Rework Digilines chest

Fix various bugs regarding spurious messages being sent, item stack
swapping not being reported properly, etc.. Change from sending strings
to sending tables. Enhance Pipeworks tube support by reporting which
side an item is added or removed via tube or filter-injector.

inventory.lua

@@ -1,33 +1,52 @@
 local pipeworks_enabled = minetest.get_modpath("pipeworks") ~= nil
 
-local function sendMessage(pos, msg, channel)
-	if channel == nil then
-		channel = minetest.get_meta(pos):get_string("channel")
-	end
+-- Sends a message onto the Digilines network.
+-- pos: the position of the Digilines chest node.
+-- action: the action string indicating what happened.
+-- stack: the ItemStack that the action acted on (optional).
+-- side: which side of the chest the action occurred (optional).
+local function send_message(pos, action, stack, side)
+	local channel = minetest.get_meta(pos):get_string("channel")
+	local msg = {
+		action = action,
+		stack = stack and stack:to_table(),
+		-- Duplicate the vector in case the caller expects it not to change.
+		side = side and vector.new(side)
+	}
 	digilines.receptor_send(pos, digilines.rules.default, channel, msg)
 end
 
-local function maybeString(stack)
-	if type(stack)=='string' then return stack
-	elseif type(stack)=='table' then return dump(stack)
-	else return stack:to_string()
+-- Checks if the inventory has become empty and, if so, sends an empty message.
+local function check_empty(pos)
+	if minetest.get_meta(pos):get_inventory():is_empty("main") then
+		send_message(pos, "empty")
 	end
 end
 
-local function can_insert(pos, stack)
-	local can = minetest.get_meta(pos):get_inventory():room_for_item("main", stack)
-	if can then
-		sendMessage(pos,"put "..maybeString(stack))
-	else
-		-- overflow and lost means that items are gonna be out as entities :/
-		sendMessage(pos,"lost "..maybeString(stack))
+-- Checks if the inventory has become full for a particular type of item and,
+-- if so, sends a full message.
+local function check_full(pos, stack)
+	local one_item_stack = ItemStack(stack)
+	one_item_stack:set_count(1)
+	if not minetest.get_meta(pos):get_inventory():room_for_item("main", one_item_stack) then
+		send_message(pos, "full", one_item_stack)
 	end
-	return can
 end
 
 local tubeconn = pipeworks_enabled and "^pipeworks_tube_connection_wooden.png" or ""
 local tubescan = pipeworks_enabled and function(pos) pipeworks.scan_for_tube_objects(pos) end or nil
 
