craftguide/init.lua

craftguide = {}

local pdata = {}
local core = core

-- Caches
local init_items    = {}
local searches      = {}
local recipes_cache = {}
local usages_cache  = {}
local fuel_cache    = {}

local progressive_mode = core.settings:get_bool("craftguide_progressive_mode")
local sfinv_only = core.settings:get_bool("craftguide_sfinv_only") and rawget(_G, "sfinv")

local after = core.after
local colorize = core.colorize
local reg_items = core.registered_items
local show_formspec = core.show_formspec
local globalstep = core.register_globalstep
local on_shutdown = core.register_on_shutdown
local get_craft_result = core.get_craft_result
local get_players = core.get_connected_players
local on_joinplayer = core.register_on_joinplayer
local register_command = core.register_chatcommand
local get_all_recipes = core.get_all_craft_recipes
local get_player_by_name = core.get_player_by_name
local on_mods_loaded = core.register_on_mods_loaded
local on_leaveplayer = core.register_on_leaveplayer
local serialize, deserialize = core.serialize, core.deserialize
local on_receive_fields = core.register_on_player_receive_fields

local ESC = core.formspec_escape
local S = core.get_translator("craftguide")

local maxn, sort, concat, copy =
	table.maxn, table.sort, table.concat, table.copy

local fmt, find, gmatch, match, sub, split, upper, lower =
	string.format, string.find, string.gmatch, string.match,
	string.sub, string.split, string.upper, string.lower

local min, max, floor, ceil = math.min, math.max, math.floor, math.ceil
local pairs, next = pairs, next
local vec_add, vec_mul = vector.add, vector.multiply

local ROWS  = sfinv_only and 9 or 11
local LINES = 5
local IPP   = ROWS * LINES
local GRID_LIMIT = 8

local FMT = {
	box = "box[%f,%f;%f,%f;%s]",
	label = "label[%f,%f;%s]",
	image = "image[%f,%f;%f,%f;%s]",
	button = "button[%f,%f;%f,%f;%s;%s]",
	tooltip = "tooltip[%f,%f;%f,%f;%s]",
	item_image = "item_image[%f,%f;%f,%f;%s]",
	image_button = "image_button[%f,%f;%f,%f;%s;%s;%s]",
	item_image_button = "item_image_button[%f,%f;%f,%f;%s;%s;%s]",
}

craftguide.group_stereotypes = {
	wool         = "wool:white",
	dye          = "dye:white",
	water_bucket = "bucket:bucket_water",
	vessel       = "vessels:glass_bottle",
	coal         = "default:coal_lump",
	flower       = "flowers:dandelion_yellow",
	mesecon_conductor_craftable = "mesecons:wire_00000000_off",
}

local function table_replace(t, val, new)
	for k, v in pairs(t) do
		if v == val then
			t[k] = new
		end
	end
end

local function __func()
	return debug.getinfo(2, "n").name
end

local function is_str(x)
	return type(x) == "string"
end

local function is_num(x)
	return type(x) == "number"
end

local function is_table(x)
	return type(x) == "table"
end

local function is_func(x)
	return type(x) == "function"
end

local custom_crafts, craft_types = {}, {}

function craftguide.register_craft_type(name, def)
	local func = "craftguide." .. __func() .. "(): "
	assert(is_str(name), func .. "'name' field missing")
	assert(is_str(def.description), func .. "'description' field missing")
	assert(is_str(def.icon), func .. "'icon' field missing")

	craft_types[name] = def
end

function craftguide.register_craft(def)
	if def.result then
		def.output = def.result -- Backward compatibility
	end

	if not is_str(def.output) then
		def.output = ""
	end

	if not is_table(def.items) then
		def.items = {}
	end

	if not is_num(def.width) then
		def.width = 0
	end

	if def.grid then
		if not is_table(def.grid) then
			def.grid = {}
		end

		local cp = copy(def.grid)
		sort(cp, function(a, b)
			return #a > #b
		end)

		def.width = #cp[1]

		for i = 1, #def.grid do
			while #def.grid[i] < def.width do
				def.grid[i] = def.grid[i] .. " "
			end
		end

		local c = 1
		for symbol in gmatch(concat(def.grid), ".") do
			def.items[c] = def.key[symbol]
			c = c + 1
		end
	end

