-- this spawns additional worms around the center of the map_gen_settings
-- storage.average_worm_amount_per_chunk sets the average amount of worms
-- (default = 1)

local Event = require 'utils.event'
local math_random = math.random
local turrets = {
    [1] = 'small-worm-turret',
    [2] = 'medium-worm-turret',
    [3] = 'big-worm-turret',
    [4] = 'behemoth-worm-turret'
}

local tile_coords = {}
for x = 0, 31, 1 do
    for y = 0, 31, 1 do
        tile_coords[#tile_coords + 1] = { x, y }
    end
end

local function on_chunk_generated(event)
    local surface = event.surface
    if not storage.worm_distance then
        storage.worm_distance = surface.map_gen_settings.starting_area * 200
    end
    --local starting_distance = surface.map_gen_settings.starting_area * 200
    local left_top = event.area.left_top
    local chunk_distance_to_center = math.sqrt(left_top.x ^ 2 + left_top.y ^ 2)
    if storage.worm_distance > chunk_distance_to_center then
        return
    end

    local highest_worm_tier = math.floor((chunk_distance_to_center - storage.worm_distance) * 0.002) + 1
    if highest_worm_tier > 4 then
        highest_worm_tier = 4
    end

    if not storage.average_worm_amount_per_chunk then
        storage.average_worm_amount_per_chunk = 1
    end
    local worm_amount = math_random(math.floor(storage.average_worm_amount_per_chunk * 0.5), math.ceil(storage.average_worm_amount_per_chunk * 1.5))

    for _ = 1, worm_amount, 1 do
        local coord_modifier = tile_coords[math_random(1, #tile_coords)]
        local pos = { left_top.x + coord_modifier[1], left_top.y + coord_modifier[2] }
        local name = turrets[math_random(1, highest_worm_tier)]
        local position = surface.find_non_colliding_position('big-worm-turret', pos, 8, 1)
        if position then
            surface.create_entity({ name = name, position = position, force = 'enemy' })
        end
    end
end

Event.add(defines.events.on_chunk_generated, on_chunk_generated)
