Program.cs

using SDP_Project;
using System.ComponentModel.DataAnnotations;

var grabberoo = new Grabberoo();
var restaurants = new List<Restaurant>([
    CreateItalianRestaurant(),
    CreateChineseRestaurant(),
    CreateFastFoodRestaurant()
]);

while (true)
{
    Console.WriteLine("\n===== Welcome to Grabberoo =====");
    Console.WriteLine("1. Place a new order");
    Console.WriteLine("2. View favourite orders");
    Console.WriteLine("3. Exit");
    int mainChoice = GetIntInput("Select an option (1-3): ", 1, 3);

    if (mainChoice == 1)
    {
        PlaceOrder(restaurants, grabberoo);
    }
    else if (mainChoice == 2)
    {
        ViewFavouriteOrders(grabberoo, restaurants); 
    }
    else if (mainChoice == 3)
    {
        Console.WriteLine("Thank you for using Grabberoo!");
        break;
    }
}

/****** Menu creation ******/

static Menu CreateItalianMenu()
{
    var pastaMenu = new Menu("Pasta");
    pastaMenu.Add(new Pasta
    {
        Name = "Spaghetti Carbonara",
        Description = "Yummy carbonara.",
        BasePrice = 10.0,
        PastaType = "spaghetti",
        SauceType = "creamy"
    });
    pastaMenu.Add(new Pasta
    {
        Name = "Penne Arrabbiata",
        Description = "Penne with spicy arrabbiata sauce.",
        BasePrice = 11.0,
        PastaType = "penne",
        SauceType = "spicy tomato"
    });
    pastaMenu.Add(new Pasta
    {
        Name = "Fettuccine Alfredo",
        Description = "Fettuccine with creamy alfredo sauce.",
        BasePrice = 12.0,
        PastaType = "fettuccine",
        SauceType = "creamy",
        Discount = 2.0
    });
    var pizzaMenu = new Menu("Pizza");
    pizzaMenu.Add(new Pizza
    {
        Name = "Hawaiian Pizza",
        Description = "Hawaiian Pizza with thin crust and tomato sauce",
        BasePrice = 11.0,
        Crust = "thin",
        SauceType = "tomato"
    });
    pizzaMenu.Add(new Pizza
    {
        Name = "Pepperoni Pizza",
        Description = "Pepperoni Pizza with thick crust and tomato sauce",
        BasePrice = 11.0,
        Crust = "thick",
        SauceType = "tomato"
    });
    pizzaMenu.Add(new Pizza
    {
        Name = "Durian Pizza",
        Description = "Delicious Durian Pizza with thick crust and durian sauce",
        BasePrice = 15.0,
        Crust = "thick",
        SauceType = "durian"
    });
    return new Menu("Italian") { Components = [pastaMenu, pizzaMenu] };
}

static Menu CreateChineseMenu()
{
    var riceMenu = new Menu("Rice");
    riceMenu.Add(new FriedRice
    {
        Name = "Egg Fried Rice",
        Description = "Fried Rice with Egg",
        BasePrice = 8.99,
        CookingStyle = "Wok Hei",
        SpiceLevel = 3
    });
    riceMenu.Add(new FriedRice
    {
        Name = "Chilli Crab Egg Fried Rice",
        Description = "Fried Rice with Chilli Crab and Egg",
        BasePrice = 20.0,
        CookingStyle = "Wok Hei",
        SpiceLevel = 4
    });
    var noodleMenu = new Menu("Noodle");
    noodleMenu.Add(new BeeHoon
    {
        Name = "Fried Bee Hoon",
        Description = "Fried Bee Hoon Noodle",
        BasePrice = 7.0,
        CookingStyle = "Wok-Hei",
        SpiceLevel = 1
    });
    noodleMenu.Add(new BeeHoon
    {
        Name = "Seafood Bee Hoon",
        Description = "Bee Hoon noodle with different types of seafood such as crab, lobster, stingray etc",
        BasePrice = 15.0,
        CookingStyle = "Wok-Hei",
        SpiceLevel = 2
    });
    noodleMenu.Add(new BeeHoon
    {
        Name = "Curry Bee Hoon",
        Description = "Bee Hoon noodle with curry sauce",
        BasePrice = 6.0,
        CookingStyle = "steamed",
        SpiceLevel = 1
    });
    return new Menu("Chinese") { Components = [riceMenu, noodleMenu] };
}

