Show item usages in craft guide

When the craft guide is showing a craft, the output slot is now a button,
which causes the craft guide to show ways in which that output can be
used.  This mirrors the way input slots are buttons that show recipes
for the selected ingredient.  Usages of an item can be iterated through
in the same way as recipes for the item.  This incidentally offers some
ability to retrace one's steps through a crafting chain, without storing
actual history.

7 files changed, 97 insertions, 51 deletions

diff --git a/api.lua b/api.lua
index 882971e..23dd6d4 100644
--- a/api.lua
+++ b/api.lua
@@ -42,6 +42,25 @@ minetest.after(0.01, function()
 			end
 		end
 	end
+	for _, recipes in pairs(unified_inventory.crafts_for.recipe) do
+		for _, recipe in ipairs(recipes) do
+			local ingredient_items = {}
+			for _, spec in ipairs(recipe.items) do
+				local matches_spec = unified_inventory.canonical_item_spec_matcher(spec)
+				for _, name in ipairs(unified_inventory.items_list) do
+					if matches_spec(name) then
+						ingredient_items[name] = true
+					end
+				end
+			end
+			for name, _ in pairs(ingredient_items) do
+				if unified_inventory.crafts_for.usage[name] == nil then
+					unified_inventory.crafts_for.usage[name] = {}
+				end
+				table.insert(unified_inventory.crafts_for.usage[name], recipe)
+			end
+		end
+	end
 end)
 
 
@@ -101,10 +120,10 @@ function unified_inventory.register_craft(options)
 	if options.type == "normal" and options.width == 0 then
 		options = { type = "shapeless", items = options.items, output = options.output, width = 0 }
 	end
-	if unified_inventory.crafts_table[itemstack:get_name()] == nil then
-		unified_inventory.crafts_table[itemstack:get_name()] = {}
+	if unified_inventory.crafts_for.recipe[itemstack:get_name()] == nil then
+		unified_inventory.crafts_for.recipe[itemstack:get_name()] = {}
 	end
-	table.insert(unified_inventory.crafts_table[itemstack:get_name()],options)
+	table.insert(unified_inventory.crafts_for.recipe[itemstack:get_name()],options)
 end
 
 
diff --git a/callbacks.lua b/callbacks.lua
index ad7c1ed..605d8e5 100644
--- a/callbacks.lua
+++ b/callbacks.lua
@@ -14,28 +14,15 @@ minetest.register_on_joinplayer(function(player)
 	unified_inventory.filtered_items_list[player_name] =
 			unified_inventory.items_list
 	unified_inventory.activefilter[player_name] = ""
-	unified_inventory.apply_filter(player, "")
+	unified_inventory.active_search_direction[player_name] = "nochange"
+	unified_inventory.apply_filter(player, "", "nochange")
 	unified_inventory.current_searchbox[player_name] = ""
 	unified_inventory.alternate[player_name] = 1
 	unified_inventory.current_item[player_name] = nil
+	unified_inventory.current_craft_direction[player_name] = "recipe"
 	unified_inventory.set_inventory_formspec(player,
 			unified_inventory.default)
 
-	-- Crafting guide inventories
-	local inv = minetest.create_detached_inventory(player_name.."craftrecipe", {
-		allow_put = function(inv, listname, index, stack, player)
-			return 0
-		end,
-		allow_take = function(inv, listname, index, stack, player)
-			return 0
-		end,
-		allow_move = function(inv, from_list, from_index, to_list,
-				to_index, count, player)
-			return 0
-		end,
-	})
-	inv:set_size("output", 1)
-
 	-- Refill slot
 	local refill = minetest.create_detached_inventory(player_name.."refill", {
 		allow_put = function(inv, listname, index, stack, player)
@@ -122,12 +109,16 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 	local clicked_item = nil
 	for name, value in pairs(fields) do
 		if string.sub(name, 1, 12) == "item_button_" then
-			clicked_item = unified_inventory.demangle_for_formspec(string.sub(name, 13))
+			local new_dir, mangled_item = string.match(name, "^item_button_([a-z]+)_(.*)$")
+			clicked_item = unified_inventory.demangle_for_formspec(mangled_item)
 			if string.sub(clicked_item, 1, 6) == "group:" then
 				minetest.sound_play("click", {to_player=player_name, gain = 0.1})
-				unified_inventory.apply_filter(player, clicked_item)
+				unified_inventory.apply_filter(player, clicked_item, new_dir)
 				return
 			end
+			if new_dir == "recipe" or new_dir == "usage" then
+				unified_inventory.current_craft_direction[player_name] = new_dir
+			end
 			break
 		end
 	end
@@ -156,7 +147,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 	end
 