+-- A place to remember things from allow_metadata_inventory_put to
+-- on_metadata_inventory_put. This is a hack due to issue
+-- minetest/minetest#6534 that should be removed once that’s fixed.
+local last_inventory_put_index
+local last_inventory_put_stack
+
+-- A place to remember things from allow_metadata_inventory_take to
+-- tube.remove_items. This is a hack due to issue minetest-mods/pipeworks#205
+-- that should be removed once that’s fixed.
+local last_inventory_take_index
+
 minetest.register_alias("digilines_inventory:chest", "digilines:chest")
 minetest.register_node("digilines:chest", {
 	description = "Digiline Chest",
@@ -86,63 +105,106 @@ minetest.register_node("digilines:chest", {
 			return not pipeworks.connects.facingFront(i,param2)
 		end,
 		input_inventory = "main",
-		can_insert = function(pos, _, stack)
-			return can_insert(pos, stack)
-		end,
-		insert_object = function(pos, _, stack)
-			local inv = minetest.get_meta(pos):get_inventory()
-			local leftover = inv:add_item("main", stack)
-			local count = leftover:get_count()
-			if count == 0 then
-				local derpstack = stack:get_name()..' 1'
-				if not inv:room_for_item("main", derpstack) then
-					-- when you can't put a single more of whatever you just put,
-					-- you'll get a put for it, then a full
-					sendMessage(pos,"full "..maybeString(stack)..' '..tostring(count))
+		can_insert = function(pos, _, stack, direction)
+			local ret = minetest.get_meta(pos):get_inventory():room_for_item("main", stack)
+			if not ret then
+				-- The stack cannot be accepted. It will never be passed to
+				-- insert_object, but it should be reported as a toverflow.
+				-- Here, direction = direction item is moving, which is into
+				-- side.
+				local side = vector.multiply(direction, -1)
+				send_message(pos, "toverflow", stack, side)
 			end
-			else
-				-- this happens when the chest has received two stacks in a row and
-				-- filled up exactly with the first one.
-				-- You get a put for the first stack, a put for the second
-				-- and then a overflow with the first in stack and the second in leftover
-				-- and NO full?
-				sendMessage(pos,"overflow "..maybeString(stack)..' '..tostring(count))
+			return ret
+		end,
+		insert_object = function(pos, _, stack, direction)
+			-- Here, direction = direction item is moving, which is into side.
+			local side = vector.multiply(direction, -1)
+			local leftover = minetest.get_meta(pos):get_inventory():add_item("main", stack)
+			local leftover_count = leftover:get_count()
+			local stack_count = stack:get_count()
+			if leftover_count ~= stack_count then
+				-- Some items were added. Report them.
+				stack:set_count(stack_count - leftover_count)
+				send_message(pos, "tput", stack, side)
+				check_full(pos, stack)
+			end
+			if leftover_count ~= 0 then
+				-- Some items could not be added and bounced back. Report them.
+				send_message(pos, "toverflow", leftover, side)
 			end
 			return leftover
 		end,
+		remove_items = function(pos, _, stack, dir, count)
+			-- Here, stack is the ItemStack in our own inventory that is being
+			-- pulled from, NOT the stack that is actually pulled out.
+			-- Combining it with count gives the stack that is pulled out.
+			-- Also, note that Pipeworks doesn’t pass the index to this
+			-- function, so we use the one recorded in
+			-- allow_metadata_inventory_take; because we don’t implement
+			-- tube.can_remove, Pipeworks will call
+			-- allow_metadata_inventory_take instead and will pass it the
+			-- index.
+			local taken = stack:take_item(count)
+			minetest.get_meta(pos):get_inventory():set_stack("main", last_inventory_take_index, stack)
+			send_message(pos, "ttake", taken, dir)
+			check_empty(pos)
+			return taken
+		end,
 	},
-	allow_metadata_inventory_put = function(pos, _, _, stack)
-		if not can_insert(pos, stack) then
-			sendMessage(pos,"uoverflow "..maybeString(stack))
-		end
+	allow_metadata_inventory_put = function(pos, _, index, stack)
+		-- Remember what was in the target slot before the put; see
+		-- on_metadata_inventory_put for why we care.
+		last_inventory_put_index = index
+		last_inventory_put_stack = minetest.get_meta(pos):get_inventory():get_stack("main", index)
 		return stack:get_count()
 	end,
-	on_metadata_inventory_move = function(pos, _, _, _, _, _, player)
+	allow_metadata_inventory_take = function(_, _, index, stack)
+		-- Remember the index value; see tube.remove_items for why we care.
+		last_inventory_take_index = index
+		return stack:get_count()
+	end,
+	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 chest at "..minetest.pos_to_string(pos))
 	end,
-	on_metadata_inventory_put = function(pos, _, _, stack, player)
-		local channel = minetest.get_meta(pos):get_string("channel")
-		local send = function(msg)
-			sendMessage(pos,msg,channel)
-		end
-		-- direction is only for furnaces
-		-- as the item has already been put, can_insert should return false if the chest is now full.
-		local derpstack = stack:get_name()..' 1'
-		if can_insert(pos,derpstack) then
-			send("uput "..maybeString(stack))
+	on_metadata_inventory_put = function(pos, _, index, stack, player)
+		-- Get what was in the target slot before the put; it has disappeared
+		-- by now (been replaced by the result of the put action) but we saved
+		-- it in allow_metadata_inventory_put. This should always work
+		-- (allow_metadata_inventory_put should AFAICT always be called
+		-- immediately before on_metadata_inventory_put), but in case of
+		-- something weird happening, just fall back to using an empty
+		-- ItemStack rather than crashing.
+		local old_stack
+		if last_inventory_put_index == index then
+			old_stack = last_inventory_put_stack
+			last_inventory_put_index = nil
+			last_inventory_put_stack = nil
 		else
-			send("ufull "..maybeString(stack))
+			old_stack = ItemStack(nil)
 		end
+		-- If the player tries to place a stack into an inventory, there’s
+		-- already a stack there, and the existing stack is either of a
+		-- different item type or full, then obviously the stacks can’t be
+		-- merged; instead the stacks are swapped. This information is not
+		-- reported to mods (Minetest core neither tells us that a particular
+		-- action was a swap, nor tells us a take followed by a put). In core,
+		-- the condition for swapping is that you try to add the new stack to
+		-- the existing stack and the leftovers are as big as the original
+		-- stack to put. Replicate that logic here using the old stack saved in
+		-- allow_metadata_inventory_put. If a swap happened, report it to the
+		-- Digilines network as a utake followed by a uput.
+		local leftovers = old_stack:add_item(stack)
+		if leftovers:get_count() == stack:get_count() then
+			send_message(pos, "utake", old_stack)
+		end
+		send_message(pos, "uput", stack)
+		check_full(pos, stack)
 		minetest.log("action", player:get_player_name().." puts stuff into chest at "..minetest.pos_to_string(pos))
 	end,
-	on_metadata_inventory_take = function(pos, listname, _, stack, player)
-		local meta = minetest.get_meta(pos)
-		local channel = meta:get_string("channel")
-		local inv = meta:get_inventory()
-		if inv:is_empty(listname) then
-			sendMessage(pos, "empty", channel)
-		end
-		sendMessage(pos,"utake "..maybeString(stack))
+	on_metadata_inventory_take = function(pos, _, index, stack, player)
+		send_message(pos, "utake", stack)
+		check_empty(pos)
 		minetest.log("action", player:get_player_name().." takes stuff from chest at "..minetest.pos_to_string(pos))
 	end
 })