-- LUALOCALS < ---------------------------------------------------------
local math, minetest
    = math, minetest
local math_floor, math_min, math_random
    = math.floor, math.min, math.random
-- LUALOCALS > ---------------------------------------------------------

local modname = minetest.get_current_modname()

local spawners = {}

local function calc_scalar(params, def)
	if not def then return 0 end
	local total = 0
	for i = 1, math_min(#params, #def) do
		total = total + params[i] * def[i]
	end
	return total
end

local function calc_vector(params, def)
	if not def then return {x = 0, y = 0, z = 0} end
	return {
		x = calc_scalar(params, def.x),
		y = calc_scalar(params, def.y),
		z = calc_scalar(params, def.z)
	}
end

local function spawn(def, pnum)
	local params = {1, pnum / def.amount}
	for _ = 1, 12 do params[#params + 1] = math_random() end
	minetest.add_particle({
			pos = calc_vector(params, def.pos),
			velocity = calc_vector(params, def.velocity),
			acceleration = calc_vector(params, def.acceleration),
			expirationtime = calc_scalar(params, def.expirationtime),
			size = calc_scalar(params, def.size),
			glow = calc_scalar(params, def.glow),
			collisiondetection = def.collisiondetection,
			collision_removal = def.collision_removal,
			object_collision = def.object_collision,
			vertical = def.vertical,
			texture = def.texture,
			playername = def.playername,
			animation = def.animation
		})
end

minetest.register_entity(modname .. ":spawner", {
		initial_properties = {
			physical = false,
			collide_with_objects = false,
			collisionbox = {0, 0, 0, 0, 0, 0},
			visual_size = {x = 0, y = 0},
			is_visible = false,
			static_save = false
		},
		on_activate = function(self, data)
			if not data then return self.object:remove() end
			data = minetest.deserialize(data)
			self.id = data.id
			self.def = data.def
			self.age = 0
			if self.def.time <= 0 then -- corner case
				for i = 1, self.def.amount do spawn(self.def, i) end
				spawners[self.id] = nil
				return self.object:remove()
			end
		end,
		on_step = function(self, dtime)
			local start = self.age
			self.age = self.age + dtime
			if self.age > self.def.time then self.age = self.def.time end

			local pstart = math_floor(self.def.amount * start / self.def.time)
			local pend = math_floor(self.def.amount * self.age / self.def.time)
			for i = pstart + 1, pend do spawn(self.def, i) end

			if self.age >= self.def.time then
				spawners[self.id] = nil
				return self.object:remove()
			end
		end
	})

minetest.add_particlespawner_advanced = minetest.add_particlespawner_advanced or function(def)
	local params = {1, 0.5}
	for _ = 1, 12 do params[#params + 1] = 0.5 end
	local pos = calc_vector(params, def.pos)
	local id = #spawners + 1
	local obj = minetest.add_entity(pos, modname .. ":spawner",
		minetest.serialize({id = id, def = def}))
	if not obj then return end
	spawners[id] = obj
	return id
end

minetest.delete_particlespawner_advanced = minetest.delete_particlespawner_advanced or function(id)
	if not id then return end
	local obj = spawners[id]
	if not obj then return end
	obj:remove()
	spawners[id] = nil
end