, spawnonly=spawn, blue=blue+neutral, blueonly=blue, red=red+neutral, redonly=red.
-- @field #table ctable Table with the valid coalitions from choice self.friendly.
-- @field #table aircraft Table which holds the basic aircraft properties (speed, range, ...).
-- @field #number Vcruisemax Max cruise speed in m/s (250 m/s = 900 km/h = 486 kt) set by user.
-- @field #number Vclimb Default climb rate in ft/min.
-- @field #number AlphaDescent Default angle of descenti in degrees. A value of 3.6 follows the 3:1 rule of 3 miles of travel and 1000 ft descent.
-- @field #string roe ROE of spawned groups, default is weapon hold (this is a peaceful class for civil aircraft or ferry missions). Possible: "hold", "return", "free".
-- @field #string rot ROT of spawned groups, default is no reaction. Possible: "noreaction", "passive", "evade".
-- @field #number takeoff Takeoff type. 0=coldorhot.
-- @field #number landing Landing type. Determines if we actually land at an airport or treat it as zone.
-- @field #number mindist Min distance from departure to destination in meters. Default 5 km.
-- @field #number maxdist Max distance from departure to destination in meters. Default 5000 km.
-- @field #table airports_map All airports available on current map (Caucasus, Nevada, Normandy, ...).
-- @field #table airports All airports of friedly coalitions.
-- @field #boolean random_departure By default a random friendly airport is chosen as departure.
-- @field #boolean random_destination By default a random friendly airport is chosen as destination.
-- @field #table departure_ports Array containing the names of the destination airports or zones.
-- @field #table destination_ports Array containing the names of the destination airports or zones.
-- @field #number Ndestination_Airports Number of destination airports set via SetDestination().
-- @field #number Ndestination_Zones Number of destination zones set via SetDestination().
-- @field #number Ndeparture_Airports Number of departure airports set via SetDeparture().
-- @field #number Ndeparture_Zones Number of departure zones set via SetDeparture.
-- @field #table excluded_ports Array containing the names of explicitly excluded airports.
-- @field #boolean destinationzone Destination is a zone and not an airport.
-- @field #table return_zones Array containing the names of the return zones.
-- @field #boolean returnzone Zone where aircraft will fly to before returning to their departure airport.
-- @field Core.Zone#ZONE departure_Azone Zone containing the departure airports.
-- @field Core.Zone#ZONE destination_Azone Zone containing the destination airports.
-- @field #boolean addfriendlydepartures Add all friendly airports to departures.
-- @field #boolean addfriendlydestinations Add all friendly airports to destinations.
-- @field #table ratcraft Array with the spawned RAT aircraft.
-- @field #number Tinactive Time in seconds after which inactive units will be destroyed. Default is 300 seconds.
-- @field #boolean reportstatus Aircraft report status.
-- @field #number statusinterval Intervall between status checks (and reports if enabled).
-- @field #boolean placemarkers Place markers of waypoints on F10 map.
-- @field #number FLcruise Cruise altitude of aircraft. Default FL200 for planes and F005 for helos.
-- @field #number FLuser Flight level set by users explicitly.
-- @field #number FLminuser Minimum flight level set by user.
-- @field #number FLmaxuser Maximum flight level set by user.
-- @field #boolean commute Aircraft commute between departure and destination, i.e. when respawned the departure airport becomes the new destiation.
-- @field #boolean starshape If true, aircraft travel A-->B-->A-->C-->A-->D... for commute.
-- @field #string homebase Home base for commute and return zone. Aircraft will always return to this base but otherwise travel in a star shaped way.
-- @field #boolean continuejourney Aircraft will continue their journey, i.e. get respawned at their destination with a new random destination.
-- @field #number ngroups Number of groups to be spawned in total.
-- @field #number alive Number of groups which are alive.
-- @field #boolean f10menu If true, add an F10 radiomenu for RAT. Default is false.
-- @field #table Menu F10 menu items for this RAT object.
-- @field #string SubMenuName Submenu name for RAT object.
-- @field #boolean respawn_at_landing Respawn aircraft the moment they land rather than at engine shutdown.
-- @field #boolean norespawn Aircraft will not be respawned after they have finished their route.
-- @field #boolean respawn_after_takeoff Aircraft will be respawned directly after take-off.
-- @field #boolean respawn_after_crash Aircraft will be respawned after a crash, e.g. when they get shot down.
-- @field #boolean respawn_inair Aircraft are allowed to spawned in air if they cannot be respawned on ground because there is not free parking spot. Default is true.
-- @field #number respawn_delay Delay in seconds until a repawn happens.
-- @field #table markerids Array with marker IDs.
-- @field #table waypointdescriptions Table with strings for waypoint descriptions of markers.
-- @field #table waypointstatus Table with strings of waypoint status.
-- @field #string livery Livery of the aircraft set by user.
-- @field #string skill Skill of AI.
-- @field #boolean ATCswitch Enable/disable ATC if set to true/false.
-- @field #boolean radio If true/false disables radio messages from the RAT groups.
-- @field #number frequency Radio frequency used by the RAT groups.
-- @field #string modulation Ratio modulation. Either "FM" or "AM".
-- @field #boolean uncontrolled If true aircraft are spawned in uncontrolled state and will only sit on their parking spots. They can later be activated.
-- @field #boolean invisible If true aircraft are set to invisible for other AI forces.
-- @field #boolean immortal If true, aircraft are spawned as immortal.
-- @field #boolean activate_uncontrolled If true, uncontrolled are activated randomly after certain time intervals.
-- @field #number activate_delay Delay in seconds before first uncontrolled group is activated. Default is 5 seconds.
-- @field #number activate_delta Time interval in seconds between activation of uncontrolled groups. Default is 5 seconds.
-- @field #number activate_frand Randomization factor of time interval (activate_delta) between activating uncontrolled groups. Default is 0.
-- @field #number activate_max Maximum number of uncontrolled aircraft, which will be activated at the same time. Default is 1.
-- @field #string onboardnum Sets the onboard number prefix. Same as setting "TAIL #" in the mission editor.
-- @field #number onboardnum0 (Optional) Starting value of the automatically appended numbering of aircraft within a flight. Default is 1.
-- @field #boolean checkonrunway Aircraft are checked if they were accidentally spawned on the runway. Default is true.
-- @field #number onrunwayradius Distance (in meters) from a runway spawn point until a unit is considered to have accidentally been spawned on a runway. Default is 75 m.
-- @field #number onrunwaymaxretry Number of respawn retries (on ground) at other airports if a group gets accidentally spawned on the runway. Default is 3.
-- @field #boolean checkontop Aircraft are checked if they were accidentally spawned on top of another unit. Default is true.
-- @field #number ontopradius Radius in meters until which a unit is considered to be on top of another. Default is 2 m.
-- @field Wrapper.Airbase#AIRBASE.TerminalType termtype Type of terminal to be used when spawning at an airbase.
-- @field #number  parkingscanradius Radius in meters until which parking spots are scanned for obstacles like other units, statics or scenery.
-- @field #boolean parkingscanscenery If true, area around parking spots is scanned for scenery objects. Default is false.
-- @field #boolean parkingverysafe If true, parking spots are considered as non-free until a possible aircraft has left and taken off. Default false.
-- @field #boolean despawnair If true, aircraft are despawned when they reach their destination zone. Default.
-- @field #boolean eplrs If true, turn on EPLSR datalink for the RAT group.
-- @field #number NspawnMax Max number of spawns.
-- @extends Core.Spawn#SPAWN

--- Implements an easy to use way to randomly fill your map with AI aircraft.
--
-- ## Airport Selection
--
-- ![Process](..\Presentations\RAT\RAT_Airport_Selection.png)
--
-- ### Default settings:
--
-- * By default, aircraft are spawned at airports of their own coalition (blue or red) or neutral airports.
-- * Destination airports are by default also of neutral or of the same coalition as the template group of the spawned aircraft.
-- * Possible destinations are restricted by their distance to the departure airport. The maximal distance depends on the max range of spawned aircraft type and its initial fuel amount.
--
-- ### The default behavior can be changed:
--
-- * A specific departure and/or destination airport can be chosen.
-- * Valid coalitions can be set, e.g. only red, blue or neutral, all three "colours".
-- * It is possible to start in air within a zone or within a zone above an airport of the map.
--
-- ## Flight Plan
--
-- ![Process](..\Presentations\RAT\RAT_Flight_Plan.png)
--
-- * A general flight plan has five main airborne segments: Climb, cruise, descent, holding and final approach.
-- * Events monitored during the flight are: birth, engine-start, take-off, landing and engine-shutdown.
-- * The default flight level (FL) is set to ~FL200, i.e. 20000 feet ASL but randomized for each aircraft.
-- Service ceiling of aircraft type is into account for max FL as well as the distance between departure and destination.
-- * Maximal distance between destination and departure airports depends on range and initial fuel of aircraft.
-- * Climb rate is set to a moderate value of ~1500 ft/min.
-- * The standard descent rate follows the 3:1 rule, i.e. 1000 ft decent per 3 miles of travel. Hence, angle of descent is ~3.6 degrees.
-- * A holding point is randomly selected at a distance between 5 and 10 km away from destination airport.
-- * The altitude of the holding point is ~1200 m AGL. Holding patterns might or might not happen with variable duration.
-- * If an aircraft is spawned in air, the procedure omits taxi and take-off and starts with the climb/cruising part.
-- * All values are randomized for each spawned aircraft.
--
-- ## Mission Editor Setup
--
-- ![Process](..\Presentations\RAT\RAT_Mission_Setup.png)
--
-- Basic mission setup is very simple and essentially a three step process:
--
-- * Place your aircraft **anywhere** on the map. It really does not matter where you put it.
-- * Give the group a good name. In the example above the group is named "RAT_YAK".
-- * Activate the "LATE ACTIVATION" tick box. Note that this aircraft will not be spawned itself but serves a template for each RAT aircraft spawned when the mission starts.
--
-- Voilà, your already done!
--
-- Optionally, you can set a specific livery for the aircraft or give it some weapons.
-- However, the aircraft will by default not engage any enemies. Think of them as being on a peaceful or ferry mission.
--
-- ## Basic Lua Script
--
-- ![Process](..\Presentations\RAT\RAT_Basic_Lua_Script.png)
--
-- The basic Lua script for one template group consists of two simple lines as shown in the picture above.
--
-- * **Line 2** creates a new RAT object "yak". The only required parameter for the constructor @{#RAT.New}() is the name of the group as defined in the mission editor. In this example it is "RAT_YAK".
-- * **Line 5** trigger the command to spawn the aircraft. The (optional) parameter for the @{#RAT.Spawn}() function is the number of aircraft to be spawned of this object.
-- By default each of these aircraft gets a random departure airport anywhere on the map and a random destination airport, which lies within range of the of the selected aircraft type.
--
-- In this simple example aircraft are respawned with a completely new flightplan when they have reached their destination airport.
-- The "old" aircraft is despawned (destroyed) after it has shut-down its engines and a new aircraft of the same type is spawned at a random departure airport anywhere on the map.
-- Hence, the default flight plan for a RAT aircraft will be: Fly from airport A to B, get respawned at C and fly to D, get respawned at E and fly to F, ...
-- This ensures that you always have a constant number of AI aircraft on your map.
--
-- ## Parking Problems
--
-- One big issue in DCS is that not all aircraft can be spawned on every airport or airbase. In particular, bigger aircraft might not have a valid parking spot at smaller airports and
-- airstrips. This can lead to multiple problems in DCS.
--
-- * Landing: When an aircraft tries to land at an airport where it does not have a valid parking spot, it is immediately despawned the moment its wheels touch the runway, i.e.
-- when a landing event is triggered. This leads to the loss of the RAT aircraft. On possible way to circumvent the this problem is to let another RAT aircraft spawn at landing
-- and not when it shuts down its engines. See the @{#RAT.RespawnAfterLanding}() function.
-- * Spawning: When a big aircraft is dynamically spawned on a small airbase a few things can go wrong. For example, it could be spawned at a parking spot with a shelter.
-- Or it could be damaged by a scenery object when it is taxiing out to the runway, or it could overlap with other aircraft on parking spots near by.
--
-- You can check yourself if an aircraft has a valid parking spot at an airbase by dragging its group on the airport in the mission editor and set it to start from ramp.
-- If it stays at the airport, it has a valid parking spot, if it jumps to another airport, it does not have a valid parking spot on that airbase.
--
-- ### Setting the Terminal Type
-- Each parking spot has a specific type depending on its size or if a helicopter spot or a shelter etc. The classification is not perfect but it is the best we have.
-- If you encounter problems described above, you can request a specific terminal type for the RAT aircraft. This can be done by the @{#RAT.SetTerminalType}(*terminaltype*)
-- function. The parameter *terminaltype* can be set as follows
--
-- * AIRBASE.TerminalType.HelicopterOnly: Special spots for Helicopers.
-- * AIRBASE.TerminalType.Shelter: Hardened Air Shelter. Currently only on Caucaus map.
-- * AIRBASE.TerminalType.OpenMed: Open/Shelter air airplane only.
-- * AIRBASE.TerminalType.OpenBig: Open air spawn points. Generally larger but does not guarantee large aircraft are capable of spawning there.
-- * AIRBASE.TerminalType.OpenMedOrBig: Combines OpenMed and OpenBig spots.
-- * AIRBASE.TerminalType.HelicopterUsable: Combines HelicopterOnly, OpenMed and OpenBig.
-- * AIRBASE.TerminalType.FighterAircraft: Combines Shelter, OpenMed and OpenBig spots. So effectively all spots usable by fixed wing aircraft.
--
-- So for example
--      c17=RAT:New("C-17")
--      c17:SetTerminalType(AIRBASE.TerminalType.OpenBig)
--      c17:Spawn(5)
--
-- This would randomly spawn five C-17s but only on airports which have big open air parking spots. Note that also only destination airports are allowed
-- which do have this type of parking spot. This should ensure that the aircraft is able to land at the destination without being despawned immediately.
--
-- Also, the aircraft are spawned only on the requested parking spot types and not on any other type. If no parking spot of this type is available at the
-- moment of spawning, the group is automatically spawned in air above the selected airport.
--
-- ## Examples
--
-- Here are a few examples, how you can modify the default settings of RAT class objects.
--
-- ### Specify Departure and Destinations
--
-- ![Process](..\Presentations\RAT\RAT_Examples_Specify_Departure_and_Destination.png)
--
-- In the picture above you find a few possibilities how to modify the default behaviour to spawn at random airports and fly to random destinations.
--
-- In particular, you can specify fixed departure and/or destination airports. This is done via the @{#RAT.SetDeparture}() or @{#RAT.SetDestination}() functions, respectively.
--
-- * If you only fix a specific departure airport via @{#RAT.SetDeparture}() all aircraft will be spawned at that airport and get random destination airports.
-- * If you only fix the destination airport via @{#RAT.SetDestination}(), aircraft a spawned at random departure airports but will all fly to the destination airport.
-- * If you fix departure and destination airports, aircraft will only travel from between those airports.
-- When the aircraft reaches its destination, it will be respawned at its departure and fly again to its destination.
--
-- There is also an option that allows aircraft to "continue their journey" from their destination. This is achieved by the @{#RAT.ContinueJourney}() function.
-- In that case, when the aircraft arrives at its first destination it will be respawned at that very airport and get a new random destination.
-- So the flight plan in this case would be: Fly from airport A to B, then from B to C, then from C to D, ...
--
-- It is also possible to make aircraft "commute" between two airports, i.e. flying from airport A to B and then back from B to A, etc.
-- This can be done by the @{#RAT.Commute}() function. Note that if no departure or destination airports are specified, the first departure and destination are chosen randomly.
-- Then the aircraft will fly back and forth between those two airports indefinitely.
--
--
-- ### Spawn in Air
--
-- ![Process](..\Presentations\RAT\RAT_Examples_Spawn_in_Air.png)
--
-- Aircraft can also be spawned in air rather than at airports on the ground. This is done by setting @{#RAT.SetTakeoff}() to "air".
--
-- By default, aircraft are spawned randomly above airports of the map.
--
-- The @{#RAT.SetDeparture}() option can be used to specify zones, which have been defined in the mission editor as departure zones.
-- Aircraft will then be spawned at a random point within the zone or zones.
--
-- Note that @{#RAT.SetDeparture}() also accepts airport names. For an air takeoff these are treated like zones with a radius of XX kilometers.
-- Again, aircraft are spawned at random points within these zones around the airport.
--
-- ### Misc Options
--
-- ![Process](..\Presentations\RAT\RAT_Examples_Misc.png)
--
-- The default "takeoff" type of RAT aircraft is that they are spawned with hot or cold engines.
-- The choice is random, so 50% of aircraft will be spawned with hot engines while the other 50% will be spawned with cold engines.
-- This setting can be changed using the @{#RAT.SetTakeoff}() function. The possible parameters for starting on ground are:
--
-- *  @{#RAT.SetTakeoff}("cold"), which means that all aircraft are spawned with their engines off,
-- *  @{#RAT.SetTakeoff}("hot"), which means that all aircraft are spawned with their engines on,
-- *  @{#RAT.SetTakeoff}("runway"), which means that all aircraft are spawned already at the runway ready to takeoff.
-- Note that in this case the default spawn intervall is set to 180 seconds in order to avoid aircraft jams on the runway. Generally, this takeoff at runways should be used with care and problems are to be expected.
--
--
-- The options @{#RAT.SetMinDistance}() and @{#RAT.SetMaxDistance}() can be used to restrict the range from departure to destination. For example
--
-- * @{#RAT.SetMinDistance}(100) will cause only random destination airports to be selected which are **at least** 100 km away from the departure airport.
-- * @{#RAT.SetMaxDistance}(150) will allow only destination airports which are **less than** 150 km away from the departure airport.
--
-- ![Process](..\Presentations\RAT\RAT_Gaussian.png)
--
-- By default planes get a cruise altitude of ~20,000 ft ASL. The actual altitude is sampled from a Gaussian distribution. The picture shows this distribution
-- if one would spawn 1000 planes. As can be seen most planes get a cruising alt of around FL200. Other values are possible but less likely the further away
-- one gets from the expectation value.
--
-- The expectation value, i.e. the altitude most aircraft get, can be set with the function @{#RAT.SetFLcruise}().
-- It is possible to restrict the minimum cruise altitude by @{#RAT.SetFLmin}() and the maximum cruise altitude by @{#RAT.SetFLmax}()
--
-- The cruise altitude can also be given in meters ASL by the functions @{#RAT.SetCruiseAltitude}(), @{#RAT.SetMinCruiseAltitude}() and @{#RAT.SetMaxCruiseAltitude}().
--
-- For example:
--
-- * @{#RAT.SetFLcruise}(300) will cause most planes fly around FL300.
-- * @{#RAT.SetFLmin}(100) restricts the cruising alt such that no plane will fly below FL100. Note that this automatically changes the minimum distance from departure to destination.
-- That means that only destinations are possible for which the aircraft has had enough time to reach that flight level and descent again.
-- * @{#RAT.SetFLmax}(200) will restrict the cruise alt to maximum FL200, i.e. no aircraft will travel above this height.
--
--
-- @field #RAT
RAT={
  ClassName = "RAT",        -- Name of class: RAT = Random Air Traffic.
  Debug=false,              -- Turn debug messages on or off.
  templategroup=nil,        -- Template group for the RAT aircraft.
  alias=nil,                -- Alias for spawned group.
  spawninitialized=false,   -- If RAT:Spawn() was already called this is set to true to prevent users to call it again.
  spawndelay=5,             -- Delay time in seconds before first spawning happens.
  spawninterval=5,          -- Interval between spawning units/groups. Note that we add a randomization of 50%.
  coalition = nil,          -- Coalition of spawn group template.
  country = nil,            -- Country of the group template.
  category = nil,           -- Category of aircarft: "plane" or "heli".
  groupsize=nil,            -- Number of aircraft in the group.
  friendly = "same",        -- Possible departure/destination airport: same=spawn+neutral, spawnonly=spawn, blue=blue+neutral, blueonly=blue, red=red+neutral, redonly=red, neutral.
  ctable = {},              -- Table with the valid coalitions from choice self.friendly.
  aircraft = {},            -- Table which holds the basic aircraft properties (speed, range, ...).
  Vcruisemax=nil,           -- Max cruise speed in set by user.
  Vclimb=1500,              -- Default climb rate in ft/min.
  AlphaDescent=3.6,         -- Default angle of descenti in degrees. A value of 3.6 follows the 3:1 rule of 3 miles of travel and 1000 ft descent.
  roe = "hold",             -- ROE of spawned groups, default is weapon hold (this is a peaceful class for civil aircraft or ferry missions). Possible: "hold", "return", "free".
  rot = "noreaction",       -- ROT of spawned groups, default is no reaction. Possible: "noreaction", "passive", "evade".
  takeoff = 0,              -- Takeoff type. 0=coldorhot.
  landing = 9,              -- Landing type. 9=landing.
  mindist = 5000,           -- Min distance from departure to destination in meters. Default 5 km.
  maxdist = 5000000,        -- Max distance from departure to destination in meters. Default 5000 km.
  airports_map={},          -- All airports available on current map (Caucasus, Nevada, Normandy, ...).
  airports={},              -- All airports of friedly coalitions.
  random_departure=true,    -- By default a random friendly airport is chosen as departure.
  random_destination=true,  -- By default a random friendly airport is chosen as destination.
  departure_ports={},       -- Array containing the names of the departure airports or zones.
  destination_ports={},     -- Array containing the names of the destination airports or zones.
  Ndestination_Airports=0,  -- Number of destination airports set via SetDestination().
  Ndestination_Zones=0,     -- Number of destination zones set via SetDestination().
  Ndeparture_Airports=0,    -- Number of departure airports set via SetDeparture().
  Ndeparture_Zones=0,       -- Number of departure zones set via SetDeparture.
  destinationzone=false,    -- Destination is a zone and not an airport.
  return_zones={},          -- Array containing the names of return zones.
  returnzone=false,         -- Aircraft will fly to a zone and back.
  excluded_ports={},        -- Array containing the names of explicitly excluded airports.
  departure_Azone=nil,      -- Zone containing the departure airports.
  destination_Azone=nil,    -- Zone containing the destination airports.
  addfriendlydepartures=false,   -- Add all friendly airports to departures.
  addfriendlydestinations=false, -- Add all friendly airports to destinations.
  ratcraft={},              -- Array with the spawned RAT aircraft.
  Tinactive=600,            -- Time in seconds after which inactive units will be destroyed. Default is 600 seconds.
  reportstatus=false,       -- Aircraft report status.
  statusinterval=30,        -- Intervall between status checks (and reports if enabled).
  placemarkers=false,       -- Place markers of waypoints on F10 map.
  FLcruise=nil,             -- Cruise altitude of aircraft. Default FL200 for planes and F005 for helos.
  FLminuser=nil,            -- Minimum flight level set by user.
  FLmaxuser=nil,            -- Maximum flight level set by user.
  FLuser=nil,               -- Flight level set by users explicitly.
  commute=false,            -- Aircraft commute between departure and destination, i.e. when respawned the departure airport becomes the new destiation.
  starshape=false,          -- If true, aircraft travel A-->B-->A-->C-->A-->D... for commute.
  homebase=nil,             -- Home base for commute.
  continuejourney=false,    -- Aircraft will continue their journey, i.e. get respawned at their destination with a new random destination.
  alive=0,                  -- Number of groups which are alive.
  ngroups=nil,              -- Number of groups to be spawned in total.
  f10menu=false,            -- Add an F10 menu for RAT.
  Menu={},                  -- F10 menu items for this RAT object.
  SubMenuName=nil,          -- Submenu name for RAT object.
  respawn_at_landing=false, -- Respawn aircraft the moment they land rather than at engine shutdown.
  norespawn=false,          -- Aircraft will not get respawned.
  respawn_after_takeoff=false, -- Aircraft will be respawned directly after takeoff.
  respawn_after_crash=true, -- Aircraft will be respawned after a crash.
  respawn_inair=true,        -- Aircraft are spawned in air if there is no free parking spot on the ground.
  respawn_delay=0,        -- Delay in seconds until repawn happens after landing.
  markerids={},             -- Array with marker IDs.
  waypointdescriptions={},  -- Array with descriptions for waypoint markers.
  waypointstatus={},        -- Array with status info on waypoints.
  livery=nil,               -- Livery of the aircraft.
  skill="High",             -- Skill of AI.
  ATCswitch=true,           -- Enable ATC.
  radio=nil,                -- If true/false disables radio messages from the RAT groups.
  frequency=nil,            -- Radio frequency used by the RAT groups.
  modulation=nil,           -- Ratio modulation. Either "FM" or "AM".
  actype=nil,               -- Aircraft type set by user. Changes the type of the template group.
  uncontrolled=false,       -- Spawn uncontrolled aircraft.
  invisible=false,          -- Spawn aircraft as invisible.
  immortal=false,           -- Spawn aircraft as indestructible.
  activate_uncontrolled=false, -- Activate uncontrolled aircraft (randomly).
  activate_delay=5,         -- Delay in seconds before first uncontrolled group is activated.
  activate_delta=5,         -- Time interval in seconds between activation of uncontrolled groups.
  activate_frand=0,         -- Randomization factor of time interval (activate_delta) between activating uncontrolled groups.
  activate_max=1,           -- Max number of uncontrolle aircraft, which will be activated at a time.
  onboardnum=nil,           -- Tail number.
  onboardnum0=1,            -- (Optional) Starting value of the automatically appended numbering of aircraft within a flight. Default is one.
  checkonrunway=true,       -- Check whether aircraft have been spawned on the runway.
  onrunwayradius=75,        -- Distance from a runway spawn point until a unit is considered to have accidentally been spawned on a runway.
  onrunwaymaxretry=3,       -- Number of respawn retries (on ground) at other airports if a group gets accidentally spawned on the runway.
  checkontop=false,         -- Check whether aircraft have been spawned on top of another unit.
  ontopradius=2,            -- Radius in meters until which a unit is considered to be on top of another.
  termtype=nil,             -- Terminal type.
  parkingscanradius=40,     -- Scan radius.
  parkingscanscenery=false, -- Scan parking spots for scenery obstacles.
  parkingverysafe=false,    -- Very safe option.
  despawnair=true,
  eplrs=false,
}

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Categories of the RAT class.
-- @type RAT.cat
-- @field #string plane Plane.
-- @field #string heli Heli.
RAT.cat={
  plane="plane",
  heli="heli",
}

--- RAT waypoint type.
-- @type RAT.wp
RAT.wp={
  coldorhot=0,
  air=1,
  runway=2,
  hot=3,
  cold=4,
  climb=5,
  cruise=6,
  descent=7,
  holding=8,
  landing=9,
  finalwp=10,
}

--- RAT aircraft status.
-- @type RAT.status
RAT.status={
  -- Waypoint states.
  Departure="At departure point",
  Climb="Climbing",
  Cruise="Cruising",
  Uturn="Flying back home",
  Descent="Descending",
  DescentHolding="Descend to holding point",
  Holding="Holding",
  Destination="Arrived at destination",
  -- Spawn states.
  Uncontrolled="Uncontrolled",
  Spawned="Spawned",
  -- Event states.
  EventBirthAir="Born in air",
  EventBirth="Ready and starting engines",
  EventEngineStartAir="On journey", -- Started engines (in air)
  EventEngineStart="Started engines and taxiing",
  EventTakeoff="Airborne after take-off",
  EventLand="Landed and taxiing",
  EventEngineShutdown="Engines off",
  EventDead="Dead",
  EventCrash="Crashed",
}

--- Datastructure of a spawned RAT group.
-- @type RAT.RatCraft
-- @field #number index Spawn index.
-- @field Wrapper.Group#Group group The aircraft group.
-- @field Ops.FlightGroup#FLIGHTGROUP flightgroup The flight group.
-- @field Wrapper.Airbase#AIRBASE destination Destination of this group. Can also be a ZONE.
-- @field Wrapper.Airbase#AIRBASE departure Departure place of this group. Can also be a ZONE.
-- @field #table waypoints Waypoints.
-- @field #boolean airborne Whether this group is airborne.
-- @field #number nunits Number of units.
-- @field Core.Point#COORDINATE Pnow Current position.
-- @field #number Distance Distance travelled in meters.
-- @field #number takeoff Takeoff type.
-- @field #number landing Laning type.
-- @field #table wpdesc Waypoint descriptins.
-- @field #table wpstatus Waypoint status.
-- @field #boolean active Whether the group is active or uncontrolled.
-- @field #string status Status of the group.
-- @field #string livery Livery of the group.
-- @field #boolean despawnme Despawn group if `true` in the next status update.
-- @field #number nrespawn Number of respawns.

