local S = minetest.get_translator("pipeworks")
-- cache some recipe data to avoid calling the slow function
-- minetest.get_craft_result() every second
local autocrafterCache = {}

local craft_time = 1

local function count_index(invlist)
	local index = {}
	for _, stack in pairs(invlist) do
		stack = ItemStack(stack)
		if not stack:is_empty() then
			local stack_name = stack:get_name()
			index[stack_name] = (index[stack_name] or 0) + stack:get_count()
		end
	end
	return index
end

local function get_item_info(stack)
	local name = stack:get_name()
	local def = minetest.registered_items[name]
	local description = def and def.description or S("Unknown item")
	return description, name
end

-- Get best matching recipe for what user has put in crafting grid.
-- This function does not consider crafting method (mix vs craft)
local function get_matching_craft(output_name, example_recipe)
	local recipes = minetest.get_all_craft_recipes(output_name)
	if not recipes then
		return example_recipe
	end

	if 1 == #recipes then
		return recipes[1].items
	end

	local index_example = count_index(example_recipe)
	local best_score = 0
	local index_recipe, best_index, score, group
	for i = 1, #recipes do
		score = 0
		index_recipe = count_index(recipes[i].items)
		for recipe_item_name, _ in pairs(index_recipe) do
			if index_example[recipe_item_name] then
				score = score + 1
			elseif recipe_item_name:sub(1, 6) == "group:" then
				group = recipe_item_name:sub(7)
				for example_item_name, _ in pairs(index_example) do
					if minetest.get_item_group(example_item_name, group) > 0 then
						score = score + 1
						break
					end
				end
			end
		end
		if best_score < score then
			best_index = i
			best_score = score
		end
	end

	return best_index and recipes[best_index].items or example_recipe
end

local function get_craft(pos, inventory, hash)
	local hash = hash or minetest.hash_node_position(pos)
	local craft = autocrafterCache[hash]
	if craft then return craft end

	local example_recipe = inventory:get_list("recipe")
	local output, decremented_input = minetest.get_craft_result({
		method = "normal", width = 3, items = example_recipe
	})

	local recipe = example_recipe
	if output and not output.item:is_empty() then
		recipe = get_matching_craft(output.item:get_name(), example_recipe)
	end

	craft = {
		recipe = recipe,
		consumption = count_index(recipe),
		output = output,
		decremented_input = decremented_input.items
	}
	autocrafterCache[hash] = craft
	return craft
end

-- From a consumption table with groups and an inventory index, build
-- a consumption table without groups
local function calculate_consumption(inv_index, consumption_with_groups)
	inv_index = table.copy(inv_index)
	consumption_with_groups = table.copy(consumption_with_groups)

	local consumption = {}
	local groups = {}

	-- First consume all non-group requirements
	-- This is done to avoid consuming a non-group item which is also
	-- in a group
	for key, count in pairs(consumption_with_groups) do
		if key:sub(1, 6) == "group:" then
			groups[#groups + 1] = key:sub(7, #key)
		else
			if not inv_index[key] or inv_index[key] < count then
				return nil
			end

			consumption[key] = (consumption[key] or 0) + count
			consumption_with_groups[key] = consumption_with_groups[key] - count
			assert(consumption_with_groups[key] == 0)
			consumption_with_groups[key] = nil
			inv_index[key] = inv_index[key] - count
			assert(inv_index[key] >= 0)
		end
	end

	-- Next, resolve groups using the remaining items in the inventory
	local take
	if #groups > 0 then
		for itemname, count in pairs(inv_index) do
			if count > 0 then
				local def = minetest.registered_items[itemname]
				local item_groups = def and def.groups or {}
				for i = 1, #groups do
					local group = groups[i]
					local groupname = "group:" .. group
					if item_groups[group] and item_groups[group] >= 1
						and consumption_with_groups[groupname] > 0
					then
						take = math.min(count, consumption_with_groups[groupname])
						consumption_with_groups[groupname] =
								consumption_with_groups[groupname] - take

						assert(consumption_with_groups[groupname] >= 0)
						consumption[itemname] =
								(consumption[itemname] or 0) + take

						inv_index[itemname] = inv_index[itemname] - take
						assert(inv_index[itemname] >= 0)
					end
				end
			end
		end
	end

