local ffi = require "ffi"
local fileUtils = require("client.src.FileUtils")

fileUtils.copyFile("client/lib/rich_presence/discord-rpc.dll","discord-rpc.dll")
local dll_path = love.filesystem.getSaveDirectory() .. "/discord-rpc"
local discordRPClib = ffi.load(dll_path)

ffi.cdef [[
typedef struct DiscordRichPresence {
    const char* state;   /* max 128 bytes */
    const char* details; /* max 128 bytes */
    int64_t startTimestamp;
    int64_t endTimestamp;
    const char* largeImageKey;  /* max 32 bytes */
    const char* largeImageText; /* max 128 bytes */
    const char* smallImageKey;  /* max 32 bytes */
    const char* smallImageText; /* max 128 bytes */
    const char* partyId;        /* max 128 bytes */
    int partySize;
    int partyMax;
    const char* matchSecret;    /* max 128 bytes */
    const char* joinSecret;     /* max 128 bytes */
    const char* spectateSecret; /* max 128 bytes */
    int8_t instance;
} DiscordRichPresence;

typedef struct DiscordUser {
    const char* userId;
    const char* username;
    const char* discriminator;
    const char* avatar;
} DiscordUser;

typedef void (*readyPtr)(const DiscordUser* request);
typedef void (*disconnectedPtr)(int errorCode, const char* message);
typedef void (*erroredPtr)(int errorCode, const char* message);
typedef void (*joinGamePtr)(const char* joinSecret);
typedef void (*spectateGamePtr)(const char* spectateSecret);
typedef void (*joinRequestPtr)(const DiscordUser* request);

typedef struct DiscordEventHandlers {
    readyPtr ready;
    disconnectedPtr disconnected;
    erroredPtr errored;
    joinGamePtr joinGame;
    spectateGamePtr spectateGame;
    joinRequestPtr joinRequest;
} DiscordEventHandlers;

void Discord_Initialize(const char* applicationId,
                        DiscordEventHandlers* handlers,
                        int autoRegister,
                        const char* optionalSteamId);

void Discord_Shutdown(void);

void Discord_RunCallbacks(void);

void Discord_UpdatePresence(const DiscordRichPresence* presence);

void Discord_ClearPresence(void);

void Discord_Respond(const char* userid, int reply);

void Discord_UpdateHandlers(DiscordEventHandlers* handlers);
]]

local discordRPC = {} -- module table

-- proxy to detect garbage collection of the module
discordRPC.gcDummy = newproxy(true)

local function unpackDiscordUser(request)
  return ffi.string(request.userId), ffi.string(request.username), ffi.string(request.discriminator), ffi.string(request.avatar)
end

-- callback proxies
-- note: callbacks are not JIT compiled (= SLOW), try to avoid doing performance critical tasks in them
-- luajit.org/ext_ffi_semantics.html
local ready_proxy =
  ffi.cast(
  "readyPtr",
  function(request)
    if discordRPC.ready then
      discordRPC.ready(unpackDiscordUser(request))
    end
  end
)

local disconnected_proxy =
  ffi.cast(
  "disconnectedPtr",
  function(errorCode, message)
    if discordRPC.disconnected then
      discordRPC.disconnected(errorCode, ffi.string(message))
    end
  end
)

local errored_proxy =
  ffi.cast(
  "erroredPtr",
  function(errorCode, message)
    if discordRPC.errored then
      discordRPC.errored(errorCode, ffi.string(message))
    end
  end
)

local joinGame_proxy =
  ffi.cast(
  "joinGamePtr",
  function(joinSecret)
    if discordRPC.joinGame then
      discordRPC.joinGame(ffi.string(joinSecret))
    end
  end
)

local spectateGame_proxy =
  ffi.cast(
  "spectateGamePtr",
  function(spectateSecret)
    if discordRPC.spectateGame then
      discordRPC.spectateGame(ffi.string(spectateSecret))
    end
  end
)

local joinRequest_proxy =
  ffi.cast(
  "joinRequestPtr",
  function(request)
    if discordRPC.joinRequest then
      discordRPC.joinRequest(unpackDiscordUser(request))
    end
  end
)

-- helpers
local function checkArg(arg, argType, argName, func, maybeNil)
  assert(type(arg) == argType or (maybeNil and arg == nil), string.format('Argument "%s" to function "%s" has to be of type "%s"', argName, func, argType))
end

local function checkStrArg(arg, maxLen, argName, func, maybeNil)
  if maxLen then
    assert(type(arg) == "string" and arg:len() <= maxLen or (maybeNil and arg == nil), string.format('Argument "%s" of function "%s" has to be of type string with maximum length %d', argName, func, maxLen))
  else
    checkArg(arg, "string", argName, func, true)
  end
end

local function checkIntArg(arg, maxBits, argName, func, maybeNil)
  maxBits = math.min(maxBits or 32, 52) -- lua number (double) can only store integers < 2^53
  local maxVal = 2 ^ (maxBits - 1) -- assuming signed integers, which, for now, are the only ones in use
  assert(type(arg) == "number" and math.floor(arg) == arg and arg < maxVal and arg >= -maxVal or (maybeNil and arg == nil), string.format('Argument "%s" of function "%s" has to be a whole number <= %d', argName, func, maxVal))
end