--- RAT friendly coalitions.
-- @type RAT.coal
RAT.coal={
  same="same",
  sameonly="sameonly",
  neutral="neutral",
}

--- RAT unit conversions.
-- @type RAT.unit
RAT.unit={
  ft2meter=0.305,
  kmh2ms=0.278,
  FL2m=30.48,
  nm2km=1.852,
  nm2m=1852,
}

--- RAT rules of engagement.
-- @type RAT.ROE
RAT.ROE={
  weaponhold="hold",
  weaponfree="free",
  returnfire="return",
}

--- RAT reaction to threat.
-- @type RAT.ROT
RAT.ROT={
  evade="evade",
  passive="passive",
  noreaction="noreaction",
}

--- RAT ATC.
-- @type RAT.ATC
-- @field #boolean init True if ATC was initialized.
-- @field #table flight List of flights.
-- @field #table airport List of airports.
-- @field #number unregistered Enumerator for unregistered flights unregistered=-1.
-- @field #number Nclearance Number of flights that get landing clearance simultaniously. Default 2.
-- @field #number delay Delay between landing flights in seconds. Default 240 sec.
-- @field #boolean messages If `true`, ATC sends messages.
-- @field #number T0 Time stamp [sec, timer.getTime()] when ATC was initialized.
-- @field #number onfinal Enumerator onfinal=100.
RAT.ATC={
  init=false,
  flight={},
  airport={},
  unregistered=-1,
  onfinal=-100,
  Nclearance=2,
  delay=240,
  messages=true,
}

--- Running number of placed markers on the F10 map.
-- @field #number markerid
RAT.markerid=0

--- Main F10 menu.
-- @field #string MenuF10
RAT.MenuF10=nil

--- Some ID to identify who we are in output of the DCS.log file.
-- @field #string id
RAT.id="RAT | "

--- RAT version.
-- @list version
RAT.version={
  version = "3.0.0",
  print = true,
}

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--TODO list:
--TODO: Add unlimited fuel option (and disable range check). This also needs to be added to FLIGHTGROUP
--TODO: 
--TODO: Add max number of spawns
--TODO: Add Stop function
--TODO: Integrate FLIGHTGROUP
--DONE: Add scheduled spawn.
--DONE: Add possibility to spawn in air.
--DONE: Add departure zones for air start.
--DONE: Make more functions to adjust/set RAT parameters.
--DONE: Clean up debug messages.
--DONE: Improve flight plan. Especially check FL against route length.
--DONE: Add event handlers.
--DONE: Respawn units when they have landed.
--DONE: Change ROE state.
--DONE: Make ROE state user function
--DONE: Improve status reports.
--DONE: Check compatibility with other #SPAWN functions. nope, not all!
--DONE: Add possibility to continue journey at destination. Need "place" in event data for that.
--DONE: Add enumerators and get rid off error prone string comparisons.
--DONE: Check that FARPS are not used as airbases for planes.
--DONE: Add special cases for ships (similar to FARPs).
--DONE: Add cases for helicopters.
--DONE: Add F10 menu.
--DONE: Add markers to F10 menu.
--DONE: Add respawn limit. Later...
--DONE: Make takeoff method random between cold and hot start.
--DONE: Check out uncontrolled spawning. Not now!
--DONE: Check aircraft spawning in air at Sochi after third aircraft was spawned. ==> DCS behaviour.
--DONE: Improve despawn after stationary. Might lead to despawning if many aircraft spawn at the same time.
--DONE: Check why birth event is not handled. ==> Seems to be okay if it is called _OnBirth rather than _OnBirthday. Dont know why actually!?
--DONE: Improve behaviour when no destination or departure airports were found. Leads to crash, e.g. 1184: attempt to get length of local 'destinations' (a nil value)
--DONE: Check cases where aircraft get shot down.
--DONE: Handle the case where more than 10 RAT objects are spawned. Likewise, more than 10 groups of one object. Causes problems with the number of menu items! ==> not now!
--DONE: Add custom livery choice if possible.
--DONE: Add function to include all airports to selected destinations/departures.
--DONE: Find way to respawn aircraft at same position where the last was despawned for commute and journey.
--TODO: Check that same alias is not given twice. Need to store previous ones and compare.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Constructor New
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Create a new RAT object.
-- @param #RAT self
-- @param #string groupname Name of the group as defined in the mission editor. This group is serving as a template for all spawned units.
-- @param #string alias (Optional) Alias of the group. This is and optional parameter but must(!) be used if the same template group is used for more than one RAT object.
-- @return #RAT Object of RAT class or nil if the group does not exist in the mission editor.
-- @usage yak1:RAT("RAT_YAK") will create a RAT object called "yak1". The template group in the mission editor must have the name "RAT_YAK".
-- @usage yak2:RAT("RAT_YAK", "Yak2") will create a RAT object "yak2". The template group in the mission editor must have the name "RAT_YAK" but the group will be called "Yak2" in e.g. the F10 menu.
function RAT:New(groupname, alias)

  -- Inherit SPAWN class.
  self=BASE:Inherit(self, SPAWN:NewWithAlias(groupname, alias)) -- #RAT
  
  -- Log id.
  self.lid=string.format("RAT %s | ", alias or groupname)
  
  -- Version info.
  if RAT.version.print then
    env.info(self.lid.."Version "..RAT.version.version)
    RAT.version.print=false
  end  

  -- Welcome message.
  self:F(self.lid..string.format("Creating new RAT object from template: %s.", groupname))

  -- Set alias.
  alias=alias or groupname

  -- Alias of groupname.
  self.alias=alias

  -- Get template group defined in the mission editor.
  local DCSgroup=Group.getByName(groupname)

  -- Check the group actually exists.
  if DCSgroup==nil then
    self:E(self.lid..string.format("ERROR: Group with name %s does not exist in the mission editor!", groupname))
    return nil
  end

  -- Store template group.
  self.templategroup=GROUP:FindByName(groupname)

  -- Get number of aircraft in group.
  self.groupsize=self.templategroup:GetSize()

  -- Set own coalition.
  self.coalition=DCSgroup:getCoalition()

  -- Initialize aircraft parameters based on ME group template.
  self:_InitAircraft(DCSgroup)

  -- Get all airports of current map (Caucasus, NTTR, Normandy, ...).
  self:_GetAirportsOfMap()

  return self
end

--- Stop RAT spawning by unhandling events, stoping schedulers etc.
-- @param #RAT self
-- @param #number delay Delay before stop in seconds.
function RAT:Stop(delay)
  self:T3(self.lid..string.format("Stopping RAT! Delay %s sec!", tostring(delay)))

  if delay and delay>0 then
    self:T2(self.lid..string.format("Stopping RAT in %d sec!", delay))
    self:ScheduleOnce(delay, RAT.Stop, self)
  else
  
    self:T(self.lid.."Stopping RAT: Clearing schedulers and unhandling events!")
  
    if self.sid_Activate then
      self.Scheduler:ScheduleStop(self.sid_Activate)
    end
    
    if self.sid_Spawn then
      self.Scheduler:ScheduleStop(self.sid_Spawn)
    end
    
    if self.sid_Status then
      self.Scheduler:ScheduleStop(self.sid_Status)
    end
  
  
    if self.Scheduler then
      self.Scheduler:Clear()
    end
    
    self.norespawn=true    
    
    -- Un-Handle events.
    self:UnHandleEvent(EVENTS.Birth)
    self:UnHandleEvent(EVENTS.EngineStartup)
    self:UnHandleEvent(EVENTS.Takeoff)
    self:UnHandleEvent(EVENTS.Land)
    self:UnHandleEvent(EVENTS.EngineShutdown)
    self:UnHandleEvent(EVENTS.Dead)
    self:UnHandleEvent(EVENTS.Crash)
    self:UnHandleEvent(EVENTS.Hit)    
  
  end
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Spawn function
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Triggers the spawning of AI aircraft. Note that all additional options should be set before giving the spawn command.
-- @param #RAT self
-- @param #number naircraft (Optional) Number of aircraft to spawn. Default is one aircraft.
-- @return #boolean True if spawning was successful or nil if nothing was spawned.
-- @usage yak:Spawn(5) will spawn five aircraft. By default aircraft will spawn at neutral and red airports if the template group is part of the red coalition.
function RAT:Spawn(naircraft)

  -- Make sure that this function is only been called once per RAT object.
  if self.spawninitialized==true then
    self:E("ERROR: Spawn function should only be called once per RAT object! Exiting and returning nil.")
    return nil
  else
    self.spawninitialized=true
  end

  -- Number of aircraft to spawn. Default is one.
  self.ngroups=naircraft or 1

  -- Init RAT ATC if not already done.
  if self.ATCswitch and not RAT.ATC.init then
    RAT._ATCInit(self.airports_map)
  end

  -- Create F10 main menu if it does not exists yet.
  if self.f10menu and not RAT.MenuF10 then
    RAT.MenuF10 = MENU_MISSION:New("RAT")
  end

    -- Set the coalition table based on choice of self.coalition and self.friendly.
  self:_SetCoalitionTable()

  -- Get all airports of this map belonging to friendly coalition(s).
  self:_GetAirportsOfCoalition()

  -- Set sub-menu name if it has not been set by user.
  if not self.SubMenuName then
    self.SubMenuName=self.alias
  end

  -- Get all departure airports inside a Moose zone.
  if self.departure_Azone~=nil then
    self.departure_ports=self:_GetAirportsInZone(self.departure_Azone)
  end

  -- Get all destination airports inside a Moose zone.
  if self.destination_Azone~=nil then
    self.destination_ports=self:_GetAirportsInZone(self.destination_Azone)
  end

  -- Add all friendly airports to possible departures/destinations
  if self.addfriendlydepartures then
    self:_AddFriendlyAirports(self.departure_ports)
  end
  if self.addfriendlydestinations then
    self:_AddFriendlyAirports(self.destination_ports)
  end

  -- Setting and possibly correction min/max/cruise flight levels.
  if self.FLcruise==nil then
    -- Default flight level (ASL).
    if self.category==RAT.cat.plane then
      -- For planes: FL200 = 20000 ft = 6096 m.
      self.FLcruise=200*RAT.unit.FL2m
    else
      -- For helos: FL005 = 500 ft = 152 m.
      self.FLcruise=005*RAT.unit.FL2m
    end
  end

  -- Enable helos to go to destinations 100 meters away.
  if self.category==RAT.cat.heli then
    self.mindist=50
  end

  -- Run consistency checks.
  self:_CheckConsistency()

  -- Settings info
  local text=string.format("\n******************************************************\n")
  text=text..string.format("Spawning %i aircraft from template %s of type %s.\n", self.ngroups, self.SpawnTemplatePrefix, self.aircraft.type)
  text=text..string.format("Alias: %s\n", self.alias)
  text=text..string.format("Category: %s\n", self.category)
  text=text..string.format("Friendly coalitions: %s\n", self.friendly)
  text=text..string.format("Number of airports on map  : %i\n", #self.airports_map)
  text=text..string.format("Number of friendly airports: %i\n", #self.airports)
  text=text..string.format("Totally random departure: %s\n", tostring(self.random_departure))
  if not self.random_departure then
    text=text..string.format("Number of departure airports: %d\n", self.Ndeparture_Airports)
    text=text..string.format("Number of departure zones   : %d\n", self.Ndeparture_Zones)
  end
  text=text..string.format("Totally random destination: %s\n", tostring(self.random_destination))
  if not self.random_destination then
    text=text..string.format("Number of destination airports: %d\n", self.Ndestination_Airports)
    text=text..string.format("Number of destination zones   : %d\n", self.Ndestination_Zones)
  end
  text=text..string.format("Min dist to destination: %4.1f\n", self.mindist)
  text=text..string.format("Max dist to destination: %4.1f\n", self.maxdist)
  text=text..string.format("Terminal type: %s\n", tostring(self.termtype))
  text=text..string.format("Takeoff type: %i\n", self.takeoff)
  text=text..string.format("Landing type: %i\n", self.landing)
  text=text..string.format("Commute: %s\n", tostring(self.commute))
  text=text..string.format("Journey: %s\n", tostring(self.continuejourney))
  text=text..string.format("Destination Zone: %s\n", tostring(self.destinationzone))
  text=text..string.format("Return Zone: %s\n", tostring(self.returnzone))
  text=text..string.format("Spawn delay: %4.1f\n", self.spawndelay)
  text=text..string.format("Spawn interval: %4.1f\n", self.spawninterval)
  text=text..string.format("Respawn delay: %s\n", tostring(self.respawn_delay))
  text=text..string.format("Respawn off: %s\n", tostring(self.norespawn))
  text=text..string.format("Respawn after landing: %s\n", tostring(self.respawn_at_landing))
  text=text..string.format("Respawn after take-off: %s\n", tostring(self.respawn_after_takeoff))
  text=text..string.format("Respawn after crash: %s\n", tostring(self.respawn_after_crash))
  text=text..string.format("Respawn in air: %s\n", tostring(self.respawn_inair))
  text=text..string.format("ROE: %s\n", tostring(self.roe))
  text=text..string.format("ROT: %s\n", tostring(self.rot))
  text=text..string.format("Immortal: %s\n", tostring(self.immortal))
  text=text..string.format("Invisible: %s\n", tostring(self.invisible))
  text=text..string.format("Vclimb: %4.1f\n", self.Vclimb)
  text=text..string.format("AlphaDescent: %4.2f\n", self.AlphaDescent)
  text=text..string.format("Vcruisemax: %s\n", tostring(self.Vcruisemax))
  text=text..string.format("FLcruise =  %6.1f km = FL%3.0f\n", self.FLcruise/1000, self.FLcruise/RAT.unit.FL2m)
  text=text..string.format("FLuser: %s\n", tostring(self.Fluser))
  text=text..string.format("FLminuser: %s\n", tostring(self.FLminuser))
  text=text..string.format("FLmaxuser: %s\n", tostring(self.FLmaxuser))
  text=text..string.format("Place markers: %s\n", tostring(self.placemarkers))
  text=text..string.format("Report status: %s\n", tostring(self.reportstatus))
  text=text..string.format("Status interval: %4.1f\n", self.statusinterval)
  text=text..string.format("Time inactive: %4.1f\n", self.Tinactive)
  text=text..string.format("Create F10 menu : %s\n", tostring(self.f10menu))
  text=text..string.format("F10 submenu name: %s\n", self.SubMenuName)
  text=text..string.format("ATC enabled : %s\n", tostring(self.ATCswitch))
  text=text..string.format("Radio comms      : %s\n", tostring(self.radio))
  text=text..string.format("Radio frequency  : %s\n", tostring(self.frequency))
  text=text..string.format("Radio modulation : %s\n", tostring(self.frequency))
  text=text..string.format("Tail # prefix    : %s\n", tostring(self.onboardnum))
  text=text..string.format("Check on runway: %s\n", tostring(self.checkonrunway))
  text=text..string.format("Max respawn attempts: %s\n", tostring(self.onrunwaymaxretry))
  text=text..string.format("Check on top: %s\n", tostring(self.checkontop))
  text=text..string.format("Uncontrolled: %s\n", tostring(self.uncontrolled))
  if self.uncontrolled and self.activate_uncontrolled then
    text=text..string.format("Uncontrolled max  : %4.1f\n", self.activate_max)
    text=text..string.format("Uncontrolled delay: %4.1f\n", self.activate_delay)
    text=text..string.format("Uncontrolled delta: %4.1f\n", self.activate_delta)
    text=text..string.format("Uncontrolled frand: %4.1f\n", self.activate_frand)
  end
  if self.livery then
    text=text..string.format("Available liveries:\n")
    for _,livery in pairs(self.livery) do
      text=text..string.format("- %s\n", livery)
    end
  end
  text=text..string.format("******************************************************\n")
  self:T(self.lid..text)

  -- Create submenus.
  if self.f10menu then
    self.Menu[self.SubMenuName]=MENU_MISSION:New(self.SubMenuName, RAT.MenuF10)
    self.Menu[self.SubMenuName]["groups"]=MENU_MISSION:New("Groups", self.Menu[self.SubMenuName])
    MENU_MISSION_COMMAND:New("Spawn new group", self.Menu[self.SubMenuName], self._SpawnWithRoute, self)
    MENU_MISSION_COMMAND:New("Delete markers", self.Menu[self.SubMenuName], self._DeleteMarkers, self)
    MENU_MISSION_COMMAND:New("Status report", self.Menu[self.SubMenuName], self.Status, self, true)
  end

  -- Schedule spawning of aircraft.
  local Tstart=self.spawndelay
  local dt=self.spawninterval
  -- Ensure that interval is >= 180 seconds if spawn at runway is chosen. Aircraft need time to takeoff or the runway gets jammed.
  if self.takeoff==RAT.wp.runway and not self.random_departure then
    dt=math.max(dt, 180)
  end
  local Tstop=Tstart+dt*(self.ngroups-1)

  -- Status check and report scheduler.
  self.sid_Status=self:ScheduleRepeat(Tstart+1, self.statusinterval, nil, nil, RAT.Status, self)
  

  -- Handle events.
  self:HandleEvent(EVENTS.Birth,          self._OnBirth)
  self:HandleEvent(EVENTS.EngineStartup,  self._OnEngineStartup)
  self:HandleEvent(EVENTS.Takeoff,        self._OnTakeoff)
  self:HandleEvent(EVENTS.Land,           self._OnLand)
  self:HandleEvent(EVENTS.EngineShutdown, self._OnEngineShutdown)
  self:HandleEvent(EVENTS.Dead,           self._OnDeadOrCrash)
  self:HandleEvent(EVENTS.Crash,          self._OnDeadOrCrash)
  self:HandleEvent(EVENTS.Hit,            self._OnHit)

  -- No groups should be spawned.
  if self.ngroups==0 then
    return nil
  end

  -- Start scheduled spawning.
  self.sid_Spawn=self:ScheduleRepeat(Tstart, dt, 0.0, Tstop, RAT._SpawnWithRoute, self)

  -- Start scheduled activation of uncontrolled groups.
  if self.uncontrolled and self.activate_uncontrolled then
    self.sid_Activate=self:ScheduleRepeat(self.activate_delay, self.activate_delta, self.activate_frand, nil, RAT._ActivateUncontrolled, self)
  end

  return true
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Consistency Check
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Function checks consistency of user input and automatically adjusts parameters if necessary.
-- @param #RAT self
function RAT:_CheckConsistency()
  self:F2()

  -- User has used SetDeparture()
  if not self.random_departure then

    -- Count departure airports and zones.
    for _,name in pairs(self.departure_ports) do
      if self:_AirportExists(name) then
        self.Ndeparture_Airports=self.Ndeparture_Airports+1
      elseif self:_ZoneExists(name) then
        self.Ndeparture_Zones=self.Ndeparture_Zones+1
      end
    end

    -- What can go wrong?
    -- Only zones but not takeoff air == > Enable takeoff air.
    if self.Ndeparture_Zones>0 and self.takeoff~=RAT.wp.air then
      self.takeoff=RAT.wp.air
      self:E(self.lid..string.format("WARNING: At least one zone defined as departure and takeoff is NOT set to air. Enabling air start for RAT group %s!", self.alias))
    end
    -- No airport and no zone specified.
    if self.Ndeparture_Airports==0 and self.Ndeparture_Zone==0 then
      self.random_departure=true
      local text=string.format("No airports or zones found given in SetDeparture(). Enabling random departure airports for RAT group %s!", self.alias)
      self:E(self.lid.."ERROR: "..text)
      MESSAGE:New(text, 30):ToAll()
    end
  end

  -- User has used SetDestination()
  if not self.random_destination then

    -- Count destination airports and zones.
    for _,name in pairs(self.destination_ports) do
      if self:_AirportExists(name) then
        self.Ndestination_Airports=self.Ndestination_Airports+1
      elseif self:_ZoneExists(name) then
        self.Ndestination_Zones=self.Ndestination_Zones+1
      end
    end

    -- One zone specified as destination ==> Enable destination zone.
    -- This does not apply to return zone because the destination is the zone and not the final destination which can be an airport.
    if self.Ndestination_Zones>0 and self.landing~=RAT.wp.air and not self.returnzone then
      self.landing=RAT.wp.air
      self.destinationzone=true
      self:E(self.lid.."WARNING: At least one zone defined as destination and landing is NOT set to air. Enabling destination zone!")
    end
    -- No specified airport and no zone found at all.
    if self.Ndestination_Airports==0 and self.Ndestination_Zones==0 then
      self.random_destination=true
      local text="No airports or zones found given in SetDestination(). Enabling random destination airports!"
      self:E(self.lid.."ERROR: "..text)
      MESSAGE:New(text, 30):ToAll()
    end
  end

  -- Destination zone and return zone should not be used together.
  if self.destinationzone and self.returnzone then
    self:E(self.lid.."ERROR: Destination zone _and_ return to zone not possible! Disabling return to zone.")
    self.returnzone=false
  end
  -- If returning to a zone, we set the landing type to "air" if takeoff is in air.
  -- Because if we start in air we want to end in air. But default landing is ground.
  if self.returnzone and self.takeoff==RAT.wp.air then
    self.landing=RAT.wp.air
  end

  -- Ensure that neither FLmin nor FLmax are above the aircrafts service ceiling.
  if self.FLminuser then
    self.FLminuser=math.min(self.FLminuser, self.aircraft.ceiling)
  end
  if self.FLmaxuser then
    self.FLmaxuser=math.min(self.FLmaxuser, self.aircraft.ceiling)
  end
  if self.FLcruise then
    self.FLcruise=math.min(self.FLcruise, self.aircraft.ceiling)
  end

  -- FL min > FL max case ==> spaw values
  if self.FLminuser and self.FLmaxuser then
    if self.FLminuser > self.FLmaxuser then
      local min=self.FLminuser
      local max=self.FLmaxuser
      self.FLminuser=max
      self.FLmaxuser=min
    end
  end

  -- Cruise alt < FL min
  if self.FLminuser and self.FLcruise<self.FLminuser then
    -- Here we have two possibilities.
    -- 1) Set cruise alt to min FL, i.e. shift cruise alt up.
    -- 2) Set min FL to cruise alt, i.e. shift min FL down.
    self.FLcruise=self.FLminuser
  end

  -- Cruise alt > FL max
  if self.FLmaxuser and self.FLcruise>self.FLmaxuser then
    self.FLcruise=self.FLmaxuser
  end

  -- Uncontrolled aircraft must start with engines off.
  if self.uncontrolled then
    -- SOLVED: Strangly, it does not work with RAT.wp.cold only with RAT.wp.hot!
    -- Figured out why. SPAWN:SpawnWithIndex is overwriting some values. Now it should work with cold as expected!
    self.takeoff=RAT.wp.cold
  end
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- User functions
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Set the friendly coalitions from which the airports can be used as departure and destination.
-- @param #RAT self
-- @param #string friendly "same"=own coalition+neutral (default), "sameonly"=own coalition only, "neutral"=all neutral airports.
-- Default is "same", so aircraft will use airports of the coalition their spawn template has plus all neutral airports.
-- @return #RAT RAT self object.
-- @usage yak:SetCoalition("neutral") will spawn aircraft randomly on all neutral airports.
-- @usage yak:SetCoalition("sameonly") will spawn aircraft randomly on airports belonging to the same coalition only as the template.
function RAT:SetCoalition(friendly)
  self:F2(friendly)
  if friendly:lower()=="sameonly" then
    self.friendly=RAT.coal.sameonly
  elseif friendly:lower()=="neutral" then
    self.friendly=RAT.coal.neutral
  else
    self.friendly=RAT.coal.same
  end
  return self
end

--- Set coalition of RAT group. You can make red templates blue and vice versa.
-- Note that a country is also set automatically if it has not done before via RAT:SetCountry.
--
-- * For blue, the country is set to USA.
-- * For red, the country is set to RUSSIA.
-- * For neutral, the country is set to SWITZERLAND.
--
-- This is important, since it is ultimately the COUNTRY that determines the coalition of the aircraft.
-- You can set the country explicitly via the RAT:SetCountry() function if necessary.
-- @param #RAT self
-- @param #string color Color of coalition, i.e. "red" or blue" or "neutral".
-- @return #RAT RAT self object.
function RAT:SetCoalitionAircraft(color)
  self:F2(color)
  if color:lower()=="blue" then
    self.coalition=coalition.side.BLUE
    if not self.country then
      self.country=country.id.USA
    end
  elseif color:lower()=="red" then
    self.coalition=coalition.side.RED
    if not self.country then
      self.country=country.id.RUSSIA
    end
  elseif color:lower()=="neutral" then
    self.coalition=coalition.side.NEUTRAL
    if not self.country then
      self.country=country.id.SWITZERLAND
    end
  end
  return self
end

--- Set country of RAT group.
-- See [DCS_enum_country](https://wiki.hoggitworld.com/view/DCS_enum_country).
--
-- This overrules the coalition settings. So if you want your group to be of a specific coalition, you have to set a country that is part of that coalition.
-- @param #RAT self
-- @param DCS#country.id id DCS country enumerator ID. For example country.id.USA or country.id.RUSSIA.
-- @return #RAT RAT self object.
function RAT:SetCountry(id)
  self:F2(id)
  self.country=id
  return self
end

--- Set the terminal type the aircraft use when spawning at an airbase. See [DCS_func_getParking](https://wiki.hoggitworld.com/view/DCS_func_getParking).
-- Note that some additional terminal types have been introduced. Check @{Wrapper.Airbase#AIRBASE} class for details.
-- Also note that only airports which have this kind of terminal are possible departures and/or destinations.
-- @param #RAT self
-- @param Wrapper.Airbase#AIRBASE.TerminalType termtype Type of terminal. Use enumerator AIRBASE.TerminalType.XXX.
-- @return #RAT RAT self object.
--
-- @usage
-- c17=RAT:New("C-17 BIG Plane")
-- c17:SetTerminalType(AIRBASE.TerminalType.OpenBig) -- Only very big parking spots are used.
-- c17:Spawn(5)
function RAT:SetTerminalType(termtype)
  self:F2(termtype)
  self.termtype=termtype
  return self
end

--- Set the scan radius around parking spots. Parking spot is considered to be occupied if any obstacle is found with the radius.
-- @param #RAT self
-- @param #number radius Radius in meters. Default 50 m.
-- @return #RAT RAT self object.
function RAT:SetParkingScanRadius(radius)
  self:F2(radius)
  self.parkingscanradius=radius or 50
  return self
end

--- Enables scanning for scenery objects around parking spots which might block the spot.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetParkingScanSceneryON()
  self:F2()
  self.parkingscanscenery=true
  return self
end

--- Disables scanning for scenery objects around parking spots which might block the spot. This is also the default setting.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetParkingScanSceneryOFF()
  self:F2()
  self.parkingscanscenery=false
  return self
end

--- A parking spot is not free until a possible aircraft has left and taken off.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetParkingSpotSafeON()
  self:F2()
  self.parkingverysafe=true
  return self
end

--- A parking spot is free as soon as possible aircraft has left the place. This is the default.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetParkingSpotSafeOFF()
  self:F2()
  self.parkingverysafe=false
  return self
end

--- Aircraft that reach their destination zone are not despawned. They will probably go the the nearest airbase and try to land.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetDespawnAirOFF()
  self.despawnair=false
  return self
end

--- Set takeoff type. Starting cold at airport, starting hot at airport, starting at runway, starting in the air.
-- Default is "takeoff-coldorhot". So there is a 50% chance that the aircraft starts with cold engines and 50% that it starts with hot engines.
-- @param #RAT self
-- @param #string type Type can be "takeoff-cold" or "cold", "takeoff-hot" or "hot", "takeoff-runway" or "runway", "air".
-- @return #RAT RAT self object.
-- @usage RAT:Takeoff("hot") will spawn RAT objects at airports with engines started.
-- @usage RAT:Takeoff("cold") will spawn RAT objects at airports with engines off.
-- @usage RAT:Takeoff("air") will spawn RAT objects in air over random airports or within pre-defined zones.
function RAT:SetTakeoff(type)
  self:F2(type)

  local _Type
  if type:lower()=="takeoff-cold" or type:lower()=="cold" then
    _Type=RAT.wp.cold
  elseif type:lower()=="takeoff-hot" or type:lower()=="hot" then
    _Type=RAT.wp.hot
  elseif type:lower()=="takeoff-runway" or type:lower()=="runway" then
    _Type=RAT.wp.runway
  elseif type:lower()=="air" then
    _Type=RAT.wp.air
  else
    _Type=RAT.wp.coldorhot
  end

  self.takeoff=_Type

  return self
end

--- Set takeoff type cold. Aircraft will spawn at a parking spot with engines off.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetTakeoffCold()
  self.takeoff=RAT.wp.cold
  return self
end

--- Set takeoff type to hot. Aircraft will spawn at a parking spot with engines on.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetTakeoffHot()
  self.takeoff=RAT.wp.hot
  return self
end

--- Set takeoff type to runway. Aircraft will spawn directly on the runway.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetTakeoffRunway()
  self.takeoff=RAT.wp.runway
  return self
end