	-- Finally, check everything has been consumed
	for key, count in pairs(consumption_with_groups) do
		if count > 0 then
			return nil
		end
	end

	return consumption
end

local function has_room_for_output(list_output, index_output)
	local name
	local empty_count = 0
	for _, item in pairs(list_output) do
		if item:is_empty() then
			empty_count = empty_count + 1
		else
			name = item:get_name()
			if index_output[name] then
				index_output[name] = index_output[name] - item:get_free_space()
			end
		end
	end
	for _, count in pairs(index_output) do
		if count > 0 then
			empty_count = empty_count - 1
		end
	end
	if empty_count < 0 then
		return false
	end

	return true
end

local function autocraft(inventory, craft)
	if not craft then return false end

	-- check if output and all replacements fit in dst
	local output = craft.output.item
	local out_items = count_index(craft.decremented_input)
	out_items[output:get_name()] =
			(out_items[output:get_name()] or 0) + output:get_count()

	if not has_room_for_output(inventory:get_list("dst"), out_items) then
		return false
	end

	-- check if we have enough material available
	local inv_index = count_index(inventory:get_list("src"))
	local consumption = calculate_consumption(inv_index, craft.consumption)
	if not consumption then
		return false
	end

	-- consume material
	for itemname, number in pairs(consumption) do
		-- We have to do that since remove_item does not work if count > stack_max
		for _ = 1, number do
			inventory:remove_item("src", ItemStack(itemname))
		end
	end

	-- craft the result into the dst inventory and add any "replacements" as well
	inventory:add_item("dst", output)
	local leftover
	for i = 1, 9 do
		leftover = inventory:add_item("dst", craft.decremented_input[i])
		if leftover and not leftover:is_empty() then
			minetest.log("warning", "[pipeworks] autocrafter didn't " ..
				"calculate output space correctly.")
		end
	end
	return true
end

-- returns false to stop the timer, true to continue running
-- is started only from start_autocrafter(pos) after sanity checks and
-- recipe is cached
local function run_autocrafter(pos, elapsed)
	local meta = minetest.get_meta(pos)
	local inventory = meta:get_inventory()
	local craft = get_craft(pos, inventory)
	local output_item = craft.output.item
	-- only use crafts that have an actual result
	if output_item:is_empty() then
		meta:set_string("infotext", S("unconfigured Autocrafter: unknown recipe"))
		return false
	end

	for _ = 1, math.floor(elapsed / craft_time) do
		local continue = autocraft(inventory, craft)
		if not continue then return false end
	end
	return true
end

local function start_crafter(pos)
	local meta = minetest.get_meta(pos)
	if meta:get_int("enabled") == 1 then
		local timer = minetest.get_node_timer(pos)
		if not timer:is_started() then
			timer:start(craft_time)
		end
	end
end

local function after_inventory_change(pos)
	start_crafter(pos)
end

-- note, that this function assumes allready being updated to virtual items
-- and doesn't handle recipes with stacksizes > 1
local function after_recipe_change(pos, inventory)
	local hash = minetest.hash_node_position(pos)
	local meta = minetest.get_meta(pos)
	autocrafterCache[hash] = nil
	-- if we emptied the grid, there's no point in keeping it running or cached
	if inventory:is_empty("recipe") then
		minetest.get_node_timer(pos):stop()
		meta:set_string("infotext", S("unconfigured Autocrafter"))
		inventory:set_stack("output", 1, "")
		return
	end
	local craft = get_craft(pos, inventory, hash)
	local output_item = craft.output.item
	local description, name = get_item_info(output_item)
	meta:set_string("infotext", S("'@1' Autocrafter (@2)", description, name))
	inventory:set_stack("output", 1, output_item)