-- function wrappers
function discordRPC.initialize(applicationId, autoRegister, optionalSteamId)
  local func = "discordRPC.Initialize"
  checkStrArg(applicationId, nil, "applicationId", func)
  checkArg(autoRegister, "boolean", "autoRegister", func)
  if optionalSteamId ~= nil then
    checkStrArg(optionalSteamId, nil, "optionalSteamId", func)
  end

  local eventHandlers = ffi.new("struct DiscordEventHandlers")
  eventHandlers.ready = ready_proxy
  eventHandlers.disconnected = disconnected_proxy
  eventHandlers.errored = errored_proxy
  eventHandlers.joinGame = joinGame_proxy
  eventHandlers.spectateGame = spectateGame_proxy
  eventHandlers.joinRequest = joinRequest_proxy

  discordRPClib.Discord_Initialize(applicationId, eventHandlers, autoRegister and 1 or 0, optionalSteamId)
end

function discordRPC.shutdown()
  discordRPClib.Discord_Shutdown()
end

function discordRPC.runCallbacks()
  discordRPClib.Discord_RunCallbacks()
end
-- http://luajit.org/ext_ffi_semantics.html#callback :
-- It is not allowed, to let an FFI call into a C function (runCallbacks)
-- get JIT-compiled, which in turn calls a callback, calling into Lua again (e.g. discordRPC.ready).
-- Usually this attempt is caught by the interpreter first and the C function
-- is blacklisted for compilation.
-- solution:
-- "Then you'll need to manually turn off JIT-compilation with jit.off() for
-- the surrounding Lua function that invokes such a message polling function."
jit.off(discordRPC.runCallbacks)

function discordRPC.updatePresence(presence)
  local func = "discordRPC.updatePresence"
  checkArg(presence, "table", "presence", func)

  -- -1 for string length because of 0-termination
  checkStrArg(presence.state, 127, "presence.state", func, true)
  checkStrArg(presence.details, 127, "presence.details", func, true)

  checkIntArg(presence.startTimestamp, 64, "presence.startTimestamp", func, true)
  checkIntArg(presence.endTimestamp, 64, "presence.endTimestamp", func, true)

  checkStrArg(presence.largeImageKey, 31, "presence.largeImageKey", func, true)
  checkStrArg(presence.largeImageText, 127, "presence.largeImageText", func, true)
  checkStrArg(presence.smallImageKey, 31, "presence.smallImageKey", func, true)
  checkStrArg(presence.smallImageText, 127, "presence.smallImageText", func, true)
  checkStrArg(presence.partyId, 127, "presence.partyId", func, true)

  checkIntArg(presence.partySize, 32, "presence.partySize", func, true)
  checkIntArg(presence.partyMax, 32, "presence.partyMax", func, true)

  checkStrArg(presence.matchSecret, 127, "presence.matchSecret", func, true)
  checkStrArg(presence.joinSecret, 127, "presence.joinSecret", func, true)
  checkStrArg(presence.spectateSecret, 127, "presence.spectateSecret", func, true)

  checkIntArg(presence.instance, 8, "presence.instance", func, true)

  local cpresence = ffi.new("struct DiscordRichPresence")
  cpresence.state = presence.state
  cpresence.details = presence.details
  cpresence.startTimestamp = presence.startTimestamp or 0
  cpresence.endTimestamp = presence.endTimestamp or 0
  cpresence.largeImageKey = presence.largeImageKey
  cpresence.largeImageText = presence.largeImageText
  cpresence.smallImageKey = presence.smallImageKey
  cpresence.smallImageText = presence.smallImageText
  cpresence.partyId = presence.partyId
  cpresence.partySize = presence.partySize or 0
  cpresence.partyMax = presence.partyMax or 0
  cpresence.matchSecret = presence.matchSecret
  cpresence.joinSecret = presence.joinSecret
  cpresence.spectateSecret = presence.spectateSecret
  cpresence.instance = presence.instance or 0

  discordRPClib.Discord_UpdatePresence(cpresence)
end

function discordRPC.clearPresence()
  discordRPClib.Discord_ClearPresence()
end

local replyMap = {
  no = 0,
  yes = 1,
  ignore = 2
}

-- maybe let reply take ints too (0, 1, 2) and add constants to the module
function discordRPC.respond(userId, reply)
  checkStrArg(userId, nil, "userId", "discordRPC.respond")
  assert(replyMap[reply], 'Argument \'reply\' to discordRPC.respond has to be one of "yes", "no" or "ignore"')
  discordRPClib.Discord_Respond(userId, replyMap[reply])
end

-- garbage collection callback
getmetatable(discordRPC.gcDummy).__gc = function()
  discordRPC.shutdown()
  ready_proxy:free()
  disconnected_proxy:free()
  errored_proxy:free()
  joinGame_proxy:free()
  spectateGame_proxy:free()
  joinRequest_proxy:free()
end

return discordRPC
