Use of string.format instead of concat

Fix two bugs

init.lua

@@ -24,6 +24,7 @@ craftguide.intllib = S
 local remove, maxn, sort, concat = table.remove, table.maxn, table.sort, table.concat
 local vector_add, vector_mul = vector.add, vector.multiply
 local min, max, floor, ceil = math.min, math.max, math.floor, math.ceil
+local fmt = string.format
 
 local DEFAULT_SIZE = 10
 local MIN_LIMIT, MAX_LIMIT = 10, 12
@@ -43,11 +44,23 @@ local group_stereotypes = {
 }
 
 local function extract_groups(str)
-	if str:sub(1,6) ~= "group:" then return end
+	if str:sub(1,6) ~= "group:" then
+		return
+	end
+
 	return str:sub(7):split(",")
 end
 
+local function __func()
+	return debug.getinfo(2, "n").name
+end
+
 function craftguide.register_craft_type(name, def)
+	local func = "craftguide." .. __func() .. "(): "
+	assert(name, func .. "'name' field missing")
+	assert(def.description, func .. "'description' field missing")
+	assert(def.icon, func .. "'icon' field missing")
+
 	if not craftguide.craft_types[name] then
 		craftguide.craft_types[name] = def
 	end
@@ -59,6 +72,12 @@ craftguide.register_craft_type("digging", {
 })
 
 function craftguide.register_craft(def)
+	local func = "craftguide." .. __func() .. "(): "
+	assert(def.type,  func .. "'type' field missing")
+	assert(def.width, func .. "'width' field missing")
+	assert(def.output, func .. "'output' field missing")
+	assert(def.items,  func .. "'items' field missing")
+
 	craftguide.custom_crafts[#craftguide.custom_crafts + 1] = def
 end
 
@@ -69,8 +88,14 @@ craftguide.register_craft({
 	items  = {"default:stone"},
 })
 
-local function colorize(str)
+local color_codes = {
-	return mt.colorize("#FFFF00", str)
+	red = "#FF0000",
+	yellow = "#FFFF00",
+}
+
+local function colorize(str, color)
+	color = color or "yellow"
+	return mt.colorize(color_codes[color], str)
 end
 
 local function get_fueltime(item)
@@ -80,10 +105,10 @@ end
 local function reset_datas(data)
 	data.show_usage = nil
 	data.filter     = ""
-	data.item       = nil
+	data.input      = nil
 	data.pagenum    = 1
 	data.rnum       = 1
-	data.fuel       = nil
+	data.items      = progressive_mode and data.init_filter_items or datas.init_items
 end
 
 local function in_table(T)
@@ -166,15 +191,24 @@ local function get_tooltip(item, recipe_type, cooktime, groups)
 	return has_extras and tooltip .. "]" or ""
 end
 
-local function _get_recipe(iX, iY, xoffset, recipe_num, recipes, show_usage)
+local function get_recipe_fs(iX, iY, xoffset, recipe_num, recipes, show_usage)
-	local fs, recipes_total = {}, #recipes
+	if not recipes[1] then
-	if recipes_total > 1 then
+		return ""
-		fs[#fs + 1] = "button[" .. (iX - (sfinv_only and 2.2 or 2.6)) .. "," ..
-			(iY + (sfinv_only and 3.9 or 3.3)) .. ";2.2,1;alternate;" ..
-			(show_usage and S("Usage") or S("Recipe")) .. " " ..
-			S("@1 of @2", recipe_num, recipes_total) .. "]"
 	end
 
+	local fs = {}
+
+	fs[#fs + 1] = fmt("button[%f,%f;%f,%f;%s;%s %u %s %u]",
+		iX - (sfinv_only and 2.2 or 2.6),
+		iY + (sfinv_only and 3.9 or 3.3),
+		2.2,
+		1,
+		"alternate",
+		show_usage and S("Usage") or S("Recipe"),
+		recipe_num,
+		S("of"),
+		#recipes)
+
 	local recipe_type = recipes[recipe_num].type
 	local items = recipes[recipe_num].items
 	local width = recipes[recipe_num].width
@@ -190,8 +224,10 @@ local function _get_recipe(iX, iY, xoffset, recipe_num, recipes, show_usage)
 	local rightest, s_btn_size = 0
 
