using System;

using System.Collections.Generic;

using System.Linq;

​

namespace Main

{

    public class Program

    {

        public static void Main()

        {

            List<IYourEntity> lstYourEntitiesModifiedSince = GetAllModifiedSince(DateTime.UtcNow);

            foreach (var item in lstYourEntitiesModifiedSince)

            {

                var myItem = item as YourEntity1;

                Console.WriteLine(string.Format("{0}: {1}", myItem.Id, myItem.YourEntityName));

            }

            List<EntityAdapter<IYourEntity, IMyEntity>> lstMyEntitiesModifiedSince = lstYourEntitiesModifiedSince.ToEntityAdapterList();

            foreach (var item in lstMyEntitiesModifiedSince)

            {

                var myItem = item.CastToMyEntityType() as MyEntity1;

                Console.WriteLine(string.Format("{0}: {1}", myItem.Id, myItem.MyEntityName));

            }

        }

​

        public static List<IYourEntity> GetAllModifiedSince(DateTime modifiedSince)

        {

            List<IYourEntity> yourEntityList = new List<IYourEntity>();

            yourEntityList.Add(new YourEntity1()

            {Id = 1, YourEntityName = "Charlie"});

            yourEntityList.Add(new YourEntity1()

            {Id = 2, YourEntityName = "Sarah"});

            return yourEntityList as List<IYourEntity>;

        }

    }

}

​

public interface IYourEntity

{

    int Id

    {

        get;

        set;

    }

}

​

public class YourEntity1 : IYourEntity

{

    public int Id

    {

        get;

        set;

    }

​

    public string YourEntityName

    {

        get;

        set;

    }

}

​

public interface IMyEntity

{

    int Id

    {

        get;

        set;

    }

​

    DateTime CreatedOn

    {

        get;

        set;

    }

}

​

public class MyEntity1 : IMyEntity

{

    public int Id

    {

        get;

        set;

    }

​

    public string MyEntityName

    {

        get;

        set;

    }

​

    public DateTime CreatedOn

    {

        get;

        set;

    }

}

​

public interface IMyEntityConverter

{

    IMyEntity Convert(IYourEntity yourEntity);

}

​

public class MyEntity1Converter : IMyEntityConverter

{

    public IMyEntity Convert(IYourEntity yourEntity) 

    {

        var castedYourEntity = yourEntity as YourEntity1;

        return new MyEntity1() 

        {

            Id = castedYourEntity.Id, 

            MyEntityName = castedYourEntity.YourEntityName, 

            CreatedOn = DateTime.UtcNow

        };

    }

}

​

public class EntityAdapter<YourType, MyType>

    where YourType : IYourEntity

    where MyType : IMyEntity

{

    protected YourType wrappedEntity;

    protected IMyEntityConverter converter;

    public EntityAdapter(YourType wrappedEntity, IMyEntityConverter converter) 

    {

        this.wrappedEntity = wrappedEntity;

        this.converter = converter;

    }

    public static implicit operator YourType(EntityAdapter<YourType, MyType> entityAdapter) => entityAdapter.wrappedEntity;

    public static explicit operator MyType(EntityAdapter<YourType, MyType> entityAdapter) => 

        (MyType) entityAdapter.converter.Convert(entityAdapter.wrappedEntity);

    public MyType CastToMyEntityType()

    {

        return (MyType) this;

    }

}

​

public static class EntityAdapterExtensions

{

    public static List<IMyEntity> ToIMyEntityList(this List<EntityAdapter<IYourEntity, IMyEntity>> lstEntityAdapters)

    {

        return lstEntityAdapters.ConvertAll(e => e.CastToMyEntityType());

    }

    public static List<EntityAdapter<IYourEntity, IMyEntity>> ToEntityAdapterList(this List<IYourEntity> lstYourEntities)

    {

        return lstYourEntities.Select(e => 

        {                    

            switch (e)

            {

                case YourEntity1 yourEntity1:

                    return new EntityAdapter<IYourEntity, IMyEntity>(yourEntity1, new MyEntity1Converter());

                default:

                    throw new NotSupportedException("You forgot to map " + e.GetType());

            }

        }).ToList();

    }

}