static Menu CreateFastFoodMenu()
{
    var burgerMenu = new Menu("Burger");
    burgerMenu.Add(new Burger
    {
        Name = "Hamburger",
        Description = "Hamburger with beef",
        BasePrice = 8.0,
        HasFrenchFries = false,
        Drink = false
    });
    burgerMenu.Add(new Burger
    {
        Name = "Chilli Crab Burger",
        Description = "Chilli Crab Burger Meal with Fries and Drinks",
        BasePrice = 10.0,
        HasFrenchFries = true,
        Drink = true
    });
    var sandwichMenu = new Menu("Sandwich");
    sandwichMenu.Add(new Sandwich
    {
        Name = "Ham Sandwich",
        Description = "Ham Sandwich Alacarte",
        BasePrice = 5.0,
        Drink = false
    });
    sandwichMenu.Add(new Sandwich
    {
        Name = "Smoke Duck Sandwich Meal",
        Description = "Smoke Duck Sandwich Meal with drink",
        BasePrice = 8.0,
        Drink = true
    });
    return new Menu("Fast food") { Components = [burgerMenu, sandwichMenu] };
}

/****** Restaurant creation ******/

static ItalianRestaurant CreateItalianRestaurant()
{
    return new ItalianRestaurant
    {
        Name = "Bella Italia",
        Address = "123 Italian Street",
        Menu = CreateItalianMenu(),
        StoreWideDiscount = 15.0,  // 15% discount
        DiscountDescription = "Italian Week Special! 15% off all orders!"
    };
}

static ChineseRestaurant CreateChineseRestaurant()
{
    return new ChineseRestaurant
    {
        Name = "Golden Dragon",
        Address = "456 China Town",
        Menu = CreateChineseMenu(),
        StoreWideDiscount = 10.0,  // 10% discount
        DiscountDescription = "Chinese New Year Celebration! 10% off all orders!"
    };
}

static FastFoodRestaurant CreateFastFoodRestaurant()
{
    return new FastFoodRestaurant
    {
        Name = "Quick Bite",
        Address = "789 Fast Lane",
        Menu = CreateFastFoodMenu(),
        StoreWideDiscount = 20.0,  // 20% discount
        DiscountDescription = "Weekend Madness! 20% off all orders!"
    };
}

/****** Order placing ******/

static void PlaceOrder(List<Restaurant> restaurants, Grabberoo grabberoo)
{
    // Allow the user to select a restaurant
    Console.WriteLine("\nPlease select a restaurant:");
    for (var i = 0; i < restaurants.Count; i++)
    {
        Console.WriteLine($"{i + 1}. {restaurants[i].Name}");
    }

    var restaurantChoice = GetIntInput($"Enter choice (1-{restaurants.Count}): ", 1, restaurants.Count);
    var selectedRestaurant = restaurants[restaurantChoice - 1];

    // Display the restaurant's menu, including special offers
    Console.WriteLine($"\n--- Menu for {selectedRestaurant.Name} ---");

    // Display restaurant discount information if available
    if (selectedRestaurant.StoreWideDiscount > 0)
    {
        Console.WriteLine($"SPECIAL OFFER: {selectedRestaurant.DiscountDescription}");
    }

    PrintMenu(selectedRestaurant.Menu);
    var itemCount = selectedRestaurant.Menu.ItemCount;


    var orderItems = new List<OrderItem>();
    while (true)
    {
        var itemChoice = GetIntInput($"\nSelect an item by number (1-{itemCount}): ", 1, itemCount);
        var menuItem = selectedRestaurant.Menu.GetItem(itemChoice - 1);
        var orderItem = ApplyDecoratorsToItem(new BasicOrderItem { MenuItem = menuItem });
        orderItem.Quantity = GetIntInput("Enter quantity: ", 1, 100);
        orderItems.Add(orderItem);
        if (!GetYesNoInput("Add another item? (Y/N): ")) break;
    }