--- Set takeoff type to cold or hot. Aircraft will spawn at a parking spot with 50:50 change of engines on or off.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetTakeoffColdOrHot()
  self.takeoff=RAT.wp.coldorhot
  return self
end

--- Set takeoff type to air. Aircraft will spawn in the air.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:SetTakeoffAir()
  self.takeoff=RAT.wp.air
  return self
end

--- Set possible departure ports. This can be an airport or a zone.
-- @param #RAT self
-- @param #string departurenames Name or table of names of departure airports or zones.
-- @return #RAT RAT self object.
-- @usage RAT:SetDeparture("Sochi-Adler") will spawn RAT objects at Sochi-Adler airport.
-- @usage RAT:SetDeparture({"Sochi-Adler", "Gudauta"}) will spawn RAT aircraft radomly at Sochi-Adler or Gudauta airport.
-- @usage RAT:SetDeparture({"Zone A", "Gudauta"}) will spawn RAT aircraft in air randomly within Zone A, or within a zone around Gudauta airport. Note that this also requires RAT:takeoff("air") to be set.
function RAT:SetDeparture(departurenames)
  self:F2(departurenames)

  -- Random departure is deactivated now that user specified departure ports.
  self.random_departure=false

  -- Convert input to table.
  local names
  if type(departurenames)=="table" then
    names=departurenames
  elseif type(departurenames)=="string" then
    names={departurenames}
  else
    -- error message
    self:E(self.lid.."ERROR: Input parameter must be a string or a table in SetDeparture()!")
  end

  -- Put names into arrays.
  for _,name in pairs(names) do

    if self:_AirportExists(name) then
      -- If an airport with this name exists, we put it in the ports array.
      table.insert(self.departure_ports, name)
    elseif self:_ZoneExists(name) then
      -- If it is not an airport, we assume it is a zone.
      table.insert(self.departure_ports, name)
     else
      self:E(self.lid.."ERROR: No departure airport or zone found with name "..name)
    end

  end

  return self
end

--- Set name of destination airports or zones for the AI aircraft.
-- @param #RAT self
-- @param #string destinationnames Name of the destination airport or #table of destination airports.
-- @return #RAT RAT self object.
-- @usage RAT:SetDestination("Krymsk") makes all aircraft of this RAT object fly to Krymsk airport.
function RAT:SetDestination(destinationnames)
  self:F2(destinationnames)

  -- Random departure is deactivated now that user specified departure ports.
  self.random_destination=false

  -- Convert input to table
  local names
  if type(destinationnames)=="table" then
    names=destinationnames
  elseif type(destinationnames)=="string" then
    names={destinationnames}
  else
    -- Error message.
    self:E(self.lid.."ERROR: Input parameter must be a string or a table in SetDestination()!")
  end

  -- Put names into arrays.
  for _,name in pairs(names) do

    if self:_AirportExists(name) then
      -- If an airport with this name exists, we put it in the ports array.
      table.insert(self.destination_ports, name)
    elseif self:_ZoneExists(name) then
      -- If it is not an airport, we assume it is a zone.
      table.insert(self.destination_ports, name)
    else
      self:E(self.lid.."ERROR: No destination airport or zone found with name "..name)
    end

  end

  return self
end

--- Destinations are treated as zones. Aircraft will not land but rather be despawned when they reach a random point in the zone.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:DestinationZone()
  self:F2()

  -- Destination is a zone. Needs special care.
  self.destinationzone=true

  -- Landing type is "air" because we don't actually land at the airport.
  self.landing=RAT.wp.air

  return self
end

--- Aircraft will fly to a random point within a zone and then return to its departure airport or zone.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:ReturnZone()
  self:F2()
  -- Destination is a zone. Needs special care.
  self.returnzone=true
  return self
end


--- Include all airports which lie in a zone as possible destinations.
-- @param #RAT self
-- @param Core.Zone#ZONE zone Zone in which the destination airports lie. Has to be a MOOSE zone.
-- @return #RAT RAT self object.
function RAT:SetDestinationsFromZone(zone)
  self:F2(zone)

  -- Random departure is deactivated now that user specified departure ports.
  self.random_destination=false

  -- Set zone.
  self.destination_Azone=zone

  return self
end

--- Include all airports which lie in a zone as possible destinations.
-- @param #RAT self
-- @param Core.Zone#ZONE zone Zone in which the departure airports lie. Has to be a MOOSE zone.
-- @return #RAT RAT self object.
function RAT:SetDeparturesFromZone(zone)
  self:F2(zone)

  -- Random departure is deactivated now that user specified departure ports.
  self.random_departure=false

  -- Set zone.
  self.departure_Azone=zone

  return self
end

--- Add all friendly airports to the list of possible departures.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:AddFriendlyAirportsToDepartures()
  self:F2()
  self.addfriendlydepartures=true
  return self
end

--- Add all friendly airports to the list of possible destinations
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:AddFriendlyAirportsToDestinations()
  self:F2()
  self.addfriendlydestinations=true
  return self
end

--- Airports, FARPs and ships explicitly excluded as departures and destinations.
-- @param #RAT self
-- @param #string ports Name or table of names of excluded airports.
-- @return #RAT RAT self object.
function RAT:ExcludedAirports(ports)
  self:F2(ports)
  if type(ports)=="string" then
    self.excluded_ports={ports}
  else
    self.excluded_ports=ports
  end
  return self
end

--- Set skill of AI aircraft. Default is "High".
-- @param #RAT self
-- @param #string skill Skill, options are "Average", "Good", "High", "Excellent" and "Random". Parameter is case insensitive.
-- @return #RAT RAT self object.
function RAT:SetAISkill(skill)
  self:F2(skill)
  if skill:lower()=="average" then
    self.skill="Average"
  elseif skill:lower()=="good" then
    self.skill="Good"
  elseif skill:lower()=="excellent" then
    self.skill="Excellent"
  elseif skill:lower()=="random" then
    self.skill="Random"
  else
    self.skill="High"
  end
  return self
end

--- Set livery of aircraft. If more than one livery is specified in a table, the actually used one is chosen randomly from the selection.
-- @param #RAT self
-- @param #table skins Name of livery or table of names of liveries.
-- @return #RAT RAT self object.
function RAT:Livery(skins)
  self:F2(skins)
  if type(skins)=="string" then
    self.livery={skins}
  else
    self.livery=skins
  end
  return self
end

--- Change aircraft type. This is a dirty hack which allows to change the aircraft type of the template group.
-- Note that all parameters like cruise speed, climb rate, range etc are still taken from the template group which likely leads to strange behaviour.
-- @param #RAT self
-- @param #string actype Type of aircraft which is spawned independent of the template group. Use with care and expect problems!
-- @return #RAT RAT self object.
function RAT:ChangeAircraft(actype)
  self:F2(actype)
  self.actype=actype
  return self
end

--- Aircraft will continue their journey from their destination. This means they are respawned at their destination and get a new random destination.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:ContinueJourney()
  self:F2()
  self.continuejourney=true
  self.commute=false
  return self
end

--- Aircraft will commute between their departure and destination airports or zones.
-- @param #RAT self
-- @param #boolean starshape If true, keep homebase, i.e. travel A-->B-->A-->C-->A-->D... instead of A-->B-->A-->B-->A...
-- @return #RAT RAT self object.
function RAT:Commute(starshape)
  self:F2()
  self.commute=true
  self.continuejourney=false
  if starshape then
    self.starshape=starshape
  else
    self.starshape=false
  end
  return self
end

--- Set the delay before first group is spawned.
-- @param #RAT self
-- @param #number delay Delay in seconds. Default is 5 seconds. Minimum delay is 0.5 seconds.
-- @return #RAT RAT self object.
function RAT:SetSpawnDelay(delay)
  self:F2(delay)
  delay=delay or 5
  self.spawndelay=math.max(0.5, delay)
  return self
end

--- Set the interval between spawnings of the template group.
-- @param #RAT self
-- @param #number interval Interval in seconds. Default is 5 seconds. Minimum is 0.5 seconds.
-- @return #RAT RAT self object.
function RAT:SetSpawnInterval(interval)
  self:F2(interval)
  interval=interval or 5
  self.spawninterval=math.max(0.5, interval)
  return self
end

--- Set max number of groups that will be spawned. When this limit is reached, no more RAT groups are spawned.
-- @param #RAT self
-- @param #number Nmax Max number of groups. Default `nil`=unlimited.
-- @return #RAT RAT self object.
function RAT:SetSpawnLimit(Nmax)
  self.NspawnMax=Nmax
  return self
end

--- Make aircraft respawn the moment they land rather than at engine shut down.
-- @param #RAT self
-- @param #number delay (Optional) Delay in seconds until respawn happens after landing. Default is 1 second. Minimum is 1 second.
-- @return #RAT RAT self object.
function RAT:RespawnAfterLanding(delay)
  self:F2(delay)
  self.respawn_at_landing=true
  self:SetRespawnDelay(delay)
  return self
end

--- Sets the delay between despawning and respawning aircraft.
-- @param #RAT self
-- @param #number delay Delay in seconds until respawn happens. Default is 1 second. Minimum is 1 second.
-- @return #RAT RAT self object.
function RAT:SetRespawnDelay(delay)
  self:F2(delay)
  delay = delay or 1.0
  delay=math.max(1.0, delay)
  self.respawn_delay=delay
  return self
end

--- Aircraft will not get respawned when they finished their route.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:NoRespawn()
  self:F2()
  self.norespawn=true
  return self
end

--- Number of tries to respawn an aircraft in case it has accidentally been spawned on runway.
-- @param #RAT self
-- @param #number n Number of retries. Default is 3.
-- @return #RAT RAT self object.
function RAT:SetMaxRespawnTriedWhenSpawnedOnRunway(n)
  self:F2(n)
  n=n or 3
  self.onrunwaymaxretry=n
  return self
end

--- A new aircraft is spawned directly after the last one took off. This creates a lot of outbound traffic. Aircraft are not respawned after they reached their destination.
-- Therefore, this option is not to be used with the "commute" or "continue journey" options.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RespawnAfterTakeoff()
  self:F2()
  self.respawn_after_takeoff=true
  return self
end

--- Aircraft will be respawned after they crashed or get shot down. This is the default behavior.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RespawnAfterCrashON()
  self:F2()
  self.respawn_after_crash=true
  return self
end

--- Aircraft will not be respawned after they crashed or get shot down.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RespawnAfterCrashOFF()
  self:F2()
  self.respawn_after_crash=false
  return self
end

--- If aircraft cannot be spawned on parking spots, it is allowed to spawn them in air above the same airport. Note that this is also the default behavior.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RespawnInAirAllowed()
  self:F2()
  self.respawn_inair=true
  return self
end

--- If aircraft cannot be spawned on parking spots, it is NOT allowed to spawn them in air. This has only impact if aircraft are supposed to be spawned on the ground (and not in a zone).
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RespawnInAirNotAllowed()
  self:F2()
  self.respawn_inair=false
  return self
end

--- Check if aircraft have accidentally been spawned on the runway. If so they will be removed immediately.
-- @param #RAT self
-- @param #boolean switch If true, check is performed. If false, this check is omitted.
-- @param #number radius Distance in meters until a unit is considered to have spawned accidentally on the runway. Default is 75 m.
-- @return #RAT RAT self object.
function RAT:CheckOnRunway(switch, distance)
  self:F2(switch)
  if switch==nil then
    switch=true
  end
  self.checkonrunway=switch
  self.onrunwayradius=distance or 75
  return self
end

--- Check if aircraft have accidentally been spawned on top of each other. If yes, they will be removed immediately.
-- @param #RAT self
-- @param #boolean switch If true, check is performed. If false, this check is omitted.
-- @param #number radius Radius in meters until which a unit is considered to be on top of each other. Default is 2 m.
-- @return #RAT RAT self object.
function RAT:CheckOnTop(switch, radius)
  self:F2(switch)
  if switch==nil then
    switch=true
  end
  self.checkontop=switch
  self.ontopradius=radius or 2
  return self
end

--- Enable Radio. Overrules the ME setting.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RadioON()
  self:F2()
  self.radio=true
  return self
end

--- Disable Radio. Overrules the ME setting.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RadioOFF()
  self:F2()
  self.radio=false
  return self
end

--- Set radio frequency.
-- @param #RAT self
-- @param #number frequency Radio frequency.
-- @return #RAT RAT self object.
function RAT:RadioFrequency(frequency)
  self:F2(frequency)
  self.frequency=frequency
  return self
end

--- Set radio modulation. Default is AM.
-- @param #RAT self
-- @param #string modulation Either "FM" or "AM". If no value is given, modulation is set to AM.
-- @return #RAT RAT self object.
function RAT:RadioModulation(modulation)
  self:F2(modulation)
  if modulation=="AM" then
    self.modulation=radio.modulation.AM
  elseif modulation=="FM" then
    self.modulation=radio.modulation.FM
  else
    self.modulation=radio.modulation.AM
  end
  return self
end

--- Radio menu On. Default is off.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RadioMenuON()
  self:F2()
  self.f10menu=true
  return self
end

--- Radio menu Off. This is the default setting.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:RadioMenuOFF()
  self:F2()
  self.f10menu=false
  return self
end

--- Aircraft are invisible.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:Invisible()
  self:F2()
  self.invisible=true
  return self
end

--- Turn EPLRS datalink on/off.
-- @param #RAT self
-- @param #boolean switch If true (or nil), turn EPLRS on.
-- @return #RAT RAT self object.
function RAT:SetEPLRS(switch)
  if switch==nil or switch==true then
    self.eplrs=true
  else
    self.eplrs=false
  end
  return self
end

--- Aircraft are immortal.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:Immortal()
  self:F2()
  self.immortal=true
  return self
end

--- Spawn aircraft in uncontrolled state. Aircraft will only sit at their parking spots. They can be activated randomly by the RAT:ActivateUncontrolled() function.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:Uncontrolled()
  self:F2()
  self.uncontrolled=true
  return self
end

--- Define how aircraft that are spawned in uncontrolled state are activate.
-- @param #RAT self
-- @param #number maxactivated Maximal numnber of activated aircraft. Absolute maximum will be the number of spawned groups. Default is 1.
-- @param #number delay Time delay in seconds before (first) aircraft is activated. Default is 1 second.
-- @param #number delta Time difference in seconds before next aircraft is activated. Default is 1 second.
-- @param #number frand Factor [0,...,1] for randomization of time difference between aircraft activations. Default is 0, i.e. no randomization.
-- @return #RAT RAT self object.
function RAT:ActivateUncontrolled(maxactivated, delay, delta, frand)
  self:F2({max=maxactivated, delay=delay, delta=delta, rand=frand})

  self.activate_uncontrolled=true
  self.activate_max=maxactivated or 1
  self.activate_delay=delay or 1
  self.activate_delta=delta or 1
  self.activate_frand=frand or 0

  -- Ensure min delay is one second.
  self.activate_delay=math.max(self.activate_delay,1)

  -- Ensure min delta is one second.
  self.activate_delta=math.max(self.activate_delta,0)

  -- Ensure frand is in [0,...,1]
  self.activate_frand=math.max(self.activate_frand,0)
  self.activate_frand=math.min(self.activate_frand,1)

  return self
end

--- Set the time after which inactive groups will be destroyed.
-- @param #RAT self
-- @param #number time Time in seconds. Default is 600 seconds = 10 minutes. Minimum is 60 seconds.
-- @return #RAT RAT self object.
function RAT:TimeDestroyInactive(time)
  self:F2(time)
  time=time or self.Tinactive
  time=math.max(time, 60)
  self.Tinactive=time
  return self
end

--- Set the maximum cruise speed of the aircraft.
-- @param #RAT self
-- @param #number speed Speed in km/h.
-- @return #RAT RAT self object.
function RAT:SetMaxCruiseSpeed(speed)
  self:F2(speed)
  -- Convert to m/s.
  self.Vcruisemax=speed/3.6
  return self
end

--- Set the climb rate. This automatically sets the climb angle.
-- @param #RAT self
-- @param #number rate Climb rate in ft/min. Default is 1500 ft/min. Minimum is 100 ft/min. Maximum is 15,000 ft/min.
-- @return #RAT RAT self object.
function RAT:SetClimbRate(rate)
  self:F2(rate)
  rate=rate or self.Vclimb
  rate=math.max(rate, 100)
  rate=math.min(rate, 15000)
  self.Vclimb=rate
  return self
end

--- Set the angle of descent. Default is 3.6 degrees, which corresponds to 3000 ft descent after one mile of travel.
-- @param #RAT self
-- @param #number angle Angle of descent in degrees. Minimum is 0.5 deg. Maximum 50 deg.
-- @return #RAT RAT self object.
function RAT:SetDescentAngle(angle)
  self:F2(angle)
  angle=angle or self.AlphaDescent
  angle=math.max(angle, 0.5)
  angle=math.min(angle, 50)
  self.AlphaDescent=angle
  return self
end

--- Set rules of engagement (ROE). Default is weapon hold. This is a peaceful class.
-- @param #RAT self
-- @param #string roe "hold" = weapon hold, "return" = return fire, "free" = weapons free.
-- @return #RAT RAT self object.
function RAT:SetROE(roe)
  self:F2(roe)
  if roe=="return" then
    self.roe=RAT.ROE.returnfire
  elseif roe=="free" then
    self.roe=RAT.ROE.weaponfree
  else
    self.roe=RAT.ROE.weaponhold
  end
  return self
end

--- Set reaction to threat (ROT). Default is no reaction, i.e. aircraft will simply ignore all enemies.
-- @param #RAT self
-- @param #string rot "noreaction" = no reaction to threats, "passive" = passive defence, "evade" = evade enemy attacks.
-- @return #RAT RAT self object.
function RAT:SetROT(rot)
  self:F2(rot)
  if rot=="passive" then
    self.rot=RAT.ROT.passive
  elseif rot=="evade" then
    self.rot=RAT.ROT.evade
  else
    self.rot=RAT.ROT.noreaction
  end
  return self
end

--- Set the name of the F10 submenu. Default is the name of the template group.
-- @param #RAT self
-- @param #string name Submenu name.
-- @return #RAT RAT self object.
function RAT:MenuName(name)
  self:F2(name)
  self.SubMenuName=tostring(name)
  return self
end

--- Enable ATC, which manages the landing queue for RAT aircraft if they arrive simultaniously at the same airport.
-- @param #RAT self
-- @param #boolean switch Enable ATC (true) or Disable ATC (false). No argument means ATC enabled.
-- @return #RAT RAT self object.
function RAT:EnableATC(switch)
  self:F2(switch)
  if switch==nil then
    switch=true
  end
  self.ATCswitch=switch
  return self
end

--- Turn messages from ATC on or off. Default is on. This setting effects all RAT objects and groups!
-- @param #RAT self
-- @param #boolean switch Enable (true) or disable (false) messages from ATC.
-- @return #RAT RAT self object.
function RAT:ATC_Messages(switch)
  self:F2(switch)
  if switch==nil then
    switch=true
  end
  RAT.ATC.messages=switch
  return self
end

--- Max number of planes that get landing clearance of the RAT ATC. This setting effects all RAT objects and groups!
-- @param #RAT self
-- @param #number n Number of aircraft that are allowed to land simultaniously. Default is 2.
-- @return #RAT RAT self object.
function RAT:ATC_Clearance(n)
  self:F2(n)
  RAT.ATC.Nclearance=n or 2
  return self
end

--- Delay between granting landing clearance for simultanious landings. This setting effects all RAT objects and groups!
-- @param #RAT self
-- @param #number time Delay time when the next aircraft will get landing clearance event if the previous one did not land yet. Default is 240 sec.
-- @return #RAT RAT self object.
function RAT:ATC_Delay(time)
  self:F2(time)
  RAT.ATC.delay=time or 240
  return self
end

--- Set minimum distance between departure and destination. Default is 5 km.
-- Minimum distance should not be smaller than maybe ~100 meters to ensure that departure and destination are different.
-- @param #RAT self
-- @param #number dist Distance in km.
-- @return #RAT RAT self object.
function RAT:SetMinDistance(dist)
  self:F2(dist)
  -- Distance in meters. Absolute minimum is 500 m.
  self.mindist=math.max(100, dist*1000)
  return self
end

--- Set maximum distance between departure and destination. Default is 5000 km but aircarft range is also taken into account automatically.
-- @param #RAT self
-- @param #number dist Distance in km.
-- @return #RAT RAT self object.
function RAT:SetMaxDistance(dist)
  self:F2(dist)
  -- Distance in meters.
  self.maxdist=dist*1000
  return self
end

--- Turn debug messages on or off. Default is off.
-- @param #RAT self
-- @param #boolean switch Turn debug on=true or off=false. No argument means on.
-- @return #RAT RAT self object.
function RAT:_Debug(switch)
  self:F2(switch)
  if switch==nil then
    switch=true
  end
  self.Debug=switch
  return self
end

--- Enable debug mode. More output in dcs.log file and onscreen messages to all.
-- @param #RAT self
-- @return #RAT RAT self object.
function RAT:Debugmode()
  self:F2()
  self.Debug=true
  return self
end

--- Aircraft report status update messages along the route.
-- @param #RAT self
-- @param #boolean switch Swtich reports on (true) or off (false). No argument is on.
-- @return #RAT RAT self object.
function RAT:StatusReports(switch)
  self:F2(switch)
  if switch==nil then
    switch=true
  end
  self.reportstatus=switch
  return self
end

--- Place markers of waypoints on the F10 map. Default is off.
-- @param #RAT self
-- @param #boolean switch true=yes, false=no.
-- @return #RAT RAT self object.
function RAT:PlaceMarkers(switch)
  self:F2(switch)
  if switch==nil then
    switch=true
  end
  self.placemarkers=switch
  return self
end

--- Set flight level. Setting this value will overrule all other logic. Aircraft will try to fly at this height regardless.
-- @param #RAT self
-- @param #number FL Fight Level in hundrets of feet. E.g. FL200 = 20000 ft ASL.
-- @return #RAT RAT self object.
function RAT:SetFL(FL)
  self:F2(FL)
  FL=FL or self.FLcruise
  FL=math.max(FL,0)
  self.FLuser=FL*RAT.unit.FL2m
  return self
end

--- Set max flight level. Setting this value will overrule all other logic. Aircraft will try to fly at less than this FL regardless.
-- @param #RAT self
-- @param #number FL Maximum Fight Level in hundrets of feet.
-- @return #RAT RAT self object.
function RAT:SetFLmax(FL)
  self:F2(FL)
  self.FLmaxuser=FL*RAT.unit.FL2m
  return self
end

--- Set max cruising altitude above sea level.
-- @param #RAT self
-- @param #number alt Altitude ASL in meters.
-- @return #RAT RAT self object.
function RAT:SetMaxCruiseAltitude(alt)
  self:F2(alt)
  self.FLmaxuser=alt
  return self
end

--- Set min flight level. Setting this value will overrule all other logic. Aircraft will try to fly at higher than this FL regardless.
-- @param #RAT self
-- @param #number FL Maximum Fight Level in hundrets of feet.
-- @return #RAT RAT self object.
function RAT:SetFLmin(FL)
  self:F2(FL)
  self.FLminuser=FL*RAT.unit.FL2m
  return self
end

--- Set min cruising altitude above sea level.
-- @param #RAT self
-- @param #number alt Altitude ASL in meters.
-- @return #RAT RAT self object.
function RAT:SetMinCruiseAltitude(alt)
  self:F2(alt)
  self.FLminuser=alt
  return self
end

--- Set flight level of cruising part. This is still be checked for consitancy with selected route and prone to radomization.
-- Default is FL200 for planes and FL005 for helicopters.
-- @param #RAT self
-- @param #number FL Flight level in hundrets of feet. E.g. FL200 = 20000 ft ASL.
-- @return #RAT RAT self object.
function RAT:SetFLcruise(FL)
  self:F2(FL)
  self.FLcruise=FL*RAT.unit.FL2m
  return self
end

--- Set cruising altitude. This is still be checked for consitancy with selected route and prone to radomization.
-- @param #RAT self
-- @param #number alt Cruising altitude ASL in meters.
-- @return #RAT RAT self object.
function RAT:SetCruiseAltitude(alt)
  self:F2(alt)
  self.FLcruise=alt
  return self
end

--- Set onboard number prefix. Same as setting "TAIL #" in the mission editor. Note that if you dont use this function, the values defined in the template group of the ME are taken.
-- @param #RAT self
-- @param #string tailnumprefix String of the tail number prefix. If flight consists of more than one aircraft, two digits are appended automatically, i.e. <tailnumprefix>001, <tailnumprefix>002, ...
-- @param #number zero (Optional) Starting value of the automatically appended numbering of aircraft within a flight. Default is 0.
-- @return #RAT RAT self object.
function RAT:SetOnboardNum(tailnumprefix, zero)
  self:F2({tailnumprefix=tailnumprefix, zero=zero})
  self.onboardnum=tailnumprefix
  if zero ~= nil then
    self.onboardnum0=zero
  end
  return self
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-- Private functions
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Initialize basic parameters of the aircraft based on its (template) group in the mission editor.
-- @param #RAT self
-- @param DCS#Group DCSgroup Group of the aircraft in the mission editor.
function RAT:_InitAircraft(DCSgroup)
  self:F2(DCSgroup)

  local DCSunit=DCSgroup:getUnit(1)
  local DCSdesc=DCSunit:getDesc()
  local DCScategory=DCSgroup:getCategory()
  local DCStype=DCSunit:getTypeName()

  -- set category
  if DCScategory==Group.Category.AIRPLANE then
    self.category=RAT.cat.plane
  elseif DCScategory==Group.Category.HELICOPTER then
    self.category=RAT.cat.heli
  else
    self.category="other"
    self:E(self.lid.."ERROR: Group of RAT is neither airplane nor helicopter!")
  end

  -- Get type of aircraft.
  self.aircraft.type=DCStype

  -- inital fuel in %
  self.aircraft.fuel=DCSunit:getFuel()

  -- operational range in NM converted to m
  self.aircraft.Rmax = DCSdesc.range*RAT.unit.nm2m

  -- effective range taking fuel into accound and a 5% reserve
  self.aircraft.Reff = self.aircraft.Rmax*self.aircraft.fuel*0.95

  -- max airspeed from group
  self.aircraft.Vmax = DCSdesc.speedMax

  -- max climb speed in m/s
  self.aircraft.Vymax=DCSdesc.VyMax

  -- service ceiling in meters
  self.aircraft.ceiling=DCSdesc.Hmax

  -- Store all descriptors.
  --self.aircraft.descriptors=DCSdesc

  -- aircraft dimensions
  if DCSdesc.box then
    self.aircraft.length=DCSdesc.box.max.x
    self.aircraft.height=DCSdesc.box.max.y
    self.aircraft.width=DCSdesc.box.max.z
  elseif DCStype == "Mirage-F1CE" then
    self.aircraft.length=16
    self.aircraft.height=5
    self.aircraft.width=9
  elseif DCStype == "Saab340" then      --   <- These lines added
    self.aircraft.length=19.73          --   <- These lines added
    self.aircraft.height=6.97           --   <- These lines added
    self.aircraft.width=21.44           --   <- These lines added
  end

  self.aircraft.box=math.max(self.aircraft.length,self.aircraft.width)

  -- info message
  local text=string.format("\n******************************************************\n")
  text=text..string.format("Aircraft parameters:\n")
  text=text..string.format("Template group  =  %s\n",       self.SpawnTemplatePrefix)
  text=text..string.format("Alias           =  %s\n",       self.alias)
  text=text..string.format("Category        =  %s\n",       self.category)
  text=text..string.format("Type            =  %s\n",       self.aircraft.type)
  text=text..string.format("Length (x)      = %6.1f m\n",   self.aircraft.length)
  text=text..string.format("Width  (z)      = %6.1f m\n",   self.aircraft.width)
  text=text..string.format("Height (y)      = %6.1f m\n",   self.aircraft.height)
  text=text..string.format("Max air speed   = %6.1f m/s\n", self.aircraft.Vmax)
  text=text..string.format("Max climb speed = %6.1f m/s\n", self.aircraft.Vymax)
  text=text..string.format("Initial Fuel    = %6.1f\n",     self.aircraft.fuel*100)
  text=text..string.format("Max range       = %6.1f km\n",  self.aircraft.Rmax/1000)
  text=text..string.format("Eff range       = %6.1f km (with 95 percent initial fuel amount)\n",  self.aircraft.Reff/1000)
  text=text..string.format("Ceiling         = %6.1f km = FL%3.0f\n", self.aircraft.ceiling/1000, self.aircraft.ceiling/RAT.unit.FL2m)
  text=text..string.format("******************************************************\n")
  self:T(self.lid..text)

end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Spawn the AI aircraft with a route.
-- Sets the departure and destination airports and waypoints.
-- Modifies the spawn template.
-- Sets ROE/ROT.
-- Initializes the ratcraft array and group menu.
-- @param #RAT self
-- @param #string _departure (Optional) Name of departure airbase.
-- @param #string _destination (Optional) Name of destination airbase.
-- @param #number _takeoff Takeoff type id.
-- @param #number _landing Landing type id.
-- @param #string _livery Livery to use for this group.
-- @param #table _waypoint First waypoint to be used (for continue journey, commute, etc).
-- @param Core.Point#COORDINATE _lastpos (Optional) Position where the aircraft will be spawned.
-- @param #number _nrespawn Number of already performed respawn attempts (e.g. spawning on runway bug).
-- @param #table parkingdata Explicitly specify the parking spots when spawning at an airport.
-- @return #number Spawn index.
function RAT:_SpawnWithRoute(_departure, _destination, _takeoff, _landing, _livery, _waypoint, _lastpos, _nrespawn, parkingdata)
  self:F({rat=self.lid, departure=_departure, destination=_destination, takeoff=_takeoff, landing=_landing, livery=_livery, waypoint=_waypoint, lastpos=_lastpos, nrespawn=_nrespawn})
  