	custom_crafts[#custom_crafts + 1] = def
end

local recipe_filters = {}

function craftguide.add_recipe_filter(name, f)
	local func = "craftguide." .. __func() .. "(): "
	assert(is_str(name), func .. "filter name missing")
	assert(is_func(f), func .. "filter function missing")

	recipe_filters[name] = f
end

function craftguide.remove_recipe_filter(name)
	recipe_filters[name] = nil
end

function craftguide.set_recipe_filter(name, f)
	local func = "craftguide." .. __func() .. "(): "
	assert(is_str(name), func .. "filter name missing")
	assert(is_func(f), func .. "filter function missing")

	recipe_filters = {[name] = f}
end

function craftguide.get_recipe_filters()
	return recipe_filters
end

local function apply_recipe_filters(recipes, player)
	for _, filter in pairs(recipe_filters) do
		recipes = filter(recipes, player)
	end

	return recipes
end

local search_filters = {}

function craftguide.add_search_filter(name, f)
	local func = "craftguide." .. __func() .. "(): "
	assert(is_str(name), func .. "filter name missing")
	assert(is_func(f), func .. "filter function missing")

	search_filters[name] = f
end

function craftguide.remove_search_filter(name)
	search_filters[name] = nil
end

function craftguide.get_search_filters()
	return search_filters
end

local function item_has_groups(item_groups, groups)
	for i = 1, #groups do
		local group = groups[i]
		if (item_groups[group] or 0) == 0 then return end
	end

	return true
end

local function extract_groups(str)
	return split(sub(str, 7), ",")
end

local function item_in_recipe(item, recipe)
	for _, recipe_item in pairs(recipe.items) do
		if recipe_item == item then
			return true
		end
	end
end

local function groups_item_in_recipe(item, recipe)
	local item_groups = reg_items[item].groups

	for _, recipe_item in pairs(recipe.items) do
		if sub(recipe_item, 1,6) == "group:" then
			local groups = extract_groups(recipe_item)
			if item_has_groups(item_groups, groups) then
				local usage = copy(recipe)
				table_replace(usage.items, recipe_item, item)
				return usage
			end
		end
	end
end

local function get_usages(item)
	local usages, c = {}, 0

	for _, recipes in pairs(recipes_cache) do
	for i = 1, #recipes do
		local recipe = recipes[i]
		if item_in_recipe(item, recipe) then
			c = c + 1
			usages[c] = recipe
		else
			recipe = groups_item_in_recipe(item, recipe)
			if recipe then
				c = c + 1
				usages[c] = recipe
			end
		end
	end
	end

	if fuel_cache[item] then
		usages[#usages + 1] = {type = "fuel", width = 1, items = {item}}
	end

	return usages
end

local function get_filtered_items(player, data)
	local items, c = {}, 0
	local known = 0

	for i = 1, #init_items do
		local item = init_items[i]
		local recipes = recipes_cache[item]
		local usages = usages_cache[item]

		recipes = #apply_recipe_filters(recipes or {}, player)
		usages  = #apply_recipe_filters(usages or {}, player)

		if recipes > 0 or usages > 0 then
			if not data then
				c = c + 1
				items[c] = item
			else
				known = known + recipes + usages
			end
		end
	end

	if data then
		data.known_recipes = known
	else
		return items
	end
end

local function cache_recipes(output)
	local recipes = get_all_recipes(output) or {}

	for i = 1, #custom_crafts do
		local custom_craft = custom_crafts[i]
		if match(custom_craft.output, "%S*") == output then
			recipes[#recipes + 1] = custom_craft
		end
	end

	if #recipes > 0 then
		recipes_cache[output] = recipes
	end
end

local function cache_usages(item)
	local usages = get_usages(item)
	if #usages > 0 then
		usages_cache[item] = usages
	end
end

local function get_recipes(item, data, player)
	local recipes = recipes_cache[item]
	local usages = usages_cache[item]

	if recipes then
		recipes = apply_recipe_filters(recipes, player)
	end

	local no_recipes = not recipes or #recipes == 0
	if no_recipes and not usages then
		return
	elseif usages and no_recipes then
		data.show_usages = true
	end

