First version 🐈

currency_migrate.lua

@@ -0,0 +1,97 @@
+-- Combine stacks into a new list
+local function compress_list(list)
+	local items = {}
+	local new_list = {}
+	for i, stack in pairs(list or {}) do
+		if not stack:is_empty() then
+			if stack:get_stack_max() == 1 then
+				table.insert(new_list, stack)
+			else
+				items[stack:get_name()] = (items[stack:get_name()] or 0)
+					+ stack:get_count()
+			end
+		end
+	end
+	for name, count in pairs(items) do
+		local max = ItemStack(name):get_stack_max()
+
+		repeat
+			local take = math.min(max, count)
+			local stack = ItemStack(name)
+			stack:set_count(take)
+			table.insert(new_list, stack)
+			count = count - take
+		until count == 0
+	end
+	return new_list
+end
+
+local function list_add_list(inv, list_name, list)
+	local leftover_list = {}
+	for i, stack in pairs(list or {}) do
+		local leftover = inv:add_item(list_name, stack)
+		if not leftover:is_empty() then
+			table.insert(leftover_list, leftover)
+		end
+	end
+	if #leftover_list > 0 then
+		minetest.log("warning", "[exchange_shop] List " .. list_name
+			.. " is full. Possible item loss!")
+	end
+	return leftover_list
+end
+
+local function migrate_shop_node(pos, node)
+	local meta = minetest.get_meta(pos)
+	local owner = meta:get_string("owner")
+	local title = meta:get_string("infotext")
+	local inv = meta:get_inventory()
+	local def = minetest.registered_nodes[exchange_shop.shopname]
+
+	-- Create new slots
+	def.on_construct(pos)
+	meta:set_string("owner", owner)
+	meta:set_string("infotext", title)
+
+	list_add_list(inv, "custm", inv:get_list("customers_gave"))
+	inv:set_size("customers_gave", 0)
+
+	local new_owner_gives = compress_list(inv:get_list("owner_gives"))
+	local new_owner_wants = compress_list(inv:get_list("owner_wants"))
+	local dst_gives = "cust_og"
+	local dst_wants = "cust_ow"
+	if #new_owner_gives > 4 or #new_owner_wants > 4 then
+		-- Not enough space (from 6 slots to 4)
+		-- redirect everything to the stock
+		dst_gives = "stock"
+		dst_wants = "custm"
+	end
+	list_add_list(inv, dst_gives, new_owner_gives)
+	list_add_list(inv, dst_wants, new_owner_wants)
+
+	inv:set_size("owner_gives", 0)
+	inv:set_size("owner_takes", 0)
+
+	node.name = exchange_shop.shopname
+	minetest.swap_node(pos, node)
+end
+
+minetest.register_lbm({
+	label = "currency shop to exchange shop migration",
+        name = "exchange_shop:currency_migrate",
+        nodenames = { "currency:shop" },
+        run_at_every_load = true, -- TODO this for testing only
+	action = migrate_shop_node
+})
+
+-- Clean up garbage
+minetest.register_on_joinplayer(function(player)
+	local inv = player:get_inventory()
+	for i, name in pairs({"customer_gives", "customer_gets"}) do
+		if inv:get_size(name) > 0 then
+			local leftover = list_add_list(inv, "main", inv:get_list(name))
+			list_add_list(inv, "craft", leftover)
+			inv:set_size(name, 0)
+		end
+	end
+end)