-- Function to get the disk ID from the bottom drive
local function getDiskID()
    -- Wrap the disk drive at the bottom of the computer
    local drive = peripheral.wrap("bottom")

    if drive and peripheral.getType("bottom") == "drive" then
        -- Check if there is a disk in the drive
        if drive.isDiskPresent() then
            -- Get the disk ID
            local diskID = drive.getDiskID()
            return diskID
        else
            print("No disk present in the drive.")
        end
    else
        print("No drive found at the bottom.")
    end
    return nil
end

-- Function to list all cards in /disk/Cards
local function listCards()
    local cardDir = "/disk/Cards/"
    local files = fs.list(cardDir)
    if #files > 0 then
        print("Cards in /disk/Cards:")
        for _, file in ipairs(files) do
            print("- " .. file)
        end
    else
        print("No cards found in /disk/Cards.")
    end
end

-- Function to link a card
local function linkCard()
    while true do
        print("\nLink Card:")
        print("1. Insert Card to Link")
        print("2. Enter Card ID")
        print("0. Back to Main Menu")
        local choice = tonumber(read())

        if choice == 1 then
            print("Insert a disk to link...")
            local diskID = getDiskID()
            if diskID then
                local cardFileName = "/disk/Cards/" .. diskID .. ".ID"
                local file = fs.open(cardFileName, "w")
                file.close()
                print("Card linked successfully.")
            end
        elseif choice == 2 then
            print("Enter the card ID:")
            local cardID = read()

            local cardFileName = "/disk/Cards/" .. cardID .. ".ID"
            local file = fs.open(cardFileName, "w")
            file.close()

            print("Card linked successfully.")
        elseif choice == 0 then
            break  -- Back to main menu
        else
            print("Invalid choice. Please enter 1, 2, or 0.")
        end
    end
end

-- Function to unlink a card
local function unlinkCard()
    while true do
        print("\nUnlink Card:")
        print("1. Insert Card to Unlink")
        print("2. Enter Card ID")
        print("0. Back to Main Menu")
        local choice = tonumber(read())

        if choice == 1 then
            print("Insert a disk to unlink...")
            local diskID = getDiskID()
            if diskID then
                local cardFileName = "/disk/Cards/" .. diskID .. ".ID"
                if fs.exists(cardFileName) then
                    fs.delete(cardFileName)
                    print("Card unlinked successfully.")
                else
                    print("No matching card found to unlink.")
                end
            end
        elseif choice == 2 then
            print("Enter the card ID:")
            local cardID = read()

            local cardFileName = "/disk/Cards/" .. cardID .. ".ID"
            if fs.exists(cardFileName) then
                fs.delete(cardFileName)
                print("Card unlinked successfully.")
            else
                print("No matching card found to unlink.")
            end
        elseif choice == 0 then
            break  -- Back to main menu
        else
            print("Invalid choice. Please enter 1, 2, or 0.")
        end
    end
end

-- Main program loop
while true do
    print("\nCard System")
    print("1. List Cards")
    print("2. Link Card")
    print("3. Unlink Card")
    print("0. Exit")

    local choice = tonumber(read())

    if choice == 1 then
        listCards()
    elseif choice == 2 then
        linkCard()
    elseif choice == 3 then
        unlinkCard()
    elseif choice == 0 then
        print("Exiting...")
        break
    else
        print("Invalid choice. Please enter a number from the menu.")
    end
end