	if data.show_usages then
		recipes = apply_recipe_filters(usages_cache[item], player)
		if recipes and #recipes == 0 then return end
	end

	return recipes
end

local function get_burntime(item)
	return get_craft_result({method = "fuel", width = 1, items = {item}}).time
end

local function cache_fuel(item)
	local burntime = get_burntime(item)
	if burntime > 0 then
		fuel_cache[item] = burntime
		return true
	end
end

local function groups_to_item(groups)
	if #groups == 1 then
		local group = groups[1]
		local def_gr = "default:" .. group
		local stereotypes = craftguide.group_stereotypes
		local stereotype = stereotypes and stereotypes[group]

		if stereotype then
			return stereotype
		elseif reg_items[def_gr] then
			return def_gr
		end
	end

	for name, def in pairs(reg_items) do
		if item_has_groups(def.groups, groups) then
			return name
		end
	end

	return ""
end

local function get_tooltip(item, groups, cooktime, burntime)
	local tooltip

	if groups then
		local groupstr, c = {}, 0

		for i = 1, #groups do
			c = c + 1
			groupstr[c] = colorize("yellow", groups[i])
		end

		groupstr = concat(groupstr, ", ")
		tooltip = S("Any item belonging to the group(s): @1", groupstr)
	else
		local def = reg_items[item]

		tooltip = def and def.description or
			(def and match(item, ":.*"):gsub("%W%l", upper):sub(2):gsub("_", " ") or
			 S("Unknown Item (@1)", item))
	end

	if cooktime then
		tooltip = tooltip .. "\n" ..
			S("Cooking time: @1", colorize("yellow", cooktime))
	end

	if burntime then
		tooltip = tooltip .. "\n" ..
			S("Burning time: @1", colorize("yellow", burntime))
	end

	return fmt("tooltip[%s;%s]", item, ESC(tooltip))
end

local function get_recipe_fs(data)
	local fs = {}
	local recipe = data.recipes[data.rnum]
	local width = recipe.width
	local xoffset = sfinv_only and 4 or 4.92
	local cooktime, shapeless

	if recipe.type == "cooking" then
		cooktime, width = width, 1
	elseif width == 0 then
		shapeless = true
		local n = #recipe.items
		width = n <= 4 and 2 or min(3, n)
	end

	local rows = ceil(maxn(recipe.items) / width)
	local rightest, btn_size, s_btn_size = 0, 1.1

	local btn_lab = data.show_usages and
		ESC(S("Usage @1 of @2", data.rnum, #data.recipes)) or
		ESC(S("Recipe @1 of @2", data.rnum, #data.recipes))

	fs[#fs + 1] = fmt(FMT.button,
		sfinv_only and 5.8 or 7.4,
		sfinv_only and 8 or 8.4,
		2.2,
		1,
		"alternate",
		btn_lab)

	if width > GRID_LIMIT or rows > GRID_LIMIT then
		fs[#fs + 1] = fmt(FMT.label,
			sfinv_only and 2 or 3,
			7,
			ESC(S("Recipe is too big to be displayed (@1x@2)", width, rows)))

		return concat(fs)
	end

	for i = 1, width * rows do
		local item = recipe.items[i] or ""
		local X = ceil((i - 1) % width - width) + xoffset -
			(sfinv_only and 0 or 0.2)
		local Y = ceil(i / width + (sfinv_only and 6 or 7) - min(2, rows))

		if width > 3 or rows > 3 then
			local xof = 1 - 4 / width
			local yof = 1 - 4 / rows
			local x_y = width > rows and xof or yof

			btn_size = width > rows and
				(3.5 + (xof * 2)) / width or (3.5 + (yof * 2)) / rows
			s_btn_size = btn_size