    Console.WriteLine("\nChoose order type:");
    Console.WriteLine("1. Standard Delivery");
    Console.WriteLine("2. Express Delivery");
    int orderType = GetIntInput("Enter choice (1-2): ", 1, 2);

    // Collect address and time
    var deliveryAddress = GetStringInput("Enter delivery address: ");
    DateTime deliveryTime;
    do
    {
        string dtStr = GetStringInput("Enter delivery time (yyyy-MM-dd HH:mm): ");
        if (!DateTime.TryParse(dtStr, out deliveryTime))
            Console.WriteLine("Invalid date/time format. Try again.");
    } while (deliveryTime < DateTime.Now);

    // Calculate amount 
    double amount = 0;
    foreach (var item in orderItems)
        amount += item.Cost;

    // Create order, set initial state and strategy
    var order = new Order
    {
        Id = Guid.NewGuid().ToString(),
        DeliveryAddress = deliveryAddress,
        DeliveryTime = deliveryTime,
        Amount = amount,
        PaymentStrategy = new CashOnDelivery(), // Temporary, will be replaced after price breakdown
        OrderItems = orderItems
    };

    // Store original amount before restaurant discount
    double originalAmount = orderItems.Sum(item => item.Cost);

    // Set the restaurant and recalculate total with discounts
    order.SetRestaurant(selectedRestaurant);

    // Create the OrderProcessor
    OrderProcessor orderProcessor;
    if (orderType == 1)
        orderProcessor = new StandardOrderProcessor(order, selectedRestaurant);
    else
        orderProcessor = new ExpressOrderProcessor(order, selectedRestaurant);

    // Process order and show total price
    orderProcessor.ProcessOrder();
    double restaurantDeliveryPrice = selectedRestaurant.RestaurantDeliveryPrice;
    double processorFee = 0;
    if (orderProcessor is StandardOrderProcessor sop)
        processorFee = sop.DeliveryFee;
    else if (orderProcessor is ExpressOrderProcessor eop)
        processorFee = eop.ExpressCharge;

    double combinedDeliveryPrice = restaurantDeliveryPrice + processorFee;
    double totalPrice = orderProcessor.CalculatePrice();

    // Set the total price for payment processing
    order.TotalPrice = totalPrice;

    // Display order summary 
    Console.WriteLine("\nOrder Summary:");
    foreach (var item in orderItems)
    {
        Console.WriteLine($"- {item.Name} x{item.Quantity} ({item.Cost:C})");
    }

    Console.WriteLine($"Subtotal: {originalAmount:C}");

    if (selectedRestaurant.StoreWideDiscount > 0)
    {
        double storeDiscountAmount = originalAmount - order.Amount;
        Console.WriteLine($"Restaurant Discount ({selectedRestaurant.StoreWideDiscount}%): -{storeDiscountAmount:C}");
    }


    Console.WriteLine($"Delivery fee: {combinedDeliveryPrice:C}");

    Console.WriteLine($"Grand total: {totalPrice:C}");

    if (selectedRestaurant.StoreWideDiscount > 0)
    {
        double savings = originalAmount - order.Amount;
        Console.WriteLine($"\nYou saved {savings:C} with the restaurant discount!");
    }


    Console.WriteLine("\nSelect payment method:");
    Console.WriteLine("1. Credit Card");
    Console.WriteLine("2. PayPal");
    Console.WriteLine("3. Cash On Delivery");
    int paymentChoice = GetIntInput("Enter choice (1-3): ", 1, 3);