	after_inventory_change(pos)
end

-- clean out unknown items and groups, which would be handled like unknown
-- items in the crafting grid
-- if minetest supports query by group one day, this might replace them
-- with a canonical version instead
local function normalize(item_list)
	for i = 1, #item_list do
		local name = item_list[i]
		if not minetest.registered_items[name] then
			item_list[i] = ""
		end
	end
	return item_list
end

local function on_output_change(pos, inventory, stack)
	if not stack then
		inventory:set_list("output", {})
		inventory:set_list("recipe", {})
	else
		local input = minetest.get_craft_recipe(stack:get_name())
		if not input.items or input.type ~= "normal" then return end
		local items, width = normalize(input.items), input.width
		local item_idx, width_idx = 1, 1
		for i = 1, 9 do
			if width_idx <= width then
				inventory:set_stack("recipe", i, items[item_idx])
				item_idx = item_idx + 1
			else
				inventory:set_stack("recipe", i, ItemStack(""))
			end
			width_idx = (width_idx < 3) and (width_idx + 1) or 1
		end
		-- we'll set the output slot in after_recipe_change to the actual
		-- result of the new recipe
	end
	after_recipe_change(pos, inventory)
end

-- returns false if we shouldn't bother attempting to start the timer again
-- after this
local function update_meta(meta, enabled)
	local state = enabled and "on" or "off"
	meta:set_int("enabled", enabled and 1 or 0)
	local list_backgrounds = ""
	if minetest.get_modpath("i3") or minetest.get_modpath("mcl_formspec") then
		list_backgrounds = "style_type[box;colors=#666]"
		for i = 0, 2 do
			for j = 0, 2 do
				list_backgrounds = list_backgrounds .. "box[" ..
					0.22 + (i * 1.25) .. "," .. 0.22 + (j * 1.25) .. ";1,1;]"
			end
		end
		for i = 0, 3 do
			for j = 0, 2 do
				list_backgrounds = list_backgrounds .. "box[" ..
					5.28 + (i * 1.25) .. "," .. 0.22 + (j * 1.25) .. ";1,1;]"
			end
		end
		for i = 0, 7 do
			for j = 0, 2 do
				list_backgrounds = list_backgrounds .. "box[" ..
					0.22 + (i * 1.25) .. "," .. 5 + (j * 1.25) .. ";1,1;]"
			end
		end
	end
	local size = "10.2,14"
	local fs =
		"formspec_version[2]" ..
		"size[" .. size .. "]" ..
		pipeworks.fs_helpers.get_prepends(size) ..
		list_backgrounds ..
		"list[context;recipe;0.22,0.22;3,3;]" ..
		"image[4,1.45;1,1;[combine:16x16^[noalpha^[colorize:#141318:255]" ..
		"list[context;output;4,1.45;1,1;]" ..
		"image_button[4,2.6;1,0.6;pipeworks_button_" .. state .. ".png;" ..
		state .. ";;;false;pipeworks_button_interm.png]" ..
		"list[context;dst;5.28,0.22;4,3;]" ..
		"list[context;src;0.22,5;8,3;]" ..
		pipeworks.fs_helpers.get_inv(9) ..
		"listring[current_player;main]" ..
		"listring[context;src]" ..
		"listring[current_player;main]" ..
		"listring[context;dst]" ..
		"listring[current_player;main]"
	if minetest.get_modpath("digilines") then
		fs = fs .. "field[0.22,4.1;4.5,0.75;channel;" .. S("Channel") ..
			";${channel}]" ..
			"button[5,4.1;1.5,0.75;set_channel;" .. S("Set") .. "]" ..
			"button_exit[6.8,4.1;2,0.75;close;" .. S("Close") .. "]"
	end
	meta:set_string("formspec", fs)