			X = (btn_size * ((i - 1) % width) + xoffset -
				(sfinv_only and 2.8 or 2.84)) * (0.83 - (x_y / 5))
			Y = (btn_size * floor((i - 1) / width) +
				(5 + ((sfinv_only and 0.81 or 1.97) + x_y))) * (0.86 - (x_y / 5))
		end

		if X > rightest then
			rightest = X
		end

		local groups

		if sub(item, 1,6) == "group:" then
			groups = extract_groups(item)
			item = groups_to_item(groups)
		end

		local label = groups and "\nG" or ""

		fs[#fs + 1] = fmt(FMT.item_image_button,
			X,
			Y + (sfinv_only and 0.7 or 0),
			btn_size,
			btn_size,
			item,
			match(item, "%S*"),
			ESC(label))

		local burntime = fuel_cache[item]

		if groups or cooktime or burntime then
			fs[#fs + 1] = get_tooltip(item, groups, cooktime, burntime)
		end
	end

	local custom_recipe = craft_types[recipe.type]

	if custom_recipe or shapeless or recipe.type == "cooking" then
		local icon = custom_recipe and custom_recipe.icon or
			     shapeless and "shapeless" or "furnace"

		if not custom_recipe then
			icon = fmt("craftguide_%s.png^[resize:16x16", icon)
		end

		fs[#fs + 1] = fmt(FMT.image,
			min(3.9, rightest) + 1.2,
			sfinv_only and 6.2 or 6.55,
			0.5,
			0.5,
			icon)

		local tooltip = custom_recipe and custom_recipe.description or
				shapeless and S("Shapeless") or S("Cooking")

		fs[#fs + 1] = fmt("tooltip[%f,%f;%f,%f;%s]",
			rightest + 1.2,
			sfinv_only and 6.2 or 6.55,
			0.5,
			0.5,
			ESC(tooltip))
	end

	local arrow_X  = rightest + (s_btn_size or 1.1)
	local output_X = arrow_X + 0.9

	fs[#fs + 1] = fmt(FMT.image,
		arrow_X,
		sfinv_only and 6.85 or 7.2,
		0.9,
		0.7,
		"craftguide_arrow.png")

	if recipe.type == "fuel" then
		fs[#fs + 1] = fmt(FMT.image,
			output_X,
			sfinv_only and 6.68 or 7,
			1.1,
			1.1,
			"craftguide_fire.png")
	else
		local output_name = match(recipe.output, "%S+")
		local burntime = fuel_cache[output_name]

		fs[#fs + 1] = fmt(FMT.item_image_button,
			output_X,
			sfinv_only and 6.7 or 7,
			1.1,
			1.1,
			recipe.output,
			ESC(output_name),
			"")

		if burntime then
			fs[#fs + 1] = get_tooltip(output_name, nil, nil, burntime)

			fs[#fs + 1] = fmt(FMT.image,
				output_X + 1,
				sfinv_only and 6.83 or 7.1,
				0.6,
				0.4,
				"craftguide_arrow.png")

			fs[#fs + 1] = fmt(FMT.image,
				output_X + 1.6,
				sfinv_only and 6.68 or 6.95,
				0.6,
				0.6,
				"craftguide_fire.png")
		end
	end

	return concat(fs)
end

local function make_formspec(name)
	local data = pdata[name]
	data.pagemax = max(1, ceil(#data.items / IPP))

	local fs = {}

	if not sfinv_only then
		fs[#fs + 1] = fmt("size[%f,%f;]", 9.62, 9)

		fs[#fs + 1] = [[
			no_prepend[]
			background[1,1;1,1;craftguide_bg.png;true]
		]]
	end

	fs[#fs + 1] = fmt("field[0.3,0.33;%f,1;filter;;%s]",
		sfinv_only and 2.75 or 2.72,
		ESC(data.filter))

	fs[#fs + 1] = fmt([[
		image_button[%f,0.09;0.85,0.85;craftguide_search_icon.png;search;]
		image_button[%f,0.09;0.85,0.85;craftguide_clear_icon.png;clear;]
		field_close_on_enter[filter;false]
	]],
		sfinv_only and 2.65 or 2.6,
		sfinv_only and 3.35 or 3.3)

	fs[#fs + 1] = fmt("label[%f,%f;%s / %u]",
		sfinv_only and 6.3 or 7.8,
		0.22,
		colorize("yellow", data.pagenum),
		data.pagemax)

	fs[#fs + 1] = fmt([[
		image_button[%f,0.12;0.8,0.8;craftguide_prev_icon.png;prev;]
		image_button[%f,0.12;0.8,0.8;craftguide_next_icon.png;next;]
		]],
		sfinv_only and 5.5 or 6.88,
		sfinv_only and 7.25 or 8.8)