  -- Check if max spawn limit exists and is reached. SpawnIndex counting starts at 0, hence greater equal and not greater.
  if self.NspawnMax and self.SpawnIndex>=self.NspawnMax then
    self:T(self.lid..string.format("Max limit of spawns reached %d >= %d! Will not spawn any more groups", self.NspawnMax, self.SpawnIndex))
    return
  else
    self:T2(self.lid..string.format("Spawning with spawn index=%d", self.SpawnIndex))
  end

  -- Set takeoff type.
  local takeoff=self.takeoff
  local landing=self.landing

  -- Overrule takeoff/landing by what comes in.
  if _takeoff then
    takeoff=_takeoff
  end
  if _landing then
    landing=_landing
  end

  -- Random choice between cold and hot.
  if takeoff==RAT.wp.coldorhot then
    local temp={RAT.wp.cold, RAT.wp.hot}
    takeoff=temp[math.random(2)]
  end

  -- Number of respawn attempts after spawning on runway.
  local nrespawn=0
  if _nrespawn then
    nrespawn=_nrespawn
  end

  -- Set flight plan.
  local departure, destination, waypoints, wpdesc, wpstatus = self:_SetRoute(takeoff, landing, _departure, _destination, _waypoint)

  -- Return nil if we could not find a departure destination or waypoints
  if not (departure and destination and waypoints) then
    return nil
  end

  -- Set (another) livery.
  local livery
  if _livery then
    -- Take livery from previous flight (continue journey).
    livery=_livery
  elseif self.livery then
    -- Choose random livery.
    livery=self.livery[math.random(#self.livery)]
    local text=string.format("Chosen livery for group %s: %s", self:_AnticipatedGroupName(), livery)
    self:T(self.lid..text)
  else
    livery=nil
  end
  
  -- We set the aircraft to uncontrolled if the departure airbase has a FLIGHTCONTROL.
  local uncontrolled=self.uncontrolled
  local isFlightcontrol=self:_IsFlightControlAirbase(departure)
  if takeoff~=RAT.wp.air and departure and isFlightcontrol then
    takeoff=RAT.wp.cold
    uncontrolled=true
  end 

  -- Modify the spawn template to follow the flight plan.
  local successful=self:_ModifySpawnTemplate(waypoints, livery, _lastpos, departure, takeoff, parkingdata, uncontrolled)
  if not successful then
    return nil
  end

  -- Actually spawn the group.
  local group=self:SpawnWithIndex(self.SpawnIndex) -- Wrapper.Group#GROUP
  
  -- Group name.
  local groupname=group:GetName()
  
  -- Create a flightgroup object.
  local flightgroup=FLIGHTGROUP:New(group)
  
  -- Setting holding time to nil so that flight never gets landing clearance. This is done by the RAT ATC (FC sets holdtime to nil in FLIGHTGROUP).
  if self.ATCswitch then
    flightgroup.holdtime=nil
  end
  
  -- No automatic despawning if group gets stuck.
  flightgroup.stuckDespawn=false
  
  
  -- Increase counter of alive groups (also uncontrolled ones).
  self.alive=self.alive+1
  self:T(self.lid..string.format("Alive groups counter now = %d.",self.alive))

  -- ATC is monitoring this flight (if it is supposed to land).
  if self.ATCswitch and landing==RAT.wp.landing then
  
    -- Get destination airbase name. For returnzone, this is the departure airbase.
    local airbasename=destination:GetName()
    if self.returnzone then
      airbasename=departure:GetName()
    end
    
    -- Add flight (if there is no FC at the airbase)
    if not self:_IsFlightControlAirbase(airbasename) then
      self:_ATCAddFlight(groupname, airbasename)
    end
  end

  -- Place markers of waypoints on F10 map.
  if self.placemarkers then
    self:_PlaceMarkers(waypoints, wpdesc, self.SpawnIndex)
  end
  
  -- Set group ready for takeoff at the FLIGHTCONTROL (if we do not do via a scheduler).
  if isFlightcontrol and not self.activate_uncontrolled then
    local N=math.random(120)
    self:T(self.lid..string.format("Flight will be ready for takeoff in %d seconds", N))
    flightgroup:SetReadyForTakeoff(true, N)
  end

  -- Set group to be invisible.
  if self.invisible then
    flightgroup:SetDefaultInvisible(true)
    flightgroup:SwitchInvisible(true)
  end

  -- Set group to be immortal.
  if self.immortal then
    flightgroup:SetDefaultImmortal(true)
    flightgroup:SwitchImmortal(true)
  end

  -- Set group to be immortal.
  if self.eplrs then
    flightgroup:SetDefaultEPLRS(true)
    flightgroup:SwitchEPLRS(true)
  end

  -- Set ROE, default is "weapon hold".
  self:_SetROE(flightgroup, self.roe)

  -- Set ROT, default is "no reaction".
  self:_SetROT(flightgroup, self.rot)
  
  -- Init ratcraft array.
  local ratcraft={} --#RAT.RatCraft
  ratcraft.index=self.SpawnIndex
  ratcraft.group=group
  ratcraft.flightgroup=flightgroup
  ratcraft.destination=destination
  ratcraft.departure=departure
  ratcraft.waypoints=waypoints
  ratcraft.airborne=group:InAir()
  ratcraft.nunits=group:GetInitialSize()
  
  -- Initial and current position. For calculating the travelled distance.
  ratcraft.Pnow=group:GetCoordinate()
  ratcraft.Distance=0

  -- Each aircraft gets its own takeoff type.
  ratcraft.takeoff=takeoff
  ratcraft.landing=landing
  ratcraft.wpdesc=wpdesc
  ratcraft.wpstatus=wpstatus

  -- Aircraft is active or spawned in uncontrolled state.
  ratcraft.active=not uncontrolled

  -- Set status to spawned. This will be overwritten in birth event.
  ratcraft.status=RAT.status.Spawned

  -- Livery
  ratcraft.livery=livery

  -- If this switch is set to true, the aircraft will be despawned the next time the status function is called.
  ratcraft.despawnme=false

  -- Number of preformed spawn attempts for this group.
  ratcraft.nrespawn=nrespawn
  
  -- Add ratcaft to table.
  self.ratcraft[self.SpawnIndex]=ratcraft

  -- Create submenu for this group.
  if self.f10menu then
    local name=self.aircraft.type.." ID "..tostring(self.SpawnIndex)
    -- F10/RAT/<templatename>/Group X
    self.Menu[self.SubMenuName].groups[self.SpawnIndex]=MENU_MISSION:New(name, self.Menu[self.SubMenuName].groups)
    -- F10/RAT/<templatename>/Group X/Set ROE
    self.Menu[self.SubMenuName].groups[self.SpawnIndex]["roe"]=MENU_MISSION:New("Set ROE", self.Menu[self.SubMenuName].groups[self.SpawnIndex])
    MENU_MISSION_COMMAND:New("Weapons hold", self.Menu[self.SubMenuName].groups[self.SpawnIndex]["roe"], self._SetROE, self, flightgroup, RAT.ROE.weaponhold)
    MENU_MISSION_COMMAND:New("Weapons free", self.Menu[self.SubMenuName].groups[self.SpawnIndex]["roe"], self._SetROE, self, flightgroup, RAT.ROE.weaponfree)
    MENU_MISSION_COMMAND:New("Return fire",  self.Menu[self.SubMenuName].groups[self.SpawnIndex]["roe"], self._SetROE, self, flightgroup, RAT.ROE.returnfire)
    -- F10/RAT/<templatename>/Group X/Set ROT
    self.Menu[self.SubMenuName].groups[self.SpawnIndex]["rot"]=MENU_MISSION:New("Set ROT", self.Menu[self.SubMenuName].groups[self.SpawnIndex])
    MENU_MISSION_COMMAND:New("No reaction",     self.Menu[self.SubMenuName].groups[self.SpawnIndex]["rot"], self._SetROT, self, flightgroup, RAT.ROT.noreaction)
    MENU_MISSION_COMMAND:New("Passive defense", self.Menu[self.SubMenuName].groups[self.SpawnIndex]["rot"], self._SetROT, self, flightgroup, RAT.ROT.passive)
    MENU_MISSION_COMMAND:New("Evade on fire",   self.Menu[self.SubMenuName].groups[self.SpawnIndex]["rot"], self._SetROT, self, flightgroup, RAT.ROT.evade)
    -- F10/RAT/<templatename>/Group X/
    MENU_MISSION_COMMAND:New("Despawn group",  self.Menu[self.SubMenuName].groups[self.SpawnIndex], self._Despawn, self, group)
    MENU_MISSION_COMMAND:New("Place markers",  self.Menu[self.SubMenuName].groups[self.SpawnIndex], self._PlaceMarkers, self, waypoints, self.SpawnIndex)
    MENU_MISSION_COMMAND:New("Status report",  self.Menu[self.SubMenuName].groups[self.SpawnIndex], self.Status, self, true, self.SpawnIndex)
  end

  --- Function called when passing a waypoint.
  function flightgroup.OnAfterPassingWaypoint(Flightgroup, From, Event, To, Waypoint)
    local waypoint=Waypoint --Ops.OpsGroup#OPSGROUP.Waypoint
    local flightgroup=Flightgroup --Ops.FlightGroup#FLIGHTGROUP
    
    local wpid=waypoint.uid
    
    local ratcraft=self:_GetRatcraftFromGroup(flightgroup.group)
    
    local wpdescription=tostring(ratcraft.wpdesc[wpid])
    local wpstatus=ratcraft.wpstatus[wpid]
    
    -- Debug info.
    self:T(self.lid..string.format("RAT passed waypoint %s [uid=%d]: %s [status=%s]", waypoint.name, wpid, wpdescription, wpstatus))

    -- Set status    
    self:_SetStatus(group, wpstatus)
    
    if waypoint.uid==3 then
      --flightgroup:SelfDestruction(Delay,ExplosionPower,ElementName)    
    end
  
  end
  
  --- Function called when passing the FINAL waypoint
  function flightgroup.OnAfterPassedFinalWaypoint(flightgroup, From, Event, To)
  
    self:T(self.lid..string.format("RAT passed FINAL waypoint"))
    
    local ratcraft=self:_GetRatcraftFromGroup(flightgroup.group)
    
    -- Info message.
    local text=string.format("Flight %s arrived at final destination %s.", group:GetName(), destination:GetName())
    MESSAGE:New(text, 10):ToAllIf(self.reportstatus)
    self:T(self.lid..text)

    if landing==RAT.wp.air then
      -- Final waypoint is air ==> Despawn flight
    
      -- Info message.
      local text=string.format("Activating despawn switch for flight %s! Group will be detroyed soon.", group:GetName())
      MESSAGE:New(text, 10):ToAllIf(self.Debug)
      self:T(self.lid..text)
      
      -- Enable despawn switch. Next time the status function is called, the aircraft will be despawned.
      ratcraft.despawnme=true
    end    
    
  end
  
  --- Function called when flight is RTB.
  function flightgroup.OnAfterRTB(flightgroup, From, Event, To, airbase, SpeedTo, SpeedHold, SpeedLand)
    self:T(self.lid..string.format("RAT group is RTB"))
  end
  
  --- Function called when flight is holding.
  function flightgroup.OnAfterHolding(Flightgroup, From, Event, To)
    local flightgroup=Flightgroup --Ops.FlightGroup#FLIGHTGROUP
    
    local ratcraft=self:_GetRatcraftFromGroup(flightgroup.group)
    
    local destinationname=ratcraft.destination:GetName()
    
    -- Aircraft arrived at holding point
    local text=string.format("Flight %s to %s ATC: Holding and awaiting landing clearance.", groupname, destinationname)
    self:T(self.lid..text)
    MESSAGE:New(text, 10):ToAllIf(self.reportstatus)

    -- Get FLIGHTCONTROL if there is any.    
    local fc=_DATABASE:GetFlightControl(destinationname)
    
    -- Register aircraft at RAT ATC (but only if there is no FLIGHTCONTROL)
    if self.ATCswitch and not fc then
      self:T(self.lid..string.format("RAT group is HOLDING ==> ATCRegisterFlight"))
    
      -- Create F10 menu
      if self.f10menu then       
        MENU_MISSION_COMMAND:New("Clear for landing", self.Menu[self.SubMenuName].groups[self.SpawnIndex], flightgroup.ClearToLand, flightgroup)
      end
      
      -- Register at ATC
      RAT._ATCRegisterFlight(groupname, timer.getTime())
    end
  end
  
  --- Function called when the group landed at an airbase.
  function flightgroup.OnAfterLanded(Flightgroup, From, Event, To, Airport)
    self:T(self.lid..string.format("RAT group landed at airbase"))
  end
  
  --- Function called when the group arrived at their parking positions.
  function flightgroup.OnAfterArrived(Flightgroup, From, Event, To)
    self:T(self.lid..string.format("RAT group arrived"))
  end
  
  --- Function called when a group got stuck.
  function flightgroup.OnAfterStuck(Flightgroup, From, Event, To, Stucktime)
    local flightgroup=Flightgroup --Ops.FlightGroup#FLIGHTGROUP
    self:T(self.lid..string.format("Group %s got stuck for %d seconds", flightgroup:GetName(), Stucktime))
    if Stucktime>10*60 then
      self:_Respawn(flightgroup.group)
    end
  
  end
  

  return self.SpawnIndex
end

--- Check if a given airbase has a FLIGHTCONTROL.
-- @param #RAT self
-- @param Wrapper.Airbase#AIRBASE airbase The airbase.
-- @return #boolean `true` if the airbase has a FLIGHTCONTROL.
function RAT:_IsFlightControlAirbase(airbase)
  
  if type(airbase)=="table" then
    airbase=airbase:GetName()
  end
  
  if airbase then
  
    local fc=_DATABASE:GetFlightControl(airbase)
    
    if fc then
      self:T(self.lid..string.format("Airbase %s has a FLIGHTCONTROL running", airbase))
      return true
    else
      return false
    end
  
  end
  
  return nil
end

--- Clear flight for landing. Sets tigger value to 1.
-- @param #RAT self
-- @param #string name Name of flight to be cleared for landing.
function RAT:ClearForLanding(name)
  trigger.action.setUserFlag(name, 1)
  local flagvalue=trigger.misc.getUserFlag(name)
  self:T(self.lid.."ATC: User flag value (landing) for "..name.." set to "..flagvalue)
end

--- Despawn the original group and re-spawn a new one.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group The group that should be respawned.
-- @param Core.Point#COORDINATE lastpos Last known position of the group.
-- @param #number delay Delay before despawn in seconds.
function RAT:_Respawn(group, lastpos, delay)

  if delay and delay>0 then
  
    self:ScheduleOnce(delay, RAT._Respawn, self, group, lastpos, 0)
  
  else
    if group then
      self:T(self.lid..string.format("Respawning ratcraft from group %s", group:GetName()))
    else
      self:E(self.lid..string.format("ERROR: group is nil in _Respawn!"))
      return nil
    end
    
    -- Get ratcraft from group.
    local ratcraft=self:_GetRatcraftFromGroup(group)

    -- Get last known position.    
    lastpos=lastpos or group:GetCoordinate()
  
    -- Get departure and destination from previous journey.
    local departure=ratcraft.departure
    local destination=ratcraft.destination   --Wrapper.Airbase#AIRBASE
    local takeoff=ratcraft.takeoff
    local landing=ratcraft.landing
    local livery=ratcraft.livery
    local lastwp=ratcraft.waypoints[#ratcraft.waypoints]
    local flightgroup=ratcraft.flightgroup
    
    
    -- In case we stay at the same airport, we save the parking data to respawn at the same spot.
    local parkingdata=nil
    if self.continuejourney or self.commute then
      for _,_element in pairs(flightgroup.elements) do
        local element=_element --Ops.OpsGroup#OPSGROUP.Element
            
        if element.parking then
          -- Init table.
          if parkingdata==nil then
            parkingdata={}
          end
          
          self:T(self.lid..string.format("Element %s was parking at spot id=%d", element.name, element.parking.TerminalID))
          table.insert(parkingdata, UTILS.DeepCopy(element.parking))
        else
          self:E(self.lid..string.format("WARNING: Element %s did NOT have a not parking spot!", tostring(element.name)))
        end
      end
    end
    
    -- Despawn old group.
    self:_Despawn(ratcraft.group)
  
    local _departure=nil
    local _destination=nil --Wrapper.Airbase#AIRBASE
    local _takeoff=nil
    local _landing=nil
    local _livery=nil
    local _lastwp=nil
    local _lastpos=nil
  
    if self.continuejourney then
    
      ---
      -- Continue Journey
      ---
  
      -- We continue our journey from the old departure airport.
      _departure=destination:GetName()
  
      -- Use the same livery for next aircraft.
      _livery=livery
  
      -- Last known position of the aircraft, which should be the sparking spot location.
      -- Note: we have to check that it was supposed to land and not respawned directly after landing or after takeoff.
      -- DONE: Need to think if continuejourney with respawn_after_takeoff actually makes sense?
      --       No, does not make sense. Disable it in consistency check.
      if landing==RAT.wp.landing and not (self.respawn_at_landing or self.respawn_after_takeoff) then
        -- Check that we have an airport or FARP but not a ship (which would be categroy 1).
        if destination:GetCategory()==4 then
          _lastpos=lastpos
        end
      end
  
      if self.destinationzone then
  
        -- Case: X --> Zone --> Zone --> Zone
        _takeoff=RAT.wp.air
        _landing=RAT.wp.air
  
      elseif self.returnzone then
  
        -- Case: X --> Zone --> X,  X --> Zone --> X
        -- We flew to a zone and back. Takeoff type does not change.
        _takeoff=self.takeoff
  
        -- If we took of in air we also want to land "in air".
        if self.takeoff==RAT.wp.air then
          _landing=RAT.wp.air
        else
          _landing=RAT.wp.landing
        end
  
        -- Departure stays the same. (The destination is the zone here.)
        _departure=departure:GetName()
  
      else
  
        -- Default case. Takeoff and landing type does not change.
        _takeoff=self.takeoff
        _landing=self.landing
  
      end
  
    elseif self.commute then
    
      ---
      -- Commute
      ---
    
      -- We commute between departure and destination.
  
      if self.starshape==true then
        if destination:GetName()==self.homebase then
          -- We are at our home base ==> destination is again randomly selected.
          _departure=self.homebase
          _destination=nil -- destination will be set anew
        else
          -- We are not a our home base ==> we fly back to our home base.
          _departure=destination:GetName()
          _destination=self.homebase
        end
      else
        -- Simply switch departure and destination.
        _departure=destination:GetName()
        _destination=departure:GetName()
      end
  
      -- Use the same livery for next aircraft.
      _livery=livery
  
      -- Last known position of the aircraft, which should be the sparking spot location.
      -- Note: we have to check that it was supposed to land and not respawned directly after landing or after takeoff.
      -- TODO: Need to think if commute with respawn_after_takeoff actually makes sense.
      if landing==RAT.wp.landing and lastpos and not (self.respawn_at_landing or self.respawn_after_takeoff) then
        -- Check that we have landed on an airport or FARP but not a ship (which would be categroy 1).
        if destination:GetCategory()==4 then
          _lastpos=lastpos
        end
      end
  
      -- Handle takeoff type.
      if self.destinationzone then
        -- self.takeoff is either RAT.wp.air or RAT.wp.cold
        -- self.landing is RAT.wp.Air
  
        if self.takeoff==RAT.wp.air then
  
          -- Case: Zone <--> Zone (both have takeoff air)
          _takeoff=RAT.wp.air  -- = self.takeoff (because we just checked)
          _landing=RAT.wp.air  -- = self.landing (because destinationzone)
  
        else
  
          -- Case: Airport <--> Zone
          if takeoff==RAT.wp.air then
            -- Last takeoff was air so we are at the airport now, takeoff is from ground.
            _takeoff=self.takeoff   -- must be either hot/cold/runway/hotcold
            _landing=RAT.wp.air     -- must be air = self.landing (because destinationzone)
          else
            -- Last takeoff was on ground so we are at a zone now ==> takeoff in air, landing at airport.
            _takeoff=RAT.wp.air
            _landing=RAT.wp.landing
          end
  
        end
  
      elseif self.returnzone then
  
        -- We flew to a zone and back. No need to swap departure and destination.
        _departure=departure:GetName()
        _destination=destination:GetName()
  
        -- Takeoff and landing should also not change.
        _takeoff=self.takeoff
        _landing=self.landing
  
      end
  
    end
  
    -- Take the last waypoint as initial waypoint for next plane.
    if _takeoff==RAT.wp.air and (self.continuejourney or self.commute) then
      _lastwp=lastwp
    end
  
    -- Debug
    self:T2({departure=_departure, destination=_destination, takeoff=_takeoff, landing=_landing, livery=_livery, lastwp=_lastwp})
  
    -- We should give it at least 3 sec since this seems to be the time until free parking spots after despawn are available again (Sirri Island test).
    local respawndelay=self.respawn_delay or 1
  
    -- Spawn new group.
    self:T(self.lid..string.format("%s delayed respawn in %.1f seconds.", self.alias, respawndelay))  
    self:ScheduleOnce(respawndelay, RAT._SpawnWithRoute, self,_departure,_destination,_takeoff,_landing,_livery, nil,_lastpos, nil, parkingdata)
    
  end

end

--- Despawn group. The `FLIGHTGROUP` is despawned and stopped. The ratcraft is removed from the self.ratcraft table. Menues are removed.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Group to be despawned.
-- @param #number delay Delay in seconds before the despawn happens. Default is immidiately.
function RAT:_Despawn(group, delay)

  if delay and delay>0 then
    -- Delayed call.
    self:ScheduleOnce(delay, RAT._Despawn, self, group, 0)
  else

    if group then
  
      -- Get spawnindex of group.
      local index=self:GetSpawnIndexFromGroup(group)
  
      if index then
      
        -- Debug info.
        self:T(self.lid..string.format("Despawning group %s (index=%d)", group:GetName(), index))
      
        -- Get ratcraft.
        local ratcraft=self.ratcraft[index] --#RAT.RatCraft
        
        -- Despawn flightgroup and stop.
        ratcraft.flightgroup:Despawn()
        ratcraft.flightgroup:__Stop(0.1)
        
        -- Nil ratcraft in table.
        self.ratcraft[index].group=nil
        self.ratcraft[index]["status"]="Dead"        
        self.ratcraft[index]=nil
 
        -- Remove submenu for this group.
        if self.f10menu and self.SubMenuName ~= nil then
          self.Menu[self.SubMenuName]["groups"][index]:Remove()
        end
  
      end
    end
  end
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Set the route of the AI plane. Due to DCS landing bug, this has to be done before the unit is spawned.
-- @param #RAT self
-- @param #number takeoff Takeoff type. Could also be air start.
-- @param #number landing Landing type. Could also be a destination in air.
-- @param Wrapper.Airbase#AIRBASE _departure (Optional) Departure airbase.
-- @param Wrapper.Airbase#AIRBASE _destination (Optional) Destination airbase.
-- @param #table _waypoint Initial waypoint.
-- @return Wrapper.Airbase#AIRBASE Departure airbase.
-- @return Wrapper.Airbase#AIRBASE Destination airbase.
-- @return #table Table of flight plan waypoints.
-- @return #table Table of waypoint descriptions.
-- @return #table Table of waypoint status.
function RAT:_SetRoute(takeoff, landing, _departure, _destination, _waypoint)

  -- Max cruise speed.
  local VxCruiseMax
  if self.Vcruisemax then
    -- User input.
    VxCruiseMax = math.min(self.Vcruisemax, self.aircraft.Vmax)
  else
    -- Max cruise speed 90% of Vmax or 900 km/h whichever is lower.
    VxCruiseMax = math.min(self.aircraft.Vmax*0.90, 250)
  end

  -- Min cruise speed 70% of max cruise or 600 km/h whichever is lower.
  local VxCruiseMin = math.min(VxCruiseMax*0.70, 166)

  -- Cruise speed (randomized). Expectation value at midpoint between min and max.
  local VxCruise = UTILS.RandomGaussian((VxCruiseMax-VxCruiseMin)/2+VxCruiseMin, (VxCruiseMax-VxCruiseMax)/4, VxCruiseMin, VxCruiseMax)

  -- Climb speed 90% ov Vmax but max 720 km/h.
  local VxClimb = math.min(self.aircraft.Vmax*0.90, 200)

  -- Descent speed 60% of Vmax but max 500 km/h.
  local VxDescent = math.min(self.aircraft.Vmax*0.60, 140)

  -- Holding speed is 90% of descent speed.
  local VxHolding = VxDescent*0.9

  -- Final leg is 90% of holding speed.
  local VxFinal = VxHolding*0.9

  -- Reasonably civil climb speed Vy=1500 ft/min = 7.6 m/s but max aircraft specific climb rate.
  local VyClimb=math.min(self.Vclimb*RAT.unit.ft2meter/60, self.aircraft.Vymax)

  -- Climb angle in rad.
  local AlphaClimb=math.asin(VyClimb/VxClimb)

  -- Descent angle in rad.
  local AlphaDescent=math.rad(self.AlphaDescent)

  -- Expected cruise level (peak of Gaussian distribution)
  local FLcruise_expect=self.FLcruise


  -- DEPARTURE AIRPORT
  -- Departure airport or zone.
  local departure=nil --Wrapper.Airbase#AIRBASE
  if _departure then
    if self:_AirportExists(_departure) then
      -- Check if new departure is an airport.
      departure=AIRBASE:FindByName(_departure)
      -- If we spawn in air, we convert departure to a zone.
      if takeoff == RAT.wp.air then
        departure=departure:GetZone()
      end
    elseif self:_ZoneExists(_departure) then
      -- If it's not an airport, check whether it's a zone.
      departure=ZONE:FindByName(_departure)
    else
      local text=string.format("ERROR! Specified departure airport %s does not exist for %s.", _departure, self.alias)
      self:E(self.lid..text)
    end

  else
    departure=self:_PickDeparture(takeoff)
    if self.commute and self.starshape==true and self.homebase==nil then
      self.homebase=departure:GetName()
    end
  end

  -- Return nil if no departure could be found.
  if not departure then
    local text=string.format("ERROR! No valid departure airport could be found for %s.", self.alias)
    self:E(self.lid..text)
    return nil
  end

  -- Coordinates of departure point.
  local Pdeparture  --Core.Point#COORDINATE
  if takeoff==RAT.wp.air then
    if _waypoint then
      -- Use coordinates of previous flight (commute or journey).
      Pdeparture=COORDINATE:New(_waypoint.x, _waypoint.alt, _waypoint.y)
    else
      -- For an air start, we take a random point within the spawn zone.
      local vec2=departure:GetRandomVec2()
      Pdeparture=COORDINATE:NewFromVec2(vec2)
      end
  else
    Pdeparture=departure:GetCoordinate()
  end

  -- Height ASL of departure point.
  local H_departure
  if takeoff==RAT.wp.air then
    -- Absolute minimum AGL
    local Hmin
    if self.category==RAT.cat.plane then
      Hmin=1000
    else
      Hmin=50
    end
    -- Departure altitude is 70% of default cruise with 30% variation and limited to 1000 m AGL (50 m for helos).
    H_departure=self:_Randomize(FLcruise_expect*0.7, 0.3, Pdeparture.y+Hmin, FLcruise_expect)
    if self.FLminuser then
      H_departure=math.max(H_departure,self.FLminuser)
    end
    -- Use alt of last flight.
    if _waypoint then
      H_departure=_waypoint.alt
    end
  else
    H_departure=Pdeparture.y
  end

  -- Adjust min distance between departure and destination for user set min flight level.
  local mindist=self.mindist
  if self.FLminuser then

