local autocrafterCache={}

function addCacheEntry(pos,recipe,result,new)
    if autocrafterCache[pos.x] == nil then autocrafterCache[pos.x] = {} end
    if autocrafterCache[pos.x][pos.y] == nil then autocrafterCache[pos.x][pos.y] = {} end
    if autocrafterCache[pos.x][pos.y][pos.z] == nil then autocrafterCache[pos.x][pos.z] = {} end
    autocrafterCache[pos.x][pos.y][pos.z] = {["recipe"] = recipe, ["result"] = result, ["new"] = new}
end

function getCacheEntry(pos)
    if autocrafterCache[pos.x] == nil then return nil,nil,nil end
    if autocrafterCache[pos.x][pos.y] == nil then return nil,nil,nil end
    if autocrafterCache[pos.x][pos.y][pos.z] == nil then return nil,nil,nil end
    return autocrafterCache[pos.x][pos.y][pos.z]["recipe"], autocrafterCache[pos.x][pos.y][pos.z]["result"], autocrafterCache[pos.x][pos.y][pos.z]["new"]
end

function autocraft(inventory,pos)
	local recipe=inventory:get_list("recipe")
        local recipe_last
        local result
        local new

        recipe_last, result, new = getCacheEntry(pos)
        if recipe_last ~=nil then
            local recipeUnchanged = true
            for i=1,9 do
                --print ("recipe_base"..i.." ")
                --print (recipe[i]:get_name())
                --print (recipe[i]:get_count())
                --print (recipe_last[i]:get_name())
                --print (recipe_last[i]:get_count())
                if recipe[i]:get_name() ~= recipe_last[i]:get_name() then
                    recipeUnchanged = False
                    break
                end
                if recipe[i]:get_count() ~= recipe_last[i]:get_count() then
                    recipeUnchanged = False
                    break
                end
            end
            if recipeUnchanged then
                -- print("autocrafter recipe unchanged")
            else
                print("autocrafter recipe changed at pos("..pos.x..","..pos.y..","..pos.z..")")
                for i=1,9 do
                        recipe_last[i] = recipe[i]
                        recipe[i]=ItemStack({name=recipe[i]:get_name(),count=1})
                end
                result,new=minetest.get_craft_result({method="normal",width=3,items=recipe})
                addCacheEntry(pos,recipe_last,result,new)
            end
        else
            print("first call for this autocrafter at pos("..pos.x..","..pos.y..","..pos.z..")")
            recipe_last={}
            for i=1,9 do
                recipe_last[i] = recipe[i]
                --print (recipe_last[i]:get_name())
                recipe[i]=ItemStack({name=recipe[i]:get_name(),count=1})
            end
            result,new=minetest.get_craft_result({method="normal",width=3,items=recipe})
            addCacheEntry(pos,recipe_last,result,new)
        end

        local input=inventory:get_list("input")
	if result.item:is_empty() then return end
	result=result.item
	if not inventory:room_for_item("dst", result) then return end
	local to_use={}
	for _,item in ipairs(recipe) do
		if item~=nil and not item:is_empty() then
			if to_use[item:get_name()]==nil then
				to_use[item:get_name()]=1
			else
				to_use[item:get_name()]=to_use[item:get_name()]+1
			end
		end
	end
	local stack
	for itemname,number in pairs(to_use) do
		stack=ItemStack({name=itemname, count=number})
		if not inventory:contains_item("src",stack) then return end
	end
	for itemname,number in pairs(to_use) do
		stack=ItemStack({name=itemname, count=number})
		inventory:remove_item("src",stack)
	end
	inventory:add_item("dst",result)
	for i=1,9 do
		inventory:add_item("dst",new.items[i])
	end
end

minetest.register_node("pipeworks:autocrafter",{
	description = "Autocrafter",
	drawtype="normal",
	tiles={"pipeworks_autocrafter.png"},
	groups={snappy=3,tubedevice=1,tubedevice_receiver=1},
	tube={insert_object=function(pos,node,stack,direction)
			local meta=minetest.get_meta(pos)
			local inv=meta:get_inventory()
			return inv:add_item("src",stack)
		end,
		can_insert=function(pos,node,stack,direction)
			local meta=minetest.get_meta(pos)
			local inv=meta:get_inventory()
			return inv:room_for_item("src",stack)
		end,
		input_inventory="dst",
		connect_sides={left=1, right=1, front=1, back=1, top=1, bottom=1}},
	on_construct = function(pos)
		local meta = minetest.get_meta(pos)
		meta:set_string("formspec",
				"size[8,11]"..
				"list[current_name;recipe;0,0;3,3;]"..
				"list[current_name;src;0,3.5;8,3;]"..
				"list[current_name;dst;4,0;4,3;]"..
				"list[current_player;main;0,7;8,4;]")
		meta:set_string("infotext", "Autocrafter")
		local inv = meta:get_inventory()
		inv:set_size("src",3*8)
		inv:set_size("recipe",3*3)
		inv:set_size("dst",4*3)
	end,
	can_dig = function(pos,player)
		local meta = minetest.get_meta(pos);
		local inv = meta:get_inventory()
		return (inv:is_empty("src") and inv:is_empty("recipe") and inv:is_empty("dst"))
	end,
	after_place_node = tube_scanforobjects,
	after_dig_node = tube_scanforobjects,
})

minetest.register_abm({nodenames={"pipeworks:autocrafter"},interval=1,chance=1,
			action=function(pos,node)
				local meta=minetest.get_meta(pos)
				local inv=meta:get_inventory()
				autocraft(inv,pos)
			end
})