Bookshelf: Count written and empty books

mods/default/nodes.lua

@@ -2137,23 +2137,41 @@ local bookshelf_formspec =
 	"listring[current_player;main]" ..
 	default.get_hotbar_bg(0,2.85)
 
-local function get_bookshelf_formspec(inv)
+local function update_bookshelf(pos)
+	local meta = minetest.get_meta(pos)
+	local inv = meta:get_inventory()
+	local invlist = inv:get_list("books")
+
 	local formspec = bookshelf_formspec
-	local invlist = inv and inv:get_list("books")
 	-- Inventory slots overlay
 	local bx, by = 0, 0.3
+	local n_written, n_empty = 0, 0
 	for i = 1, 16 do
 		if i == 9 then
 			bx = 0
 			by = by + 1
 		end
-		if not invlist or invlist[i]:is_empty() then
+		local stack = invlist[i]
+		if stack:is_empty() then
 			formspec = formspec ..
 				"image[" .. bx .. "," .. by .. ";1,1;default_bookshelf_slot.png]"
+		else
+			local metatable = stack:get_meta():to_table() or {}
+			if metatable.fields and metatable.fields.text then
+				n_written = n_written + stack:get_count()
+			else
+				n_empty = n_empty + stack:get_count()
+			end
 		end
 		bx = bx + 1
 	end
-	return formspec
+	meta:set_string("formspec", formspec)
+	if n_written + n_empty == 0 then
+		meta:set_string("infotext", "Empty Bookshelf")
+	else
+		meta:set_string("infotext", "Bookshelf (" .. n_written ..
+			" written, " .. n_empty .. " empty books)")
+	end
 end
 
 minetest.register_node("default:bookshelf", {
@@ -2167,9 +2185,9 @@ minetest.register_node("default:bookshelf", {
 
 	on_construct = function(pos)
 		local meta = minetest.get_meta(pos)
-		meta:set_string("formspec", get_bookshelf_formspec(nil))
 		local inv = meta:get_inventory()
 		inv:set_size("books", 8 * 2)
+		update_bookshelf(pos)
 	end,
 	can_dig = function(pos,player)
 		local inv = minetest.get_meta(pos):get_inventory()
@@ -2184,20 +2202,17 @@ minetest.register_node("default:bookshelf", {
 	on_metadata_inventory_move = function(pos, from_list, from_index, to_list, to_index, count, player)
 		minetest.log("action", player:get_player_name() ..
 			" moves stuff in bookshelf at " .. minetest.pos_to_string(pos))
-		local meta = minetest.get_meta(pos)
+		update_bookshelf(pos)
-		meta:set_string("formspec", get_bookshelf_formspec(meta:get_inventory()))
 	end,
 	on_metadata_inventory_put = function(pos, listname, index, stack, player)
 		minetest.log("action", player:get_player_name() ..
-			" moves stuff to bookshelf at " .. minetest.pos_to_string(pos))
+			" puts stuff to bookshelf at " .. minetest.pos_to_string(pos))
-		local meta = minetest.get_meta(pos)
+		update_bookshelf(pos)
-		meta:set_string("formspec", get_bookshelf_formspec(meta:get_inventory()))
 	end,
 	on_metadata_inventory_take = function(pos, listname, index, stack, player)
 		minetest.log("action", player:get_player_name() ..
 			" takes stuff from bookshelf at " .. minetest.pos_to_string(pos))
-		local meta = minetest.get_meta(pos)
+		update_bookshelf(pos)
-		meta:set_string("formspec", get_bookshelf_formspec(meta:get_inventory()))
 	end,
 	on_blast = function(pos)
 		local drops = {}