minetest_game/mods/default/furnace.lua

--
-- Formspecs
--

local function active_formspec(fuel_percent, item_percent)
	local formspec = 
		"size[8,8.5]"..
		default.gui_bg..
		default.gui_bg_img..
		default.gui_slots..
		"list[current_name;src;2.75,0.5;1,1;]"..
		"list[current_name;fuel;2.75,2.5;1,1;]"..
		"image[2.75,1.5;1,1;default_furnace_fire_bg.png^[lowpart:"..
		(100-fuel_percent)..":default_furnace_fire_fg.png]"..
		"image[3.75,1.5;1,1;gui_furnace_arrow_bg.png^[lowpart:"..
		(item_percent)..":gui_furnace_arrow_fg.png^[transformR270]"..
		"list[current_name;dst;4.75,0.96;2,2;]"..
		"list[current_player;main;0,4.25;8,1;]"..
		"list[current_player;main;0,5.5;8,3;8]"..
		"listring[current_name;dst]"..
		"listring[current_player;main]"..
		"listring[current_name;src]"..
		"listring[current_player;main]"..
		default.get_hotbar_bg(0, 4.25)
	return formspec
end

local inactive_formspec =
	"size[8,8.5]"..
	default.gui_bg..
	default.gui_bg_img..
	default.gui_slots..
	"list[current_name;src;2.75,0.5;1,1;]"..
	"list[current_name;fuel;2.75,2.5;1,1;]"..
	"image[2.75,1.5;1,1;default_furnace_fire_bg.png]"..
	"image[3.75,1.5;1,1;gui_furnace_arrow_bg.png^[transformR270]"..
	"list[current_name;dst;4.75,0.96;2,2;]"..
	"list[current_player;main;0,4.25;8,1;]"..
	"list[current_player;main;0,5.5;8,3;8]"..
	"listring[current_name;dst]"..
	"listring[current_player;main]"..
	"listring[current_name;src]"..
	"listring[current_player;main]"..
	default.get_hotbar_bg(0, 4.25)

--
-- Node callback functions that are the same for active and inactive furnace
--

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

local function allow_metadata_inventory_put(pos, listname, index, stack, player)
	if minetest.is_protected(pos, player:get_player_name()) then
		return 0
	end
	local meta = minetest.get_meta(pos)
	local inv = meta:get_inventory()
	if listname == "fuel" then
		if minetest.get_craft_result({method="fuel", width=1, items={stack}}).time ~= 0 then
			if inv:is_empty("src") then
				meta:set_string("infotext", "Furnace is empty")
			end
			return stack:get_count()
		else
			return 0
		end
	elseif listname == "src" then
		return stack:get_count()
	elseif listname == "dst" then
		return 0
	end
end

local function allow_metadata_inventory_move(pos, from_list, from_index, to_list, to_index, count, player)
	local meta = minetest.get_meta(pos)
	local inv = meta:get_inventory()
	local stack = inv:get_stack(from_list, from_index)
	return allow_metadata_inventory_put(pos, to_list, to_index, stack, player)
end

local function allow_metadata_inventory_take(pos, listname, index, stack, player)
	if minetest.is_protected(pos, player:get_player_name()) then
		return 0
	end
	return stack:get_count()
end

local function swap_node(pos, name)
	local node = minetest.get_node(pos)
	if node.name == name then
		return
	end
	node.name = name
	minetest.swap_node(pos, node)
end

local function furnace_node_timer(pos, elapsed)
	--
	-- Inizialize metadata
	--
	local meta = minetest.get_meta(pos)
	local fuel_time = meta:get_float("fuel_time") or 0
	local src_time = meta:get_float("src_time") or 0
	local fuel_totaltime = meta:get_float("fuel_totaltime") or 0

	local inv = meta:get_inventory()
	local srclist = inv:get_list("src")
	local fuellist = inv:get_list("fuel")
	local dstlist = inv:get_list("dst")

	--
	-- Cooking
	--

	-- Check if we have cookable content
	local cooked, aftercooked = minetest.get_craft_result({method = "cooking", width = 1, items = srclist})
	local cookable = true

	if cooked.time == 0 then
		cookable = false
	end

	-- Check if we have enough fuel to burn
	if fuel_time < fuel_totaltime then
		-- The furnace is currently active and has enough fuel
		fuel_time = fuel_time + 1