 	if recipe_type ~= "cooking" and (width > GRID_LIMIT or rows > GRID_LIMIT) then
-		fs[#fs + 1] = "label[" .. ((iX / 2) - 2) .. "," .. (iY + 2.2) .. ";" ..
+		fs[#fs + 1] = fmt("label[%f,%f;%s]",
-			S("Recipe is too big to be displayed (@1x@2)", width, rows) .. "]"
+			(iX / 2) - 2,
+			iY + 2.2,
+			S("Recipe is too big to be displayed (@1x@2)", width, rows))
 
 		return concat(fs)
 	else
@@ -214,60 +250,93 @@ local function _get_recipe(iX, iY, xoffset, recipe_num, recipes, show_usage)
 			local groups = extract_groups(v)
 			local label = groups and "\nG" or ""
 			local item_r = group_to_item(v)
-			local tltip = get_tooltip(item_r, recipe_type, cooktime, groups)
+			local tltp = get_tooltip(item_r, recipe_type, cooktime, groups)
 
-			fs[#fs + 1] = "item_image_button[" .. X .. "," ..
+			fs[#fs + 1] = fmt("item_image_button[%f,%f;%f,%f;%s;%s;%s]",
-				(Y + (sfinv_only and 0.7 or 0.2)) .. ";" ..
+				X,
-				BUTTON_SIZE .. "," .. BUTTON_SIZE .. ";" .. item_r ..
+				Y + (sfinv_only and 0.7 or 0.2),
-				";" .. item_r:match("%S*") .. ";" .. label .. "]" .. tltip
+				BUTTON_SIZE,
+				BUTTON_SIZE,
+				item_r,
+				item_r:match("%S*"),
+				label)
+
+			fs[#fs + 1] = tltp
 		end
 
 		BUTTON_SIZE = 1.1
 	end
 
 	local custom_recipe = craftguide.craft_types[recipe_type]
-	if recipe_type == "cooking" or (recipe_type == "normal" and width == 0) or
+	if recipe_type == "cooking" or custom_recipe or
-			custom_recipe then
+			(recipe_type == "normal" and width == 0) then
+
 		local icon = recipe_type == "cooking" and "furnace" or "shapeless"
-		local coords = (rightest + 1.2) .. "," ..
-			       (iY + (sfinv_only and 2.2 or 1.7)) ..
-			       ";0.5,0.5;"
 
-		fs[#fs + 1] = "image[" .. coords ..
+		fs[#fs + 1] = fmt("image[%f,%f;%f,%f;%s]",
-			(custom_recipe and custom_recipe.icon or
+			rightest + 1.2,
-			 "craftguide_" .. icon .. ".png^[resize:16x16") .. "]"
+			iY + (sfinv_only and 2.2 or 1.7),
+			0.5,
+			0.5,
+			custom_recipe and custom_recipe.icon or
+				"craftguide_" .. icon .. ".png^[resize:16x16")
 
-		fs[#fs + 1] = "tooltip[" .. coords ..
+		fs[#fs + 1] = fmt("tooltip[%f,%f;%f,%f;%s]",
-			(custom_recipe and custom_recipe.description or
+			rightest + 1.2,
-			 recipe_type:gsub("^%l", string.upper)) .. "]"
+			iY + (sfinv_only and 2.2 or 1.7),
+			0.5,
+			0.5,
+			custom_recipe and custom_recipe.description or
+				recipe_type:gsub("^%l", string.upper))
 	end
 
 	local output = recipes[recipe_num].output
 	local output_s = output:match("%S+")
-	local output_is_fuel = get_fueltime(output) > 0
 
 	local arrow_X  = rightest + (s_btn_size or BUTTON_SIZE)
 	local output_X = arrow_X + 0.9
 
-	fs[#fs + 1] = "image[" .. arrow_X .. "," ..
+	fs[#fs + 1] = fmt("image[%f,%f;%f,%f;%s]",
-		(iY + (sfinv_only and 2.85 or 2.35)) ..
+		arrow_X,
-		";0.9,0.7;craftguide_arrow.png]"
+		iY + (sfinv_only and 2.85 or 2.35),
+		0.9,
+		0.7,
+		"craftguide_arrow.png")
 