    PaymentStrategy paymentStrategy;
    if (paymentChoice == 1)
    {
        string cardNumber;
        do
        {
            cardNumber = GetStringInput("Enter card number (12-19 digits): ");
            if (string.IsNullOrWhiteSpace(cardNumber) || cardNumber.Length < 12 || cardNumber.Length > 19 || !IsAllDigits(cardNumber))
                Console.WriteLine("Invalid card number. Must be 12-19 digits.");
            else break;
        } while (true);

        string expiryDate;
        do
        {
            expiryDate = GetStringInput("Enter expiry date (MM/YY): ");
            if (!IsValidExpiryDate(expiryDate))
                Console.WriteLine("Invalid date. Please enter a valid expiry date in MM/YY format, not expired.");
            else break;
        } while (true);

        string cvv;
        do
        {
            cvv = GetStringInput("Enter CVV (3-4 digits): ");
            if (string.IsNullOrWhiteSpace(cvv) || cvv.Length < 3 || cvv.Length > 4 || !IsAllDigits(cvv))
                Console.WriteLine("Invalid CVV. Must be 3-4 digits.");
            else break;
        } while (true);

        paymentStrategy = new CreditCardPayment
        {
            CardNumber = cardNumber,
            ExpiryDate = expiryDate,
            CVV = cvv
        };
    }
    else if (paymentChoice == 2)
    {
        string email;
        do
        {
            email = GetStringInput("Enter PayPal Email: ");
            if (!IsValidEmail(email))
                Console.WriteLine("Invalid email format. Try again.");
        } while (!IsValidEmail(email));
        string password = GetStringInput("Enter PayPal Password: ");
        paymentStrategy = new PayPalPayment { Email = email, Password = password };
    }
    else // Cash On Delivery
    {
        Console.WriteLine("Cash On Delivery selected.");
        paymentStrategy = new CashOnDelivery();
    }

    // Set the correct payment strategy after collecting payment details
    order.PaymentStrategy = paymentStrategy;

    // State-driven workflow
    while (order.State != null)
    {

        // Show available actions based on current state

        order.Submit();

        if (order.State is PendingPaymentState)
        {
            Console.WriteLine("1. Pay");
            Console.WriteLine("2. Cancel");
            int choice = GetIntInput("Choose action: ", 1, 2);
            if (choice == 1)
            {
                order.Pay();
                Console.WriteLine("Processing payment...");
                Console.WriteLine("Press 1 to Cancel, or wait 5 seconds for restaurant response...");
                Console.WriteLine("1. Cancel");

                DateTime endTime = DateTime.Now.AddSeconds(5);
                bool cancelled = false;

                while (DateTime.Now < endTime)
                {
                    if (Console.KeyAvailable)
                    {
                        var key = Console.ReadKey(true);
                        if (key.KeyChar == '1')
                        {
                            order.Cancel();
                            cancelled = true;
                            break;
                        }
                    }
                    Thread.Sleep(100);
                }

                if (!cancelled)
                {
                    // Simulate restaurant decision: 80% confirm, 20% reject
                    var rand = new Random();
                    int outcome = rand.Next(1, 101); // 1 to 100

                    if (outcome <= 80)
                    {
                        Console.WriteLine("Restaurant has CONFIRMED your order.");
                        order.Confirm();
                    }
                    else
                    {
                        Console.WriteLine("Restaurant has REJECTED your order.");
                        order.Reject();
                        break;
                    }
                }
                else
                {
                    break;
                }
            }
            else order.Cancel();
            if (order.State == null) break;
        }
        else if (order.State is PendingConfirmationState)
        {
            // If order is still active, allow user to cancel
            if (order.State != null)
            {
                if (GetYesNoInput("Would you like to cancel your order? (Y/N): "))
                {
                    order.Cancel();
                    break;
                }
            }
        }
        else if (order.State is OrderConfirmedState)
        {
            Console.WriteLine("Order Preparation about to start");
            Console.WriteLine("Press 1 to Cancel, or wait 5 seconds to continue...");
            Console.WriteLine("1. Cancel");


