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

function load(name)
    local file = fs.open(name, "r")
    if not file then
        if name == "open_positions" then
            save({{x=-5,y=2,z=-5,side="down"}}, name)
        else
            save({}, name)
        end
        return load(name)
    else
        local data = file.readAll()
        file.close()
        return textutils.unserialize(data)
    end
end

function clear_search_bar()
    term.setTextColor(colors.cyan)
    paintutils.drawFilledBox(1,screen_height,screen_width,screen_height,colors.gray)
    term.setCursorPos(1,screen_height)
end

function show_title(title)
    paintutils.drawLine(1,1,screen_height,1,colors.cyan)
    term.setCursorPos(1,1)
    term.write(title)
    clear_search_bar()
end

function empty_inventory(side)
    for i=1, 15 do
        inventory.pushItem(side, i)
    end
end

function condense_inventory()
    inventory.condenseItems()
    local inventory_items = inventory.getAllStacks()
    inventory.swapStacks(#inventory_items, 16)
    return inventory_items
end

function next_position(position)
    local new_position = {x = position.x, y = position.y, z = position.z, side = position.side}
    if position.side == "down" then
        new_position.side = "up"
    else
        new_position.side = "down"
        if position.x == 5 then
            new_position.x = -5
            if position.z == 5 then
                new_position.z = -5
                new_position.y = position.y + 3
            else
                new_position.z = position.z + 1
            end
        else
            if position.x == -1 and position.z == 0 then
                new_position.x = position.x + 2
            else
                new_position.x = position.x + 1
            end
        end
    end
    return new_position
end

function earliest_order(position_1, position_2)
    if position_1.y > position_2.y then
        return true
    elseif position_1.y == position_2.y then
        if position_1.z > position_2.z then
            return true
        elseif position_1.z == position_2.z then
            if position_1.x > position_2.x then
                return true
            elseif position_1.x == position_2.x then
                if position_1.side == "up" then
                    return true
                end
            end
        end
    end
end

function next_open_position()
    if #open_positions > 1 then
        table.sort(open_positions, earliest_order)
        return table.remove(open_positions)
    else
        local position = table.remove(open_positions)
        table.insert(open_positions, next_position(position))
        return position
    end
end

function safe_string(text)
    local new_text = {}
    for i = 1, #text do
        local val = string.byte(text, i)
        new_text[i] = (val > 31 and val < 127) and val or 32
    end
    return string.char(unpack(new_text))
end

function register_item(stack)
    local string_id = stack.id..stack.dmg..stack.raw_name..stack.display_name
    stack.string_id = safe_string(string_id)
    for _, existing_item in ipairs(items) do
        if existing_item.string_id == stack.string_id then
            local item = existing_item
            break
        end
    end
    if not item then
        item = {}
        item.string_id = stack.string_id
        item.damage = stack.dmg
        item.max_damage = stack.max_dmg
        item.max_stack = stack.max_size
        item.recipes = {}
        item.quantity = 0
        item.position = next_open_position()
        item.slot = {}
        item.display_name = stack.display_name
        item.mod_name = stack.mod
        table.insert(items, item)
    end
    if item.position == nil then
        item.position = next_open_position()
    end
    return item
end

function check_inventory(inventory_items)
    local items_to_store = {}
    for i = 1, #inventory_items - 1 do
        table.insert(items_to_store, register(inventory_items[i].basic()))
    end
    return items_to_store
end

function closest_order(item_1, item_2)
    return distance_away(item_1.position) > distance_away(item_2.position)
end

function give_item_slots(items_to_store)
    for i = 1, #items_to_store do
        table.insert(items_to_store[i].slot, i)
    end
end

function deposit_item(item)
    go_to(item.position)
    for _, slot_number in ipairs(item.slot) do
        local amount = inventory.pushItem(item.position.side, slot_number)
        item.quantity = item.quantity + amount
    end
    item.slot = {}
    save(items, "items")
end

function store_items(items_to_store)
    give_item_slots(items_to_store)
    while #items_to_store > 0 do
        table.sort(items_to_store, closest_order)
        local closest_item = items_to_store[#items_to_store]
        deposit_item(closest_item)
        table.remove(items_to_store)
    end
end

function store_inventory()
    show_title("Storing Inventory")
    inventory_items = condense_inventory()
    local items_to_store = check_inventory(inventory_items)
    store_items(items_to_store)
end

function search(s1, s2)
    local s1 = string.lower(string.gsub(string.gsub(s1, " ", ""), "_", ""))
    local s2 = string.lower(string.gsub(string.gsub(s2, " ", ""), "_", ""))
    return string.find(s1, s2)
end