	-- toggling the button doesn't quite call for running a recipe change check
	-- so instead we run a minimal version for infotext setting only
	-- this might be more written code, but actually executes less
	local output = meta:get_inventory():get_stack("output", 1)
	if output:is_empty() then -- doesn't matter if paused or not
		meta:set_string("infotext", S("unconfigured Autocrafter"))
		return false
	end

	local description, name = get_item_info(output)
	local infotext = enabled and S("'@1' Autocrafter (@2)", description, name)
				or S("paused '@1' Autocrafter", description)

	meta:set_string("infotext", infotext)
	return enabled
end

-- 1st version of the autocrafter had actual items in the crafting grid
-- the 2nd replaced these with virtual items, dropped the content on update and
--   set "virtual_items" to string "1"
-- the third added an output inventory, changed the formspec and added a button
--   for enabling/disabling
-- so we work out way backwards on this history and update each single case
--   to the newest version
local function upgrade_autocrafter(pos, meta)
	local meta = meta or minetest.get_meta(pos)
	local inv = meta:get_inventory()

	if inv:get_size("output") == 0 then -- we are version 2 or 1
		inv:set_size("output", 1)
		-- migrate the old autocrafters into an "enabled" state
		update_meta(meta, true)

		if meta:get_string("virtual_items") == "1" then -- we are version 2
			-- we already dropped stuff, so lets remove the metadatasetting
			-- (we are not being called again for this node)
			meta:set_string("virtual_items", "")
		else -- we are version 1
			local recipe = inv:get_list("recipe")
			if not recipe then return end
			for idx, stack in ipairs(recipe) do
				if not stack:is_empty() then
					minetest.add_item(pos, stack)
					stack:set_count(1)
					stack:set_wear(0)
					inv:set_stack("recipe", idx, stack)
				end
			end
		end

		-- update the recipe, cache, and start the crafter
		autocrafterCache[minetest.hash_node_position(pos)] = nil
		after_recipe_change(pos, inv)
	end
end

minetest.register_node("pipeworks:autocrafter", {
	description = S("Autocrafter"),
	drawtype = "normal",
	tiles = {"pipeworks_autocrafter.png"},
	groups = {snappy = 3, tubedevice = 1, tubedevice_receiver = 1, dig_generic = 1, axey=1, handy=1, pickaxey=1},
	is_ground_content = false,
	_mcl_hardness=0.8,
	tube = {insert_object = function(pos, node, stack, direction)
			local meta = minetest.get_meta(pos)
			local inv = meta:get_inventory()
			local added = inv:add_item("src", stack)
			after_inventory_change(pos)
			return added
		end,
		can_insert = function(pos, node, stack, direction)
			local meta = minetest.get_meta(pos)
			local inv = meta:get_inventory()
			return inv:room_for_item("src", stack)
		end,
		input_inventory = "dst",
		connect_sides = {
			left = 1, right = 1, front = 1, back = 1, top = 1, bottom = 1
			}
	},
	on_construct = function(pos)
		local meta = minetest.get_meta(pos)
		local inv = meta:get_inventory()
		inv:set_size("src", 3 * 8)
		inv:set_size("recipe", 3 * 3)
		inv:set_size("dst", 4 * 3)
		inv:set_size("output", 1)
		update_meta(meta, false)
	end,
	on_receive_fields = function(pos, formname, fields, sender)
		if (fields.quit and not fields.key_enter_field)
			or not pipeworks.may_configure(pos, sender)
		then
			return
		end
		local meta = minetest.get_meta(pos)
		if fields.on then
			update_meta(meta, false)
			minetest.get_node_timer(pos):stop()
		elseif fields.off then
			if update_meta(meta, true) then
				start_crafter(pos)
			end
		end
		if fields.channel then
			meta:set_string("channel", fields.channel)
		end
	end,
	can_dig = function(pos, player)
		upgrade_autocrafter(pos)
		local meta = minetest.get_meta(pos)
		local inv = meta:get_inventory()
		return (inv:is_empty("src") and inv:is_empty("dst"))
	end,
	after_place_node = pipeworks.scan_for_tube_objects,
	after_dig_node = function(pos)
		pipeworks.scan_for_tube_objects(pos)
	end,
	on_destruct = function(pos)
		autocrafterCache[minetest.hash_node_position(pos)] = nil
	end,
	allow_metadata_inventory_put = function(pos, listname, index, stack, player)
		if not pipeworks.may_configure(pos, player) then return 0 end
		upgrade_autocrafter(pos)
		local inv = minetest.get_meta(pos):get_inventory()
		if listname == "recipe" then
			stack:set_count(1)
			inv:set_stack(listname, index, stack)
			after_recipe_change(pos, inv)
			return 0
		elseif listname == "output" then
			on_output_change(pos, inv, stack)
			return 0
		end
		after_inventory_change(pos)
		return stack:get_count()
	end,
	allow_metadata_inventory_take = function(pos, listname, index, stack, player)
		if not pipeworks.may_configure(pos, player) then
			minetest.log("action", string.format("%s attempted to take from " ..
				"autocrafter at %s",
				player:get_player_name(), minetest.pos_to_string(pos)))
			return 0
		end
		upgrade_autocrafter(pos)
		local inv = minetest.get_meta(pos):get_inventory()
		if listname == "recipe" then
			inv:set_stack(listname, index, ItemStack(""))
			after_recipe_change(pos, inv)
			return 0
		elseif listname == "output" then
			on_output_change(pos, inv, nil)
			return 0
		end
		after_inventory_change(pos)
		return stack:get_count()
	end,
	allow_metadata_inventory_move = function(
			pos, from_list, from_index, to_list, to_index, count, player)