	if #data.items == 0 then
		local no_item = S("No item to show")
		local pos = sfinv_only and 3 or 3.8

		if next(recipe_filters) and #init_items > 0 and data.filter == "" then
			no_item = S("Collect items to reveal more recipes")
			pos = pos - 1
		end

		fs[#fs + 1] = fmt(FMT.label, pos, 2, ESC(no_item))
	end

	local first_item = (data.pagenum - 1) * IPP
	for i = first_item, first_item + IPP - 1 do
		local item = data.items[i + 1]
		if not item then break end

		local X = i % ROWS
		local Y = (i % IPP - X) / ROWS + 1

		fs[#fs + 1] = fmt("item_image_button[%f,%f;%f,%f;%s;%s_inv;]",
			X - (X * (sfinv_only and 0.12 or 0.14)),
			Y - (Y * 0.1) + 0.1,
			1,
			1,
			item,
			item)
	end

	if data.recipes and #data.recipes > 0 then
		fs[#fs + 1] = get_recipe_fs(data)
	end

	return concat(fs)
end

local show_fs = function(player, name)
	if sfinv_only then
		sfinv.set_player_inventory_formspec(player)
	else
		show_formspec(name, "craftguide", make_formspec(name))
	end
end

craftguide.add_search_filter("groups", function(item, groups)
	local itemdef = reg_items[item]
	local has_groups = true

	for i = 1, #groups do
		local group = groups[i]
		if not itemdef.groups[group] then
			has_groups = nil
			break
		end
	end

	return has_groups
end)

local function search(data)
	local filter = data.filter

	if searches[filter] then
		data.items = searches[filter]
		return
	end

	local opt = "^(.-)%+([%w_]+)=([%w_,]+)"
	local search_filter = next(search_filters) and match(filter, opt)
	local filters = {}

	if search_filter then
		for filter_name, values in gmatch(filter, sub(opt, 6)) do
			if search_filters[filter_name] then
				values = split(values, ",")
				filters[filter_name] = values
			end
		end
	end

	local filtered_list, c = {}, 0

	for i = 1, #data.items_raw do
		local item = data.items_raw[i]
		local def  = reg_items[item]
		local desc = (def and def.description) and lower(def.description) or ""
		local search_in = item .. " " .. desc
		local to_add

		if search_filter then
			for filter_name, values in pairs(filters) do
				local func = search_filters[filter_name]
				to_add = func(item, values) and (search_filter == "" or
					find(search_in, search_filter, 1, true))
			end
		else
			to_add = find(search_in, filter, 1, true)
		end

		if to_add then
			c = c + 1
			filtered_list[c] = item
		end
	end

	if not next(recipe_filters) then
		-- Cache the results only if searched 2 times
		if searches[filter] == nil then
			searches[filter] = false
		else
			searches[filter] = filtered_list
		end
	end

	data.items = filtered_list
end

local function init_data(name)
	pdata[name] = {
		filter    = "",
		pagenum   = 1,
		items     = init_items,
		items_raw = init_items,
	}
end

local function reset_data(data)
	data.filter      = ""
	data.pagenum     = 1
	data.rnum        = 1
	data.query_item  = nil
	data.show_usages = nil
	data.recipes     = nil
	data.items       = data.items_raw
end

local function check_item(def)
	return not (def.groups.not_in_craft_guide == 1 or
		def.groups.not_in_creative_inventory == 1) and
		def.description and def.description ~= ""
end

local function get_init_items()
	local items, c = {}, 0

	for name, def in pairs(reg_items) do
		if check_item(def) then
			cache_fuel(name)
			cache_recipes(name)

			c = c + 1
			items[c] = name
		end
	end

	c = 0

	for i = 1, #items do
		local name = items[i]
		cache_usages(name)

		if recipes_cache[name] or usages_cache[name] then
			c = c + 1
			init_items[c] = name
		end
	end

	sort(init_items)
end

local function _fields(player, fields)
	local name = player:get_player_name()
	local data = pdata[name]
	local _f   = fields

	if _f.clear then
		reset_data(data)
		show_fs(player, name)
		return true

	elseif _f.alternate then
		if #data.recipes == 1 then return end
		local num_next = data.rnum + 1
		data.rnum = data.recipes[num_next] and num_next or 1

