public interface IBasketService { void AddItem(Product product, int quantity); void RemoveItem(Product product, int quantity); void ClearBasket(); ICollectionGetItems(); decimal GetTotal(); }
public class BasketService : IBasketService { private readonly ListIn this example, the `BasketService` class implements the `IBasketService` interface. It uses a list of `BasketItem` objects to store the items in the basket. The `AddItem` method checks if the product already exists in the basket, and either increments its quantity or adds a new `BasketItem` to the list. The package library for `IBasketService` is not specified, as it could be part of a larger e-commerce library or part of a custom solution for a specific e-commerce application._items; public BasketService() { _items = new List (); } public void AddItem(Product product, int quantity) { var existingItem = _items.FirstOrDefault(x => x.Product.Id == product.Id); if (existingItem != null) { existingItem.Quantity += quantity; } else { _items.Add(new BasketItem(product, quantity)); } } // other methods omitted for brevity }