using System;

using Unity;

public class Program

{

    public static void Main()

    {

        // Container / Injector

        var container = new UnityContainer();

        container

            .RegisterSingleton<IDrinkMachine, DrinkMachine>()

            .RegisterSingleton<IDrinkFactory, CocoColaFactory>()

            .RegisterSingleton<IDrink, CocaCola>()

            // .RegisterSingleton<IDrinkFactory, PepsiFactory>()

            // .RegisterSingleton<IDrink, Pepsi>()

            .RegisterFactory<IDrinkFactory>(c => new CocoColaFactory(

                create: () => c.Resolve<IDrink>()

            ));

        IDrinkMachine drinkMachine = container.Resolve<IDrinkMachine>();

        IDrink drink = drinkMachine.DispenseDrink();

        Console.WriteLine(drink.Name);

    }

}

​

// Interface

public interface IDrinkMachine

{

    public IDrink DispenseDrink();

}

​

// Interface

public interface IDrinkFactory

{

  public IDrink Create();   

}

​

// Interface

public interface IDrink

{

    string Name { get; }

}

​

// Client 

public class DrinkMachine : IDrinkMachine

{

  private IDrinkFactory _drinkFactory;

​

  public DrinkMachine(IDrinkFactory drinkFactory)

  {

    _drinkFactory = drinkFactory;

  }

  public IDrink DispenseDrink()

  {

    return _drinkFactory.Create();

  }

}

​

// CocaColaFactory / Service / Dependency

public class CocoColaFactory : IDrinkFactory

{

  private Func<IDrink> _create;

  public CocoColaFactory(Func<IDrink> create)

  { 

    _create = create;

  }

​

  public IDrink Create () => _create();

}

​

public class CocaCola : IDrink

{

    public string Name

    {

        get => "Coca-Cola";

    }

}

​

// PepsiFactory / Service / Dependency

public class PepsiFactory : IDrinkFactory

{

  private Func<IDrink> _create;

  public PepsiFactory(Func<IDrink> create)

  { 

    _create = create;

  }

​

  public IDrink Create () => _create();

}

​

public class Pepsi : IDrink

{

    public string Name

    {

        get => "Pepsi";

    }

}

​