-	fs[#fs + 1] = "item_image_button[" .. output_X .. "," ..
+	if output == "BURN" then
-		(iY + (sfinv_only and 2.7 or 2.2)) .. ";" ..
+		fs[#fs + 1] = fmt("image[%f,%f;%f,%f;%s]",
-		BUTTON_SIZE .. "," .. BUTTON_SIZE .. ";" ..
+			output_X,
-		output .. ";" .. output_s .. ";]"
+			iY + (sfinv_only and 2.68 or 2.18),
+			1.1,
+			1.1,
+			"craftguide_fire.png")
+	else
+		fs[#fs + 1] = fmt("item_image_button[%f,%f;%f,%f;%s;%s;]",
+			output_X,
+			iY + (sfinv_only and 2.7 or 2.2),
+			BUTTON_SIZE,
+			BUTTON_SIZE,
+			output,
+			output_s)
+	end
 
 	fs[#fs + 1] = get_tooltip(output_s)
 
+	local output_is_fuel = get_fueltime(output) > 0
 	if output_is_fuel then
-		fs[#fs + 1] = "image[" .. (output_X + 1) .. "," ..
+		fs[#fs + 1] = fmt("image[%f,%f;%f,%f;%s]",
-			(iY + (sfinv_only and 2.83 or 2.33)) ..
+			output_X + 1,
-			";0.6,0.4;craftguide_arrow.png]"
+			iY + (sfinv_only and 2.83 or 2.33),
+			0.6,
+			0.4,
+			"craftguide_arrow.png")
 
-		fs[#fs + 1] = "image[" .. (output_X + 1.6) .. "," ..
+		fs[#fs + 1] = fmt("image[%f,%f;%f,%f;%s]",
-			(iY + (sfinv_only and 2.68 or 2.18)) ..
+			output_X + 1.6,
-			";0.6,0.6;craftguide_fire.png]"
+			iY + (sfinv_only and 2.68 or 2.18),
+			0.6,
+			0.6,
+			"craftguide_fire.png")
 	end
 
 	return concat(fs)
@@ -287,7 +356,6 @@ local function get_formspec(player_name)
 	local fs = {}
 	if not sfinv_only then
 		fs[#fs + 1] = "size[" .. (data.iX - 0.35) .. "," .. (iY + 4) .. ";]"
-		fs[#fs + 1] = "background[1,1;1,1;craftguide_bg.png;true]"
 		fs[#fs + 1] = "tooltip[size_inc;" .. S("Increase window size") .. "]"
 		fs[#fs + 1] = "tooltip[size_dec;" .. S("Decrease window size") .. "]"
 		fs[#fs + 1] = "image_button[" .. (data.iX * 0.47) ..
@@ -297,6 +365,7 @@ local function get_formspec(player_name)
 	end
 
 	fs[#fs + 1] = [[
+		"background[1,1;1,1;craftguide_bg.png;true]"
 		image_button[2.4,0.12;0.8,0.8;craftguide_search_icon.png;search;]
 		image_button[3.05,0.12;0.8,0.8;craftguide_clear_icon.png;clear;]
 		field_close_on_enter[filter;false]
@@ -308,8 +377,8 @@ local function get_formspec(player_name)
 	fs[#fs + 1] = "tooltip[next;" .. S("Next page") .. "]"
 	fs[#fs + 1] = "image_button[" .. (data.iX - (sfinv_only and 2.6 or 3.1)) ..
 			",0.12;0.8,0.8;craftguide_prev_icon.png;prev;]"
-	fs[#fs + 1] = "label[" .. (data.iX - (sfinv_only and 1.7 or 2.2)) .. ",0.22;" ..
+	fs[#fs + 1] = "label[" .. (data.iX - (sfinv_only and 1.7 or 2.2)) ..
-			colorize(data.pagenum) .. " / " .. data.pagemax .. "]"
+			",0.22;" .. colorize(data.pagenum) .. " / " .. data.pagemax .. "]"
 	fs[#fs + 1] = "image_button[" .. (data.iX - (sfinv_only and 0.7 or 1.2) -
 			(data.iX >= 11 and 0.08 or 0)) ..
 			",0.12;0.8,0.8;craftguide_next_icon.png;next;]"
@@ -318,51 +387,40 @@ local function get_formspec(player_name)
 	local xoffset = data.iX / 2.15
 
 	if not next(data.items) then
-		fs[#fs + 1] = "label[" .. ((data.iX / 2) - 1) ..
+		fs[#fs + 1] = fmt("label[%f,%f;%s]",
-				",2;" .. S("No item to show") .. "]"
+			(data.iX / 2) - 1,
+			2,
+			S("No item to show"))
 	end
 
 	local first_item = (data.pagenum - 1) * ipp
 	for i = first_item, first_item + ipp - 1 do
 		local name = data.items[i + 1]
-		if not name then break end
+		if not name then
+			break
+		end
+
 		local X = i % data.iX
 		local Y = (i % ipp - X) / data.iX + 1
 