 	if fields.searchbutton then
-		unified_inventory.apply_filter(player, unified_inventory.current_searchbox[player_name])
+		unified_inventory.apply_filter(player, unified_inventory.current_searchbox[player_name], "nochange")
 		unified_inventory.current_searchbox[player_name] = ""
 		unified_inventory.set_inventory_formspec(player,
 				unified_inventory.current_page[player_name])
@@ -172,7 +163,7 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 		if item_name then
 			local alternates = 0
 			local alternate = unified_inventory.alternate[player_name]
-			local crafts = unified_inventory.crafts_table[item_name]
+			local crafts = unified_inventory.crafts_for[unified_inventory.current_craft_direction[player_name]][item_name]
 			if crafts ~= nil then
 				alternates = #crafts
 			end
diff --git a/group.lua b/group.lua
index e509006..9bf6895 100644
--- a/group.lua
+++ b/group.lua
@@ -1,3 +1,25 @@
+function unified_inventory.canonical_item_spec_matcher(spec)
+	local specname = ItemStack(spec):get_name()
+	if specname:sub(1, 6) == "group:" then
+		local group_names = specname:sub(7):split(",")
+		return function (itemname)
+			local itemdef = minetest.registered_items[itemname]
+			for _, group_name in ipairs(group_names) do
+				if (itemdef.groups[group_name] or 0) == 0 then
+					return false
+				end
+			end
+			return true
+		end
+	else
+		return function (itemname) return itemname == specname end
+	end
+end
+
+function unified_inventory.item_matches_spec(item, spec)
+	local itemname = ItemStack(item):get_name()
+	return unified_inventory.canonical_item_spec_matcher(spec)(itemname)
+end
 
 unified_inventory.registered_group_items = {
 	mesecon_conductor_craftable = "mesecons:wire_00000000_off",
diff --git a/init.lua b/init.lua
index f91e048..0542e36 100644
--- a/init.lua
+++ b/init.lua
@@ -6,14 +6,15 @@ local worldpath = minetest.get_worldpath()
 -- Data tables definitions
 unified_inventory = {}
 unified_inventory.activefilter = {}
+unified_inventory.active_search_direction = {}
 unified_inventory.alternate = {}
 unified_inventory.current_page = {}
 unified_inventory.current_searchbox = {}
 unified_inventory.current_index = {}
 unified_inventory.current_item = {}
+unified_inventory.current_craft_direction = {}
 unified_inventory.registered_craft_types = {}
-unified_inventory.crafts_table = {}
-unified_inventory.crafts_table_count = 0
+unified_inventory.crafts_for = { usage = {}, recipe = {} }
 unified_inventory.players = {}
 unified_inventory.items_list_size = 0
 unified_inventory.items_list = {}
diff --git a/internal.lua b/internal.lua
index 2323e07..4d9c10b 100644
--- a/internal.lua
+++ b/internal.lua
@@ -71,6 +71,7 @@ function unified_inventory.get_formspec(player, page)
 	if #unified_inventory.filtered_items_list[player_name] == 0 then
 		formspec = formspec.."label[8.2,0;No matching items]"
 	else
+		local dir = unified_inventory.active_search_direction[player_name]
 		local list_index = unified_inventory.current_index[player_name]
 		local page = math.floor(list_index / (80) + 1)
 		local pagemax = math.floor(
@@ -84,7 +85,7 @@ function unified_inventory.get_formspec(player, page)
 				formspec = formspec.."item_image_button["
 						..(8.2 + x * 0.7)..","
 						..(1   + y * 0.7)..";.81,.81;"
-						..name..";item_button_"
+						..name..";item_button_"..dir.."_"
 						..unified_inventory.mangle_for_formspec(name)..";]"
 				list_index = list_index + 1
 			end
@@ -108,7 +109,7 @@ function unified_inventory.set_inventory_formspec(player, page)
 end
 
 --apply filter to the inventory list (create filtered copy of full one)
-function unified_inventory.apply_filter(player, filter)
+function unified_inventory.apply_filter(player, filter, search_dir)
 	local player_name = player:get_player_name()
 	local lfilter = string.lower(filter)
 	local ffilter
@@ -139,6 +140,7 @@ function unified_inventory.apply_filter(player, filter)
 	unified_inventory.filtered_items_list_size[player_name] = #unified_inventory.filtered_items_list[player_name]
 	unified_inventory.current_index[player_name] = 1
 	unified_inventory.activefilter[player_name] = filter
+	unified_inventory.active_search_direction[player_name] = search_dir
 	unified_inventory.set_inventory_formspec(player,
 			unified_inventory.current_page[player_name])
 end
diff --git a/register.lua b/register.lua
index 3815f05..1c8eb54 100644
--- a/register.lua
+++ b/register.lua
@@ -169,6 +169,23 @@ local function stack_image_button(x, y, w, h, buttonname_prefix, item)
 			label)
 end
 
+local recipe_text = {
+	recipe = "Recipe",
+	usage = "Usage",
+}
+local no_recipe_text = {
+	recipe = "No recipes",
+	usage = "No usages",
+}
+local role_text = {
+	recipe = "Result",
+	usage = "Ingredient",
+}
+local other_dir = {
+	recipe = "usage",
+	usage = "recipe",
+}
+
 unified_inventory.register_page("craftguide", {
 	get_formspec = function(player)
 		local player_name = player:get_player_name()
@@ -179,36 +196,33 @@ unified_inventory.register_page("craftguide", {
 		local item_name = unified_inventory.current_item[player_name]
 		if not item_name then return {formspec=formspec} end
 
