using System;

using System.Collections.Generic;

using System.Linq;

using Microsoft.Practices.Unity;

​

​

    public class Program

    {

        public static void Main(string[] args)

        {

            // For main program comment this and uncomment the below code for 

            // running unit tests

            IUnityContainer uContainer = new UnityContainer()

                .RegisterType<IProductRepository, ProductRepository>();

            // For unit test

            //IUnityContainer uContainer = new UnityContainer()

            //  .RegisterType<IProductRepository, MockProductRepository>();

            ProductService service = uContainer.Resolve<ProductService>();

            List<int> productIds = new List<int>();

            productIds.Add(1);

            productIds.Add(2);

            productIds.Add(3);

​

            IList<Product> products = service.CalculateProductsPrice(productIds);

​

            foreach (Product p in products)

            {

                Console.WriteLine(" Product Name {0} Cost {1} Sales Tax {2}", p.Name, p.Price.FinalSellingPrice, p.Price.SalesTax);

            }

​

            Console.WriteLine(" Total Cost {0} Total Sales Tax {1}", products.Sum(x => x.Price.FinalSellingPrice), products.Sum(x => x.Price.SalesTax));

            Console.ReadLine();

        }

        #region interfaces

        public interface ISalesTaxStrategy

        {

            decimal ApplySalesTaxTo(decimal OriginalSalePrice);

        }

        public interface IProductRepository

        {

            Product FindById(int id);

        }

        #endregion

        #region Classes

        public class Product

        {

            public Product(int id, SalesTaxType category, string name, Price price)

            {

                Id = id;

                Category = category;

                Name = name;

                Price = price;

            }

​

            public int Id { get; set; }

            public SalesTaxType Category { get; set; }

            public string Name { get; set; }

            public Price Price { get; set; }

        }

        public class Price

        {

            private ISalesTaxStrategy _salesTaxStrategy = new NullTaxStrategy();

            private decimal _sellingPrice;

​

            public Price(decimal SellingPrice)

            {

                _sellingPrice = SellingPrice;

            }

​

            public void SetSalesTaxStrategy(ISalesTaxStrategy SalesTaxStrategy)

            {

                _salesTaxStrategy = SalesTaxStrategy;

            }

​

            public decimal FinalSellingPrice

            {

                get { return _salesTaxStrategy.ApplySalesTaxTo(_sellingPrice); }

            }

​

            public decimal SalesTax

            {

                get

                {

                    if (FinalSellingPrice > _sellingPrice)

                        return (FinalSellingPrice - _sellingPrice);

                    else

                        return 0;

                }

            }

        }

        #endregion

        #region Strategy Classes

        public class NullTaxStrategy : ISalesTaxStrategy

        {

            public decimal ApplySalesTaxTo(decimal OriginalSalePrice)

            {

                return OriginalSalePrice;

            }

        }

        public class CategoryATaxStrategy : ISalesTaxStrategy

        {

            public decimal ApplySalesTaxTo(decimal OriginalSalePrice)

            {

                decimal price = OriginalSalePrice;

                price = price * 1.1M;

                return price;

            }

        }

        public class CategoryBTaxStrategy : ISalesTaxStrategy

        {

            public decimal ApplySalesTaxTo(decimal OriginalSalePrice)

            {

                decimal price = OriginalSalePrice;

                price = price * 1.2M;

                return price;

            }

        }

        #endregion

        #region Helper Classes

​

​

        public static class SalesTaxFactory

        {

            public static ISalesTaxStrategy GetSalesTaxStrategyFor(SalesTaxType salesTaxType)

            {

                switch (salesTaxType)

                {

                    case SalesTaxType.CategoryA:

                        return new CategoryATaxStrategy();

                    case SalesTaxType.CategoryB:

                        return new CategoryBTaxStrategy();

                    default:

                        return new NullTaxStrategy();

                }

            }

        }

        #endregion

        #region Repository Classes

        public class ProductRepository : IProductRepository

        {

            List<Product> products = new List<Product>();

            public ProductRepository()

            {

                // initializing . This should come via ORM

                //Entity Framework

                Product pA = new Product(1, SalesTaxType.CategoryA, "PCategoryA", new Price(100M));

                Product pB = new Product(2, SalesTaxType.CategoryB, "PCategoryB", new Price(100M));

                Product pC = new Product(3, SalesTaxType.CategoryC, "PCategoryC", new Price(100M));

                products.Add(pA);

                products.Add(pB);

                products.Add(pC);

            }

​

            #region IProductRepository Members

​

            public Product FindById(int id)

            {

                Product found = products.Where(x => x.Id == id).First();

                if (found == null)

                    throw new ArgumentNullException();

​

                return found;

            }

​

            #endregion

        }

        public class MockProductRepository : IProductRepository

        {

            List<Product> products = new List<Product>();

            public MockProductRepository()

            {

                // Test Data

                Product pA = new Product(1, SalesTaxType.CategoryA, "PCategoryA", new Price(100M));

                Product pB = new Product(2, SalesTaxType.CategoryB, "PCategoryB", new Price(100M));

                Product pC = new Product(3, SalesTaxType.CategoryC, "PCategoryC", new Price(100M));

                products.Add(pA);

                products.Add(pB);

                products.Add(pC);

            }

​

            #region IProductRepository Members

​

            public Product FindById(int id)

            {

                Product found = products.Where(x => x.Id == id).First();

                if (found == null)

                    throw new ArgumentNullException();

​

                return found;

            }

​

            #endregion

        }

        #endregion

        #region Enums

        public enum SalesTaxType

        {

            CategoryA = 0,

            CategoryB = 1,

            CategoryC = 2

        }

        #endregion

        #region Service

        public class ProductService

        {

            private IProductRepository _productRepository;

​

            public ProductService(IProductRepository productRepository)

            {

                _productRepository = productRepository;

            }

​

            public IList<Product> CalculateProductsPrice(List<int> productIds)

            {

                IList<Product> products = new List<Product>();

                foreach (int id in productIds)

                {

                    Product p = _productRepository.FindById(id);

                    ISalesTaxStrategy strategy = SalesTaxFactory.GetSalesTaxStrategyFor(p.Category);

                    p.Price.SetSalesTaxStrategy(strategy);

                    products.Add(p);

                }

​

                return products;

            }

        }

        #endregion

​

    }

​

​

​

​