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 surface.name ~= 'mirror_terrain' then
        return
    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 starting_distance > chunk_distance_to_center then
        return
    end

    local highest_worm_tier = math.floor((chunk_distance_to_center - starting_distance) * 0.0025) + 1
    if highest_worm_tier > 4 then
        highest_worm_tier = 4
    end

    for _ = 1, 4, 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)