using System;

using System.Collections.Generic;

using Microsoft.Extensions.DependencyInjection;

​

namespace fl.shopper.example

{

    internal class Program

    {

        private static void Main(string[] args)

        {

            var services = CreateServices();

            Shopper app = services.GetRequiredService<Shopper>();

            app.GoShopping();

        }

​

        private static ServiceProvider CreateServices()

        {

            var serviceProvider = new ServiceCollection()

                .AddSingleton<Shopper>()                

                .BuildServiceProvider();

​

            return serviceProvider;

        }

    }

​

    public class Shopper(IShoppingCart cart)

    {

        public IShoppingCart Cart = cart;

​

        public void GoShopping()

        {   

            // Cart.AddItem(new CartItem ("SHIRT", "Red Shirt", 14.99, 1));

            // Cart.AddItem(new CartItem ("SHIRT", "Blue Shirt", 8.99, 1));

            // Cart.AddItem(new CartItem ("SHIRT", "Green Shirt", 17.99, 1));

            // Cart.AddItem(new CartItem ("PANTS", "Pants", 14.99, 2));

            // Cart.AddCoupon(new BuyOneShirtGetOneFreeCoupon());

            // NOTE: Buy-One-Get-One discount must first be applied to the least exspensive item.

            // Cart.AddCoupon(new TenPercentOffEntirePurchase());

            // NOTE: 10% Off coupon should NOT be applied to any free cart items

            Cart.CheckOut();

            PrintCartContents();

        }

        private void PrintCartContents(){

            Console.WriteLine($"{"SKU",-14} {"Description",-40}  {"QTY",-5}  {"Cost",-10}");

            Console.WriteLine(new string ('-',66));

            foreach(var item in Cart.Items)

            {

                Console.WriteLine($"{item.Sku,-14} {item.Description,-40}  {item.Qty,-5}  {item.Cost.ToString("C"),-10}");

            }

            Console.WriteLine(new string ('-',66));

            Console.WriteLine($"{"Sub-Total",35}: {Cart.SubTotal().ToString("C"),10}");

            Console.WriteLine($"{"Tax",35}: {Cart.Tax().ToString("C"),10}");

            Console.WriteLine($"{"Discounts",35}: {Cart.Discounts().ToString("C"),10}");

            Console.WriteLine($"{"Total",35}: {Cart.Total().ToString("C"),10}");

        }

    }

​

    public interface IShoppingCart{

        void AddItem(ICartItem item); 

        void AddCoupon(ICoupon coupon); 

        IReadOnlyList<ICartItem> Items{get;}

        double SubTotal();

        double Discounts();

        double Tax();

        double Total();

        void CheckOut();

    }

    public interface ICartItem{

        string Sku{get;}

        string Description{get;}

        double Cost{get;}

        int Qty{get;}

    }

    public interface ICoupon{

        void Apply(IShoppingCart cart);

    }

    public interface IShoppingConfig{

        double TaxRate {get;}

    }

}