using System;

public class Program

{

    public static void Main()

    {

        Pizza largePizza = new LargePizza();

        //largePizza = new Cheese(largePizza);

        //largePizza = new Ham(largePizza);

        largePizza = new Ham(largePizza);

        largePizza = new Cheese(largePizza);

        Console.WriteLine(largePizza.GetDescription());

        Console.WriteLine("{0:C2}", largePizza.CalculateCost());

    }

}

​

public abstract class Pizza

{

    public string Description { get; set; }

    public abstract string GetDescription();

    public abstract double CalculateCost();

}

​

public class SmallPizza : Pizza

{

    public SmallPizza()

    {

        Description = "Small Pizza";

    }

    public override string GetDescription()

    {

        return Description;

    }

    public override double CalculateCost()

    {

        return 3.00;

    }

}

public class LargePizza : Pizza

{

    public LargePizza()

    {

        Description = "Large Pizza";

    }

    public override string GetDescription()

    {

        return Description;

    }

    public override double CalculateCost()

    {

        return 9.00;

    }

}

​

public class PizzaDecorator : Pizza

{

    protected Pizza _pizza;

    public PizzaDecorator(Pizza pizza)

    {

        _pizza = pizza;

    }

    public override string GetDescription()

    {

        return _pizza.Description;

    }

    public override double CalculateCost()

    {

        return _pizza.CalculateCost();

    }

}

​

public class Peppers : PizzaDecorator

{

    public Peppers(Pizza pizza)

        : base(pizza)

        {

            Description = "Peppers";

        }

    public override string GetDescription()

    {

        return string.Format("{0}, {1}", _pizza.GetDescription(), Description);

    }

    public override double CalculateCost()

    {

        return _pizza.CalculateCost() + 2.00;

    }

}

​

public class Ham : PizzaDecorator

{

    public Ham(Pizza pizza)

        : base ( pizza)

        {

            Description = "Ham";

        }

    public override string GetDescription()

    {

        return string.Format("{0}, {1}", _pizza.GetDescription(), Description);

    }

    public override double CalculateCost()

    {

        return _pizza.CalculateCost() + 2.50;

    }

}

​

public class Cheese : PizzaDecorator

{

    public Cheese(Pizza pizza)

        : base(pizza)

        {

            Description = "Cheese";

        }

    public override string GetDescription()

    {

        return string.Format("{0}, {1}", _pizza.GetDescription(), Description);

    }

    public override double CalculateCost()

    {

        return base.CalculateCost() + 1.25;

    }

}