using System;

​

public static class Program

{

    public static void Main(string[] args)

    {

        var price = 100m;

        var dm = new DiscountManager(new DefaultAccountDiscountCalculatorFactory(), new DefaultLoyaltyDiscountCalculator());

        var newPrice = dm.ApplyDiscount(price, AccountStatus.MostValuableCustomer, 10);

        Console.WriteLine(newPrice);

        var dm2 = new DiscountManager(new DefaultAccountDiscountCalculatorFactory(), new SpecialLoyaltyDiscountCalculator());

        var newPrice2 = dm2.ApplyDiscount(price, AccountStatus.MostValuableCustomer, 10);

        Console.WriteLine(newPrice2);

    }

}

​

public class DiscountManager

{

  private readonly IAccountDiscountCalculatorFactory _factory;

  private readonly ILoyaltyDiscountCalculator _loyaltyDiscountCalculator;

  public DiscountManager(IAccountDiscountCalculatorFactory factory, ILoyaltyDiscountCalculator loyaltyDiscountCalculator)

  {

    _factory = factory;

    _loyaltyDiscountCalculator = loyaltyDiscountCalculator;

  }

  public decimal ApplyDiscount(decimal price, AccountStatus accountStatus, int timeOfHavingAccountInYears)

  {

    decimal priceAfterDiscount = 0;

    priceAfterDiscount = _factory.GetAccountDiscountCalculator(accountStatus).ApplyDiscount(price);

    priceAfterDiscount = _loyaltyDiscountCalculator.ApplyDiscount(priceAfterDiscount, timeOfHavingAccountInYears);

    return priceAfterDiscount;

  }

}

​

​

​

public interface ILoyaltyDiscountCalculator

{

  decimal ApplyDiscount(decimal price, int timeOfHavingAccountInYears);

}

public class DefaultLoyaltyDiscountCalculator : ILoyaltyDiscountCalculator

{

  public decimal ApplyDiscount(decimal price, int timeOfHavingAccountInYears)

  {

    decimal discountForLoyaltyInPercentage = (timeOfHavingAccountInYears > Constants.MAXIMUM_DISCOUNT_FOR_LOYALTY) ? (decimal)Constants.MAXIMUM_DISCOUNT_FOR_LOYALTY/100 : (decimal)timeOfHavingAccountInYears/100;

    return price - (discountForLoyaltyInPercentage * price);

  }

}

​

​

​

​

​

​

​

​

public class SpecialLoyaltyDiscountCalculator : ILoyaltyDiscountCalculator

{

    public decimal ApplyDiscount(decimal price, int timeOfHavingAccountInYears)

    {

        decimal discountForSpecialLoyaltyInPercentage = (timeOfHavingAccountInYears > Constants.MAXIMUM_DISCOUNT_FOR_SPECIAL_LOYALTY) ? (decimal)Constants.MAXIMUM_DISCOUNT_FOR_SPECIAL_LOYALTY/100 : (decimal)timeOfHavingAccountInYears/100;

        return price - (discountForSpecialLoyaltyInPercentage * price);

    }

}

​

​

​

​

​

​

​

​

​

public interface IAccountDiscountCalculatorFactory

{

  IAccountDiscountCalculator GetAccountDiscountCalculator(AccountStatus accountStatus);

}

public class DefaultAccountDiscountCalculatorFactory : IAccountDiscountCalculatorFactory

{

  public IAccountDiscountCalculator GetAccountDiscountCalculator(AccountStatus accountStatus)

  {

    IAccountDiscountCalculator calculator;

    switch (accountStatus)

    {

      case AccountStatus.NotRegistered:

        calculator = new NotRegisteredDiscountCalculator();

        break;

      case AccountStatus.SimpleCustomer:

        calculator = new SimpleCustomerDiscountCalculator();

        break;

      case AccountStatus.ValuableCustomer:

        calculator = new ValuableCustomerDiscountCalculator();

        break;

      case AccountStatus.MostValuableCustomer:

        calculator = new MostValuableCustomerDiscountCalculator();

        break;

      default:

        throw new NotImplementedException();

    }

    return calculator;

  }

}

​

public interface IAccountDiscountCalculator

{

  decimal ApplyDiscount(decimal price);

}

public class NotRegisteredDiscountCalculator : IAccountDiscountCalculator

{

  public decimal ApplyDiscount(decimal price)

  {

    return price;

  }

}

public class SimpleCustomerDiscountCalculator : IAccountDiscountCalculator

{

  public decimal ApplyDiscount(decimal price)

  {

    return price - (Constants.DISCOUNT_FOR_SIMPLE_CUSTOMERS * price);

  }

}

public class ValuableCustomerDiscountCalculator : IAccountDiscountCalculator

{

  public decimal ApplyDiscount(decimal price)

  {

    return price - (Constants.DISCOUNT_FOR_VALUABLE_CUSTOMERS * price);

  }

}

public class MostValuableCustomerDiscountCalculator : IAccountDiscountCalculator

{

  public decimal ApplyDiscount(decimal price)

  {

    return price - (Constants.DISCOUNT_FOR_MOST_VALUABLE_CUSTOMERS * price);

  }

}

​

public static class PriceExtensions

{

  public static decimal ApplyDiscountForAccountStatus(this decimal price, decimal discountSize)

  {

    return price - (discountSize * price);

  }

  public static decimal ApplyDiscountForTimeOfHavingAccount(this decimal price, int timeOfHavingAccountInYears)

  {

     decimal discountForLoyaltyInPercentage = (timeOfHavingAccountInYears > Constants.MAXIMUM_DISCOUNT_FOR_LOYALTY) ? (decimal)Constants.MAXIMUM_DISCOUNT_FOR_LOYALTY/100 : (decimal)timeOfHavingAccountInYears/100;

    return price - (discountForLoyaltyInPercentage * price);

  }

}

​

public static class Constants

{

  public const int MAXIMUM_DISCOUNT_FOR_LOYALTY = 5;

  public const decimal DISCOUNT_FOR_SIMPLE_CUSTOMERS = 0.1m;

  public const decimal DISCOUNT_FOR_VALUABLE_CUSTOMERS = 0.3m;

  public const decimal DISCOUNT_FOR_MOST_VALUABLE_CUSTOMERS = 0.5m;

    public const decimal MAXIMUM_DISCOUNT_FOR_SPECIAL_LOYALTY = 10;

}

​

public enum AccountStatus

{

  NotRegistered = 1,

  SimpleCustomer = 2,

  ValuableCustomer = 3,

  MostValuableCustomer = 4

}