Design-Patterns/patterns/decorator/IceCreamDecorations/Program.cs

public interface IIceCream
{
   void Prepare();
   decimal GetPrice();
}

public class ChocolateIceCream : IIceCream
{
   public void Prepare()
   {
      Console.WriteLine("Preparing a chocolate ice cream.");
   }

   public decimal GetPrice()
   {
      return 2.50m; // base price for chocolate ice cream
   }
}

public class VanillaIceCream : IIceCream
{
   public void Prepare()
   {
      Console.WriteLine("Preparing a vanilla ice cream.");
   }

   public decimal GetPrice()
   {
      return 2.00m; // base price for vanilla ice cream
   }
}

public abstract class IceCreamDecorator(IIceCream decorated) : IIceCream
{
   protected IIceCream _decorated = decorated;
   public abstract void Prepare();
   public abstract decimal GetPrice();
}

public class SprinkleDecorator(IIceCream decorated)
   : IceCreamDecorator(decorated)
{
   public override void Prepare()
   {
      // call the base first
      _decorated.Prepare();
      Console.WriteLine("Adding sprinkles!");
   }

   public override decimal GetPrice()
   {
      return _decorated.GetPrice() + 0.50m; // add price for sprinkles
   }
}

public class ChocolateSyrupDecorator(IIceCream decorated)
   : IceCreamDecorator(decorated)
{
   public override void Prepare()
   {
      // call the base prepare first
      _decorated.Prepare();
      Console.WriteLine("Adding chocolate syrup!");
   }

   public override decimal GetPrice()
   {
      return _decorated.GetPrice() + 0.75m; // add price for chocolate syrup
   }
}

public class CaramelSyrupDecorator(IIceCream decorated)
   : IceCreamDecorator(decorated)
{
   public override void Prepare()
   {
      // call the base prepare first
      _decorated.Prepare();
      Console.WriteLine("Adding caramel syrup!");
   }

   public override decimal GetPrice()
   {
      return _decorated.GetPrice() + 0.75m; // add price for caramel syrup
   }
}

internal class Program
{
   static void Main(string[] args)
   {
      decimal price = new CaramelSyrupDecorator(
         new ChocolateSyrupDecorator(
            new SprinkleDecorator(
                new ChocolateIceCream()
                )
         )
      ).GetPrice();

      Console.WriteLine($"Total price: {price:C}");
   }
}