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EDIT: Answer for: BCdotWEB

- About the using statements, my bad that I copied it from the temporary repo for code review. In my real solution I have more dlls and they have other namespaces - About splitting by "type". If I understood correctly, you mean entities, enums, events. I've taken it from this repo CleanArchitecture , but I probably misunderstood something. - "SaveDeliveryset" name for method is redundant I agree, it was previous in bigger interface and I forgot refactor it - For getVersionInfo it is probably very bad naming, but as you see I have a problem with that for the whole project - About "IsAllAreEqual" same I forgot to refactor it, because previously I looked for all changes not for every change. Thanks for pointing that - do not call something a "xxxxxxxList". I know that is a bad thing, I will name a plural car, cars. But it is my mistake that I named the entity with plural.

About your last paragraph:

As you said I use DI and interfaces, because I have some unit tests for it. I am probably doing it so much, because of the Dependency Inversion definition. That I should not instantiate the implementation because it will probably break the Open/Close principle. I really try to stick with rules, but probably I understand them well in some small examples, but totally get lost in real big business scenario which means that I don't understand them :D

I know that this is a lot of classes and interfaces. But if it was putted in single method in single class it won't be so big. This also my concern if I am not split to much the code. I'm not asking for an in-depth review of the code and pointing out fixes in each class. Small tips on what to pay attention to and what I can improve in total approach will also very helpful.

I know that this is a lot of classes and interfaces. But if it was putted in single method in single class it won't be so big. This also my concern if I am not split to much the code.

Ps. I'm not asking for an in-depth review of the code and pointing out fixes in each class. Small tips on what to pay attention to and what I can improve in total approach will also very helpful.

public class DeliverysetSaverService : IDeliverysetSaverService
 {
 private readonly IApplicationDbContext _context;
 private readonly IDeliverysetVersionInfoByIdRetrieve _deliverysetVersionInfoByIdRetrieve;
 private readonly IAssetStatusMapRetriever _assetStatusMapRetriever;
 private readonly ILogger<DeliverysetSaverService> _logger;
 private readonly IDeliverysetService _deliverySetService;
 private readonly IValidator<Deliveryset> _deliverySetValidator;
 private readonly IDeliverysetFileChangesCoordinator _deliverySetFileChangesCoordinator;
 
 public DeliverysetSaverService(IApplicationDbContext context, IDeliverysetVersionInfoByIdRetrieve deliverysetVersionInfoByIdRetrieve, IAssetStatusMapRetriever assetStatusMapRetriever, ILogger<DeliverysetSaverService> logger, IDeliverysetService deliverySetService, IValidator<Deliveryset> deliverySetValidator, IDeliverysetFileChangesCoordinator deliverySetFileChangesCoordinator)
 {
 _context = context;
 _deliverysetVersionInfoByIdRetrieve = deliverysetVersionInfoByIdRetrieve;
 _assetStatusMapRetriever = assetStatusMapRetriever;
 _logger = logger;
 _deliverySetService = deliverySetService;
 _deliverySetValidator = deliverySetValidator;
 _deliverySetFileChangesCoordinator = deliverySetFileChangesCoordinator;
 }
 
 public async Task<bool> SaveDeliveryset(Deliveryset? deliverySet, bool isDeletedFlag = false,
 CancellationToken cancellationToken = default)
 {
 if (deliverySet == null) return false;
 var validationResult = await _deliverySetValidator.ValidateAsync(deliverySet, cancellationToken);
 if (!validationResult.IsValid)
 {
 _logger.LogWarning("Deliveryset validation failed, reason: {reason}", validationResult.ToString());
 return false;
 }
 
 
 var id = new SomeIdValueObject(deliverySet.Tags.MhtId);
 
 var contentId = (await _context.Contents.SingleOrDefaultAsync(content =>
 content.ProductionNr == id.ProductionNr && content.ProgramNr == id.ProgramNr
 && content.Version == id.Version && content.Format == id.Format, cancellationToken: cancellationToken))?.Id;
 
 var (someTrafficId, _) = id;
 
 if (!contentId.HasValue)
 {
 _logger.LogWarning(
 "Content for id:{id} was not found when saving delivery set", someTrafficId);
 return false;
 }
 
 var deliverySetVersion =
 await _deliverysetVersionInfoByIdRetrieve.GetVersionInfo(contentId.Value, cancellationToken);
 
 var deliverySetChangesInfo = await _deliverySetFileChangesCoordinator.GetDeliverysetChangesInfo(deliverySetVersion, deliverySet, cancellationToken);
 if (!deliverySetChangesInfo.HasChanges)
 {
 return false;
 }
 
 var contentDeliveryset = new ContentDeliveryset
 {
 ContentDeliverysetMetadata = new ContentDeliverysetMetadata()
 {
 AssetStatusId = _assetStatusMapRetriever.GetAssetStatusMap()["some_code"].Id
 },
 Deliveryset = deliverySet,
 ContentId = contentId,
 Version = deliverySetVersion.NextVersion,
 DeliverysetId = deliverySet.Id,
 SubtitleFiles = deliverySetChangesInfo.SubtitleFiles.ToList(),
 VideoFiles = deliverySetChangesInfo.VideoFiles.ToList(),
 IsDeleted = isDeletedFlag
 };
 
