public interface IProductTax
{
    bool IsApplicableTo(IProduct product);
    decimal Compute(IProduct product);
}

public class TaxProcessor : ITaxProcessor
{
    List<IProductTax> SalesTaxes;
    public TaxProcessor()
    {
        SalesTaxes = new List<IProductTax>()
        {
            new SalesTax(),
            new ImportDuty()
        };
    }
    public decimal ComputeTotalTax(IProduct product)
    {
        decimal computedSalesTax = 0;
        foreach (var tax in SalesTaxes)
        {
            computedSalesTax += tax.Compute(product);
        }

        return computedSalesTax;
    }
}

public class SalesTax : IProductTax
{
    public decimal Compute(IProduct product)
    {
        if (IsApplicableTo(product))
            return product.Price * 0.1m;
        return 0m;
    }

    public bool IsApplicableTo(IProduct product)
    {
        return !product.ItemType.HasFlag(ItemTypes.SalesTaxEmptedItemTypes);
    }
}

public class ImportDuty : IProductTax
{
    public decimal Compute(IProduct product)
    {
        if (IsApplicableTo(product))
            return product.Price * 0.05m;
        return 0m;
    }

    public bool IsApplicableTo(IProduct product)
    {
        return product.IsImport;
    }
}

public class BillProcessor
{
    public BillProcessor(ITaxProcessor salesTaxProcess)
    {
        SalesTaxProcessor = salesTaxProcess;
    }

    public Reciept ProcessCart(List<ShoppingItem> shoppingCart)
    {
        var billedShopppingItems = new List<BilledShopppingItem>();
        decimal totalTaxForCart = 0;
        decimal totalBilledAmount = 0;
        foreach (var shoppingItem in shoppingCart)
        {
            decimal individualTax = SalesTaxProcessor.ComputeTotalTax(shoppingItem.Product);
            decimal taxForAllProducts = individualTax * shoppingItem.Quantity;

            decimal totalPrice = shoppingItem.Product.Price * shoppingItem.Quantity;
            decimal totalPriceAfterTax = totalPrice + taxForAllProducts;

            billedShopppingItems.Add(new BilledShopppingItem(shoppingItem, taxForAllProducts,
                totalPriceAfterTax));

            totalTaxForCart += taxForAllProducts;
            totalBilledAmount += totalPriceAfterTax;
        }
        return new Reciept(billedShopppingItems, totalBilledAmount, totalTaxForCart);
    }

    public ITaxProcessor SalesTaxProcessor { get; }
}

public class ShoppingItem
{
    public ShoppingItem(IProduct product, int quantity)
    {
        Product = product;
        Quantity = quantity;
    }

    public IProduct Product { get; }
    public int Quantity { get; }
}

public class Product : IProduct
{
    public Product(string name, decimal price, bool isImport, ItemTypes itemType)
    {
        Name = name;
        Price = price;
        IsImport = isImport;
        ItemType = itemType;
    }

    public string Name { get; }
    public decimal Price { get; }
    public bool IsImport { get; }
    public ItemTypes ItemType { get; }
}

public class BilledShopppingItem
{
    public BilledShopppingItem(ShoppingItem shoppingItem, decimal tax, decimal totalPrice)
    {
        ShoppingItem = shoppingItem;
        Tax = tax;
        TotalPrice = totalPrice;
    }

    public ShoppingItem ShoppingItem { get; }
    public decimal Tax { get; }
    public decimal TotalPrice { get; }
}

public class Reciept
{
    public Reciept(List<BilledShopppingItem> processedShoppingCart, decimal totalBillAmount, decimal totalSalesTax)
    {
        ProcessedShoppingCart = processedShoppingCart;
        TotalBillAmount = totalBillAmount;
        TotalSalesTax = totalSalesTax;
    }

    public void PrintBill()
    {
        foreach (var processedItem in ProcessedShoppingCart)
        {
            Console.WriteLine($"{processedItem.ShoppingItem.Product.Name} { processedItem.TotalPrice }");
        }
        Console.WriteLine($"Sales Taxes {TotalSalesTax}");
        Console.WriteLine($"Total {TotalBillAmount}");
    }
    public List<BilledShopppingItem> ProcessedShoppingCart { get; }
    public decimal TotalBillAmount { get; }
    public decimal TotalSalesTax { get; }
}

[Flags]
public enum ItemTypes
{
    None = 0,
    Book = 1 << 0,
    Food = 1 << 1,
    Medical = 1 << 2,
    Others = 1 << 3,
    SalesTaxEmptedItemTypes = Book | Food | Medical
}