elepower/elepower_farming/nodes/spawner.lua

-- How many seconds there are between runs
local SPAWNER_TICK = 10

local function can_dig(pos, player)
	local meta = minetest.get_meta(pos)
	local inv = meta:get_inventory()
	return inv:is_empty("src")
end

local function spawn(pos, mob)
	-- get meta and command
	local meta = minetest.get_meta(pos)

	-- TODO: ways to configure
	local mlig = 0  -- min light
	local xlig = 15 -- max light
	local num  = 4  -- max number
	local pla  = 24 -- player radius
	local yof  = 0  -- Y offset to spawn mob

	-- if amount is 0 then do nothing
	if num == 0 then
		return
	end

	-- are we spawning a registered mob?
	if not mobs.spawning_mobs[mob] then
		return
	end

	-- check objects inside 9x9 area around spawner
	local objs = minetest.get_objects_inside_radius(pos, 9)
	local count = 0
	local ent = nil

	-- count mob objects of same type in area
	for k, obj in ipairs(objs) do
		ent = obj:get_luaentity()

		if ent and ent.name and ent.name == mob then
			count = count + 1
		end
	end

	-- is there too many of same type?
	if count >= num then
		return
	end

	-- spawn mob if player detected and in range
	if pla > 0 then
		local in_range = 0
		local objs = minetest.get_objects_inside_radius(pos, pla)

		for _,oir in pairs(objs) do
			if oir:is_player() then
				in_range = 1
				break
			end
		end

		-- player not found
		if in_range == 0 then
			return
		end
	end

	-- find air blocks within 5 nodes of spawner
	local air = minetest.find_nodes_in_area(
		{x = pos.x - 5, y = pos.y + yof, z = pos.z - 5},
		{x = pos.x + 5, y = pos.y + yof, z = pos.z + 5},
		{"air"})

	-- spawn in random air block
	if air and #air > 0 then
		local pos2 = air[math.random(#air)]
		local lig = minetest.get_node_light(pos2) or 0

		pos2.y = pos2.y + 0.5

		-- only if light levels are within range
		if lig >= mlig and lig <= xlig and minetest.registered_entities[mob] then
			minetest.add_entity(pos2, mob)
			return true
		end
	end

	return
end

local function on_timer(pos, elapsed)
	local refresh = false
	local meta = minetest.get_meta(pos)
	local inv  = meta:get_inventory()

	local capacity = ele.helpers.get_node_property(meta, pos, "capacity")
	local usage    = ele.helpers.get_node_property(meta, pos, "usage")
	local storage  = ele.helpers.get_node_property(meta, pos, "storage")

	local work = meta:get_int("src_time")

	local egg_slot = inv:get_stack("src", 1)
	local egg_name = egg_slot:get_name()
	local mob_desc = "None"
	local active   = "Active"
	if storage > usage and not egg_slot:is_empty() and ele.helpers.get_item_group(egg_name, "spawn_egg") then
		local mob_name = egg_name:gsub("_set", "")

		if work == SPAWNER_TICK then
			local spawned = 0
			
			-- Spawn
			if spawn(pos, mob_name) then
				spawned = spawned + 1
			end

			work = 0
			if spawned > 0 then
				storage = storage - usage
			end
		else
			work = work + 1
		end

		refresh = true
		mob_desc = minetest.registered_items[mob_name].description
	else
		work = 0
		active = "Inactive"
	end

	meta:set_string("infotext", ("Powered Mob Spawner %s\nMob: %s\n%s"):format(
		active, mob_desc, ele.capacity_text(capacity, storage)))

	local power_percent = math.floor((storage / capacity)*100)
	local work_percent  = math.floor((work / SPAWNER_TICK)*100)

	meta:set_string("formspec", elefarm.formspec.spawner_formspec(work_percent, power_percent))
	meta:set_int("storage", storage)
	meta:set_int("src_time", work)

	return refresh
end

ele.register_machine("elepower_farming:spawner", {
	description  = "Powered Mob Spawner",
	ele_capacity = 64000,
	ele_inrush   = 800,
	ele_usage    = 800,
	ele_no_automatic_ports = true,
	tiles = {
		"elefarming_machine_spawner_top.png", "elefarming_machine_base.png", "elefarming_machine_side.png",
		"elefarming_machine_side.png", "elefarming_machine_side.png", "elefarming_machine_side.png",
	},
	groups = {
		oddly_breakable_by_hand = 1,
		ele_machine = 1,
		ele_user = 1,
		cracky = 1,
		tubedevice = 1,
		tubedevice_receiver = 1,
	},
	on_construct = function (pos)
		local meta = minetest.get_meta(pos)
		local inv  = meta:get_inventory()
		inv:set_size("src", 1)

		meta:set_int("src_time", 0)
		meta:set_string("formspec", elefarm.formspec.spawner_formspec(0,0))
	end,
	can_dig  = can_dig,
	on_timer = on_timer,
})