    -- We can conly consider the symmetric case, because no destination selected yet.
    local hclimb=self.FLminuser-H_departure
    local hdescent=self.FLminuser-H_departure

    -- Minimum distance for l
    local Dclimb, Ddescent, Dtot=self:_MinDistance(AlphaClimb, AlphaDescent, hclimb, hdescent)

    if takeoff==RAT.wp.air and landing==RAT.wpair then
      mindist=0         -- Takeoff and landing are in air. No mindist required.
    elseif takeoff==RAT.wp.air then
      mindist=Ddescent  -- Takeoff in air. Need only space to descent.
    elseif landing==RAT.wp.air then
      mindist=Dclimb    -- Landing "in air". Need only space to climb.
    else
      mindist=Dtot      -- Takeoff and landing on ground. Need both space to climb and descent.
    end

    -- Mindist is at least self.mindist.
    mindist=math.max(self.mindist, mindist)

    local text=string.format("Adjusting min distance to %d km (for given min FL%03d)", mindist/1000, self.FLminuser/RAT.unit.FL2m)
    self:T(self.lid..text)
  end

  -- DESTINATION AIRPORT
  local destination=nil --Wrapper.Airbase#AIRBASE
  if _destination then

    if self:_AirportExists(_destination) then

      destination=AIRBASE:FindByName(_destination)
      if landing==RAT.wp.air or self.returnzone then
        destination=destination:GetZone()
      end

    elseif self:_ZoneExists(_destination) then
      destination=ZONE:FindByName(_destination)
    else
      local text=string.format("ERROR: Specified destination airport/zone %s does not exist for %s!", _destination, self.alias)
      self:E(self.lid.."ERROR: "..text)
    end

  else

    -- This handles the case where we have a journey and the first flight is done, i.e. _departure is set.
    -- If a user specified more than two destination airport explicitly, then we will stick to this.
    -- Otherwise, the route is random from now on.
    local random=self.random_destination
    if self.continuejourney and _departure and #self.destination_ports<3 then
      random=true
    end

    -- In case of a returnzone the destination (i.e. return point) is always a zone.
    local mylanding=landing
    local acrange=self.aircraft.Reff
    if self.returnzone then
      mylanding=RAT.wp.air
      acrange=self.aircraft.Reff/2  -- Aircraft needs to go to zone and back home.
    end

    -- Pick a destination airport.
    destination=self:_PickDestination(departure, Pdeparture, mindist, math.min(acrange, self.maxdist), random, mylanding)
  end

  -- Return nil if no departure could be found.
  if not destination then
    local text=string.format("No valid destination airport could be found for %s!", self.alias)
    MESSAGE:New(text, 60):ToAll()
    self:E(self.lid.."ERROR: "..text)
    return nil
  end

  -- Check that departure and destination are not the same. Should not happen due to mindist.
  if destination:GetName()==departure:GetName() then
    local text=string.format("%s: Destination and departure are identical. Airport/zone %s.", self.alias, destination:GetName())
    MESSAGE:New(text, 30):ToAll()
    self:E(self.lid.."ERROR: "..text)
  end

  -- Get a random point inside zone return zone.
  local Preturn
  local destination_returnzone
  if self.returnzone then
    -- Get a random point inside zone return zone.
    local vec2=destination:GetRandomVec2()
    Preturn=COORDINATE:NewFromVec2(vec2)
    -- Returnzone becomes destination.
    destination_returnzone=destination
    -- Set departure to destination.
    destination=departure
  end

  -- Get destination coordinate. Either in a zone or exactly at the airport.
  local Pdestination --Core.Point#COORDINATE
  if landing==RAT.wp.air then
    local vec2=destination:GetRandomVec2()
    Pdestination=COORDINATE:NewFromVec2(vec2)
  else
    Pdestination=destination:GetCoordinate()
  end

  -- Height ASL of destination airport/zone.
  local H_destination=Pdestination.y

  -- DESCENT/HOLDING POINT
  -- Get a random point between 5 and 10 km away from the destination.
  local Rhmin=8000
  local Rhmax=20000
  if self.category==RAT.cat.heli then
    -- For helos we set a distance between 500 to 1000 m.
    Rhmin=500
    Rhmax=1000
  end

  -- Coordinates of the holding point. y is the land height at that point.
  local Vholding=Pdestination:GetRandomVec2InRadius(Rhmax, Rhmin)
  local Pholding=COORDINATE:NewFromVec2(Vholding)

  -- AGL height of holding point.
  local H_holding=Pholding.y

  -- Holding point altitude. For planes between 1600 and 2400 m AGL. For helos 160 to 240 m AGL.
  local h_holding
  if self.category==RAT.cat.plane then
    h_holding=1200
  else
    h_holding=150
  end
  h_holding=self:_Randomize(h_holding, 0.2)

  -- This is the actual height ASL of the holding point we want to fly to
  local Hh_holding=H_holding+h_holding

  -- When we dont land, we set the holding altitude to the departure or cruise alt.
  -- This is used in the calculations.
  if landing==RAT.wp.air then
    Hh_holding=H_departure
  end

  -- Distance from holding point to final destination.
  local d_holding=Pholding:Get2DDistance(Pdestination)

  -- GENERAL
  local heading
  local d_total
  if self.returnzone then

    -- Heading from departure to destination in return zone.
    heading=self:_Course(Pdeparture, Preturn)

    -- Total distance to return zone and back.
    d_total=Pdeparture:Get2DDistance(Preturn) + Preturn:Get2DDistance(Pholding)

  else
    -- Heading from departure to holding point of destination.
    heading=self:_Course(Pdeparture, Pholding)

    -- Total distance between departure and holding point near destination.
    d_total=Pdeparture:Get2DDistance(Pholding)
  end

  -- Max height in case of air start, i.e. if we only would descent to holding point for the given distance.
  if takeoff==RAT.wp.air then
    local H_departure_max
    if landing==RAT.wp.air then
      H_departure_max = H_departure  -- If we fly to a zone, there is no descent necessary.
    else
      H_departure_max = d_total * math.tan(AlphaDescent) + Hh_holding
    end
    H_departure=math.min(H_departure, H_departure_max)
  end

  --------------------------------------------

  -- Height difference between departure and destination.
  local deltaH=math.abs(H_departure-Hh_holding)

  -- Slope between departure and destination.
  local phi = math.atan(deltaH/d_total)

  -- Adjusted climb/descent angles.
  local phi_climb
  local phi_descent
  if (H_departure > Hh_holding) then
    phi_climb=AlphaClimb+phi
    phi_descent=AlphaDescent-phi
  else
    phi_climb=AlphaClimb-phi
    phi_descent=AlphaDescent+phi
  end

  -- Total distance including slope.
  local D_total
  if self.returnzone then
    D_total = math.sqrt(deltaH*deltaH+d_total/2*d_total/2)
  else
    D_total = math.sqrt(deltaH*deltaH+d_total*d_total)
  end

  -- SSA triangle for sloped case.
  local gamma=math.rad(180)-phi_climb-phi_descent
  local a = D_total*math.sin(phi_climb)/math.sin(gamma)
  local b = D_total*math.sin(phi_descent)/math.sin(gamma)
  local hphi_max  = b*math.sin(phi_climb)
  local hphi_max2 = a*math.sin(phi_descent)

  -- Height of triangle.
  local h_max1 = b*math.sin(AlphaClimb)
  local h_max2 = a*math.sin(AlphaDescent)

  -- Max height relative to departure or destination.
  local h_max
  if (H_departure > Hh_holding) then
    h_max=math.min(h_max1, h_max2)
  else
    h_max=math.max(h_max1, h_max2)
  end

  -- Max flight level aircraft can reach for given angles and distance.
  local FLmax = h_max+H_departure

  --CRUISE
  -- Min cruise alt is just above holding point at destination or departure height, whatever is larger.
  local FLmin=math.max(H_departure, Hh_holding)

  -- For helicopters we take cruise alt between 50 to 1000 meters above ground. Default cruise alt is ~150 m.
  if self.category==RAT.cat.heli then
    FLmin=math.max(H_departure, H_destination)+50
    FLmax=math.max(H_departure, H_destination)+1000
  end

  -- Ensure that FLmax not above its service ceiling.
  FLmax=math.min(FLmax, self.aircraft.ceiling)

  -- Overrule setting if user specified min/max flight level explicitly.
  if self.FLminuser then
    FLmin=math.max(self.FLminuser, FLmin)  -- Still take care that we dont fly too high.
  end
  if self.FLmaxuser then
    FLmax=math.min(self.FLmaxuser, FLmax)  -- Still take care that we dont fly too low.
  end

  -- If the route is very short we set FLmin a bit lower than FLmax.
  if FLmin>FLmax then
    FLmin=FLmax
  end

  -- Expected cruise altitude - peak of gaussian distribution.
  if FLcruise_expect<FLmin then
    FLcruise_expect=FLmin
  end
  if FLcruise_expect>FLmax then
    FLcruise_expect=FLmax
  end

  -- Set cruise altitude. Selected from Gaussian distribution but limited to FLmin and FLmax.
  local FLcruise=UTILS.RandomGaussian(FLcruise_expect, math.abs(FLmax-FLmin)/4, FLmin, FLmax)

  -- Overrule setting if user specified a flight level explicitly.
  if self.FLuser then
    FLcruise=self.FLuser
    -- Still cruise alt should be with parameters!
    FLcruise=math.max(FLcruise, FLmin)
    FLcruise=math.min(FLcruise, FLmax)
  end

  -- Climb and descent heights.
  local h_climb   = FLcruise - H_departure
  local h_descent = FLcruise - Hh_holding

  -- Distances.
  local d_climb   = h_climb/math.tan(AlphaClimb)
  local d_descent = h_descent/math.tan(AlphaDescent)
  local d_cruise  = d_total-d_climb-d_descent

  -- debug message
  local text=string.format("\n******************************************************\n")
  text=text..string.format("Template      =  %s\n",   self.SpawnTemplatePrefix)
  text=text..string.format("Alias         =  %s\n",   self.alias)
  text=text..string.format("Group name    =  %s\n\n", self:_AnticipatedGroupName())
  text=text..string.format("Speeds:\n")
  text=text..string.format("VxCruiseMin   = %6.1f m/s = %5.1f km/h\n", VxCruiseMin, VxCruiseMin*3.6)
  text=text..string.format("VxCruiseMax   = %6.1f m/s = %5.1f km/h\n", VxCruiseMax, VxCruiseMax*3.6)
  text=text..string.format("VxCruise      = %6.1f m/s = %5.1f km/h\n", VxCruise, VxCruise*3.6)
  text=text..string.format("VxClimb       = %6.1f m/s = %5.1f km/h\n", VxClimb, VxClimb*3.6)
  text=text..string.format("VxDescent     = %6.1f m/s = %5.1f km/h\n", VxDescent, VxDescent*3.6)
  text=text..string.format("VxHolding     = %6.1f m/s = %5.1f km/h\n", VxHolding, VxHolding*3.6)
  text=text..string.format("VxFinal       = %6.1f m/s = %5.1f km/h\n", VxFinal, VxFinal*3.6)
  text=text..string.format("VyClimb       = %6.1f m/s\n", VyClimb)
  text=text..string.format("\nDistances:\n")
  text=text..string.format("d_climb       = %6.1f km\n", d_climb/1000)
  text=text..string.format("d_cruise      = %6.1f km\n", d_cruise/1000)
  text=text..string.format("d_descent     = %6.1f km\n", d_descent/1000)
  text=text..string.format("d_holding     = %6.1f km\n", d_holding/1000)
  text=text..string.format("d_total       = %6.1f km\n", d_total/1000)
  text=text..string.format("\nHeights:\n")
  text=text..string.format("H_departure   = %6.1f m ASL\n", H_departure)
  text=text..string.format("H_destination = %6.1f m ASL\n", H_destination)
  text=text..string.format("H_holding     = %6.1f m ASL\n", H_holding)
  text=text..string.format("h_climb       = %6.1f m\n",     h_climb)
  text=text..string.format("h_descent     = %6.1f m\n",     h_descent)
  text=text..string.format("h_holding     = %6.1f m\n",     h_holding)
  text=text..string.format("delta H       = %6.1f m\n",     deltaH)
  text=text..string.format("FLmin         = %6.1f m ASL = FL%03d\n", FLmin, FLmin/RAT.unit.FL2m)
  text=text..string.format("FLcruise      = %6.1f m ASL = FL%03d\n", FLcruise, FLcruise/RAT.unit.FL2m)
  text=text..string.format("FLmax         = %6.1f m ASL = FL%03d\n", FLmax, FLmax/RAT.unit.FL2m)
  text=text..string.format("\nAngles:\n")
  text=text..string.format("Alpha climb   = %6.2f Deg\n",   math.deg(AlphaClimb))
  text=text..string.format("Alpha descent = %6.2f Deg\n",   math.deg(AlphaDescent))
  text=text..string.format("Phi (slope)   = %6.2f Deg\n",   math.deg(phi))
  text=text..string.format("Phi climb     = %6.2f Deg\n",   math.deg(phi_climb))
  text=text..string.format("Phi descent   = %6.2f Deg\n",   math.deg(phi_descent))
  if self.Debug then
    -- Max heights and distances if we would travel at FLmax.
    local h_climb_max   = FLmax - H_departure
    local h_descent_max = FLmax - Hh_holding
    local d_climb_max   = h_climb_max/math.tan(AlphaClimb)
    local d_descent_max = h_descent_max/math.tan(AlphaDescent)
    local d_cruise_max  = d_total-d_climb_max-d_descent_max
    text=text..string.format("Heading       = %6.1f Deg\n",   heading)
    text=text..string.format("\nSSA triangle:\n")
    text=text..string.format("D_total       = %6.1f km\n",  D_total/1000)
    text=text..string.format("gamma         = %6.1f Deg\n", math.deg(gamma))
    text=text..string.format("a             = %6.1f m\n",   a)
    text=text..string.format("b             = %6.1f m\n",   b)
    text=text..string.format("hphi_max      = %6.1f m\n",   hphi_max)
    text=text..string.format("hphi_max2     = %6.1f m\n",   hphi_max2)
    text=text..string.format("h_max1        = %6.1f m\n",   h_max1)
    text=text..string.format("h_max2        = %6.1f m\n",   h_max2)
    text=text..string.format("h_max         = %6.1f m\n",   h_max)
    text=text..string.format("\nMax heights and distances:\n")
    text=text..string.format("d_climb_max   = %6.1f km\n", d_climb_max/1000)
    text=text..string.format("d_cruise_max  = %6.1f km\n", d_cruise_max/1000)
    text=text..string.format("d_descent_max = %6.1f km\n", d_descent_max/1000)
    text=text..string.format("h_climb_max   = %6.1f m\n",  h_climb_max)
    text=text..string.format("h_descent_max = %6.1f m\n",  h_descent_max)
  end
  text=text..string.format("******************************************************\n")
  self:T2(self.lid..text)

  -- Ensure that cruise distance is positve. Can be slightly negative in special cases. And we don't want to turn back.
  if d_cruise<0 then
    d_cruise=100
  end

  -- Waypoints and coordinates
  local wp={}
  local c={}
  local waypointdescriptions={}
  local waypointstatus={}
  local wpholding=nil
  local wpfinal=nil

  -- Departure/Take-off
  c[#c+1]=Pdeparture
  wp[#wp+1]=self:_Waypoint(#wp+1, "Departure", takeoff, c[#wp+1], VxClimb, H_departure, departure)
  waypointdescriptions[#wp]="Departure"
  waypointstatus[#wp]=RAT.status.Departure

  -- Climb
  if takeoff==RAT.wp.air then

    -- Air start.
    if d_climb < 5000 or d_cruise < 5000 then
      -- We omit the climb phase completely and add it to the cruise part.
      d_cruise=d_cruise+d_climb
    else
      -- Only one waypoint at the end of climb = begin of cruise.
      c[#c+1]=c[#c]:Translate(d_climb, heading)

      wp[#wp+1]=self:_Waypoint(#wp+1, "Begin of Cruise", RAT.wp.cruise, c[#wp+1], VxCruise, FLcruise)
      waypointdescriptions[#wp]="Begin of Cruise"
      waypointstatus[#wp]=RAT.status.Cruise
    end

  else

    -- Ground start.
    c[#c+1]=c[#c]:Translate(d_climb/2, heading)
    c[#c+1]=c[#c]:Translate(d_climb/2, heading)

    wp[#wp+1]=self:_Waypoint(#wp+1, "Climb", RAT.wp.climb,  c[#wp+1], VxClimb, H_departure+(FLcruise-H_departure)/2)
    waypointdescriptions[#wp]="Climb"
    waypointstatus[#wp]=RAT.status.Climb

    wp[#wp+1]=self:_Waypoint(#wp+1, "Begin of Cruise", RAT.wp.cruise, c[#wp+1], VxCruise, FLcruise)
    waypointdescriptions[#wp]="Begin of Cruise"
    waypointstatus[#wp]=RAT.status.Cruise

  end

  -- Cruise

  -- First add the little bit from begin of cruise to the return point.
  if self.returnzone then
    c[#c+1]=Preturn
    wp[#wp+1]=self:_Waypoint(#wp+1, "Return Zone", RAT.wp.cruise, c[#wp+1], VxCruise, FLcruise)
    waypointdescriptions[#wp]="Return Zone"
    waypointstatus[#wp]=RAT.status.Uturn
  end

  if landing==RAT.wp.air then

    -- Next waypoint is already the final destination.
    c[#c+1]=Pdestination
    wp[#wp+1]=self:_Waypoint(#wp+1, "Final Destination", RAT.wp.finalwp, c[#wp+1], VxCruise,  FLcruise)
    waypointdescriptions[#wp]="Final Destination"
    waypointstatus[#wp]=RAT.status.Destination

  elseif self.returnzone then

    -- The little bit back to end of cruise.
    c[#c+1]=c[#c]:Translate(d_cruise/2, heading-180)
    wp[#wp+1]=self:_Waypoint(#wp+1, "End of Cruise", RAT.wp.cruise, c[#wp+1], VxCruise,  FLcruise)
    waypointdescriptions[#wp]="End of Cruise"
    waypointstatus[#wp]=RAT.status.Descent

  else

    c[#c+1]=c[#c]:Translate(d_cruise, heading)
    wp[#wp+1]=self:_Waypoint(#wp+1, "End of Cruise", RAT.wp.cruise, c[#wp+1], VxCruise,  FLcruise)
    waypointdescriptions[#wp]="End of Cruise"
    waypointstatus[#wp]=RAT.status.Descent

  end

  -- Descent (only if we acually want to land)
  if landing==RAT.wp.landing then
    if self.returnzone then
      c[#c+1]=c[#c]:Translate(d_descent/2, heading-180)
      wp[#wp+1]=self:_Waypoint(#wp+1, "Descent", RAT.wp.descent, c[#wp+1], VxDescent, FLcruise-(FLcruise-(h_holding+H_holding))/2)
      waypointdescriptions[#wp]="Descent"
      waypointstatus[#wp]=RAT.status.DescentHolding
    else
      c[#c+1]=c[#c]:Translate(d_descent/2, heading)
      wp[#wp+1]=self:_Waypoint(#wp+1, "Descent", RAT.wp.descent, c[#wp+1], VxDescent, FLcruise-(FLcruise-(h_holding+H_holding))/2)
      waypointdescriptions[#wp]="Descent"
      waypointstatus[#wp]=RAT.status.DescentHolding
    end
  end

  -- Holding and final destination.
  if landing==RAT.wp.landing then

    -- Holding point (removed the holding point because FLIGHTGROUP sends group to holding point with RTB command after the last waypoint)
--    c[#c+1]=Pholding
--    wp[#wp+1]=self:_Waypoint(#wp+1, "Holding Point", RAT.wp.holding, c[#wp+1], VxHolding, H_holding+h_holding)
--    waypointdescriptions[#wp]="Holding Point"
--    waypointstatus[#wp]=RAT.status.Holding
--    wpholding=#wp

    -- Final destination (leave this in because FLIGHTGROUP needs to know that we want to land and removes the landing waypoint automatically)
    c[#c+1]=Pdestination
    wp[#wp+1]=self:_Waypoint(#wp+1, "Final Destination", landing, c[#wp+1], VxFinal, H_destination, destination)
    waypointdescriptions[#wp]="Final Destination"
    waypointstatus[#wp]=RAT.status.Destination

  end

  -- Final Waypoint
  wpfinal=#wp

  -- Fill table with waypoints.
  local waypoints={}
  for _,p in ipairs(wp) do
    table.insert(waypoints, p)
  end

  -- Some info on the route.
  self:_Routeinfo(waypoints, "Waypoint info in set_route:", waypointdescriptions)

  -- Return departure, destination and waypoints.
  if self.returnzone then
    -- We return the actual zone here because returning the departure leads to problems with commute.
    return departure, destination_returnzone, waypoints, waypointdescriptions, waypointstatus
  else
    return departure, destination, waypoints, waypointdescriptions, waypointstatus
  end

end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Set the departure airport of the AI. If no airport name is given explicitly an airport from the coalition is chosen randomly.
-- If takeoff style is set to "air", we use zones around the airports or the zones specified by user input.
-- @param #RAT self
-- @param #number takeoff Takeoff type.
-- @return Wrapper.Airbase#AIRBASE Departure airport if spawning at airport.
-- @return Core.Zone#ZONE Departure zone if spawning in air.
function RAT:_PickDeparture(takeoff)

  -- Array of possible departure airports or zones.
  local departures={}

  if self.random_departure then

    -- Airports of friendly coalitions.
    for _,_airport in pairs(self.airports) do

      local airport=_airport --Wrapper.Airbase#AIRBASE

      local name=airport:GetName()
      if not self:_Excluded(name) then
        if takeoff==RAT.wp.air then

          table.insert(departures, airport:GetZone())  -- insert zone object.

        else

          -- Check if airbase has the right terminals.
          local nspots=1
          if self.termtype~=nil then
            nspots=airport:GetParkingSpotsNumber(self.termtype)
          end

          if nspots>0 then
            table.insert(departures, airport)            -- insert airport object.
          end
        end
      end

    end

  else

    -- Destination airports or zones specified by user.
    for _,name in pairs(self.departure_ports) do

      local dep=nil
      if self:_AirportExists(name) then
        if takeoff==RAT.wp.air then
          dep=AIRBASE:FindByName(name):GetZone()
        else
          dep=AIRBASE:FindByName(name)
          -- Check if the airport has a valid parking spot
          if self.termtype~=nil and dep~=nil then
            local _dep=dep --Wrapper.Airbase#AIRBASE
            local nspots=_dep:GetParkingSpotsNumber(self.termtype)
            if nspots==0 then
              dep=nil
            end
          end
        end
      elseif self:_ZoneExists(name) then
        if takeoff==RAT.wp.air then
          dep=ZONE:FindByName(name)
        else
          self:E(self.lid..string.format("ERROR! Takeoff is not in air. Cannot use %s as departure.", name))
        end
      else
        self:E(self.lid..string.format("ERROR: No airport or zone found with name %s.", name))
      end

      -- Add to departures table.
      if dep then
        table.insert(departures, dep)
      end

    end

  end

    -- Info message.
  self:T(self.lid..string.format("Number of possible departures for %s= %d", self.alias, #departures))

  -- Select departure airport or zone.
  local departure=departures[math.random(#departures)]

  local text
  if departure and departure:GetName() then
    if takeoff==RAT.wp.air then
      text=string.format("%s: Chosen departure zone: %s", self.alias, departure:GetName())
    else
      text=string.format("%s: Chosen departure airport: %s (ID %d)", self.alias, departure:GetName(), departure:GetID())
    end
    --MESSAGE:New(text, 30):ToAllIf(self.Debug)
    self:T(self.lid..text)
  else
    self:E(self.lid..string.format("ERROR! No departure airport or zone found for %s.", self.alias))
    departure=nil
  end

  return departure
end

--- Pick destination airport or zone depending on departure position.
-- @param #RAT self
-- @param Wrapper.Airbase#AIRBASE departure Departure airport or zone.
-- @param Core.Point#COORDINATE q Coordinate of the departure point.
-- @param #number minrange Minimum range to q in meters.
-- @param #number maxrange Maximum range to q in meters.
-- @param #boolean random Destination is randomly selected from friendly airport (true) or from destinations specified by user input (false).
-- @param #number landing Number indicating whether we land at a destination airport or fly to a zone object.
-- @return Wrapper.Airbase#AIRBASE destination Destination airport or zone.
function RAT:_PickDestination(departure, q, minrange, maxrange, random, landing)

  -- Min/max range to destination.
  minrange=minrange or self.mindist
  maxrange=maxrange or self.maxdist

  -- All possible destinations.
  local destinations={}

  if random then

    -- Airports of friendly coalitions.
    for _,_airport in pairs(self.airports) do
      local airport=_airport --Wrapper.Airbase#AIRBASE
      local name=airport:GetName()
      if self:_IsFriendly(name) and not self:_Excluded(name) and name~=departure:GetName() then

        -- Distance from departure to possible destination
        local distance=q:Get2DDistance(airport:GetCoordinate())

        -- Check if distance form departure to destination is within min/max range.
        if distance>=minrange and distance<=maxrange then
          if landing==RAT.wp.air then
            table.insert(destinations, airport:GetZone())  -- insert zone object.
          else
            -- Check if the requested terminal type is available.
            local nspot=1
            if self.termtype then
              nspot=airport:GetParkingSpotsNumber(self.termtype)
            end
            if nspot>0 then
              table.insert(destinations, airport)            -- insert airport object.
            end
          end
        end
      end
    end

  else

    -- Destination airports or zones specified by user.
    for _,name in pairs(self.destination_ports) do

      -- Make sure departure and destination are not identical.
      if name ~= departure:GetName() then

        local dest=nil
        if self:_AirportExists(name) then
          if landing==RAT.wp.air then
            dest=AIRBASE:FindByName(name):GetZone()
          else
            dest=AIRBASE:FindByName(name)
            -- Check if the requested terminal type is available.
            local nspot=1
            if self.termtype then
              nspot=dest:GetParkingSpotsNumber(self.termtype)
            end
            if nspot==0 then
              dest=nil
            end
          end
        elseif self:_ZoneExists(name) then
          if landing==RAT.wp.air then
            dest=ZONE:FindByName(name)
          else
            self:E(self.lid..string.format("ERROR! Landing is not in air. Cannot use zone %s as destination!", name))
          end
        else
          self:E(self.lid..string.format("ERROR! No airport or zone found with name %s", name))
        end

        if dest then
          -- Distance from departure to possible destination
          local distance=q:Get2DDistance(dest:GetCoordinate())

          -- Add as possible destination if zone is within range.
          if distance>=minrange and distance<=maxrange then
            table.insert(destinations, dest)
          else
            local text=string.format("Destination %s is ouside range. Distance = %5.1f km, min = %5.1f km, max = %5.1f km.", name, distance, minrange, maxrange)
            self:T(self.lid..text)
          end
        end

      end
    end
  end

  -- Info message.
  self:T(self.lid..string.format("Number of possible destinations = %s.", #destinations))

  if #destinations > 0 then
    --- Compare distance of destination airports.
    -- @param Core.Point#COORDINATE a Coordinate of point a.
    -- @param Core.Point#COORDINATE b Coordinate of point b.
    -- @return #list Table sorted by distance.
    local function compare(a,b)
      local qa=q:Get2DDistance(a:GetCoordinate())
      local qb=q:Get2DDistance(b:GetCoordinate())
      return qa < qb
    end
    table.sort(destinations, compare)
  else
    destinations=nil
  end


  -- Randomly select one possible destination.
  local destination
  if destinations and #destinations>0 then

    -- Random selection.
    destination=destinations[math.random(#destinations)] -- Wrapper.Airbase#AIRBASE

    -- Debug message.
    local text
    if landing==RAT.wp.air then
      text=string.format("%s: Chosen destination zone: %s.", self.alias, destination:GetName())
    else
      text=string.format("%s Chosen destination airport: %s (ID %d).", self.alias, destination:GetName(), destination:GetID())
    end
    self:T(self.lid..text)
    --MESSAGE:New(text, 30):ToAllIf(self.Debug)

  else
    self:E(self.lid.."ERROR! No destination airport or zone found.")
    destination=nil
  end

  -- Return the chosen destination.
  return destination

end

--- Find airports within a zone.
-- @param #RAT self
-- @param Core.Zone#ZONE zone
-- @return #list Table with airport names that lie within the zone.
function RAT:_GetAirportsInZone(zone)
  local airports={}
  for _,airport in pairs(self.airports) do
    local name=airport:GetName()
    local coord=airport:GetCoordinate()

    if zone:IsPointVec3InZone(coord) then
      table.insert(airports, name)
    end
  end
  return airports
end

