LearningMVC/SportsStore.Domain/Entities/Cart.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace SportsStore.Domain.Entities
{
	public class Cart
	{
		private List<CartLine> lineCollection = new List<CartLine>();

		public void AddItem(Product product, int quantity)
		{
			CartLine line = lineCollection
				.Where(p => p.Product.ProductID == product.ProductID)
				.FirstOrDefault();

			if (line == null)
			{
				lineCollection.Add(new CartLine { Product = product, Quantity = quantity });
			}
			else
			{
				line.Quantity += quantity;
			}
		}

		public void RemoveLine(Product product)
		{
			lineCollection.RemoveAll(l => l.Product.ProductID == product.ProductID);
		}

		public decimal ComputeTotalValue()
		{
			return lineCollection.Sum(e => e.Product.Price * e.Quantity);
		}

		public void Clear()
		{
			lineCollection.Clear();
		}

		public IEnumerable<CartLine> Lines
		{
			get { return lineCollection; }
		}
	}

	public class CartLine
	{
		public Product Product { get; set; }
		public int Quantity { get; set; }
	}
}