factorio-clusterio/plugins/inventory_sync/module/save_crafts.lua

function save_crafts(event)
	if event.player_index then
		local player = game.get_player(event.player_index)
		local crafting_queue = {}

		-- Avoid overwriting old save
		if global.inventory_sync.saved_crafting_queue[player.name] ~= nil then
			player.print("You already have a saved crafting queue, restore it with /restore-crafts")
			return
		end

		-- Give player some more inventory space to avoid duplicating items
		player.character_inventory_slots_bonus = player.character_inventory_slots_bonus + 1000

		-- Save current items
		local inventory = player.get_main_inventory()
		local old_items = inventory.get_contents()

		-- Cancel old crafts to get the items back
		while player.crafting_queue_size > 0 do
			local old_queue = player.crafting_queue
			local queueItem = player.crafting_queue[1]

			-- Cancel craft
			player.cancel_crafting {
				index = 1,
				count = 1,
			}

			local rightmost_right_index = 0 -- 0 indexed since it is subtractive in a 1 indexed language
			local new_queue = player.crafting_queue
			while
				new_queue ~= nil and
				new_queue[#new_queue - rightmost_right_index] ~= nil and
				new_queue[#new_queue - rightmost_right_index].count >= old_queue[#old_queue - rightmost_right_index].count
			do
				rightmost_right_index = rightmost_right_index + 1
			end
			local oldItem = old_queue[#old_queue - rightmost_right_index]
			local newItem = nil
			if new_queue ~= nil then
				newItem = new_queue[#new_queue - rightmost_right_index]
			end

			-- Figure out how many items to add to queue
			local added = oldItem.count
			if newItem ~= nil then
				added = oldItem.count - newItem.count
				if oldItem.recipe ~= newItem.recipe then
					log("ERROR: Old item "..oldItem.recipe.." is not equal "..newItem.recipe)
				end
			end

			-- If the last item we added was of the same type, merge them in the queue
			if #crafting_queue > 0 and crafting_queue[#crafting_queue].recipe == oldItem.recipe then
				crafting_queue[#crafting_queue].count = crafting_queue[#crafting_queue].count + added
			else
				-- If the last item was of a different type, add a new item to the queue
				table.insert(crafting_queue, {
					recipe = oldItem.recipe,
					count = added,
				})
			end
			-- game.print("Saved craft "..oldItem.recipe)
		end

		-- Find amount of items added and remove from inventory
		local new_items = inventory.get_contents()
		local difference = {}
		for k,v in pairs(new_items) do
			local old_count = old_items[k]
			local diff = v
			if old_count ~= nil then
				diff = diff - old_count
			end
			if diff > 0 then
				local ingredient = {
					name = k,
					count = diff,
				}
				inventory.remove(ingredient)
				table.insert(difference, ingredient)
			end
		end

		-- Remove extra inventory slots
		player.character_inventory_slots_bonus = player.character_inventory_slots_bonus - 1000

		global.inventory_sync.saved_crafting_queue[player.name] = {
			crafting_queue = crafting_queue,
			ingredients = difference,
		}
	end
end

return save_crafts