            DateTime endTime = DateTime.Now.AddSeconds(5);
            bool cancelled = false;

            while (DateTime.Now < endTime)
            {
                if (Console.KeyAvailable)
                {
                    var key = Console.ReadKey(true);
                    if (key.KeyChar == '1')
                    {
                        order.Cancel();
                        cancelled = true;
                        break;
                    }
                }
                Thread.Sleep(100); // Don't burn CPU
            }

            if (!cancelled)
            {
                Console.WriteLine("No action taken. Starting preparation automatically.");
                order.StartPreparation();
                if (order.State == null) break;
            }
        }
        order.StartDelivery();
        if (order.State == null) break;
        order.CompleteDelivery();
        if (order.State == null) break;

        order.State?.Archive();
        if (order.State == null) break;


    }
    if (GetYesNoInput("Would you like to mark this order as favourite? (Y/N): "))
    {
        var markFavouriteCommand = new MarkAsFavouriteCommand(grabberoo, order);
        var favouriteButton = new MarkAsFavouriteButton(markFavouriteCommand);
        favouriteButton.Press();
    }
}
/****** Favourite orders ******/

static void ViewFavouriteOrders(Grabberoo grabberoo, List<Restaurant> restaurants)
{
    Console.WriteLine("\n--- Favourite Orders ---");

    var favouriteOrders = grabberoo.GetFavouriteOrders().ToList();
    if (favouriteOrders.Count == 0)
    {
        Console.WriteLine("No favourite orders found.");
        return;
    }

    // Display favourite orders
    for (int i = 0; i < favouriteOrders.Count; i++)
    {
        var order = favouriteOrders[i];
        // Build a summary string of items
        var itemsSummary = string.Join(", ",
            order.OrderItems.Select(item => $"{item.Name} x{item.Quantity}"));

        string discountInfo = "";
        if (order.Restaurant != null && order.Restaurant.StoreWideDiscount > 0)
        {
            discountInfo = $" | {order.Restaurant.StoreWideDiscount}% OFF";
        }

        Console.WriteLine($"{i + 1}. [{itemsSummary}] | Address: {order.DeliveryAddress} | Amount: {order.Amount:C} | Status: {order.PaymentStatus}{discountInfo}");
    }

    Console.WriteLine("\nOptions:");
    Console.WriteLine("1. Remove a favourite order");
    Console.WriteLine("2. Reorder a favourite order");
    Console.WriteLine("3. Back to main menu");
    int option = GetIntInput("Select an option (1-3): ", 1, 3);

    if (option == 1)
    {
        int removeChoice = GetIntInput($"Select order to remove (1-{favouriteOrders.Count}): ", 1, favouriteOrders.Count);
        var orderToRemove = favouriteOrders[removeChoice - 1];

        var removeFavouriteCommand = new MarkAsFavouriteCommand(grabberoo, orderToRemove);
        var favouriteButton = new MarkAsFavouriteButton(removeFavouriteCommand);
        favouriteButton.Unpress();
    }
    else if (option == 2)
    {
        int reorderChoice = GetIntInput($"Select order to reorder (1-{favouriteOrders.Count}): ", 1, favouriteOrders.Count);
        var originalOrder = favouriteOrders[reorderChoice - 1];

        var newOrder = grabberoo.ReorderFavourite(originalOrder);
        if (newOrder == null) return;

        // Find the restaurant for delivery fee calculation
        var selectedRestaurant = restaurants.FirstOrDefault(r => r.Address == originalOrder.DeliveryAddress)
            ?? restaurants[0];

        // Store original amount before restaurant discount
        double originalAmount = newOrder.OrderItems.Sum(item => item.Cost);

        // Set the restaurant and apply discounts
        newOrder.SetRestaurant(selectedRestaurant);

        Console.WriteLine("\nChoose order type:");
        Console.WriteLine("1. Standard Delivery");
        Console.WriteLine("2. Express Delivery");
        int orderType = GetIntInput("Enter choice (1-2): ", 1, 2);

