local function create_particles(surface, position, amount)	
	if not surface.valid then return end
	local math_random = math.random
	for i = 1, amount, 1 do 
		local m = math_random(8, 24)
		local m2 = m * 0.005
		
		surface.create_particle({
			name = "stone-particle",
			position = position,
			frame_speed = 0.1,
			vertical_speed = 0.1,
			height = 0.1,
			movement = {m2 - (math_random(0, m) * 0.01), m2 - (math_random(0, m) * 0.01)}
		})
	end	
end

local function spawn_worm(surface, position, evolution_index)
	if not surface.valid then return end
	local worm_raffle_table = {
		[1] = {"small-worm-turret", "small-worm-turret", "small-worm-turret", "small-worm-turret", "small-worm-turret", "small-worm-turret"},
		[2] = {"small-worm-turret", "small-worm-turret", "small-worm-turret", "small-worm-turret", "small-worm-turret", "medium-worm-turret"},
		[3] = {"small-worm-turret", "small-worm-turret", "small-worm-turret", "small-worm-turret", "medium-worm-turret", "medium-worm-turret"},
		[4] = {"small-worm-turret", "small-worm-turret", "small-worm-turret", "medium-worm-turret", "medium-worm-turret", "medium-worm-turret"},
		[5] = {"small-worm-turret", "small-worm-turret", "medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "big-worm-turret"},
		[6] = {"small-worm-turret", "medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "big-worm-turret"},
		[7] = {"medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "big-worm-turret", "big-worm-turret"},
		[8] = {"medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "big-worm-turret", "big-worm-turret"},
		[9] = {"medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "big-worm-turret", "big-worm-turret", "big-worm-turret"},
		[10] = {"medium-worm-turret", "medium-worm-turret", "medium-worm-turret", "big-worm-turret", "big-worm-turret", "big-worm-turret"}
	}
	local raffle = worm_raffle_table[evolution_index]
	local worm_name = raffle[math.random(1,#raffle)]
	surface.create_entity({name = worm_name, position = position})
end

local function unearthing_worm(surface, position)
	if not surface then return end
    	if not surface.valid then return end
	if not position then return end
	if not position.x then return end
	if not position.y then return end	
	
	local evolution_index = math.ceil(game.forces.enemy.evolution_factor * 10)
	if evolution_index < 1 then evolution_index = 1 end
	
	for t = 1, 330, 1 do
		if not global.on_tick_schedule[game.tick + t] then global.on_tick_schedule[game.tick + t] = {} end
				
		global.on_tick_schedule[game.tick + t][#global.on_tick_schedule[game.tick + t] + 1] = {
			func = create_particles,
			args = {surface, {x = position.x, y = position.y}, math.ceil(t * 0.05)}
		}										
		
		if t == 330 then
			global.on_tick_schedule[game.tick + t][#global.on_tick_schedule[game.tick + t] + 1] = {
				func = spawn_worm,
				args = {surface, {x = position.x, y = position.y}, evolution_index}
			}
		end				
	end		
end

return unearthing_worm