-		formspec = formspec.."background[0,1;8,3;ui_craftguide_form.png]"
-		formspec = formspec.."textarea[0.3,0.6;10,1;;Result: "..minetest.formspec_escape(item_name)..";]"
-		formspec = formspec.."list[detached:"..minetest.formspec_escape(player_name).."craftrecipe;output;6,1;1,1;]"
-		local craftinv = minetest.get_inventory({
-			type = "detached",
-			name = player_name.."craftrecipe"
-		})
-
-		local alternate, alternates, craft, craft_type
-		alternate = unified_inventory.alternate[player_name]
-		local crafts = unified_inventory.crafts_table[item_name]
+		local dir = unified_inventory.current_craft_direction[player_name]
+		local crafts = unified_inventory.crafts_for[dir][item_name]
+		local alternate = unified_inventory.alternate[player_name]
+		local alternates, craft
 		if crafts ~= nil and #crafts > 0 then
 			alternates = #crafts
 			craft = crafts[alternate]
 		end
 
+		formspec = formspec.."background[0,1;8,3;ui_craftguide_form.png]"
+		formspec = formspec.."textarea[0.3,0.6;10,1;;"..minetest.formspec_escape(role_text[dir]..": "..item_name)..";]"
+
 		if not craft then
-			craftinv:set_stack("output", 1, item_name)
-			craft_type = unified_inventory.craft_type_defaults("", {})
-			formspec = formspec.."label[6,3.35;No recipes]"
-			formspec = formspec.."image[4,1;1.1,1.1;ui_no.png]"
+			formspec = formspec.."label[6,3.35;"..minetest.formspec_escape(no_recipe_text[dir]).."]"
+			local no_pos = dir == "recipe" and 4 or 6
+			local item_pos = dir == "recipe" and 6 or 4
+			formspec = formspec.."image["..no_pos..",1;1.1,1.1;ui_no.png]"
+			formspec = formspec..stack_image_button(item_pos, 1, 1.1, 1.1, "item_button_"..other_dir[dir].."_", ItemStack(item_name))
 			return {formspec = formspec}
 		end
 
-		craftinv:set_stack("output", 1, craft.output)
-		craft_type = unified_inventory.registered_craft_types[craft.type] or
+		local craft_type = unified_inventory.registered_craft_types[craft.type] or
 				unified_inventory.craft_type_defaults(craft.type, {})
 		formspec = formspec.."label[6,3.35;Method:]"
 		formspec = formspec.."label[6,3.75;"
 				..minetest.formspec_escape(craft_type.description).."]"
+		formspec = formspec..stack_image_button(6, 1, 1.1, 1.1, "item_button_usage_", ItemStack(craft.output))
 		local display_size = craft_type.dynamic_display_size and craft_type.dynamic_display_size(craft) or { width = craft_type.width, height = craft_type.height }
 		local craft_width = craft_type.get_shaped_craft_width and craft_type.get_shaped_craft_width(craft) or display_size.width
 
@@ -224,7 +238,8 @@ unified_inventory.register_page("craftguide", {
 			if item then
 				formspec = formspec..stack_image_button(
 						xoffset + x, y, 1.1, 1.1,
-						"item_button_", ItemStack(item))
+						"item_button_recipe_",
+						ItemStack(item))
 			else
 				-- Fake buttons just to make grid
 				formspec = formspec.."image_button["
@@ -242,7 +257,7 @@ unified_inventory.register_page("craftguide", {
 		end
 
 		if alternates and alternates > 1 then
-			formspec = formspec.."label[0,2.6;Recipe "
+			formspec = formspec.."label[0,2.6;"..recipe_text[dir].." "
 					..tostring(alternate).." of "
 					..tostring(alternates).."]"
 					.."button[0,3.15;2,1;alternate;Alternate]"
@@ -259,17 +274,13 @@ minetest.register_on_player_receive_fields(function(player, formname, fields)
 	end
 	if not amount then return end
 	local player_name = player:get_player_name()
-	local recipe_inv = minetest.get_inventory({
-		type="detached",
-		name=player_name.."craftrecipe",
-	})
 
 	local output = unified_inventory.current_item[player_name]
 	if (not output) or (output == "") then return end
 
 	local player_inv = player:get_inventory()
 
-	local crafts = unified_inventory.crafts_table[output]
+	local crafts = unified_inventory.crafts_for[unified_inventory.current_craft_direction[player_name]][output]
 	if (not crafts) or (#crafts == 0) then return end
 
 	local alternate = unified_inventory.alternate[player_name]
diff --git a/textures/ui_craftguide_form.png b/textures/ui_craftguide_form.png
index e103c04..72572b5 100644
--- a/textures/ui_craftguide_form.png
+++ b/textures/ui_craftguide_form.png