		show_fs(player, name)
		return true

	elseif (_f.key_enter_field == "filter" or _f.search) and _f.filter ~= "" then
		local fltr = lower(_f.filter)
		if data.filter == fltr then return end

		data.filter = fltr
		data.pagenum = 1
		search(data)

		show_fs(player, name)
		return true

	elseif _f.prev or _f.next then
		if data.pagemax == 1 then return end
		data.pagenum = data.pagenum - (_f.prev and 1 or -1)

		if data.pagenum > data.pagemax then
			data.pagenum = 1
		elseif data.pagenum == 0 then
			data.pagenum = data.pagemax
		end

		show_fs(player, name)
		return true
	else
		local item
		for field in pairs(_f) do
			if find(field, ":") then
				item = field
				break
			end
		end

		if not item then
			return
		elseif sub(item, -4) == "_inv" then
			item = sub(item, 1,-5)
		end

		if item ~= data.query_item then
			data.show_usages = nil
		else
			data.show_usages = not data.show_usages
		end

		local recipes = get_recipes(item, data, player)
		if not recipes then return end

		data.query_item = item
		data.recipes    = recipes
		data.rnum       = 1

		show_fs(player, name)
		return true
	end
end

on_mods_loaded(get_init_items)

on_joinplayer(function(player)
	local name = player:get_player_name()
	init_data(name)
end)

if sfinv_only then
	sfinv.register_page("craftguide:craftguide", {
		title = S("Craft Guide"),

		get = function(self, player, context)
			local name = player:get_player_name()
			local formspec = make_formspec(name)

			return sfinv.make_formspec(player, context, formspec)
		end,

		on_enter = function(self, player, context)
			if next(recipe_filters) then
				local name = player:get_player_name()
				local data = pdata[name]

				data.items_raw = get_filtered_items(player)
				search(data)
			end
		end,

		on_player_receive_fields = function(self, player, context, fields)
			_fields(player, fields)
		end,
	})
else
	on_receive_fields(function(player, formname, fields)
		if formname == "craftguide" then
			_fields(player, fields)
		end
	end)

	local function on_use(user)
		local name = user:get_player_name()

		if next(recipe_filters) then
			local data = pdata[name]
			data.items_raw = get_filtered_items(user)
			search(data)
		end

		show_formspec(name, "craftguide", make_formspec(name))
	end

	core.register_craftitem("craftguide:book", {
		description = S("Crafting Guide"),
		inventory_image = "craftguide_book.png",
		wield_image = "craftguide_book.png",
		stack_max = 1,
		groups = {book = 1},
		on_use = function(itemstack, user)
			on_use(user)
		end
	})

	core.register_node("craftguide:sign", {
		description = S("Crafting Guide Sign"),
		drawtype = "nodebox",
		tiles = {"craftguide_sign.png"},
		inventory_image = "craftguide_sign_inv.png",
		wield_image = "craftguide_sign_inv.png",
		paramtype = "light",
		paramtype2 = "wallmounted",
		sunlight_propagates = true,
		groups = {oddly_breakable_by_hand = 1, flammable = 3},
		node_box = {
			type = "wallmounted",
			wall_top    = {-0.4375, 0.4375, -0.3125, 0.4375, 0.5, 0.3125},
			wall_bottom = {-0.4375, -0.5, -0.3125, 0.4375, -0.4375, 0.3125},
			wall_side   = {-0.5, -0.3125, -0.4375, -0.4375, 0.3125, 0.4375}
		},

		on_construct = function(pos)
			local meta = core.get_meta(pos)
			meta:set_string("infotext", "Crafting Guide Sign")
		end,

		on_rightclick = function(pos, node, user, itemstack)
			on_use(user)
		end
	})

	core.register_craft({
		output = "craftguide:book",
		recipe = {
			{"default:book"}
		}
	})

	core.register_craft({
		type = "fuel",
		recipe = "craftguide:book",
		burntime = 3
	})

	core.register_craft({
		output = "craftguide:sign",
		recipe = {
			{"default:sign_wall_wood"}
		}
	})

	core.register_craft({
		type = "fuel",
		recipe = "craftguide:sign",
		burntime = 10
	})