function result_order(r1, r2)
    local alphabetical = string.lower(r1.display_name) < string.lower(r2.display_name)
    return alphabetical or r2.quantity == 0
end

function clear_window()
    paintutils.drawFilledBox(1,2,screen_width,screen_height-1,colors.black)
    clear_search_bar()
end

function side_number(n)
    term.setCursorPos(1, n+1)
    local spaces = {}
    n_string = tostring(n)
    for i=1, 2-#n_string do
        table.insert(spaces, " ")
    end
    term.setTextColor(colors.cyan)
    term.write(table.concat(spaces)..n_string)
    term.setTextColor(colors.white)
end

function list_items(items_list)
    clear_window()
    term.setCursorPos(1,2)
    for i, item in pairs(slice(items_list, 1, screen_height-2)) do
        side_number(i)
        print(" "..item.display_name)
        term.setTextColor(colors.lightGray)
        term.write("  #"..item.quantity)
    end
    clear_search_bar()
end

function select_item(search_term)
    show_title("Fetch: \""..search_term.."\"")
    local search_results = {}
    for _, item in ipairs(items) do
        local r = search(item.display_name, search_term)
        if r then
            table.insert(search_results, item)
        end
    end
    table.sort(search_results, result_order)
    list_items(search_results)
    local choice = io.read()
    while not tonumber(choice) and tonumber(choice) > #search_results do
        choice = io.read()
    end
    return search_results[tonumber(choice)]
end

function amount_in_chest()
    store_chest.condenseItems()
    return #store_chest.getAllStacks()
end

function get_enderchest(group)
    turtle.select(16)
    turtle.placeDown()
    turtle.select(1)
end

function start_store()
    go_to({x=0, y=me.y, z=0})
    local at_home = turtle.detectDown()
    condense_inventory()
    if not at_home then
        get_enderchest("deposit")
    end
    items_left = amount_in_chest()
    while items_left > 0 do
        go_to({x=0, y=me.y, z=0})
        get_enderchest("deposit")
        while turtle.suckDown() do end
        if not at_home then
            if inventory.getStackInSlot(16) then
                inventory.pushItem("down", 16)
            end
        end
        items_left = amount_in_chest()
        if not at_home then
            turtle.select(16)
            turtle.digDown()
        end
        store_inventory()
    end
end

function number_of_stacks(full_stack, amount)
    local stacks = math.floor(amount/full_stack)
    local remaining_items = amount % full_stack
    return stacks, remaining_items
end

function fetch_item(item)
    go_to(item.position)
    local amount_to_fetch = item.amount_to_fetch
    while amount_to_fetch > 0 do
        local amount = inventory.pullItem(item.position.side, 2, amount_to_fetch)
        item.quantity = item.quantity - amount
        amount_to_fetch = amount_to_fetch - amount
    end
    if item.quantity == 0 then
        table.insert(open_positions, item.position)
        save(open_positions, "open_positions")
        item.position = nil
    end
    save(items, "items")
end

function start_fetch()
    local items_to_fetch = queue.fetch
    while #items_to_fetch > 0 do
        table.sort(items_to_fetch, closest_order)
        fetch_item(items_to_fetch[#items_to_fetch])
        table.remove(items_to_fetch)
    end
end

function do_queue()
    empty_inventory("down")
    store_inventory()
    if #queue.fetch > 0 then
        start_fetch()
    end
    if queue.store then
        start_store()
    end
    queue = {fetch = {}, store = false}
    go_to(home)
end

function menu_fetch(search_term)
    local item_to_fetch = select_item(search_term)
    show_title("Fetch: "..item_to_fetch.display_name)
    local amount = io.read()
    while not tonumber(amount) do
        amount = io.read()
    end
    item_to_fetch.amount_to_fetch = amount
    table.insert(queue.fetch, item_to_fetch)
end

function menu_store()
    queue.store = true
end

function main_menu()
    local options = {
        ["store"] = menu_store,
        ["sort"] = menu_store,
        [">"] = menu_store,
        ["fetch"] = menu_fetch,
        ["get"] = menu_fetch,
        ["<"] = menu_fetch,
        ["start"] = do_queue,
        ["go"] = do_queue,
        [""] = do_queue
    }
    while true do
        show_title(os.getComputerLabel())
        local input = io.read()
        if options[input] then
            options[input](input)
        end
    end
end

function start()
    screen_width, screen_height = term.getSize()
    queue = {to_store=false,to_fetch={}}
    home = {x=0,y=0,z=0}
    me = {x=home.x,y=home.y,z=home.z}
    store_chest = peripheral.wrap("bottom")
    fetch_chest = peripheral.wrap("right")
    inventory = peripheral.wrap("left")
    items = load("items")
    open_positions = load("open_positions")
end