Order klasa

public class Order // Ovo je AGGREGATE ROOT
{
    public Guid Id { get; private set; } // Identitet agregatnog korena
    public DateTime CreatedOn { get; private set; }
    public Address ShippingAddress { get; private set; } // Value Object
    public OrderStatus Status { get; private set; } // Stanje porudžbine

    // Kolekcija OrderItem-a (interni entiteti ili value objekti)
    // Pristup ovoj kolekciji je samo preko metoda Order agregata
    private List<OrderItem> _orderItems;
    public IReadOnlyCollection<OrderItem> OrderItems => _orderItems.AsReadOnly();

    public Money TotalPrice { get; private set; } // Izračunata vrednost, Value Object

    public Order(Guid id, DateTime createdOn, Address shippingAddress)
    {
        Id = id;
        CreatedOn = createdOn;
        ShippingAddress = shippingAddress ?? throw new ArgumentNullException(nameof(shippingAddress));
        Status = OrderStatus.Created;
        _orderItems = new List<OrderItem>();
        TotalPrice = new Money(0, "EUR"); // Inicijalna vrednost
    }

    // Sva interakcija sa agregatom ide kroz koren (Order klasu)
    public void AddItem(Product product, int quantity)
    {
        // Poslovno pravilo: ne dozvoliti negativnu količinu
        if (quantity <= 0)
        {
            throw new ArgumentException("Quantity must be positive.");
        }

        // Provera da li proizvod već postoji u porudžbini
        var existingItem = _orderItems.FirstOrDefault(item => item.ProductId == product.Id);
        if (existingItem != null)
        {
            // Ažuriranje postojeće stavke
            existingItem.IncreaseQuantity(quantity); // Ova metoda bi bila definisana unutar OrderItem
        }
        else
        {
            // Dodavanje nove stavke
            _orderItems.Add(new OrderItem(Guid.NewGuid(), product.Id, product.Name, product.Price, quantity));
        }

        // Izračunavanje ukupne cene (poslovno pravilo, konzistentnost agregata)
        CalculateTotalPrice();
    }

    public void RemoveItem(Guid orderItemId)
    {
        var itemToRemove = _orderItems.FirstOrDefault(item => item.Id == orderItemId);
        if (itemToRemove == null)
        {
            throw new InvalidOperationException("Order item not found.");
        }
        _orderItems.Remove(itemToRemove);
        CalculateTotalPrice();
    }

    public void UpdateShippingAddress(Address newAddress)
    {
        // Validacija za promenu adrese ako je potrebno (npr. samo pre isporuke)
        if (Status != OrderStatus.Created)
        {
            throw new InvalidOperationException("Shipping address can only be updated for new orders.");
        }
        ShippingAddress = newAddress;
    }

    private void CalculateTotalPrice()
    {
        decimal totalAmount = 0;
        string currency = "EUR"; // Pretpostavka jedne valute za TotalPrice

        foreach (var item in _orderItems)
        {
            totalAmount += item.ProductPrice.Amount * item.Quantity;
            // Provera valute ako su stavke u različitim valutama
            if (currency != item.ProductPrice.Currency)
            {
                // Možda kompleksnija logika za konverziju ili bacanje izuzetka
                throw new InvalidOperationException("Mixed currencies in order items.");
            }
        }
        TotalPrice = new Money(totalAmount, currency);
    }

    // Mogući unutrašnji entitet (OrderItem)
    public class OrderItem // Ovo je entitet unutar agregata, nema sopstveni repozitorijum
    {
        public Guid Id { get; private set; } // Identitet unutar agregata
        public Guid ProductId { get; private set; }
        public string ProductName { get; private set; }
        public Money ProductPrice { get; private set; } // Value Object
        public int Quantity { get; private set; }

        public OrderItem(Guid id, Guid productId, string productName, Money productPrice, int quantity)
        {
            Id = id;
            ProductId = productId;
            ProductName = productName;
            ProductPrice = productPrice;
            Quantity = quantity;
        }

        public void IncreaseQuantity(int amount)
        {
            if (amount <= 0)
            {
                throw new ArgumentException("Amount must be positive.");
            }
            Quantity += amount;
        }
    }
}

public enum OrderStatus
{
    Created,
    Paid,
    Shipped,
    Delivered,
    Cancelled
}