        OrderProcessor orderProcessor;
        if (orderType == 1)
            orderProcessor = new StandardOrderProcessor(newOrder, selectedRestaurant);
        else
            orderProcessor = new ExpressOrderProcessor(newOrder, selectedRestaurant);

        orderProcessor.ProcessOrder();
        double restaurantDeliveryPrice = selectedRestaurant.RestaurantDeliveryPrice;
        double processorFee = 0;
        if (orderProcessor is StandardOrderProcessor sop)
            processorFee = sop.DeliveryFee;
        else if (orderProcessor is ExpressOrderProcessor eop)
            processorFee = eop.ExpressCharge;

        double combinedDeliveryPrice = restaurantDeliveryPrice + processorFee;
        double totalPrice = orderProcessor.CalculatePrice();

        // Set the total price for payment processing
        newOrder.TotalPrice = totalPrice;

        // Display reorder summary 
        Console.WriteLine("\nReorder Summary:");
        foreach (var item in newOrder.OrderItems)
        {
            Console.WriteLine($"- {item.Name} x{item.Quantity} ({item.Cost:C})");
        }

        Console.WriteLine($"Subtotal: {originalAmount:C}");

        if (selectedRestaurant.StoreWideDiscount > 0)
        {
            double storeDiscountAmount = originalAmount - newOrder.Amount;
            Console.WriteLine($"Restaurant Discount ({selectedRestaurant.StoreWideDiscount}%): -{storeDiscountAmount:C}");
            Console.WriteLine($"Final Subtotal: {newOrder.Amount:C}");
        }

        Console.WriteLine($"Delivery price: {combinedDeliveryPrice:C}");

        Console.WriteLine($"Total: {totalPrice:C}");

        if (selectedRestaurant.StoreWideDiscount > 0)
        {
            double savings = originalAmount - newOrder.Amount;
            Console.WriteLine($"\nYou saved {savings:C} with the restaurant discount!");
        }

        // State-driven workflow (same as PlaceOrder)
        while (newOrder.State != null)
        {
            newOrder.Submit();

            if (newOrder.State is PendingPaymentState)
            {
                Console.WriteLine("1. Pay");
                Console.WriteLine("2. Cancel");
                int choice = GetIntInput("Choose action: ", 1, 2);
                if (choice == 1)
                {
                    newOrder.Pay();
                    Console.WriteLine("Processing payment...");
                    Console.WriteLine("Press 1 to Cancel, or wait 5 seconds for restaurant response...");
                    Console.WriteLine("1. Cancel");

                    DateTime endTime = DateTime.Now.AddSeconds(5);
                    bool cancelled = false;

                    while (DateTime.Now < endTime)
                    {
                        if (Console.KeyAvailable)
                        {
                            var key = Console.ReadKey(true);
                            if (key.KeyChar == '1')
                            {
                                newOrder.Cancel();
                                cancelled = true;
                                break;
                            }
                        }
                        Thread.Sleep(100);
                    }

                    if (!cancelled)
                    {
                        // Simulate restaurant decision: 80% confirm, 20% reject
                        var rand = new Random();
                        int outcome = rand.Next(1, 101);

                        if (outcome <= 80)
                        {
                            Console.WriteLine("Restaurant has CONFIRMED your order.");
                            newOrder.Confirm();
                        }
                        else
                        {
                            Console.WriteLine("Restaurant has REJECTED your order.");
                            newOrder.Reject();
                            break;
                        }
                    }
                    else
                    {
                        break;
                    }
                }
                else newOrder.Cancel();
                if (newOrder.State == null) break;
            }
            else if (newOrder.State is PendingConfirmationState)
            {
                if (newOrder.State != null)
                {
                    if (GetYesNoInput("Would you like to cancel your order? (Y/N): "))
                    {
                        newOrder.Cancel();
                        break;
                    }
                }
            }
            else if (newOrder.State is OrderConfirmedState)
            {
                Console.WriteLine("Order Preparation about to start");
                Console.WriteLine("Press 1 to Cancel, or wait 5 seconds to continue...");
                Console.WriteLine("1. Cancel");


