HuyProject.cs

	public class Huy
	{
		public int Id { get; }
		public string Name { get; set; }
		public long Length { get; set; }

		public Huy(int id, string name, long length)
		{
			Id = id;
			Name = name;
			Length = length;
		}
	}

	public interface IHuyRepository
	{
		Huy Get(int id);
		void Add(Huy createdHuy);
		void Modify(Huy modifiedHuy);
		void Delete(Huy deletedHuy);
	}

	public delegate void HuyCreatedHandler(Huy createdHuy);

	public delegate void HuyModifiedHandler(Huy modifiedHuy);

	public delegate void HuyDeletedHandler(Huy deletedHuy);

	public interface IHuyService
	{
		event HuyCreatedHandler HuyCreated;
		event HuyModifiedHandler HuyModified;
		event HuyDeletedHandler HuyDeleted;
	}

	public class HuyService : IHuyRepository, IHuyService
	{
		private readonly IHuyRepository _dectoratedRepository;

		public event HuyCreatedHandler HuyCreated = _ => { };
		public event HuyModifiedHandler HuyModified = _ => { };
		public event HuyDeletedHandler HuyDeleted = _ => { };

		public HuyService(IHuyRepository dectoratedRepository)
		{
			_dectoratedRepository = dectoratedRepository;
		}

		public Huy Get(int id) => _dectoratedRepository.Get(id);

		public void Add(Huy createdHuy)
		{
			_dectoratedRepository.Add(createdHuy);
			HuyCreated(createdHuy);
		}

		public void Modify(Huy modifiedHuy)
		{
			_dectoratedRepository.Modify(modifiedHuy);
			HuyModified(modifiedHuy);
		}

		public void Delete(Huy deletedHuy)
		{
			_dectoratedRepository.Delete(deletedHuy);
			HuyDeleted(deletedHuy);
		}
	}