	if rawget(_G, "sfinv_buttons") then
		sfinv_buttons.register_button("craftguide", {
			title = S("Crafting Guide"),
			tooltip = S("Shows a list of available crafting recipes, cooking recipes and fuels"),
			image = "craftguide_book.png",
			action = function(player)
				on_use(player)
			end,
		})
	end
end

if progressive_mode then
	local PLAYERS = {}
	local POLL_FREQ = 0.25

	local function item_in_inv(item, inv_items)
		local inv_items_size = #inv_items

		if sub(item, 1,6) == "group:" then
			local groups = extract_groups(item)
			for i = 1, inv_items_size do
				local inv_item = reg_items[inv_items[i]]
				if inv_item then
					local item_groups = inv_item.groups
					if item_has_groups(item_groups, groups) then
						return true
					end
				end
			end
		else
			for i = 1, inv_items_size do
				if inv_items[i] == item then
					return true
				end
			end
		end
	end

	local function recipe_in_inv(recipe, inv_items)
		for _, item in pairs(recipe.items) do
			if not item_in_inv(item, inv_items) then return end
		end

		return true
	end

	local function progressive_filter(recipes, player)
		if not recipes then
			return {}
		end

		local name = player:get_player_name()
		local data = pdata[name]

		if #data.inv_items == 0 then
			return {}
		end

		local filtered, c = {}, 0
		for i = 1, #recipes do
			local recipe = recipes[i]
			if recipe_in_inv(recipe, data.inv_items) then
				c = c + 1
				filtered[c] = recipe
			end
		end

		return filtered
	end

	local item_lists = {
		"main",
		"craft",
		"craftpreview",
	}

	local function table_merge(t, t2)
		t, t2 = t or {}, t2 or {}
		local c = #t

		for i = 1, #t2 do
			c = c + 1
			t[c] = t2[i]
		end

		return t
	end

	local function table_diff(t, t2)
		local hash = {}

		for i = 1, #t do
			local v = t[i]
			hash[v] = true
		end

		for i = 1, #t2 do
			local v = t2[i]
			hash[v] = nil
		end

		local diff, c = {}, 0

		for i = 1, #t do
			local v = t[i]
			if hash[v] then
				c = c + 1
				diff[c] = v
			end
		end

		return diff
	end

	local function get_inv_items(player)
		local inv = player:get_inventory()
		local stacks = {}

		for i = 1, #item_lists do
			local list = inv:get_list(item_lists[i])
			table_merge(stacks, list)
		end

		local inv_items, c = {}, 0

		for i = 1, #stacks do
			local stack = stacks[i]
			if not stack:is_empty() then
				local name = stack:get_name()
				if reg_items[name] then
					c = c + 1
					inv_items[c] = name
				end
			end
		end

		return inv_items
	end

	local function show_hud_success(player, data, dtime)
		local hud_info_bg = player:hud_get(data.hud.bg)

		if hud_info_bg.position.y <= 0.9 then
			data.show_hud = false
			data.hud_timer = (data.hud_timer or 0) + dtime
		end

		if data.show_hud then
			for _, def in pairs(data.hud) do
				local hud_info = player:hud_get(def)

				player:hud_change(def, "position", {
					x = hud_info.position.x,
					y = hud_info.position.y - (dtime / 5)
				})
			end

			player:hud_change(data.hud.text, "text",
				S("@1 new recipe(s) discovered!", data.discovered))

		elseif data.show_hud == false then
			if data.hud_timer > 3 then
				for _, def in pairs(data.hud) do
					local hud_info = player:hud_get(def)

					player:hud_change(def, "position", {
						x = hud_info.position.x,
						y = hud_info.position.y + (dtime / 5)
					})
				end

				if hud_info_bg.position.y >= 1 then
					data.show_hud = nil
					data.hud_timer = nil
				end
			end
		end
	end