                DateTime endTime = DateTime.Now.AddSeconds(5);
                bool cancelled = false;

                while (DateTime.Now < endTime)
                {
                    if (Console.KeyAvailable)
                    {
                        var key = Console.ReadKey(true);
                        if (key.KeyChar == '1')
                        {
                            newOrder.Cancel();
                            cancelled = true;
                            break;
                        }
                    }
                    Thread.Sleep(100);
                }

                if (!cancelled)
                {
                    Console.WriteLine("No action taken. Starting preparation automatically.");
                    newOrder.StartPreparation();
                    if (newOrder.State == null) break;
                }
            }
            newOrder.StartDelivery();
            if (newOrder.State == null) break;
            newOrder.CompleteDelivery();
            if (newOrder.State == null) break;
            newOrder.State?.Archive();
            if (newOrder.State == null) break;
        }
    }
    // else: Back to main menu
}
/****** Decorator application ******/

static OrderItem ApplyDecoratorsToItem(OrderItem orderItem)
{
    foreach (var decoratorType in orderItem.MenuItem.GetAvailableDecorators())
    {
        var attr = decoratorType
            .GetCustomAttributes(typeof(DecoratorDescriptionAttribute), false)
            .Cast<DecoratorDescriptionAttribute>()
            .FirstOrDefault() ?? throw new Exception($"Missing DecoratorDescription attribute for {decoratorType.Name}");

        if (GetYesNoInput($"{attr?.Description}? (Y/N): "))
        {
            orderItem = (OrderItem)Activator.CreateInstance(decoratorType, orderItem)!;
        }
    }

    return orderItem;
}

/****** Display helpers ******/

static void PrintMenu(Menu menu)
{
    var i = 1;
    var iter = menu.CreateIterator();
    var indent = 0;
    var itemsUntilUnindent = 0;
    while (iter.HasNext())
    {
        if (itemsUntilUnindent > 0) itemsUntilUnindent--;

        var item = (MenuComponent)iter.Next();
        var prefix = item is MenuItem ? $"{i++}. " : "";
        Console.WriteLine($"{new string(' ', indent)}{prefix}{item}");

        if (itemsUntilUnindent == 0 && indent > 0) indent -= 2;
        if (item is Menu m)
        {
            indent += 2;
            itemsUntilUnindent += m.Components.Count;
        }
    }

}

/****** Input helpers ******/

static int GetIntInput(string prompt, int min, int max)
{
    int value;
    do
    {
        Console.Write(prompt);
        string input = Console.ReadLine();
        if (int.TryParse(input, out value) && value >= min && value <= max)
            break;
        Console.WriteLine($"Please enter a number between {min} and {max}.");
    } while (true);
    return value;
}

static string GetStringInput(string prompt)
{
    string input;
    do
    {
        Console.Write(prompt);
        input = Console.ReadLine();
    } while (string.IsNullOrWhiteSpace(input));
    return input.Trim();
}

static bool IsValidEmail(string email)
{
    return email.Contains("@") && email.Contains(".");
}

static bool IsAllDigits(string value)
{
    foreach (char c in value)
    {
        if (!char.IsDigit(c))
            return false;
    }
    return true;
}

static bool IsValidExpiryDate(string expiryDate)
{
    if (string.IsNullOrWhiteSpace(expiryDate) || expiryDate.Length != 5 || expiryDate[2] != '/')
        return false;

    string[] parts = expiryDate.Split('/');
    if (parts.Length != 2) return false;

    if (!int.TryParse(parts[0], out int month) || !int.TryParse(parts[1], out int year))
        return false;

    if (month < 1 || month > 12)
        return false;

    int currentYear = DateTime.Now.Year % 100;
    int currentMonth = DateTime.Now.Month;

    if (year < currentYear)
        return false;
    if (year == currentYear && month < currentMonth)
        return false;

    return true;
}

static bool GetYesNoInput(string prompt)
{
    string input;
    do
    {
        Console.Write(prompt);
        input = Console.ReadLine()?.Trim().ToUpper();
        if (input == "Y") return true;
        if (input == "N") return false;
        Console.WriteLine("Please enter Y or N.");
    } while (true);
}