chest = peripheral.wrap("bottom")

cur_lvl = 0
cur_dir = 0

function save(t, n)
    local file = fs.open(n, "w")
    file.write(textutils.serialize(t))
    file.close()
end

function load(n)
    local file = fs.open(n, "r")
    local data = file.readAll()
    file.close()
    return textutils.unserialize(data)
end

function slice(tbl, first, last)
    local sliced = {}
    for i = first, last do
        table.insert(sliced, tbl[i])
    end
    return sliced
end

function equals(item1, item2)
    check1 = item1.id == item2.id and item1.dmg == item2.dmg
    check2 = item1.raw == item2.raw and item1.display == item2.display
    return check1 and check2
end

function contains(newItem)
	for n, item in pairs(items) do
		if equals(item, newItem) then
			return n
		end
	end
	return 0
end

function next_position()
    pos = {}
    pos.lvl = math.floor(#items / 4) + 1
    pos.dir = #items % 4
    return pos
end

function register_item(item)
    item.full = item.id..item.dmg..item.raw..item.display
    item.pos = next_position()
    item.qty = 0
    table.insert(items, item)
        save(items, "items")
end

function to_item(stack)
    item = {}
    item.id = stack.basic().id
    item.dmg = stack.basic().dmg
    item.raw = stack.basic().raw_name
    item.display = stack.basic().display_name
    n = contains(item)
    if n == 0 then
        register_item(item)
        n = #items
    end
    return items[n]
end

function go_to(pos)
	while cur_lvl > pos.lvl do
		turtle.down()
		cur_lvl = cur_lvl - 1
	end
	while cur_lvl < pos.lvl do
		turtle.up()
		cur_lvl = cur_lvl + 1
    end
    while cur_dir ~= pos.dir do
        turtle.turnRight()
        cur_dir = (cur_dir + 1) % 4
    end
end

function store(item)
    n = contains(item)
    start_amt = turtle.getItemCount()
    turtle.drop()
    items[n].qty = items[n].qty + start_amt - turtle.getItemCount()
end

function store_items(to_store)
    for i, item in pairs(to_store) do
        turtle.select(i)
        go_to(item.pos)
        store(item)
    end
    save(items, "items")
end

function clear_inv()
    for i=1, 16 do
        turtle.select(i)
        turtle.drop()
    end
    turtle.select(1)
end

function receive_items()
    chest.condenseItems()
    stacks = slice(chest.getAllStacks(), 1, 16)
    to_store = {}
    for _, stack in pairs(stacks) do
        if turtle.suckDown() then
            item = to_item(stack)
            table.insert(to_store, item)
        end
    end
    store_items(to_store)
    go_to({lvl=0,dir=0})
    clear_inv()
end

items = load("items")

while true do
    cmd = io.read()
    if cmd == ">" then
        while #chest.getAllStacks() > 0 do
            receive_items()
        end
    end
end