using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

 namespace MvcBookStore.Models

{

    public partial class ShoppingCart

    {

        BookStoreEntities storeDB = new BookStoreEntities();

        string ShoppingCartId { get; set; }

        public const string CartSessionKey = "CartId";

        public static ShoppingCart GetCart(HttpContextBase context)

        {

            var cart = new ShoppingCart();

            cart.ShoppingCartId = cart.GetCartId(context);

            return cart;

        }

        //使用帮助器方法来简化购物车的访问

        public static ShoppingCart GetCart(Controller controller)

        {

            return GetCart(controller.HttpContext);

        }

        public void AddToCart(Book book)

        {

            //获取对应的购物车对象的实例与书籍对象的实例

            var cartItem = storeDB.Carts.SingleOrDefault(c => c.CartId ==

               ShoppingCartId && c.BookId == book.Id);

            if (cartItem == null)

            {

                //如果购物车中不存在该书籍则添加该书籍

                cartItem = new Cart

                {

                    BookId = book.Id,

                    CartId = ShoppingCartId,

                    Count = 1,

                    DateCreated = DateTime.Now

                };

                storeDB.Carts.Add(cartItem);

            }

            else

            {

                //如果在购物车中该书籍已存在，则添加一个数量

                cartItem.Count++;

            }

            // 保存改变

            storeDB.SaveChanges();

        }

        public int RemoveFromCart(int id)

        {

            //获取购物车对象实例

            var cartItem = storeDB.Carts.Single(cart => cart.CartId ==

              ShoppingCartId && cart.RecordId == id);

            int itemCount = 0;

            if (cartItem != null)

            {

                if (cartItem.Count > 1)

                {

                    cartItem.Count--;

                    itemCount = cartItem.Count;

                }

                else

                {

                    storeDB.Carts.Remove(cartItem);

                }

                // 保存修改

                storeDB.SaveChanges();

            }

            return itemCount;

        }

        public void EmptyCart()

        {

            var cartItems = storeDB.Carts.Where(cart => cart.CartId ==

              ShoppingCartId);

            foreach (var cartItem in cartItems)

            {

                storeDB.Carts.Remove(cartItem);

            }

            // 保存修改

            storeDB.SaveChanges();

        }

        public List<Cart> GetCartItems()

        {

            return storeDB.Carts.Where(cart => cart.CartId ==

              ShoppingCartId).ToList();

        }

        public int GetCount()

        {

            //获取每本书的数量并相加在一起

            int? count = (from cartItems in storeDB.Carts

                          where cartItems.CartId == ShoppingCartId

                          select (int?)cartItems.Count).Sum();

            // 如果实例为null,则返回0

            return count ?? 0;

        }

        public decimal GetTotal()

        {

            //将书籍数量与单价相乘得到每本书的总价，然后相加得到购物车中的总金额

            decimal? total = (from cartItems in storeDB.Carts

                              where cartItems.CartId == ShoppingCartId

                              select (int?)cartItems.Count *

                                  cartItems.Book.Price).Sum();

            return total ?? decimal.Zero;

        }

        public int CreateOrder(Order order)

        {

            decimal orderTotal = 0;

            var cartItems = GetCartItems();

            // 在购物车中进行遍历，将每本书放入订单细节中

            foreach (var item in cartItems)

            {

                var orderDetails = new OrderDetail

                {

                    BookId = item.BookId,

                    OrderId = order.OrderId,

                    UnitPrice = item.Book.Price,

                    Quantity = item.Count

                };

                // 将购物车中每本书的价格加入购物车总金额中

                orderTotal += (item.Count * item.Book.Price);

            }

            //用购物车的总金额来设置订单的Total(总金额）属性值

            order.Total = orderTotal;

            // 保存订单

            storeDB.SaveChanges();

            // 清空购物车

            EmptyCart();

            // 将OrderId属性值作为订单编号来返回

            return order.OrderId;

        }

        //使用HttpContextBase类来允许用户使用cookies.

        public string GetCartId(HttpContextBase context)

        {

            if (context.Session[CartSessionKey] == null)

            {

                if (!string.IsNullOrWhiteSpace(context.User.Identity.Name))

                {

                    context.Session[CartSessionKey] =

                       context.User.Identity.Name;

                }

                else

                {

                    //使用System.Guid class创建一个随机GUID

                    Guid tempCartId = Guid.NewGuid();

                    //将tempCartId作为一个cookie来发送回客户端

                    context.Session[CartSessionKey] = tempCartId.ToString();

                }

            }

            return context.Session[CartSessionKey].ToString();

        }

        //当用户登陆之后，使用他们的用户名来修改购物车的CartId

        public void MigrateCart(string userName)

        {

            var shoppingCart = storeDB.Carts.Where(c => c.CartId ==

              ShoppingCartId);

            foreach (Cart item in shoppingCart)

            {

                item.CartId = userName;

            }

            storeDB.SaveChanges();

        }

    }

}

using System.Collections.Generic;

using MvcBookStore.Models;

namespace MvcBookStore.ViewModels

{

    public class ShoppingCartViewModel

    {

        public List<Cart> CartItems { get; set; }

        public decimal CartTotal { get; set; }

    }

}

namespace MvcBookStore.ViewModels

{

    public class ShoppingCartRemoveViewModel

    {

        public string Message { get; set; }

        public decimal CartTotal { get; set; }

        public int CartCount { get; set; }

        public int ItemCount { get; set; }

        public int DeleteId { get; set; }

    }

}