-		fs[#fs + 1] = "item_image_button[" ..
+		fs[#fs + 1] = fmt("item_image_button[%f,%f;%f,%f;%s;%s;]",
-			(X - (sfinv_only and 0 or (X * 0.05))) .. "," ..
+			X - (sfinv_only and 0 or (X * 0.05)),
-			Y .. ";" .. BUTTON_SIZE .. "," .. BUTTON_SIZE .. ";" ..
+			Y,
-			name .. ";" .. name .. "_inv;]"
+			BUTTON_SIZE,
+			BUTTON_SIZE,
+			name,
+			name)
 	end
 
-	if data.item and reg_items[data.item] then
+	if data.input and reg_items[data.input] then
-		if not data.recipes_item or (data.fuel and not get_recipe(data.item).items) then
-			local X = floor(xoffset) - (sfinv_only and 0 or 0.2)
-
-			fs[#fs + 1] = "item_image_button[" .. X .. "," ..
-				(iY + (sfinv_only and 2.7 or 2.2)) ..
-				";" .. BUTTON_SIZE .. "," .. BUTTON_SIZE ..
-				";" .. data.item .. ";" .. data.item .. ";]"
-
-			fs[#fs + 1] = "image[" .. (X + 1.1) .. "," ..
-				(iY + (sfinv_only and 2.85 or 2.35)) ..
-				";0.9,0.7;craftguide_arrow.png]"
-
-			fs[#fs + 1] = get_tooltip(data.item)
-
-			fs[#fs + 1] = "image[" .. (X + 2.1) .. "," ..
-				(iY + (sfinv_only and 2.68 or 2.18)) ..
-				";1.1,1.1;craftguide_fire.png]"
-		else
 		local usage = data.show_usage
-			fs[#fs + 1] = _get_recipe(data.iX,
+		fs[#fs + 1] = get_recipe_fs(data.iX,
 					    iY,
 					    xoffset,
 					    data.rnum,
 					    (usage and data.usages or data.recipes_item),
 					    usage)
 	end
-	end
 
 	fs = concat(fs)
 	data.formspec = fs
@@ -399,6 +457,7 @@ local function recipe_in_inv(inv, item_name, recipes_f)
 					end
 				end
 			end
+
 			if not group_in_inv and not item_in_inv(inv, item) then
 				show_item_recipes[i] = false
 			end
@@ -562,24 +621,30 @@ local function get_fields(player, ...)
 		formname, fields = args[1], args[2]
 	end
 
-	if not sfinv_only and formname ~= "craftguide" then return end
+	if not sfinv_only and formname ~= "craftguide" then
+		return
+	end
+
 	local player_name = player:get_player_name()
 	local data = datas[player_name]
 
 	if fields.clear then
 		reset_datas(data)
-		data.items = progressive_mode and data.init_filter_items or datas.init_items
 		show_fs(player, player_name)
 
 	elseif fields.alternate then
-		local num
+		if #(data.show_usage and data.usages or data.recipes_item) == 1 then
-		if data.show_usage then
+			return
-			num = data.usages[data.rnum + 1]
-		else
-			num = data.recipes_item[data.rnum + 1]
 		end
 
-		data.rnum = num and data.rnum + 1 or 1
+		local next_i
+		if data.show_usage then
+			next_i = data.usages[data.rnum + 1]
+		else
+			next_i = data.recipes_item[data.rnum + 1]
+		end
+
+		data.rnum = next_i and data.rnum + 1 or 1
 		show_fs(player, player_name)
 
 	elseif (fields.key_enter_field == "filter" or fields.search) and
@@ -591,7 +656,6 @@ local function get_fields(player, ...)
 
 	elseif fields.prev or fields.next then
 		data.pagenum = data.pagenum - (fields.prev and 1 or -1)
-
 		if data.pagenum > data.pagemax then
 			data.pagenum = 1
 		elseif data.pagenum == 0 then
@@ -608,49 +672,69 @@ local function get_fields(player, ...)
 
 	else for item in pairs(fields) do
 		if item:find(":") then
-			if item:sub(-4) == "_inv" then
+			if item:find("%s") then
-				item = item:sub(1,-5)
-			elseif item:find("%s") then
 				item = item:match("%S*")
 			end
 
 			local is_fuel = get_fueltime(item) > 0
 			local recipes = get_recipes(item) or {}
 			recipes = add_custom_recipes(item, recipes)
-			if not next(recipes) and not is_fuel then return end
 