--- Check if airport is excluded from possible departures and destinations.
-- @param #RAT self
-- @param #string port Name of airport, FARP or ship to check.
-- @return #boolean true if airport is excluded and false otherwise.
function RAT:_Excluded(port)
  for _,name in pairs(self.excluded_ports) do
    if name==port then
      return true
    end
  end
  return false
end

--- Check if airport is friendly, i.e. belongs to the right coalition.
-- @param #RAT self
-- @param #string port Name of airport, FARP or ship to check.
-- @return #boolean true if airport is friendly and false otherwise.
function RAT:_IsFriendly(port)
  for _,airport in pairs(self.airports) do
    local name=airport:GetName()
    if name==port then
      return true
    end
  end
  return false
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Get all airports of the current map.
-- @param #RAT self
function RAT:_GetAirportsOfMap()
  local _coalition

  for i=0,2 do -- cycle coalition.side 0=NEUTRAL, 1=RED, 2=BLUE

    -- set coalition
    if i==0 then
      _coalition=coalition.side.NEUTRAL
    elseif i==1 then
      _coalition=coalition.side.RED
    elseif i==2 then
      _coalition=coalition.side.BLUE
    end

    -- get airbases of coalition
    local ab=coalition.getAirbases(i)

    -- loop over airbases and put them in a table
    for _,airbase in pairs(ab) do

      local _id=airbase:getID()
      local _p=airbase:getPosition().p
      local _name=airbase:getName()
      local _myab=AIRBASE:FindByName(_name)

      if _myab then

        -- Add airport to table.
        table.insert(self.airports_map, _myab)

        local text="MOOSE: Airport ID = ".._myab:GetID().." and Name = ".._myab:GetName()..", Category = ".._myab:GetCategory()..", TypeName = ".._myab:GetTypeName()
        self:T(self.lid..text)

      else

        self:E(self.lid..string.format("WARNING: Airbase %s does not exsist as MOOSE object!", tostring(_name)))

      end
    end

  end
end

--- Get all "friendly" airports of the current map. Fills the self.airports{} table.
-- @param #RAT self
function RAT:_GetAirportsOfCoalition()
  for _,coalition in pairs(self.ctable) do
    for _,_airport in pairs(self.airports_map) do
      local airport=_airport --Wrapper.Airbase#AIRBASE
      local category=airport:GetAirbaseCategory()
      if airport:GetCoalition()==coalition then

        -- Planes cannot land on FARPs.
        local condition1=self.category==RAT.cat.plane and category==Airbase.Category.HELIPAD

        -- Planes cannot land on ships.
        local condition2=self.category==RAT.cat.plane and category==Airbase.Category.SHIP

        if not (condition1 or condition2) then
          table.insert(self.airports, airport)
        end
      end
    end
  end

  if #self.airports==0 then
    local text=string.format("No possible departure/destination airports found for RAT %s.", tostring(self.alias))
    MESSAGE:New(text, 10):ToAll()
    self:E(self.lid..text)
  end
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Report status of RAT groups.
-- @param #RAT self
-- @param #boolean message (Optional) Send message with report to all if true.
-- @param #number forID (Optional) Send message only for this ID.
function RAT:Status(message, forID)

  self:T(self.lid.."Checking status")

  -- Current time.
  local Tnow=timer.getTime()

  -- Alive counter.
  local nalive=0

  -- Loop over all ratcraft.
  for spawnindex,_ratcraft in pairs(self.ratcraft) do
    local ratcraft=_ratcraft --#RAT.RatCraft
  
    self:T(self.lid..string.format("Ratcraft Index=%s", tostring(spawnindex)))

    -- Get group.
    local group=ratcraft.group  --Wrapper.Group#GROUP

    if group and group:IsAlive() then
      nalive=nalive+1
      
      self:T(self.lid..string.format("Ratcraft Index=%s is ALIVE", tostring(spawnindex)))

      -- Gather some information.
      local prefix=self:_GetPrefixFromGroup(group)
      local life=self:_GetLife(group)
      local fuel=group:GetFuel()*100.0
      local airborne=group:InAir()
      local coords=group:GetCoordinate()
      local alt=coords~=nil and coords.y or 1000
      local departure=ratcraft.departure:GetName()
      local destination=ratcraft.destination:GetName()
      local type=self.aircraft.type
      local status=ratcraft.status
      local active=ratcraft.active
      local Nunits=ratcraft.nunits
      local N0units=group:GetInitialSize()

      -- Monitor travelled distance since last check.
      local Dtravel=0
      if coords and ratcraft.Pnow then
        local Dtravel=coords:Get2DDistance(ratcraft.Pnow)
        ratcraft.Pnow=coords
      end

      -- Add up the travelled distance.
      ratcraft.Distance=ratcraft.Distance+Dtravel

      -- Distance remaining to destination.
      local Ddestination=-1
      if ratcraft.Pnow then
        Ddestination=ratcraft.Pnow:Get2DDistance(ratcraft.destination:GetCoordinate())
      end

      -- Status report.
      if (forID and spawnindex==forID) or (not forID) then
        local text=string.format("ID %i of flight %s", spawnindex, prefix)
        if N0units>1 then
          text=text..string.format(" (%d/%d)\n", Nunits, N0units)
        else
          text=text.."\n"
        end
        if self.commute then
          text=text..string.format("%s commuting between %s and %s\n", type, departure, destination)
        elseif self.continuejourney then
          text=text..string.format("%s travelling from %s to %s (and continueing form there)\n", type, departure, destination)
        else
          text=text..string.format("%s travelling from %s to %s\n", type, departure, destination)
        end
        text=text..string.format("Status: %s", status)
        if airborne then
          text=text.." [airborne]\n"
        else
          text=text.." [on ground]\n"
        end
        text=text..string.format("Fuel    = %3.0f %%\n", fuel)
        text=text..string.format("Life    = %3.0f %%\n", life)
        text=text..string.format("FL%03d  = %i m ASL\n", alt/RAT.unit.FL2m, alt)
        text=text..string.format("Distance travelled = %6.1f km\n", ratcraft["Distance"]/1000)
        text=text..string.format("Distance to dest   = %6.1f km", Ddestination/1000)
        self:T(self.lid..text)
        if message then
          MESSAGE:New(text, 20):ToAll()
        end
      end

      -- Despawn groups after they have reached their destination zones.
      if ratcraft.despawnme then

        if self.norespawn or self.respawn_after_takeoff then
        
          -- Despawn old group.
          if self.despawnair then          
            self:T(self.lid..string.format("[STATUS despawnme] Flight %s will be despawned NOW and NO new group is created!", self.alias))            
            self:_Despawn(group)
          end
                
        else
        
          -- Despawn old group and respawn a new one.
          self:T(self.lid..string.format("[STATUS despawnme] Flight %s will be despawned NOW and a new group is respawned!", self.alias))
          self:_Respawn(group)
                
        end

      end

    else
      -- Group does not exist.
      local text=string.format("Group does not exist in loop ratcraft status for spawn index=%d", spawnindex)
      self:T2(self.lid..text)
      self:T2(ratcraft)
    end

  end

  -- Alive groups.
  local text=string.format("Alive groups of %s: %d, nalive=%d/%d", self.alias, self.alive, nalive, self.ngroups)
  self:T(self.lid..text)
  MESSAGE:New(text, 20):ToAllIf(message and not forID)

end

--- Remove ratcraft from self.ratcraft table.
-- @param #RAT self
-- @param #RAT.RatCraft ratcraft The ratcraft to be removed.
-- @return #RAT self
function RAT:_RemoveRatcraft(ratcraft)

  self.ratcraft[ratcraft.index]=nil

  return self
end

--- Get ratcraft from group.
-- @param #RAT self
-- @param Wrapper.Group#Group group The group object.
-- @return #RAT.RatCraft The ratcraft object.
function RAT:_GetRatcraftFromGroup(group)

  local index=self:GetSpawnIndexFromGroup(group)
  
  local ratcraft=self.ratcraft[index]

  return ratcraft
end

--- Get (relative) life of first unit of a group.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Group of unit.
-- @return #number Life of unit in percent.
function RAT:_GetLife(group)
  local life=0.0
  if group and group:IsAlive() then
    local unit=group:GetUnit(1)
    if unit then
      life=unit:GetLife()/unit:GetLife0()*100
    else
      self:T2(self.lid.."ERROR! Unit does not exist in RAT_Getlife(). Returning zero.")
    end
  else
    self:T2(self.lid.."ERROR! Group does not exist in RAT_Getlife(). Returning zero.")
  end
  return life
end

--- Set status of group.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Group.
-- @param #string status Status of group.
function RAT:_SetStatus(group, status)

  if group and group:IsAlive() then

    -- Get index from groupname.
    local ratcraft=self:_GetRatcraftFromGroup(group)

    if ratcraft then

      -- Set new status.
      ratcraft.status=status

      -- No status update message for "first waypoint", "holding"
      local no1 = status==RAT.status.Departure
      local no2 = status==RAT.status.EventBirthAir
      local no3 = status==RAT.status.Holding

      local text=string.format("Flight %s: %s", group:GetName(), status)
      self:T(self.lid..text)

      if not (no1 or no2 or no3) then
        MESSAGE:New(text, 10):ToAllIf(self.reportstatus)
      end

    end

  end
end

--- Get RatCraft from a given group.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Group.
-- @return #RAT.RatCraft Rat craft object.
function RAT:_GetRatcraftFromGroup(group)

  if group then

    -- Get index from groupname.
    local index=self:GetSpawnIndexFromGroup(group)

    if self.ratcraft[index] then
      return self.ratcraft[index]
    end
    
  end
  
  return nil
end

--- Get status of group.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Group.
-- @return #string status Status of group.
function RAT:GetStatus(group)

  if group and group:IsAlive() then

    -- Get index from groupname.
    local ratcraft=self:_GetRatcraftFromGroup(group)

    if ratcraft then

      -- Set new status.
      return ratcraft.status

    end

  end

  return "nonexistant"
end


-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Function is executed when a unit is spawned.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnBirth(EventData)
  self:F3(EventData)
  self:T3(self.lid.."Captured event birth!")

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    -- Check that the template name actually belongs to this object.
    if EventPrefix and EventPrefix == self.alias then

      local text="Event: Group "..SpawnGroup:GetName().." was born."
      self:T(self.lid..text)

      -- Set status.
      local status="unknown in birth"
      if SpawnGroup:InAir() then
        status=RAT.status.EventBirthAir
      elseif self.uncontrolled then
        status=RAT.status.Uncontrolled
      else
        status=RAT.status.EventBirth
      end
      self:_SetStatus(SpawnGroup, status)        
      

      -- Get some info ablout this flight.
      local i=self:GetSpawnIndexFromGroup(SpawnGroup)
      
      local ratcraft=self.ratcraft[i] --#RAT.RatCraft
      
      local _departure=ratcraft.departure:GetName()
      local _destination=ratcraft.destination:GetName()
      local _nrespawn=ratcraft.nrespawn
      local _takeoff=ratcraft.takeoff
      local _landing=ratcraft.landing
      local _livery=ratcraft.livery

      -- Some is only useful for an actual airbase (not a zone).
      local _airbase=AIRBASE:FindByName(_departure)

      -- Check if aircraft group was accidentally spawned on the runway.
      -- This can happen due to no parking slots available and other DCS bugs.
      local onrunway=false
      if _airbase then
        -- Check that we did not want to spawn at a runway or in air.
        if self.checkonrunway and _takeoff ~= RAT.wp.runway and _takeoff ~= RAT.wp.air then
          onrunway=_airbase:CheckOnRunWay(SpawnGroup, self.onrunwayradius, false)
        end
      end

      -- Workaround if group was spawned on runway.
      if onrunway then

        -- Error message.
        local text=string.format("ERROR: RAT group of %s was spawned on runway. Group #%d will be despawned immediately!", self.alias, i)
        MESSAGE:New(text,30):ToAllIf(self.Debug)
        self:E(self.lid..text)
        if self.Debug then
          SpawnGroup:FlareRed()
        end

        -- Despawn the group.
        self:_Despawn(SpawnGroup)

        -- Try to respawn the group if there is at least another airport or random airport selection is used.
        if (self.Ndeparture_Airports>=2 or self.random_departure) and _nrespawn<self.onrunwaymaxretry then
          -- Increase counter.
          _nrespawn=_nrespawn+1

          -- This creates a completely new group, i.e. livery etc from earlier flights (continuejourney, commute) is not taken over.
          text=string.format("Try spawning new aircraft of group %s at another location. Attempt %d of max %d.", self.alias,_nrespawn,self.onrunwaymaxretry)
          MESSAGE:New(text,10):ToAllIf(self.Debug)
          self:T(self.lid..text)

          -- Spawn new group.
          self:_SpawnWithRoute(nil, nil, nil, nil, nil, nil, nil, _nrespawn)
        else
          -- This will respawn the same fight (maybe with a different route) but already in the air.
          -- Note: Uncontrolled aircraft are not respawned in air.
          if self.respawn_inair and not self.uncontrolled then
            text=string.format("Spawning new aircraft of group %s in air since no parking slot is available at %s.", self.alias, _departure)
            MESSAGE:New(text,10):ToAll()
            self:T(self.lid..text)

            -- Spawn new group at this airport but already in air.
            self:_SpawnWithRoute(_departure, _destination, RAT.wp.air, _landing, _livery)
          end
        end
      end -- end of workaround

      -- Check if any unit of the group was spawned on top of another unit in the MOOSE data base.
      local ontop=false
      if self.checkontop and (_airbase and _airbase:GetAirbaseCategory()==Airbase.Category.AIRDROME) then
        ontop=self:_CheckOnTop(SpawnGroup, self.ontopradius)
      end

      if ontop then
        local text=string.format("ERROR: Group of %s was spawned on top of another unit. Group #%d will be despawned immediately!", self.alias, i)
        MESSAGE:New(text,30):ToAllIf(self.Debug)
        self:T(self.lid..text)
        if self.Debug then
          SpawnGroup:FlareYellow()
        end
        -- Despawn group.
        self:_Despawn(SpawnGroup)
      end
      
    end
  else
    self:T2(self.lid.."ERROR: Group does not exist in RAT:_OnBirth().")
  end
end


--- Function is executed when a unit starts its engines.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnEngineStartup(EventData)
  self:F3(EventData)
  self:T3(self.lid.."Captured event EngineStartup!")

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    -- Check that the template name actually belongs to this object.
    if EventPrefix and EventPrefix == self.alias then

      local text="Event: Group "..SpawnGroup:GetName().." started engines."
      self:T(self.lid..text)

      -- Set status.
      local status
      if SpawnGroup:InAir() then
        status=RAT.status.EventEngineStartAir
      else
        status=RAT.status.EventEngineStart
      end
      
      self:_SetStatus(SpawnGroup, status)

    end
    
  else
    self:T2(self.lid.."ERROR: Group does not exist in RAT:_EngineStartup().")
  end
end

--- Function is executed when a unit takes off.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnTakeoff(EventData)

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    -- Check that the template name actually belongs to this object.
    if EventPrefix and EventPrefix == self.alias then

      local text="Event: Group "..SpawnGroup:GetName().." is airborne."
      self:T(self.lid..text)

      -- Set status.
      local status=RAT.status.EventTakeoff
      self:_SetStatus(SpawnGroup, status)

      if self.respawn_after_takeoff then
        text="Event: Group "..SpawnGroup:GetName().." will be respawned after takeoff."
        self:T(self.lid..text)

        -- Respawn group. We respawn with no parameters from the old flight.
        self:_SpawnWithRoute(nil, nil, nil, nil, nil, nil, nil, nil)
      end
      
    end
  else
    self:T2(self.lid.."ERROR: Group does not exist in RAT:_OnTakeoff().")
  end
end

--- Function is executed when a unit lands.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnLand(EventData)

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    -- Check that the template name actually belongs to this object.
    if EventPrefix and EventPrefix == self.alias then

      local text="Event: Group "..SpawnGroup:GetName().." landed"
      self:T(self.lid..text)

      -- Set status.
      local status=RAT.status.EventLand
      self:_SetStatus(SpawnGroup, status)

      -- ATC plane landed. Take it out of the queue and set runway to free.
      if self.ATCswitch then
        RAT._ATCFlightLanded(SpawnGroup:GetName())
      end

      if self.respawn_at_landing and not self.norespawn then
        text="Event: Group "..SpawnGroup:GetName().." will be respawned"
        self:T(self.lid..text)

        -- Respawn group.
        self:_Respawn(SpawnGroup)
      end
      
    end

  else
    self:T2(self.lid.."ERROR: Group does not exist in RAT:_OnLand()")
  end
end

--- Function is executed when a unit shuts down its engines.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnEngineShutdown(EventData)
  self:F3(EventData)
  self:T3(self.lid.."Captured event EngineShutdown!")

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    -- Check that the template name actually belongs to this object.
    if EventPrefix and EventPrefix == self.alias then

      -- Despawn group only if it on the ground.
      if not SpawnGroup:InAir() then

        -- Current status.
        local currentstate=self:GetStatus(SpawnGroup)

        local text=string.format("Event: Unit %s of group %s shut down its engines. Current state %s.", EventData.IniUnitName, SpawnGroup:GetName(), currentstate)
        self:T(self.lid..text)

        -- Check that this is not the second unit of the group so that we dont trigger re- and despawns twice.
        if currentstate~=RAT.status.EventEngineShutdown and currentstate~="Dead" then

          -- Set status.
          local status=RAT.status.EventEngineShutdown
          self:_SetStatus(SpawnGroup, status)

          if not self.respawn_at_landing and not self.norespawn then
            text=string.format("Event: Group %s will be respawned. Current state %s => new state %s.", SpawnGroup:GetName(), currentstate, status)
            self:T(self.lid..text)

            -- Respawn group.
            self:_Respawn(SpawnGroup, nil, 3)
            
          else

            -- Despawn group.
            text="Event: Group "..SpawnGroup:GetName().." will be destroyed now"
            self:T(self.lid..text)
            self:_Despawn(SpawnGroup)
          
          end


        end

      end
    end

  else
    self:T2(self.lid.."ERROR: Group does not exist in RAT:_OnEngineShutdown().")
  end
end

--- Function is executed when a unit is hit.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnHit(EventData)
  self:F3(EventData)
  self:T(self.lid..string.format("Captured event Hit by %s! Initiator %s. Target %s", self.alias, tostring(EventData.IniUnitName), tostring(EventData.TgtUnitName)))

  local SpawnGroup = EventData.TgtGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    -- Check that the template name actually belongs to this object.
    if EventPrefix and EventPrefix == self.alias then
      -- Debug info.
      self:T(self.lid..string.format("Event: Group %s was hit. Unit %s.", SpawnGroup:GetName(), tostring(EventData.TgtUnitName)))

      local text=string.format("%s, unit %s was hit!", self.alias, EventData.TgtUnitName)
      MESSAGE:New(text, 10):ToAllIf(self.reportstatus or self.Debug)
    end
  end
end

--- Function is executed when a unit is dead or crashes.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnDeadOrCrash(EventData)
  self:F3(EventData)
  self:T3(self.lid.."Captured event DeadOrCrash!")

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    if EventPrefix then

      -- Check that the template name actually belongs to this object.
      if EventPrefix == self.alias then

        -- Decrease group alive counter.
        self.alive=self.alive-1

        -- Debug info.
        local text=string.format("Event: Group %s crashed or died. Alive counter = %d.", SpawnGroup:GetName(), self.alive)
        self:T(self.lid..text)

        -- Split crash and dead events.
        if EventData.id == world.event.S_EVENT_CRASH  then

          -- Call crash event. This handles when a group crashed or
          self:_OnCrash(EventData)

        elseif EventData.id == world.event.S_EVENT_DEAD  then

          -- Call dead event.
          self:_OnDead(EventData)

        end
      end
    end
  end
end

--- Function is executed when a unit is dead.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnDead(EventData)
  self:F3(EventData)
  self:T3(self.lid.."Captured event Dead!")

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    if EventPrefix then

      -- Check that the template name actually belongs to this object.
      if EventPrefix == self.alias then

        local text=string.format("Event: Group %s died. Unit %s.", SpawnGroup:GetName(), EventData.IniUnitName)
        self:T(self.lid..text)

        -- Set status.
        local status=RAT.status.EventDead
        self:_SetStatus(SpawnGroup, status)

      end
    end

  else
    self:T2(self.lid.."ERROR: Group does not exist in RAT:_OnDead().")
  end
end

--- Function is executed when a unit crashes.
-- @param #RAT self
-- @param Core.Event#EVENTDATA EventData
function RAT:_OnCrash(EventData)
  self:F3(EventData)
  self:T3(self.lid.."Captured event Crash!")

  local SpawnGroup = EventData.IniGroup --Wrapper.Group#GROUP

  if SpawnGroup then

    -- Get the template name of the group. This can be nil if this was not a spawned group.
    local EventPrefix = self:_GetPrefixFromGroup(SpawnGroup)

    -- Check that the template name actually belongs to this object.
    if EventPrefix and EventPrefix == self.alias then

      -- Get ratcraft object of this group.
      local ratcraft=self:_GetRatcraftFromGroup(SpawnGroup)
      
      if ratcraft then

        -- Update number of alive units in the group.
        ratcraft.nunits=ratcraft.nunits-1
        
        -- Number of initial units.
        local _n0=SpawnGroup:GetInitialSize()
  
        -- Debug info.
        local text=string.format("Event: Group %s crashed. Unit %s. Units still alive %d of %d.", SpawnGroup:GetName(), EventData.IniUnitName, ratcraft.nunits, _n0)
        self:T(self.lid..text)
  
        -- Set status.
        local status=RAT.status.EventCrash
        self:_SetStatus(SpawnGroup, status)
  
        -- Respawn group if all units are dead.
        if ratcraft.nunits==0 and self.respawn_after_crash and not self.norespawn then
        
          -- Debug info.
          self:T(self.lid..string.format("No units left of group %s. Group will be respawned now.", SpawnGroup:GetName()))
                    
          -- Respawn group.
          self:_Respawn(SpawnGroup)
        end
        
      else
        self:E(self.lid..string.format("ERROR: Could not find ratcraft object for crashed group %s!", SpawnGroup:GetName()))
      end

    end

  else
    if self.Debug then
      self:E(self.lid.."ERROR: Group does not exist in RAT:_OnCrash()!")
    end
  end
end


-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Create a waypoint that can be used with the Route command.
-- @param #RAT self
-- @param #number index Running index of waypoints. Starts with 1 which is normally departure/spawn waypoint.
-- @param #string description Descrition of Waypoint.
-- @param #number Type Type of waypoint.
-- @param Core.Point#COORDINATE Coord 3D coordinate of the waypoint.
-- @param #number Speed Speed in m/s.
-- @param #number Altitude Altitude in m.
-- @param Wrapper.Airbase#AIRBASE Airport Airport of object to spawn.
-- @return #table Waypoints for DCS task route or spawn template.
function RAT:_Waypoint(index, description, Type, Coord, Speed, Altitude, Airport)

  -- Altitude of input parameter or y-component of 3D-coordinate.
  local _Altitude=Altitude or Coord.y

  -- Land height at given coordinate.
  local Hland=Coord:GetLandHeight()

  -- convert type and action in DCS format
  local _Type=nil
  local _Action=nil
  local _alttype="RADIO"

  if Type==RAT.wp.cold then
    -- take-off with engine off
    _Type="TakeOffParking"
    _Action="From Parking Area"
    _Altitude = 10
    _alttype="RADIO"
  elseif Type==RAT.wp.hot then
    -- take-off with engine on
    _Type="TakeOffParkingHot"
    _Action="From Parking Area Hot"
    _Altitude = 10
    _alttype="RADIO"
  elseif Type==RAT.wp.runway then
    -- take-off from runway
    _Type="TakeOff"
    _Action="From Parking Area"
    _Altitude = 10
    _alttype="RADIO"
  elseif Type==RAT.wp.air then
    -- air start
    _Type="Turning Point"
    _Action="Turning Point"
    _alttype="BARO"
  elseif Type==RAT.wp.climb then
    _Type="Turning Point"
    _Action="Turning Point"
    _alttype="BARO"
  elseif Type==RAT.wp.cruise then
    _Type="Turning Point"
    _Action="Turning Point"
    _alttype="BARO"
  elseif Type==RAT.wp.descent then
    _Type="Turning Point"
    _Action="Turning Point"
    _alttype="BARO"
  elseif Type==RAT.wp.holding then
    _Type="Turning Point"
    _Action="Turning Point"
    --_Action="Fly Over Point"
    _alttype="BARO"
  elseif Type==RAT.wp.landing then
    _Type="Land"
    _Action="Landing"
    _Altitude = 10
    _alttype="RADIO"
  elseif Type==RAT.wp.finalwp then
    _Type="Turning Point"
    --_Action="Fly Over Point"
    _Action="Turning Point"
    _alttype="BARO"
  else
    self:E(self.lid.."ERROR: Unknown waypoint type in RAT:Waypoint() function!")
    _Type="Turning Point"
    _Action="Turning Point"
    _alttype="RADIO"
  end

  -- some debug info about input parameters
  local text=string.format("\n******************************************************\n")
  text=text..string.format("Waypoint =  %d\n", index)
  text=text..string.format("Template =  %s\n", self.SpawnTemplatePrefix)
  text=text..string.format("Alias    =  %s\n", self.alias)
  text=text..string.format("Type: %i - %s\n", Type, _Type)
  text=text..string.format("Action: %s\n", _Action)
  text=text..string.format("Coord: x = %6.1f km, y = %6.1f km, alt = %6.1f m\n", Coord.x/1000, Coord.z/1000, Coord.y)
  text=text..string.format("Speed = %6.1f m/s = %6.1f km/h = %6.1f knots\n", Speed, Speed*3.6, Speed*1.94384)
  text=text..string.format("Land     = %6.1f m ASL\n", Hland)
  text=text..string.format("Altitude = %6.1f m (%s)\n", _Altitude, _alttype)
  if Airport then
    if Type==RAT.wp.air then
      text=text..string.format("Zone = %s\n", Airport:GetName())
    else
      --text=text..string.format("Airport = %s with ID %i\n", Airport:GetName(), Airport:GetID())
      text=text..string.format("Airport = %s\n", Airport:GetName())
    end
  else
    text=text..string.format("No airport/zone specified\n")
  end
  text=text.."******************************************************\n"
  self:T2(self.lid..text)

  -- define waypoint
  local RoutePoint = {}
  -- coordinates and altitude
  RoutePoint.x = Coord.x
  RoutePoint.y = Coord.z
  RoutePoint.alt = _Altitude
  -- altitude type: BARO=ASL or RADIO=AGL
  RoutePoint.alt_type = _alttype
  -- type
  RoutePoint.type = _Type
  RoutePoint.action = _Action
  -- speed in m/s
  RoutePoint.speed = Speed
  RoutePoint.speed_locked = true
  -- ETA (not used)
  RoutePoint.ETA=nil
  RoutePoint.ETA_locked = false
  -- waypoint description
  RoutePoint.name=description

  if (Airport~=nil) and (Type~=RAT.wp.air) then
    local AirbaseID = Airport:GetID()
    local AirbaseCategory = Airport:GetAirbaseCategory()
    if AirbaseCategory == Airbase.Category.SHIP then
      RoutePoint.linkUnit = AirbaseID
      RoutePoint.helipadId = AirbaseID
    elseif AirbaseCategory == Airbase.Category.HELIPAD then
      RoutePoint.linkUnit = AirbaseID
      RoutePoint.helipadId = AirbaseID
    elseif AirbaseCategory == Airbase.Category.AIRDROME then
      RoutePoint.airdromeId = AirbaseID
    else
      self:T(self.lid.."Unknown Airport category in _Waypoint()!")
    end
  end

  -- Return waypoint.
  return RoutePoint
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Provide information about the assigned flightplan.
-- @param #RAT self
-- @param #table waypoints Waypoints of the flight plan.
-- @param #string comment Some comment to identify the provided information.
-- @param #table waypointdescriptions Waypoint descriptions.
-- @return #number total Total route length in meters.
function RAT:_Routeinfo(waypoints, comment, waypointdescriptions)
  local text=string.format("\n******************************************************\n")
  text=text..string.format("Template =  %s\n", self.SpawnTemplatePrefix)
  if comment then
    text=text..comment.."\n"
  end
  text=text..string.format("Number of waypoints = %i\n", #waypoints)
  -- info on coordinate and altitude
  for i=1,#waypoints do
    local p=waypoints[i]
    text=text..string.format("WP #%i: x = %6.1f km, y = %6.1f km, alt = %6.1f m  %s\n", i-1, p.x/1000, p.y/1000, p.alt, waypointdescriptions[i])
  end
  -- info on distance between waypoints
  local total=0.0
  for i=1,#waypoints-1 do
    local point1=waypoints[i]
    local point2=waypoints[i+1]
    local x1=point1.x
    local y1=point1.y
    local x2=point2.x
    local y2=point2.y
    local d=math.sqrt((x1-x2)^2 + (y1-y2)^2)
    local heading=self:_Course(point1, point2)
    total=total+d
    text=text..string.format("Distance from WP %i-->%i = %6.1f km. Heading = %03d :  %s - %s\n", i-1, i, d/1000, heading, waypointdescriptions[i], waypointdescriptions[i+1])
  end
  text=text..string.format("Total distance = %6.1f km\n", total/1000)
  text=text..string.format("******************************************************\n")