		-- If there is a cookable item then check if it is ready yet
		if cookable then
			src_time = src_time + 1
			if src_time >= cooked.time then
				-- Place result in dst list if possible
				if inv:room_for_item("dst", cooked.item) then
					inv:add_item("dst", cooked.item)
					inv:set_stack("src", 1, aftercooked.items[1])
					src_time = 0
				end
			end
		end
	else
		-- Furnace ran out of fuel
		if cookable then
			-- We need to get new fuel
			local fuel, afterfuel = minetest.get_craft_result({method = "fuel", width = 1, items = fuellist})

			if fuel.time == 0 then
				-- No valid fuel in fuel list
				fuel_totaltime = 0
				fuel_time = 0
				src_time = 0
			else
				-- Take fuel from fuel list
				inv:set_stack("fuel", 1, afterfuel.items[1])

				fuel_totaltime = fuel.time
				fuel_time = 0
			end
		else
			-- We don't need to get new fuel since there is no cookable item
			fuel_totaltime = 0
			fuel_time = 0
			src_time = 0
		end
	end

	--
	-- Update formspec, infotext and node
	--
	local formspec = inactive_formspec
	local item_state = ""
	local item_percent = 0
	if cookable then
		item_percent = math.floor(src_time / cooked.time * 100)
		item_state = item_percent .. "%"
	else
		if srclist[1]:is_empty() then
			item_state = "Empty"
		else
			item_state = "Not cookable"
		end
	end

	local fuel_state = "Empty"
	local active = "inactive "
	local result = false

	if fuel_time <= fuel_totaltime and fuel_totaltime ~= 0 then
		active = "active "
		local fuel_percent = math.floor(fuel_time / fuel_totaltime * 100)
		fuel_state = fuel_percent .. "%"
		formspec = active_formspec(fuel_percent, item_percent)
		swap_node(pos, "default:furnace_active")
		-- make sure timer restarts automatically
		result = true
	else
		if not fuellist[1]:is_empty() then
			fuel_state = "0%"
		end
		swap_node(pos, "default:furnace")
		-- stop timer on the inactive furnace
		local timer = minetest.get_node_timer(pos)
		timer:stop()
	end

	local infotext = "Furnace " .. active .. "(Item: " .. item_state .. "; Fuel: " .. fuel_state .. ")"

	--
	-- Set meta values
	--
	meta:set_float("fuel_totaltime", fuel_totaltime)
	meta:set_float("fuel_time", fuel_time)
	meta:set_float("src_time", src_time)
	meta:set_string("formspec", formspec)
	meta:set_string("infotext", infotext)

	return result
end

--
-- Node definitions
--

minetest.register_node("default:furnace", {
	description = "Furnace",
	tiles = {
		"default_furnace_top.png", "default_furnace_bottom.png",
		"default_furnace_side.png", "default_furnace_side.png",
		"default_furnace_side.png", "default_furnace_front.png"
	},
	paramtype2 = "facedir",
	groups = {cracky=2},
	legacy_facedir_simple = true,
	is_ground_content = false,
	sounds = default.node_sound_stone_defaults(),

	can_dig = can_dig,

	on_timer = furnace_node_timer,

	on_construct = function(pos)
		local meta = minetest.get_meta(pos)
		meta:set_string("formspec", inactive_formspec)
		local inv = meta:get_inventory()
		inv:set_size('src', 1)
		inv:set_size('fuel', 1)
		inv:set_size('dst', 4)
	end,

	on_metadata_inventory_move = function(pos)
		local timer = minetest.get_node_timer(pos)
		timer:start(1.0)
	end,
	on_metadata_inventory_put = function(pos)
		-- start timer function, it will sort out whether furnace can burn or not.
		local timer = minetest.get_node_timer(pos)
		timer:start(1.0)
	end,
	on_blast = function(pos)
		local drops = {}
		default.get_inventory_drops(pos, "src", drops)
		default.get_inventory_drops(pos, "fuel", drops)
		default.get_inventory_drops(pos, "dst", drops)
		drops[#drops+1] = "default:furnace"
		minetest.remove_node(pos)
		return drops
	end,

	allow_metadata_inventory_put = allow_metadata_inventory_put,
	allow_metadata_inventory_move = allow_metadata_inventory_move,
	allow_metadata_inventory_take = allow_metadata_inventory_take,
})

minetest.register_node("default:furnace_active", {
	description = "Furnace",
	tiles = {
		"default_furnace_top.png", "default_furnace_bottom.png",
		"default_furnace_side.png", "default_furnace_side.png",
		"default_furnace_side.png",
		{
			image = "default_furnace_front_active.png",
			backface_culling = false,
			animation = {
				type = "vertical_frames",
				aspect_w = 16,
				aspect_h = 16,
				length = 1.5
			},
		}
	},
	paramtype2 = "facedir",
	light_source = 8,
	drop = "default:furnace",
	groups = {cracky=2, not_in_creative_inventory=1},
	legacy_facedir_simple = true,
	is_ground_content = false,
	sounds = default.node_sound_stone_defaults(),
	on_timer = furnace_node_timer,

	can_dig = can_dig,

	allow_metadata_inventory_put = allow_metadata_inventory_put,
	allow_metadata_inventory_move = allow_metadata_inventory_move,
	allow_metadata_inventory_take = allow_metadata_inventory_take,
})