		if not pipeworks.may_configure(pos, player) then return 0 end
		upgrade_autocrafter(pos)
		local inv = minetest.get_meta(pos):get_inventory()
		local stack = inv:get_stack(from_list, from_index)

		if to_list == "output" then
			on_output_change(pos, inv, stack)
			return 0
		elseif from_list == "output" then
			on_output_change(pos, inv, nil)
			if to_list ~= "recipe" then
				return 0
			end -- else fall through to recipe list handling
		end

		if from_list == "recipe" or to_list == "recipe" then
			if from_list == "recipe" then
				inv:set_stack(from_list, from_index, ItemStack(""))
			end
			if to_list == "recipe" then
				stack:set_count(1)
				inv:set_stack(to_list, to_index, stack)
			end
			after_recipe_change(pos, inv)
			return 0
		end

		after_inventory_change(pos)
		return count
	end,
	on_timer = run_autocrafter,
	digiline = {
		receptor = {},
		effector = {
			action = function(pos,node,channel,msg)
				local meta = minetest.get_meta(pos)
				if channel ~= meta:get_string("channel") then return end
				if type(msg) == "table" then
					if #msg < 3 then return end
					local inv = meta:get_inventory()
					for y = 0, 2, 1 do
						for x = 1, 3, 1 do
							local slot = y * 3 + x
							if minetest.registered_items[msg[y + 1][x]] then
								inv:set_stack("recipe", slot, ItemStack(
									msg[y + 1][x]))
							else
								inv:set_stack("recipe", slot, ItemStack(""))
							end
						end
					end
					after_recipe_change(pos,inv)
				elseif msg == "get_recipe" then
					local meta = minetest.get_meta(pos)
					local inv = meta:get_inventory()
					local recipe = {}
					for y = 0, 2, 1 do
						local row = {}
						for x = 1, 3, 1 do
							local slot = y * 3 + x
							table.insert(row, inv:get_stack(
									"recipe", slot):get_name())
						end
						table.insert(recipe, row)
					end
					local setchan = meta:get_string("channel")
					local output = inv:get_stack("output", 1)
					digiline:receptor_send(pos, digiline.rules.default, setchan, {
						recipe = recipe,
						result = {
							name = output:get_name(),
							count = output:get_count(),
						}
					  })
				elseif msg == "off" then
					update_meta(meta, false)
					minetest.get_node_timer(pos):stop()
				elseif msg == "on" then
					if update_meta(meta, true) then
						start_crafter(pos)
					end
				elseif msg == "single" then
					run_autocrafter(pos,1)
				end
			end,
		},
	},
})
pipeworks.ui_cat_tube_list[#pipeworks.ui_cat_tube_list + 1] = "pipeworks:autocrafter"