  -- Debug info.
  self:T2(self.lid..text)

  -- return total route length in meters
  return total
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Anticipated group name from alias and spawn index.
-- @param #RAT self
-- @param #number index Spawnindex of group if given or self.SpawnIndex+1 by default.
-- @return #string Name the group will get after it is spawned.
function RAT:_AnticipatedGroupName(index)
  local index=index or self.SpawnIndex+1
  return string.format("%s#%03d", self.alias, index)
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Randomly activates an uncontrolled aircraft.
-- @param #RAT self
function RAT:_ActivateUncontrolled()

  -- Spawn indices of uncontrolled inactive aircraft.
  local idx={}
  local rat={}

  -- Number of active aircraft.
  local nactive=0

  -- Loop over RAT groups and count the active ones.
  for spawnindex,_ratcraft in pairs(self.ratcraft) do
    local ratcraft=_ratcraft --#RAT.RatCraft

    local group=ratcraft.group --Wrapper.Group#GROUP

    if group and group:IsAlive() then

      local text=string.format("Uncontrolled: Group = %s (spawnindex = %d), active = %s", ratcraft.group:GetName(), spawnindex, tostring(ratcraft.active))
      self:T2(self.lid..text)

      if ratcraft.active then
        nactive=nactive+1
      else
        table.insert(idx, spawnindex)
      end

    end
  end

  -- Debug message.
  local text=string.format("Uncontrolled: Ninactive = %d,  Nactive = %d (of max %d)", #idx, nactive, self.activate_max)
  self:T(self.lid..text)

  if #idx>0 and nactive<self.activate_max then

    -- Randomly pick on group, which is activated.
    local index=idx[math.random(#idx)]
    
    local ratcraft=self.ratcraft[index] --#RAT.RatCraft

    -- Get corresponding group.
    local group=ratcraft.group --Wrapper.Group#GROUP
    
    -- Get departure airbase (if exists)
    local departureAirbase=self:_GetDepartureAirbase(ratcraft)
    
    -- Get FLIGHTCONTROL of departure airbase (if it exists)
    local departureFlightControl=nil
    if departureAirbase then
      departureFlightControl=_DATABASE:GetFlightControl(departureAirbase:GetName())      
    end
        
    if departureFlightControl then
      -- Group is ready to taxi. FLIGHCONTROL will start
      self:T(self.lid..string.format("RAT group %s is ready for takeoff", group:GetName()))
      ratcraft.flightgroup:SetReadyForTakeoff(true)      
    else
      -- Start aircraft.
      self:T(self.lid..string.format("RAT group %s is switching to controlled now", group:GetName()))
      ratcraft.flightgroup:StartUncontrolled()
    end
    
    -- Set status to active.
    ratcraft.active=true
    
    -- Set status to "Ready and Starting Engines".
    self:_SetStatus(group, RAT.status.EventBirth)    
  end

end

--- Set RAT group to (in-)visible for other AI forces.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Group to be set (in)visible.
-- @param #boolean switch If true, the group is invisible. If false the group will be visible.
function RAT:_CommandInvisible(group,switch)

  -- Command structure for setting groups to invisible.
  local SetInvisible = {id = 'SetInvisible', params = {value = switch}}

  -- Execute command.
  group:SetCommand(SetInvisible)
end

--- Set RAT group to be (im-)mortal.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Group to be set (im-)mortal.
-- @param #boolean switch True enables immortality, false disables it.
function RAT:_CommandImmortal(group, switch)

  -- Command structure for setting groups to invisible.
  local SetImmortal = {id = 'SetImmortal', params = {value = switch}}

  -- Execute command.
  group:SetCommand(SetImmortal)
end


--- Get aircraft dimensions length, width, height.
-- @param #RAT self
-- @param Wrapper.Unit#UNIT unit The unit which is we want the size of.
-- @return #number Size, i.e. max(length,width) of unit.
function RAT:_GetObjectSize(unit)
  local DCSunit=unit:GetDCSObject()
  if DCSunit then
    local DCSdesc=DCSunit:getDesc()
    -- dimensions
    local length=DCSdesc.box.max.x+math.abs(DCSdesc.box.min.x)
    local height=DCSdesc.box.max.y+math.abs(DCSdesc.box.max.y)
    local width =DCSdesc.box.max.z+math.abs(DCSdesc.box.min.z)
    return math.max(length,width)
  end
  return nil
end

--- Find aircraft that have accidentally been spawned on top of each other.
-- @param #RAT self
-- @param Wrapper.Group#GROUP group Units of this group will be checked.
-- @param #number distmin Allowed distance in meters between units. Units with a distance smaller than this number are considered to be on top of each other.
-- @return #boolean True if group was destroyed because it was on top of another unit. False if otherwise.
function RAT:_CheckOnTop(group, distmin)

  distmin=distmin or 2

  for i,uniti in pairs(group:GetUnits()) do
    local uniti=uniti --Wrapper.Unit#UNIT

    if uniti then

      local namei=uniti:GetName()

      for j,unitj in pairs(_DATABASE.UNITS) do

        if unitj then
          local unitj=unitj --Wrapper.Unit#UNIT
          local namej=unitj:GetName()

          if namei ~= namej then

            local DCSuniti=uniti:GetDCSObject()
            local DCSunitj=unitj:GetDCSObject()

            if DCSuniti and DCSuniti:isExist() and DCSunitj and DCSunitj:isExist() then

              -- Distance between units.
              local _dist=uniti:GetCoordinate():Get3DDistance(unitj:GetCoordinate())

              -- Check for min distance.
              if _dist < distmin then
                if (not uniti:InAir()) and (not unitj:InAir()) then
                  -- Trigger immidiate destuction of unit.
                  self:T(self.lid..string.format("Unit %s is on top of unit %s. Distance %.2f m.", namei, namej,_dist))
                  return true
                end
              end

            end -- if DCSunit exists
          end -- if namei==namej then
        end --if unitj then
      end -- for j, unitj
    end -- if uniti then
  end -- for i,uniti in

  return false
end


--- Calculate minimum distance between departure and destination for given minimum flight level and climb/decent rates.
-- @param #RAT self
-- @param #number alpha Angle of climb [rad].
-- @param #number beta Angle of descent [rad].
-- @param #number ha Height difference between departure and cruise altiude.
-- @param #number hb Height difference between cruise altitude and destination.
-- @return #number d1 Minimum distance for climb phase to reach cruise altitude.
-- @return #number d2 Minimum distance for descent phase to reach destination height.
-- @return #number dtot Minimum total distance to climb and descent.
function RAT:_MinDistance(alpha, beta, ha, hb)
  local d1=ha/math.tan(alpha)
  local d2=hb/math.tan(beta)
  return d1, d2, d1+d2
end


--- Add names of all friendly airports to possible departure or destination airports if they are not already in the list.
-- @param #RAT self
-- @param #table ports List of departure or destination airports/zones that will be added.
function RAT:_AddFriendlyAirports(ports)
  for _,airport in pairs(self.airports) do
    if not self:_NameInList(ports, airport:GetName()) then
      table.insert(ports, airport:GetName())
    end
  end
end

--- Check if a name/string is in a list or not.
-- @param #RAT self
-- @param #table liste List of names to be checked.
-- @param #string name Name to be checked for.
function RAT:_NameInList(liste, name)
  for _,item in pairs(liste) do
    if item==name then
      return true
    end
  end
  return false
end

--- Get destination airbase of a given ratcraft.
-- @param #RAT self
-- @param #RAT.RatCraft ratcraft Ratcraft object.
-- @return Wrapper.Airbase#AIRBASE Destination airbase or nil.
function RAT:_GetDestinationAirbase(ratcraft)

  if ratcraft and ratcraft.destination then
  
    local airbase=AIRBASE:FindByName(ratcraft.destination)
    
    return airbase
  
  end

  return nil
end


--- Get departure airbase of a given ratcraft.
-- @param #RAT self
-- @param #RAT.RatCraft ratcraft Ratcraft object.
-- @return Wrapper.Airbase#AIRBASE Destination airbase or nil.
function RAT:_GetDepartureAirbase(ratcraft)

  if ratcraft and ratcraft.departure then
  
    local name=ratcraft.departure:GetName()  
    local airbase=AIRBASE:FindByName(name)
    
    return airbase  
  end

  return nil
end




--- Test if an airport exists on the current map.
-- @param #RAT self
-- @param #string name
-- @return #boolean True if airport exsits, false otherwise.
function RAT:_AirportExists(name)
  for _,airport in pairs(self.airports_map) do
    if airport:GetName()==name then
      return true
    end
  end
  return false
end

--- Test if a zone exists.
-- @param #RAT self
-- @param #string name
-- @return #boolean True if zone exsits, false otherwise.
function RAT:_ZoneExists(name)
  local z=ZONE:FindByName(name) --trigger.misc.getZone(name) as suggested by @Viking on MOOSE discord #rat
  if z then
    return true
  end
  return false
end

--- Set ROE for a group.
-- @param #RAT self
-- @param Ops.FlightGroup#FLIGHTGROUP flightgroup Group for which the ROE is set.
-- @param #string roe ROE of group.
function RAT:_SetROE(flightgroup, roe)
  
  roe=roe or self.roe
  
  self:T(self.lid.."Setting ROE to "..roe.." for group "..flightgroup:GetName())  
  
  local _roe=ENUMS.ROE.WeaponHold
  if roe==RAT.ROE.returnfire then
    _roe=ENUMS.ROE.ReturnFire
  elseif roe==RAT.ROE.weaponfree then
    _roe=ENUMS.ROE.OpenFireWeaponFree
  else
    
  end
  
  flightgroup:SetDefaultROE(_roe)
  flightgroup:SwitchROE(_roe)
  
end


--- Set ROT for a group.
-- @param #RAT self
-- @param Ops.FlightGroup#FLIGHTGROUP flightgroup Group for which the ROT is set.
-- @param #string rot ROT of group.
function RAT:_SetROT(flightgroup, rot)

  rot=rot or self.rot
  
  self:T(self.lid.."Setting ROT to "..rot.." for group "..flightgroup:GetName())
  
  local _rot=ENUMS.ROT.NoReaction
  if rot==RAT.ROT.passive then
    _rot=ENUMS.ROT.PassiveDefense
  elseif rot==RAT.ROT.evade then
    _rot=ENUMS.ROT.EvadeFire
  else
    
  end
  
  flightgroup:SetDefaultROT(_rot)
  flightgroup:SwitchROT(_rot)  
  
end


--- Create a table with the valid coalitions for departure and destination airports.
-- @param #RAT self
function RAT:_SetCoalitionTable()
  -- get all possible departures/destinations depending on coalition
  if self.friendly==RAT.coal.neutral then
    self.ctable={coalition.side.NEUTRAL}
  elseif self.friendly==RAT.coal.same then
    self.ctable={self.coalition, coalition.side.NEUTRAL}
  elseif self.friendly==RAT.coal.sameonly then
    self.ctable={self.coalition}
  else
    self:E(self.lid.."ERROR: Unknown friendly coalition in _SetCoalitionTable(). Defaulting to NEUTRAL.")
    self.ctable={self.coalition, coalition.side.NEUTRAL}
  end
end


---Determine the heading from point a to point b.
--@param #RAT self
--@param Core.Point#COORDINATE a Point from.
--@param Core.Point#COORDINATE b Point to.
--@return #number Heading/angle in degrees.
function RAT:_Course(a,b)
  local dx = b.x-a.x
  -- take the right value for y-coordinate (if we have "alt" then "y" if not "z")
  local ay
  if a.alt then
    ay=a.y
  else
    ay=a.z
  end
  local by
  if b.alt then
    by=b.y
  else
    by=b.z
  end
  local dy = by-ay
  local angle = math.deg(math.atan2(dy,dx))
  if angle < 0 then
    angle = 360 + angle
  end
  return angle
end

---Determine the heading for an aircraft to be entered in the route template.
--@param #RAT self
--@param #number course The course between two points in degrees.
--@return #number heading Heading in rad.
function RAT:_Heading(course)
  local h
  if course<=180 then
    h=math.rad(course)
  else
    h=-math.rad(360-course)
  end
  return h
end


--- Randomize a value by a certain amount.
-- @param #RAT self
-- @param #number value The value which should be randomized
-- @param #number fac Randomization factor.
-- @param #number lower (Optional) Lower limit of the returned value.
-- @param #number upper (Optional) Upper limit of the returned value.
-- @return #number Randomized value.
-- @usage _Randomize(100, 0.1) returns a value between 90 and 110, i.e. a plus/minus ten percent variation.
-- @usage _Randomize(100, 0.5, nil, 120) returns a value between 50 and 120, i.e. a plus/minus fivty percent variation with upper bound 120.
function RAT:_Randomize(value, fac, lower, upper)
  local min
  if lower then
    min=math.max(value-value*fac, lower)
  else
    min=value-value*fac
  end
  local max
  if upper then
    max=math.min(value+value*fac, upper)
  else
    max=value+value*fac
  end

  local r=math.random(min, max)

  -- debug info
  if self.Debug then
    local text=string.format("Random: value = %6.2f, fac = %4.2f, min = %6.2f, max = %6.2f, r = %6.2f", value, fac, min, max, r)
    self:T3(self.lid..text)
  end

  return r
end


--- Place markers of the waypoints. Note we assume a very specific number and type of waypoints here.
-- @param #RAT self
-- @param #table waypoints Table with waypoints.
-- @param #table waypointdescriptions Table with waypoint descriptions
-- @param #number index Spawn index of group.
function RAT:_PlaceMarkers(waypoints, waypointdescriptions, index)
  for i=1,#waypoints do
    self:_SetMarker(waypointdescriptions[i], waypoints[i], index)
    if self.Debug then
      local text=string.format("Marker at waypoint #%d: %s for flight #%d", i, waypointdescriptions[i], index)
      self:T2(self.lid..text)
    end
  end
end


--- Set a marker visible for all on the F10 map.
-- @param #RAT self
-- @param #string text Info text displayed at maker.
-- @param #table wp Position of marker coming in as waypoint, i.e. has x, y and alt components.
-- @param #number index Spawn index of group.
function RAT:_SetMarker(text, wp, index)
  RAT.markerid=RAT.markerid+1
  self.markerids[#self.markerids+1]=RAT.markerid
  if self.Debug then
    local text2=string.format("%s: placing marker with ID %d and text %s", self.alias, RAT.markerid, text)
    self:T2(self.lid..text2)
  end
  -- Convert to coordinate.
  local vec={x=wp.x, y=wp.alt, z=wp.y}
  local flight=self:GetGroupFromIndex(index):GetName()
  -- Place maker visible for all on the F10 map.
  local text1=string.format("%s:\n%s", flight, text)
  trigger.action.markToAll(RAT.markerid, text1, vec, false, "")
end

--- Delete all markers on F10 map.
-- @param #RAT self
function RAT:_DeleteMarkers()
  for k,v in ipairs(self.markerids) do
    trigger.action.removeMark(v)
  end
  for k,v in ipairs(self.markerids) do
    self.markerids[k]=nil
  end
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--- Modifies the template of the group to be spawned.
-- In particular, the waypoints of the group's flight plan are copied into the spawn template.
-- This allows to spawn at airports and also land at other airports, i.e. circumventing the DCS "landing bug".
-- @param #RAT self
-- @param #table waypoints The waypoints of the AI flight plan.
-- @param #string livery (Optional) Livery of the aircraft. All members of a flight will get the same livery.
-- @param Core.Point#COORDINATE spawnplace (Optional) Place where spawning should happen. If not present, first waypoint is taken.
-- @param Wrapper.Airbase#AIRBASE departure Departure airbase or zone.
-- @param #number takeoff Takeoff type.
-- @param #table parkingdata Parking data, i.e. parking spot coordinates and terminal ids for all units of the group.
-- @param #boolean uncontrolled If `true`, group is spawned uncontrolled.
-- @return #boolean True if modification was successful or nil if not, e.g. when no parking space was found and spawn in air is disabled.
function RAT:_ModifySpawnTemplate(waypoints, livery, spawnplace, departure, takeoff, parkingdata, uncontrolled)
  self:F2({waypoints=waypoints, livery=livery, spawnplace=spawnplace, departure=departure, takeoff=takeoff, parking=parkingdata})

  -- The 3D vector of the first waypoint, i.e. where we actually spawn the template group.
  local PointVec3 = COORDINATE:New(waypoints[1].x, waypoints[1].alt, waypoints[1].y)
  if spawnplace then
    PointVec3 = COORDINATE:NewFromCoordinate(spawnplace)
  end

  -- Template group and unit.
  local TemplateGroup = GROUP:FindByName(self.SpawnTemplatePrefix)
  local TemplateUnit=TemplateGroup:GetUnit(1)

  -- Check if we spawn on ground.
  local spawnonground=takeoff==RAT.wp.cold or takeoff==RAT.wp.hot or takeoff==RAT.wp.runway

  -- Check where we actually spawn if we spawn on ground.
  local spawnonship=false
  local spawnonfarp=false
  local spawnonrunway=false
  local spawnonairport=false
  if spawnonground then
    local AirbaseCategory = departure:GetAirbaseCategory()
    if AirbaseCategory == Airbase.Category.SHIP then
      spawnonship=true
    elseif AirbaseCategory == Airbase.Category.HELIPAD then
      spawnonfarp=true
    elseif AirbaseCategory == Airbase.Category.AIRDROME then
      spawnonairport=true
    end
    spawnonrunway=takeoff==RAT.wp.runway
  end

  local automatic=false
  if automatic and spawnonground then
    PointVec3=PointVec3:GetClosestParkingSpot(true, departure)
  end

  -- Heading from first to seconds waypoints to align units in case of air start.
  local course  = self:_Course(waypoints[1], waypoints[2])
  local heading = self:_Heading(course)

  if self:_GetSpawnIndex(self.SpawnIndex+1) then

    -- Get template from group.
    local SpawnTemplate = self.SpawnGroups[self.SpawnIndex].SpawnTemplate

    if SpawnTemplate then
      self:T(SpawnTemplate)

      -- Spawn aircraft in uncontrolled state.
      if self.uncontrolled or uncontrolled then
        -- This is used in the SPAWN:SpawnWithIndex() function. Some values are overwritten there!
        --self.SpawnUnControlled=true
        SpawnTemplate.uncontrolled=true
      end

      -- Number of units in the group. With grouping this can actually differ from the template group size!
      local nunits=#SpawnTemplate.units

      -- Array with parking spots coordinates.
      local parkingspots={}
      local parkingindex={}
      local spots

      -- Spawn happens on ground, i.e. at an airbase, a FARP or a ship.
      if spawnonground then

        -- Number of free parking spots.
        local nfree=0

        -- Set terminal type. Can also be nil.
        local termtype=self.termtype
        if spawnonrunway then
          termtype=AIRBASE.TerminalType.Runway
        end

        -- Scan options. Might make that input somehow.
        local scanradius=self.parkingscanradius
        local scanunits=true
        local scanstatics=true
        local scanscenery=self.parkingscanscenery
        local verysafe=self.parkingverysafe

        -- Get free parking spots depending on where we spawn.
        if  spawnonship or spawnonfarp or spawnonrunway then
          -- These places work procedural and have some kind of build in queue ==> Less effort.
          self:T(self.lid..string.format("Group %s is spawned on farp/ship/runway %s.", self.alias, departure:GetName()))
          nfree=departure:GetFreeParkingSpotsNumber(termtype, true)
          spots=departure:GetFreeParkingSpotsTable(termtype, true)
          -- Had a case at a Gas Platform where nfree=1 but spots from GetFreeParkingSpotsTable were empty.
          --spots=departure:GetParkingSpotsTable(termtype)
          self:T(self.lid..string.format("Free nfree=%d nspots=%d", nfree, #spots))
        elseif parkingdata~=nil then
          -- Parking data explicitly set by user as input parameter.
          self:T2("Spawning with explicit parking data")
          nfree=#parkingdata
          spots=parkingdata
        else
          -- Helo is spawned.
          if self.category==RAT.cat.heli then
            if termtype==nil then
              -- Try exclusive helo spots first.
              self:T(self.lid..string.format("Helo group %s is spawned at %s using terminal type %d.", self.alias, departure:GetName(), AIRBASE.TerminalType.HelicopterOnly))
              spots=departure:FindFreeParkingSpotForAircraft(TemplateGroup, AIRBASE.TerminalType.HelicopterOnly, scanradius, scanunits, scanstatics, scanscenery, verysafe, nunits)
              nfree=#spots
              if nfree<nunits then
                -- Not enough helo ports. Let's try also other terminal types.
                self:T(self.lid..string.format("Helo group %s is spawned at %s using terminal type %d.", self.alias, departure:GetName(), AIRBASE.TerminalType.HelicopterUsable))
                spots=departure:FindFreeParkingSpotForAircraft(TemplateGroup, AIRBASE.TerminalType.HelicopterUsable, scanradius, scanunits, scanstatics, scanscenery, verysafe, nunits)
                nfree=#spots
              end
            else
              -- Terminal type specified explicitly.
              self:T(self.lid..string.format("Helo group %s is at %s using terminal type %d.", self.alias, departure:GetName(), termtype))
              spots=departure:FindFreeParkingSpotForAircraft(TemplateGroup, termtype, scanradius, scanunits, scanstatics, scanscenery, verysafe, nunits)
              nfree=#spots
            end
          else
            -- Fixed wing aircraft is spawned.
            if termtype==nil then
            --TODO: Add some default cases for transport, bombers etc. if no explicit terminal type is provided.
            --TODO: We don't want Bombers to spawn in shelters. But I don't know a good attribute for just fighers.
            --TODO: Some attributes are "Helicopters", "Bombers", "Transports", "Battleplanes". Need to check it out.
              local bomber=TemplateUnit:HasAttribute("Bombers")
              local transport=TemplateUnit:HasAttribute("Transports")
              if bomber or transport then
                -- First we fill the potentially bigger spots.
                self:T(self.lid..string.format("Transport/bomber group %s is spawned at %s using terminal type %d.", self.alias, departure:GetName(), AIRBASE.TerminalType.OpenBig))
                spots=departure:FindFreeParkingSpotForAircraft(TemplateGroup, AIRBASE.TerminalType.OpenBig, scanradius, scanunits, scanstatics, scanscenery, verysafe, nunits)
                nfree=#spots
                if nfree<nunits then
                  -- Now we try the smaller ones.
                  self:T(self.lid..string.format("Transport/bomber group %s is at %s using terminal type %d.", self.alias, departure:GetName(), AIRBASE.TerminalType.OpenMed))
                  spots=departure:FindFreeParkingSpotForAircraft(TemplateGroup, AIRBASE.TerminalType.OpenMed, scanradius, scanunits, scanstatics, scanscenery, verysafe, nunits)
                  nfree=#spots
                end
              else
                self:T(self.lid..string.format("Fighter group %s is spawned at %s using terminal type %d.", self.alias, departure:GetName(), AIRBASE.TerminalType.FighterAircraft))
                spots=departure:FindFreeParkingSpotForAircraft(TemplateGroup, AIRBASE.TerminalType.FighterAircraft, scanradius, scanunits, scanstatics, scanscenery, verysafe, nunits)
                nfree=#spots
              end
            else
              -- Terminal type explicitly given.
              self:T(self.lid..string.format("Plane group %s is spawned at %s using terminal type %d.", self.alias, departure:GetName(), termtype))
              spots=departure:FindFreeParkingSpotForAircraft(TemplateGroup, termtype, scanradius, scanunits, scanstatics, scanscenery, verysafe, nunits)
              nfree=#spots
            end
          end
        end

        -- Get parking data (just for debugging).
        if false then
          local parkingdata=departure:GetParkingSpotsTable(termtype)
          self:T2(self.lid..string.format("Parking at %s, terminal type %s:", departure:GetName(), tostring(termtype)))
          for _,_spot in pairs(parkingdata) do
            self:T2(self.lid..string.format("%s, Termin Index = %3d, Term Type = %03d, Free = %5s, TOAC = %5s, Term ID0 = %3d, Dist2Rwy = %4d",
            departure:GetName(), _spot.TerminalID, _spot.TerminalType,tostring(_spot.Free),tostring(_spot.TOAC),_spot.TerminalID0,_spot.DistToRwy))
          end
          self:T(self.lid..string.format("%s at %s: free parking spots = %d - number of units = %d", self.alias, departure:GetName(), nfree, nunits))
        end


        -- Set this to true if not enough spots are available for emergency air start.
        local _notenough=false

        -- Need to differentiate some cases again.
        if spawnonship or spawnonfarp or spawnonrunway then

          -- On free spot required in these cases.
          if nfree >=1 then

            -- All units get the same spot. DCS takes care of the rest.
            for i=1,nunits do
              table.insert(parkingspots, spots[1].Coordinate)
              table.insert(parkingindex, spots[1].TerminalID)
            end
            -- This is actually used...
            PointVec3=spots[1].Coordinate

          else
            -- If there is absolutely not spot ==> air start!
            _notenough=true
          end

        elseif spawnonairport then

          if nfree>=nunits then

            for i=1,nunits do
              table.insert(parkingspots, spots[i].Coordinate)
              table.insert(parkingindex, spots[i].TerminalID)
            end

          else
            -- Not enough spots for the whole group ==> air start!
            _notenough=true
          end
        end

        -- Not enough spots ==> Prepare airstart.
        if _notenough then

          if self.respawn_inair and not self.SpawnUnControlled then
            self:E(self.lid..string.format("WARNING: Group %s has no parking spots at %s ==> air start!", self.SpawnTemplatePrefix, departure:GetName()))

            -- Not enough parking spots at the airport ==> Spawn in air.
            spawnonground=false
            spawnonship=false
            spawnonfarp=false
            spawnonrunway=false

            -- Set waypoint type/action to turning point.
            waypoints[1].type   = GROUPTEMPLATE.Takeoff[GROUP.Takeoff.Air][1] -- type   = Turning Point
            waypoints[1].action = GROUPTEMPLATE.Takeoff[GROUP.Takeoff.Air][2] -- action = Turning Point

            -- Adjust altitude to be 500-1000 m above the airbase.
            PointVec3.x=PointVec3.x+math.random(-1500,1500)
            PointVec3.z=PointVec3.z+math.random(-1500,1500)
            if self.category==RAT.cat.heli then
              PointVec3.y=PointVec3:GetLandHeight()+math.random(100,1000)
            else
              -- Randomize position so that multiple AC wont be spawned on top even in air.
              PointVec3.y=PointVec3:GetLandHeight()+math.random(500,3000)
            end
          else
            self:E(self.lid..string.format("WARNING: Group %s has no parking spots at %s ==> No emergency air start or uncontrolled spawning ==> No spawn!", self.SpawnTemplatePrefix, departure:GetName()))
            return nil
          end
        end

      else

        -- Air start requested initially!