	-- Workaround. Need an engine call to detect when the contents
	-- of the player inventory changed, instead
	local function poll_new_items()
		for i = 1, #PLAYERS do
			local player = PLAYERS[i]
			local name   = player:get_player_name()
			local data   = pdata[name]

			local inv_items = get_inv_items(player)
			local diff = table_diff(inv_items, data.inv_items)

			if #diff > 0 then
				data.inv_items = table_merge(diff, data.inv_items)

				local oldknown = data.known_recipes or 0
				get_filtered_items(player, data)
				data.discovered = data.known_recipes - oldknown

				if data.show_hud == nil and data.discovered > 0 then
					data.show_hud = true
				end
			end
		end

		after(POLL_FREQ, poll_new_items)
	end

	poll_new_items()

	globalstep(function(dtime)
		for i = 1, #PLAYERS do
			local player = PLAYERS[i]
			local name   = player:get_player_name()
			local data   = pdata[name]

			if data.show_hud ~= nil then
				show_hud_success(player, data, dtime)
			end
		end
	end)

	craftguide.add_recipe_filter("Default progressive filter", progressive_filter)

	on_joinplayer(function(player)
		PLAYERS = get_players()

		local meta = player:get_meta()
		local name = player:get_player_name()
		local data = pdata[name]

		data.inv_items = deserialize(meta:get_string("inv_items")) or {}
		data.known_recipes = deserialize(meta:get_string("known_recipes")) or 0

		data.hud = {
			bg = player:hud_add({
				hud_elem_type = "image",
				position      = {x = 0.78, y = 1},
				alignment     = {x = 1,    y = 1},
				scale         = {x = 370,  y = 112},
				text          = "craftguide_bg.png",
			}),

			book = player:hud_add({
				hud_elem_type = "image",
				position      = {x = 0.79, y = 1.02},
				alignment     = {x = 1,    y = 1},
				scale         = {x = 4,    y = 4},
				text          = "craftguide_book.png",
			}),

			text = player:hud_add({
				hud_elem_type = "text",
				position      = {x = 0.84, y = 1.04},
				alignment     = {x = 1,    y = 1},
				number        = 0xFFFFFF,
				text          = "",
			}),
		}
	end)

	local to_save = {
		"inv_items",
		"known_recipes",
	}

	local function save_meta(player)
		local meta = player:get_meta()
		local name = player:get_player_name()
		local data = pdata[name]

		for i = 1, #to_save do
			local meta_name = to_save[i]
			meta:set_string(meta_name, serialize(data[meta_name]))
		end
	end

	on_leaveplayer(function(player)
		PLAYERS = get_players()
		save_meta(player)
	end)

	on_shutdown(function()
		for i = 1, #PLAYERS do
			local player = PLAYERS[i]
			save_meta(player)
		end
	end)
end

on_leaveplayer(function(player)
	local name = player:get_player_name()
	pdata[name] = nil
end)

register_command("craft", {
	description = S("Show recipe(s) of the pointed node"),
	func = function(name)
		local player = get_player_by_name(name)
		local dir    = player:get_look_dir()
		local ppos   = player:get_pos()
		      ppos.y = ppos.y + 1.625

		local node_name

		for i = 1, 10 do
			local look_at = vec_add(ppos, vec_mul(dir, i))
			local node = core.get_node(look_at)

			if node.name ~= "air" then
				node_name = node.name
				break
			end
		end

		local red = colorize("red", "[craftguide] ")

		if not node_name then
			return false, red .. S("No node pointed")
		end

		local data = pdata[name]
		reset_data(data)

		local recipes = recipes_cache[node_name]
		local usages = usages_cache[node_name]

		if recipes then
			recipes = apply_recipe_filters(recipes, player)
		end

		if not recipes or #recipes == 0 then
			local ylw = colorize("yellow", node_name)
			local msg = red .. "%s: " .. ylw

			if usages then
				recipes = usages_cache[node_name]
				if #recipes > 0 then
					data.show_usages = true
				end
			elseif recipes_cache[node_name] then
				return false, fmt(msg, S("You don't know a recipe for this node"))
			else
				return false, fmt(msg, S("No recipe for this node"))
			end
		end

		data.query_item = node_name
		data.recipes = recipes

		return true, show_fs(player, name)
	end,
})

function craftguide.show(name, item, show_usages)
	local func = "craftguide." .. __func() .. "(): "
	assert(is_str(name), func .. "player name missing")

	local data = pdata[name]
	local player = get_player_by_name(name)
	local query_item = data.query_item

	reset_data(data)

	item = reg_items[item] and item or query_item

	data.query_item  = item
	data.show_usages = show_usages
	data.recipes     = get_recipes(item, data, player)

	show_fs(player, name)
end