-			if not data.show_usage and item == data.item and not progressive_mode then
+			local no_recipes = not next(recipes)
-				data.usages = get_item_usages(item)
+			if no_recipes and not is_fuel then
-				if next(data.usages) then
+				return
-					data.show_usage = true
-					data.rnum = 1
 			end
 
-				show_fs(player, player_name)
+			if item ~= data.input then
+				data.show_usage = nil
 			else
-				if progressive_mode then
+				data.show_usage = not data.show_usage
+			end
+
+			if not progressive_mode and is_fuel and no_recipes then
+				data.show_usage = true
+			end
+
+			if data.show_usage then
+				data.usages = get_item_usages(item)
+
+				if is_fuel then
+					data.usages[#data.usages + 1] = {
+						width = 1,
+						type = "normal",
+						items = {item},
+						output = "BURN",
+					}
+				end
+
+				if not next(data.usages) then
+					data.show_usage = nil
+				end
+
+			elseif progressive_mode then
 				local inv = player:get_inventory()
 				local has_item
 				recipes, has_item = recipe_in_inv(inv, item, recipes)
-					if not has_item then return end
+
+				if not has_item then
+					return
+				end
 			end
 
-				data.item          = item
+			data.input        = item
 			data.recipes_item = recipes
 			data.rnum         = 1
-				data.show_usage    = nil
-				data.fuel          = is_fuel
 
 			show_fs(player, player_name)
 		end
 	     end
 	end
 end
-end
 
 if sfinv_only then
 	sfinv.register_page("craftguide:craftguide", {
 		title = "Craft Guide",
+
 		get = function(self, player, context)
 			local player_name = player:get_player_name()
 			return sfinv.make_formspec(
@@ -659,6 +743,7 @@ if sfinv_only then
 				get_formspec(player_name)
 			)
 		end,
+
 		on_enter = function(self, player, context)
 			local player_name = player:get_player_name()
 			local data = datas[player_name]
@@ -667,6 +752,7 @@ if sfinv_only then
 				init_datas(player, player_name)
 			end
 		end,
+
 		on_player_receive_fields = function(self, player, context, fields)
 			get_fields(player, fields)
 		end,
@@ -713,10 +799,12 @@ else
 			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 = mt.get_meta(pos)
 			meta:set_string("infotext", S("Crafting Guide Sign"))
 		end,
+
 		on_rightclick = function(pos, node, user, itemstack)
 			on_use(itemstack, user)
 		end
@@ -750,10 +838,10 @@ else
 		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(nil, player)
 			end,
-			image = "craftguide_book.png",
 		})
 	end
 end
@@ -779,30 +867,44 @@ if not progressive_mode then
 			end
 
 			if not node_name then
-				return false, colorize("[craftguide] ") .. S("No node pointed")
+				return false, colorize("[craftguide] ", "red") ..
+						S("No node pointed")
 			elseif not datas[name] then
 				init_datas(player, name)
 			end
 
 			local data = datas[name]
+			reset_datas(data)
+
 			local is_fuel = get_fueltime(node_name) > 0
 			local recipes = get_recipes(node_name) or {}
 			recipes = add_custom_recipes(node_name, recipes)
+			local no_recipes = not next(recipes)
 
-			if not next(recipes) and not is_fuel then
+			if no_recipes and not is_fuel then
-				return false, colorize("[craftguide] ") ..
+				return false, colorize("[craftguide] ", "red") ..
 					S("No recipe for this node:") .. " " ..
 					colorize(node_name)
 			end
 
-			data.show_usage   = nil
+			if is_fuel and no_recipes then
-			data.filter       = ""
+				data.usages = get_item_usages(node_name)
-			data.item         = node_name
+				if is_fuel then
-			data.pagenum      = 1
+					data.usages[#data.usages + 1] = {
-			data.rnum         = 1
+						width = 1,
+						type = "normal",
+						items = {node_name},
+						output = "BURN",
+					}
+				end
+
+				if next(data.usages) then
+					data.show_usage = true
+				end
+			end
+
+			data.input = node_name
 			data.recipes_item = recipes
-			data.items        = datas.init_items
-			data.fuel         = is_fuel
 
 			return true, show_fs(player, name)
 		end,