        --PointVec3.y is already set from first waypoint here!

      end

      -- Translate the position of the Group Template to the Vec3.
      for UnitID = 1, nunits do

        -- Template of the current unit.
        local UnitTemplate = SpawnTemplate.units[UnitID]

        -- Tranlate position and preserve the relative position/formation of all aircraft.
        local SX = UnitTemplate.x
        local SY = UnitTemplate.y
        local BX = SpawnTemplate.route.points[1].x
        local BY = SpawnTemplate.route.points[1].y
        local TX = PointVec3.x + (SX-BX)
        local TY = PointVec3.z + (SY-BY)

        if spawnonground then

          -- Ships and FARPS seem to have a build in queue.
          if spawnonship or spawnonfarp or spawnonrunway or automatic then
            self:T(self.lid..string.format("RAT group %s spawning at farp, ship or runway %s.", self.alias, departure:GetName()))

            -- Spawn on ship. We take only the position of the ship.
            SpawnTemplate.units[UnitID].x   = PointVec3.x --TX
            SpawnTemplate.units[UnitID].y   = PointVec3.z --TY
            SpawnTemplate.units[UnitID].alt = PointVec3.y
          else
            self:T(self.lid..string.format("RAT group %s spawning at airbase %s on parking spot id %d", self.alias, departure:GetName(), parkingindex[UnitID]))

            -- Get coordinates of parking spot.
            SpawnTemplate.units[UnitID].x   = parkingspots[UnitID].x
            SpawnTemplate.units[UnitID].y   = parkingspots[UnitID].z
            SpawnTemplate.units[UnitID].alt = parkingspots[UnitID].y
          end

        else
          self:T(self.lid..string.format("RAT group %s spawning in air at %s.", self.alias, departure:GetName()))

          -- Spawn in air as requested initially. Original template orientation is perserved, altitude is already correctly set.
          SpawnTemplate.units[UnitID].x   = TX
          SpawnTemplate.units[UnitID].y   = TY
          SpawnTemplate.units[UnitID].alt = PointVec3.y
        end

        -- Place marker at spawn position.
        if self.Debug then
          local unitspawn=COORDINATE:New(SpawnTemplate.units[UnitID].x, SpawnTemplate.units[UnitID].alt, SpawnTemplate.units[UnitID].y)
          unitspawn:MarkToAll(string.format("RAT %s Spawnplace unit #%d", self.alias, UnitID))
        end

        -- Parking spot id.
        UnitTemplate.parking = nil
        UnitTemplate.parking_id = nil
        if parkingindex[UnitID] and not automatic then
          UnitTemplate.parking = parkingindex[UnitID]
        end

        -- Debug info.
        self:T2(self.lid..string.format("RAT group %s unit number %d: Parking    = %s",self.alias, UnitID, tostring(UnitTemplate.parking)))
        self:T2(self.lid..string.format("RAT group %s unit number %d: Parking ID = %s",self.alias, UnitID, tostring(UnitTemplate.parking_id)))


        -- Set initial heading.
        SpawnTemplate.units[UnitID].heading = heading
        SpawnTemplate.units[UnitID].psi = -heading

        -- Set livery (will be the same for all units of the group).
        if livery then
          SpawnTemplate.units[UnitID].livery_id = livery
        end

        -- Set type of aircraft.
        if self.actype then
          SpawnTemplate.units[UnitID]["type"] = self.actype
        end

        -- Set AI skill.
        SpawnTemplate.units[UnitID]["skill"] = self.skill

        -- Onboard number.
        if self.onboardnum then
          SpawnTemplate.units[UnitID]["onboard_num"] = string.format("%s%d%02d", self.onboardnum, (self.SpawnIndex-1)%10, (self.onboardnum0-1)+UnitID)
        end

        -- Modify coalition and country of template.
        SpawnTemplate.CoalitionID=self.coalition
        if self.country then
          SpawnTemplate.CountryID=self.country
        end

      end

      -- Copy waypoints into spawntemplate. By this we avoid the nasty DCS "landing bug" :)
      for i,wp in ipairs(waypoints) do
        SpawnTemplate.route.points[i]=wp
      end

      -- Also modify x,y of the template. Not sure why.
      SpawnTemplate.x = PointVec3.x
      SpawnTemplate.y = PointVec3.z

      -- Enable/disable radio. Same as checking the COMM box in the ME
      if self.radio then
        SpawnTemplate.communication=self.radio
      end

      -- Set radio frequency and modulation.
      if self.frequency then
        SpawnTemplate.frequency=self.frequency
      end
      if self.modulation then
        SpawnTemplate.modulation=self.modulation
      end

      -- Debug output.
      self:T(SpawnTemplate)
    end
  end

  return true
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--- RAT ATC
---

--- Data structure a RAT ATC airbase object.
-- @type RAT.AtcAirport
-- @field #table queue Queue.
-- @field #boolean busy Whether airport is busy.
-- @field #table onfinal List of flights on final.
-- @field #number Nonfinal Number of flights on final.
-- @field #number traffic Number of flights that landed (just for stats).
-- @field #number Tlastclearance Time stamp when last flight started final approach.

--- Data structure a RAT ATC airbase object.
-- @type RAT.AtcFlight
-- @field #string destination Name of the destination airbase.
-- @field #number Tarrive Time stamp when flight arrived at holding.
-- @field #number holding Holding time.
-- @field #number Tonfinal Time stamp when flight started final approach.

--- Initializes the ATC arrays and starts schedulers.
-- @param #table airports_map List of all airports of the map.
function RAT._ATCInit(airports_map)

  if not RAT.ATC.init then
  
    local text="Starting RAT ATC.\nSimultanious = "..RAT.ATC.Nclearance.."\n".."Delay        = "..RAT.ATC.delay
    BASE:I(RAT.id..text)
    
    for _,ap in pairs(airports_map) do
      local airbase=ap --Wrapper.Airbase#AIRBASE
      local name=airbase:GetName()
      
      local fc=_DATABASE:GetFlightControl(name)
      
      if not fc then
      
        local airport={} --#RAT.AtcAirport
        airport.queue={}
        airport.busy=false
        airport.onfinal={}
        airport.Nonfinal=0
        airport.traffic=0
        airport.Tlastclearance=nil
      
        RAT.ATC.airport[name]=airport
        
      end
    end
    
    SCHEDULER:New(nil, RAT._ATCCheck,  {}, 5, 15)
    SCHEDULER:New(nil, RAT._ATCStatus, {}, 5, 60)
    
    RAT.ATC.T0=timer.getTime()    
  end
  
  -- Init done
  RAT.ATC.init=true
end

--- Adds andd initializes a new flight after it was spawned.
-- @param #RAT self
-- @param #string name Group name of the flight.
-- @param #string dest Name of the destination airport.
function RAT:_ATCAddFlight(name, dest)
  -- Debug info
  BASE:I(RAT.id..string.format("ATC %s: Adding flight %s with destination %s.", dest, name, dest))

  -- Create new flight  
  local flight={} --#RAT.AtcFlight
  flight.destination=dest
  flight.Tarrive=-1
  flight.holding=-1
  flight.Tarrive=-1
  --flight.Tonfinal=-1
  
  RAT.ATC.flight[name]=flight
end

--- Deletes a flight from ATC lists after it landed.
-- @param #table t Table.
-- @param #string entry Flight name which shall be deleted.
function RAT._ATCDelFlight(t,entry)
  for k,_ in pairs(t) do
    if k==entry then
      BASE:I(RAT.id..string.format("Removing flight %s from queue", entry))
      t[entry]=nil
    end
  end
end

--- Registers a flight once it is near its holding point at the final destination.
-- @param #RAT self
-- @param #string name Group name of the flight.
-- @param #number time Time the fight first registered.
function RAT._ATCRegisterFlight(name, time)
  BASE:I(RAT.id..string.format("Flight %s registered at ATC for landing clearance.", name))
  RAT.ATC.flight[name].Tarrive=time
  RAT.ATC.flight[name].holding=0
end


--- ATC status report about flights.
function RAT._ATCStatus()

  -- Current time.
  local Tnow=timer.getTime()

  for name,_flight in pairs(RAT.ATC.flight) do
    local flight=_flight --#RAT.AtcFlight

    -- Holding time at destination.
    local hold=RAT.ATC.flight[name].holding
    local dest=RAT.ATC.flight[name].destination
    
    local airport=RAT.ATC.airport[dest] --#RAT.AtcAirport
    
    if airport then

      if hold >= 0 then
  
        -- Some string whether the runway is busy or not.
        local busy="Runway state is unknown"
        if airport.Nonfinal>0 then
          busy="Runway is occupied by "..airport.Nonfinal
        else
          busy="Runway is currently clear"
        end
  
        -- Aircraft is holding.
        local text=string.format("ATC %s: Flight %s is holding for %i:%02d. %s.", dest, name, hold/60, hold%60, busy)
        BASE:I(RAT.id..text)
  
      elseif hold==RAT.ATC.onfinal then
  
        -- Aircarft is on final approach for landing.
        local Tfinal=Tnow-flight.Tonfinal
  
        local text=string.format("ATC %s: Flight %s is on final. Waiting %i:%02d for landing event.", dest, name, Tfinal/60, Tfinal%60)
        BASE:I(RAT.id..text)
  
      elseif hold==RAT.ATC.unregistered then
  
        -- Aircraft has not arrived at holding point.
        --self:T(string.format("ATC %s: Flight %s is not registered yet (hold %d).", dest, name, hold))
  
      else
        BASE:E(RAT.id.."ERROR: Unknown holding time in RAT:_ATCStatus().")
      end
    else
      -- Not a RAT.ATC airport (should be managed by a FLIGHTCONTROL)
    end
  end

end

--- Main ATC function. Updates the landing queue of all airports and inceases holding time for all flights.
function RAT._ATCCheck()

  -- Init queue of flights at all airports.
  RAT._ATCQueue()

  -- Current time.
  local Tnow=timer.getTime()

  for airportname,_airport in pairs(RAT.ATC.airport) do
    local airport=_airport --#RAT.AtcAirport

    for qID,flightname in pairs(airport.queue) do
      local flight=RAT.ATC.flight[flightname] --#RAT.AtcFlight

      -- Number of aircraft in queue.
      local nqueue=#airport.queue

      -- Conditions to clear an aircraft for landing
      local landing1=false
      if airport.Tlastclearance then
        -- Landing if time is enough and less then two planes are on final.
        landing1=(Tnow-airport.Tlastclearance > RAT.ATC.delay) and airport.Nonfinal < RAT.ATC.Nclearance
      end
      
      -- No other aircraft is on final.
      local landing2=airport.Nonfinal==0


      if not landing1 and not landing2 then

        -- Update holding time.
        flight.holding=Tnow-flight.Tarrive

        -- Debug message.
        local text=string.format("ATC %s: Flight %s runway is busy. You are #%d of %d in landing queue. Your holding time is %i:%02d.", 
        airportname, flightname, qID, nqueue, flight.holding/60, flight.holding%60)
        BASE:I(RAT.id..text)

      else

        local text=string.format("ATC %s: Flight %s was cleared for landing. Your holding time was %i:%02d.", 
        airportname, flightname, flight.holding/60, flight.holding%60)
        BASE:I(RAT.id..text)

        -- Clear flight for landing.
        RAT._ATCClearForLanding(airportname, flightname)

      end

    end

  end

  -- Update queue of flights at all airports.
  RAT._ATCQueue()

end

--- Giving landing clearance for aircraft by setting user flag.
-- @param #string airportname Name of destination airport.
-- @param #string flightname Group name of flight, which gets landing clearence.
function RAT._ATCClearForLanding(airportname, flightname)

  -- Find FLIGHTGROUP in database.
  local flightgroup=_DATABASE:FindOpsGroup(flightname) --Ops.FlightGroup#FLIGHTGROUP
  
  if flightgroup then
  
    -- Give clear to land signal.
    flightgroup:ClearToLand()
    
    
    local flight=RAT.ATC.flight[flightname] --#RAT.AtcFlight
    
    -- Flight is cleared for landing.
    flight.holding=RAT.ATC.onfinal
    
    -- Current time.
    flight.Tonfinal=timer.getTime()    


    local airport=RAT.ATC.airport[airportname] --#RAT.AtcAirport
    
    -- Airport runway is busy now.
    airport.busy=true
    
    -- Flight which is landing.
    airport.onfinal[flightname]=flight
    
    -- Number of planes on final approach.
    airport.Nonfinal=airport.Nonfinal+1
    
    -- Last time an aircraft got landing clearance.
    airport.Tlastclearance=timer.getTime()

  
    -- Debug message.
    BASE:I(RAT.id..string.format("ATC %s: Flight %s cleared for landing", airportname, flightname))
  
    if string.find(flightname,"#") then
      flightname =  string.match(flightname,"^(.+)#")
    end
    local text=string.format("ATC %s: Flight %s you are cleared for landing.", airportname, flightname)  
    MESSAGE:New(text, 10):ToAllIf(RAT.ATC.messages)

  else
    BASE:E("Could not clear flight for landing!")
  end
    
end

--- Takes care of organisational stuff after a plane has landed.
-- @param #string name Group name of flight.
function RAT._ATCFlightLanded(name)

  local flight=RAT.ATC.flight[name] --#RAT.AtcFlight

  if flight then

    -- Destination airport.
    local dest=flight.destination

    -- Times for holding and final approach.
    local Tnow=timer.getTime()
    local Tfinal=Tnow-flight.Tonfinal
    local Thold=flight.Tonfinal-flight.Tarrive
    
    local airport=RAT.ATC.airport[dest] --#RAT.AtcAirport

    -- Airport is not busy any more.
    airport.busy=false

    -- No aircraft on final any more.
    airport.onfinal[name]=nil

    -- Decrease number of aircraft on final.
    airport.Nonfinal=airport.Nonfinal-1

    -- Remove this flight from list of flights.
    RAT._ATCDelFlight(RAT.ATC.flight, name)

    -- Increase landing counter to monitor traffic.
    airport.traffic=airport.traffic+1

    -- Number of planes landing per hour.
    local TrafficPerHour=airport.traffic/(timer.getTime()-RAT.ATC.T0)*3600

    -- Debug info
    BASE:I(RAT.id..string.format("ATC %s: Flight %s landed. Tholding = %i:%02d, Tfinal = %i:%02d.", dest, name, Thold/60, Thold%60, Tfinal/60, Tfinal%60))
    BASE:I(RAT.id..string.format("ATC %s: Number of flights still on final %d.", dest, airport.Nonfinal))
    BASE:I(RAT.id..string.format("ATC %s: Traffic report: Number of planes landed in total %d. Flights/hour = %3.2f.", dest, airport.traffic, TrafficPerHour))
    
    if string.find(name,"#") then
      name =  string.match(name,"^(.+)#")
    end
    local text=string.format("ATC %s: Flight %s landed. Welcome to %s.", dest, name, dest)    
    MESSAGE:New(text, 10):ToAllIf(RAT.ATC.messages)
  end

end

--- Creates a landing queue for all flights holding at airports. Aircraft with longest holding time gets first permission to land.
function RAT._ATCQueue()

  -- Current time
  local Tnow=timer.getTime()

  for airport,_ in pairs(RAT.ATC.airport) do

    -- Local airport queue.
    local _queue={}

    -- Loop over all flights.
    for name,_flight in pairs(RAT.ATC.flight) do
      local flight=_flight --#RAT.AtcFlight

      -- Update holding time (unless holing is set to onfinal=-100)
      if flight.holding>=0 then
        flight.holding=Tnow-flight.Tarrive
      end
      
      local hold=flight.holding
      local dest=flight.destination

      -- Flight is holding at this airport.
      if hold>=0 and airport==dest then
        _queue[#_queue+1]={name,hold}
      end
    end

    -- Sort queue w.r.t holding time in ascending order.
    local function compare(a,b)
      return a[2] > b[2]
    end
    table.sort(_queue, compare)

    -- Transfer queue to airport queue.
    RAT.ATC.airport[airport].queue={}
    for k,v in ipairs(_queue) do
      table.insert(RAT.ATC.airport[airport].queue, v[1])
    end

  end
end

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
--- RATMANAGER class
-- @type RATMANAGER
-- @field #string ClassName Name of the Class.
-- @field #boolean Debug If true, be more verbose on output in DCS.log file.
-- @field #table rat Array holding RAT objects etc.
-- @field #string name Name (alias) of RAT object.
-- @field #table alive Number of currently alive groups.
-- @field #table min Minimum number of RAT groups alive.
-- @field #number nrat Number of RAT objects.
-- @field #number ntot Total number of active RAT groups.
-- @field #number Tcheck Time interval in seconds between checking of alive groups.
-- @field #number dTspawn Time interval in seconds between spawns of groups.
-- @field Core.Scheduler#SCHEDULER manager Scheduler managing the RAT objects.
-- @field #number managerid Managing scheduler id.
-- @extends Core.Base#BASE

---# RATMANAGER class, extends @{Core.Base#BASE}
-- The RATMANAGER class manages spawning of multiple RAT objects in a very simple way. It is created by the  @{#RATMANAGER.New}() contructor.
-- RAT objects with different "tasks" can be defined as usual. However, they **must not** be spawned via the @{#RAT.Spawn}() function.
--
-- Instead, these objects can be added to the manager via the @{#RATMANAGER.Add}(ratobject, min) function, where the first parameter "ratobject" is the @{#RAT} object, while the second parameter "min" defines the
-- minimum number of RAT aircraft of that object, which are alive at all time.
--
-- The @{#RATMANAGER} must be started by the @{#RATMANAGER.Start}(startime) function, where the optional argument "startime" specifies the delay time in seconds after which the manager is started and the spawning beginns.
-- If desired, the @{#RATMANAGER} can be stopped by the @{#RATMANAGER.Stop}(stoptime) function. The parameter "stoptime" specifies the time delay in seconds after which the manager stops.
-- When this happens, no new aircraft will be spawned and the population will eventually decrease to zero.
--
-- When you are using a time intervall like @{#RATMANAGER.dTspawn}(delay), @{#RATMANAGER} will ignore the amount set with @{#RATMANAGER.New}(). @{#RATMANAGER.dTspawn}(delay) will spawn infinite groups.
--
-- ## Example
-- In this example, three different @{#RAT} objects are created (but not spawned manually). The @{#RATMANAGER} takes care that at least five aircraft of each type are alive and that the total number of aircraft
-- spawned is 25. The @{#RATMANAGER} is started after 30 seconds and stopped after two hours.
--
--     local a10c=RAT:New("RAT_A10C", "A-10C managed")
--     a10c:SetDeparture({"Batumi"})
--
--     local f15c=RAT:New("RAT_F15C", "F15C managed")
--     f15c:SetDeparture({"Sochi-Adler"})
--     f15c:DestinationZone()
--     f15c:SetDestination({"Zone C"})
--
--     local av8b=RAT:New("RAT_AV8B", "AV8B managed")
--     av8b:SetDeparture({"Zone C"})
--     av8b:SetTakeoff("air")
--     av8b:DestinationZone()
--     av8b:SetDestination({"Zone A"})
--
--     local manager=RATMANAGER:New(25)
--     manager:Add(a10c, 5)
--     manager:Add(f15c, 5)
--     manager:Add(av8b, 5)
--     manager:Start(30)
--     manager:Stop(7200)
--
-- @field #RATMANAGER
RATMANAGER={
  ClassName="RATMANAGER",
  Debug=false,
  rat={},
  name={},
  alive={},
  planned={},
  min={},
  nrat=0,
  ntot=nil,
  Tcheck=60,
  dTspawn=1.0,
  manager=nil,
  managerid=nil,
}

--- Some ID to identify who we are in output of the DCS.log file.
-- @field #string id
RATMANAGER.id="RATMANAGER | "

--- Creates a new RATMANAGER object.
-- @param #RATMANAGER self
-- @param #number ntot Total number of RAT flights.
-- @return #RATMANAGER RATMANAGER object
function RATMANAGER:New(ntot)

  -- Inherit BASE.
  local self=BASE:Inherit(self, BASE:New()) -- #RATMANAGER

  -- Total number of RAT groups.
  self.ntot=ntot or 1

  -- Debug info
  self:I(RATMANAGER.id..string.format("Creating manager for %d groups", ntot))

  return self
end


--- Adds a RAT object to the RAT manager. Parameter min specifies the limit how many RAT groups are at least alive.
-- @param #RATMANAGER self
-- @param #RAT ratobject RAT object to be managed.
-- @param #number min Minimum number of groups for this RAT object. Default is 1.
-- @return #RATMANAGER RATMANAGER self object.
function RATMANAGER:Add(ratobject,min)

  --Automatic respawning is disabled.
  ratobject.norespawn=true
  ratobject.f10menu=false

  -- Increase RAT object counter.
  self.nrat=self.nrat+1

  self.rat[self.nrat]=ratobject
  self.alive[self.nrat]=0
  self.planned[self.nrat]=0
  self.name[self.nrat]=ratobject.alias
  self.min[self.nrat]=min or 1

  -- Debug info.
  self:T(RATMANAGER.id..string.format("Adding ratobject %s with min flights = %d", self.name[self.nrat],self.min[self.nrat]))

  -- Call spawn to initialize RAT parameters.
  ratobject:Spawn(0)

  return self
end

--- Starts the RAT manager and spawns the initial random number RAT groups for each RAT object.
-- @param #RATMANAGER self
-- @param #number delay Time delay in seconds after which the RAT manager is started. Default is 5 seconds.
-- @return #RATMANAGER RATMANAGER self object.
function RATMANAGER:Start(delay)

  -- Time delay.
  delay=delay or 5

  if delay and delay>0 then
  
    -- Info text.
    local text=string.format(RATMANAGER.id.."RAT manager will be started in %d seconds.\n", delay)
    text=text..string.format("Managed groups:\n")
    for i=1,self.nrat do
      text=text..string.format("- %s with min groups %d\n", self.name[i], self.min[i])
    end
    text=text..string.format("Number of constantly alive groups %d", self.ntot)
    self:E(text)  
    
    -- Delayed call
    self:ScheduleOnce(delay, RATMANAGER.Start, self, 0)
    
  else

    -- Ensure that ntot is at least sum of min RAT groups.
    local n=0
    for i=1,self.nrat do
      n=n+self.min[i]
    end
    self.ntot=math.max(self.ntot, n)
  
    -- Get randum number of new RAT groups.
    local N=self:_RollDice(self.nrat, self.ntot, self.min, self.alive)
  
    -- Loop over all RAT objects and spawn groups.
    local time=0.0
    for i=1,self.nrat do
      for j=1,N[i] do
        time=time+self.dTspawn
        --SCHEDULER:New(nil, RAT._SpawnWithRoute, {self.rat[i]}, time)
        self:ScheduleOnce(time, RAT._SpawnWithRoute, self.rat[i])
      end
    end
  
    -- Start activation scheduler for uncontrolled aircraft.
    for i=1,self.nrat do
      local rat=self.rat[i] --#RAT
      if rat.uncontrolled and rat.activate_uncontrolled then
        -- Start activating stuff but not before the latest spawn has happend.
        local Tactivate=math.max(time+1, rat.activate_delay)
        --SCHEDULER:New(self.rat[i], self.rat[i]._ActivateUncontrolled, {self.rat[i]}, Tactivate, self.rat[i].activate_delta, self.rat[i].activate_frand)
        self:ScheduleRepeat(Tactivate,rat.activate_delta, rat.activate_frand, nil,rat._ActivateUncontrolled, rat)
      end
    end
  
    -- Start the manager. But not earlier than the latest spawn has happened!
    local TstartManager=math.max(time+1, self.Tcheck)
  
    -- Start manager scheduler.
    self.manager, self.managerid = SCHEDULER:New(self, self._Manage, {self}, TstartManager, self.Tcheck) --Core.Scheduler#SCHEDULER
  
    -- Info
    local text=string.format(RATMANAGER.id.."Starting RAT manager with scheduler ID %s in %d seconds. Repeat interval %d seconds.", self.managerid, TstartManager, self.Tcheck)
    self:I(text)  
  
  
  end

  return self
end


--- Stops the RAT manager.
-- @param #RATMANAGER self
-- @param #number delay Delay in seconds before the manager is stopped. Default is 1 second.
-- @return #RATMANAGER RATMANAGER self object.
function RATMANAGER:Stop(delay)
  delay=delay or 1

  
  if delay and delay>0 then
  
    self:I(RATMANAGER.id..string.format("Manager will be stopped in %d seconds.", delay))
    
    self:ScheduleOnce(delay, RATMANAGER.Stop, self, 0)
  
  else

    self:I(RATMANAGER.id..string.format("Stopping manager with scheduler ID %s", self.managerid))
    
    self.manager:Stop(self.managerid)  
  
  end
  
  
  return self
end


--- Sets the time interval between checks of alive RAT groups. Default is 60 seconds.
-- @param #RATMANAGER self
-- @param #number dt Time interval in seconds.
-- @return #RATMANAGER RATMANAGER self object.
function RATMANAGER:SetTcheck(dt)
  self.Tcheck=dt or 60
  return self
end

--- Sets the time interval between spawning of groups.
-- @param #RATMANAGER self
-- @param #number dt Time interval in seconds. Default is 1 second.
-- @return #RATMANAGER RATMANAGER self object.
function RATMANAGER:SetTspawn(dt)
  self.dTspawn=dt or 1.0
  return self
end


--- Manager function. Calculating the number of current groups and respawning new groups if necessary.
-- @param #RATMANAGER self
function RATMANAGER:_Manage()

  -- Count total number of groups.
  local ntot=self:_Count()

  -- Debug info.
  self:T(RATMANAGER.id..string.format("Number of alive groups %d. New groups to be spawned %d.", ntot, self.ntot-ntot))

  -- Get number of necessary spawns.
  local N=self:_RollDice(self.nrat, self.ntot, self.min, self.alive)

  -- Loop over all RAT objects and spawn new groups if necessary.
  local time=0.0
  for i=1,self.nrat do
    for j=1,N[i] do
      time=time+self.dTspawn
      self.planned[i]=self.planned[i]+1
      --SCHEDULER:New(nil, RATMANAGER._Spawn, {self, i}, time)
      self:ScheduleOnce(time, RATMANAGER._Spawn, self, i)
    end
  end
end

--- Instantly starts the RAT manager and spawns the initial random number RAT groups for each RAT object.
-- @param #RATMANAGER self
-- @param #RATMANAGER RATMANAGER self object.
-- @param #number i Index.
function RATMANAGER:_Spawn(i)

  local rat=self.rat[i] --#RAT
  
  rat:_SpawnWithRoute()
  self.planned[i]=self.planned[i]-1

end

--- Counts the number of alive RAT objects.
-- @param #RATMANAGER self
function RATMANAGER:_Count()

  -- Init total counter.
  local ntotal=0

  -- Loop over all RAT objects.
  for i=1,self.nrat do
    local n=0

    local ratobject=self.rat[i] --#RAT

    -- Loop over the RAT groups of this object.
    for spawnindex,ratcraft in pairs(ratobject.ratcraft) do
      local group=ratcraft.group --Wrapper.Group#GROUP
      if group and group:IsAlive() then
        n=n+1
      end
    end

    -- Alive groups of this RAT object.
    self.alive[i]=n

    -- Grand total.
    ntotal=ntotal+n

    -- Debug output.
    local text=string.format("Number of alive groups of %s = %d, planned=%d", self.name[i], n, self.planned[i])
    self:T(RATMANAGER.id..text)
  end

  -- Return grand total.
  return ntotal
end

--- Rolls the dice for the number of necessary spawns.
-- @param #RATMANAGER self
-- @param #number nrat Number of RAT objects.
-- @param #number ntot Total number of RAT flights.
-- @param #table min Minimum number of groups for each RAT object.
-- @param #table alive Number of alive groups of each RAT object.
function RATMANAGER:_RollDice(nrat,ntot,min,alive)

  -- Calculate sum.
  local function sum(A,index)
    local summe=0
    for _,i in ipairs(index) do
      summe=summe+A[i]
    end
    return summe
  end

  -- Table of number of groups.
  local N={}
  local M={}
  local P={}
  for i=1,nrat do
    local a=alive[i]+self.planned[i]
    N[#N+1]=0
    M[#M+1]=math.max(a, min[i])
    P[#P+1]=math.max(min[i]-a,0)
  end

  -- Min/max group arrays.
  local mini={}
  local maxi={}

  -- Arrays.
  local rattab={}
  for i=1,nrat do
    table.insert(rattab,i)
  end
  local done={}

  -- Number of new groups to be added.
  local nnew=ntot
  for i=1,nrat do
    nnew=nnew-alive[i]-self.planned[i]
  end

  for i=1,nrat-1 do

    -- Random entry from .
    local r=math.random(#rattab)
    -- Get value
    local j=rattab[r]

    table.remove(rattab, r)
    table.insert(done,j)

    -- Sum up the number of already distributed groups.
    local sN=sum(N, done)
    -- Sum up the minimum number of yet to be distributed groups.
    local sP=sum(P, rattab)

    -- Max number that can be distributed for this object.
    maxi[j]=nnew-sN-sP

    -- Min number that should be distributed for this object
    mini[j]=P[j]

    -- Random number of new groups for this RAT object.
    if maxi[j] >= mini[j] then
      N[j]=math.random(mini[j], maxi[j])
    else
      N[j]=0
    end

    -- Debug info
    self:T3(string.format("RATMANAGER: i=%d, alive=%d, planned=%d, min=%d, mini=%d, maxi=%d, add=%d, sumN=%d, sumP=%d", j, alive[j], self.planned[i], min[j], mini[j], maxi[j], N[j],sN, sP))

  end

  -- Last RAT object, number of groups is determined from number of already distributed groups and nnew.
  local j=rattab[1]
  N[j]=nnew-sum(N, done)
  mini[j]=nnew-sum(N, done)
  maxi[j]=nnew-sum(N, done)
  table.remove(rattab, 1)
  table.insert(done,j)

  -- Debug info
  local text=RATMANAGER.id.."\n"
  for i=1,nrat do
    text=text..string.format("%s: i=%d, alive=%d, planned=%d, min=%d, mini=%d, maxi=%d, add=%d\n", self.name[i], i, alive[i], self.planned[i], min[i], mini[i], maxi[i], N[i])
  end
  text=text..string.format("Total # of groups to add = %d", sum(N, done))
  self:T(text)

  -- Return number of groups to be spawned.
  return N
end