 await _deliverySetService.Save(contentDeliveryset, cancellationToken);
 return true;
 }
 }

public class DeliverysetFileChangesCoordinator : IDeliverysetFileChangesCoordinator
{
 private readonly IApplicationDbContext _context;
 private readonly IDeliverysetFileCopyHandlerFactory _deliverySetFileCopyHandlerFactory;
 private readonly IDeliverysetFileDetectChangesHandlerFactory _detectChangesHandlerFactory;
 private IEnumerable<VideoFiles> _videoFiles = Array.Empty<VideoFiles>();
 private IEnumerable<SubtitleFiles> _subtitleFiles = Array.Empty<SubtitleFiles>();
 private bool _anyChanges;
 public DeliverysetFileChangesCoordinator(IApplicationDbContext context, IDeliverysetFileCopyHandlerFactory deliverySetFileCopyHandlerFactory, IDeliverysetFileDetectChangesHandlerFactory detectChangesHandlerFactory)
 {
 _context = context;
 _deliverySetFileCopyHandlerFactory = deliverySetFileCopyHandlerFactory;
 _detectChangesHandlerFactory = detectChangesHandlerFactory;
 }
 public async Task<DeliverysetChangesInfo> GetDeliverysetChangesInfo(DeliverysetVersionInfo deliverySetVersionInfo, Deliveryset newDeliveryset, CancellationToken cancellationToken = default)
 {
 if (deliverySetVersionInfo.CurrentVersion == null)
 {
 return new DeliverysetChangesInfo(true, Array.Empty<VideoFiles>(), Array.Empty<SubtitleFiles>());
 }
 var currentNewestDeliveryset =
 await _context.ContentDeliveryset.AsNoTracking().Where(d => d.Id == deliverySetVersionInfo.CurrentVersion.Id)
 .Select(t => new
 {
 t.Deliveryset,
 t.VideoFiles,
 t.SubtitleFiles,
 t.Version
 }).SingleAsync(cancellationToken: cancellationToken);
 foreach (var deliverySetChange in Enum.GetValues<DeliverysetChange>())
 {
 var changesHandler = _detectChangesHandlerFactory.GetDeliverysetFileCopyHandler(deliverySetChange);
 var changesResult = changesHandler.GetDeliverysetChangesResult(currentNewestDeliveryset.Deliveryset, newDeliveryset);
 if (!changesResult.IsAllAreEqual)
 {
 _anyChanges = true;
 }
 if (changesResult.IsAllAreEqual && deliverySetChange == DeliverysetChange.Video)
 {
 var copyHandler = _deliverySetFileCopyHandlerFactory.GetDeliverysetFileCopyHandler<VideoFiles>(DeliverysetFileCopyHandler.Video);
 _videoFiles = copyHandler.GetFilesToCopy(currentNewestDeliveryset.VideoFiles);
 }
 if (deliverySetChange == DeliverysetChange.Subtitle)
 _subtitleFiles = GetSubtitlesToCopy(changesResult, currentNewestDeliveryset.SubtitleFiles);
 }
 return new DeliverysetChangesInfo(_anyChanges, _videoFiles, _subtitleFiles);
 }
 private IEnumerable<SubtitleFiles> GetSubtitlesToCopy(DeliverysetChangesResult changesResult, List<SubtitleFiles> currentDeliverysetSubFiles)
 {
 var copy = _deliverySetFileCopyHandlerFactory.GetDeliverysetFileCopyHandler<SubtitleFiles>(DeliverysetFileCopyHandler.Sub);
 bool FilterNotChangedSubtitleTypes(SubtitleFiles t) => changesResult.NotChangedByKeyList.Contains(t.SubtitleType);
 var subtitleFilesList = changesResult.IsAllAreEqual
 ? currentDeliverysetSubFiles
 : currentDeliverysetSubFiles.Where(FilterNotChangedSubtitleTypes).ToList();
 var subtitleFilesEnumerable = copy.GetFilesToCopy(subtitleFilesList);
 return subtitleFilesEnumerable;
 }
}

public class DeliverysetFileDetectChangesHandlerFactory : IDeliverysetFileDetectChangesHandlerFactory
{
 private readonly IDictionary<DeliverysetChange, IDeliverysetFileDetectChangesHandler> _map;
 public DeliverysetFileDetectChangesHandlerFactory(IDictionary<DeliverysetChange, IDeliverysetFileDetectChangesHandler> map)
 {
 _map = map;
 }
 public IDeliverysetFileDetectChangesHandler GetDeliverysetFileCopyHandler(DeliverysetChange deliverySetChange)
 {
 return _map[deliverySetChange];
 }
}

Interface IDeliverysetFileDetectChangesHandler:

public interface IDeliverysetFileDetectChangesHandler
{
 DeliverysetChangesResult GetDeliverysetChangesResult(Deliveryset currentDeliveryset, Deliveryset newDeliveryset);
}

public class DeliverysetAssetsDetectChangesHandler : IDeliverysetFileDetectChangesHandler
{
 public DeliverysetChangesResult GetDeliverysetChangesResult(Deliveryset currentDeliveryset, Deliveryset newDeliveryset)
 {
 return DeliverysetComparer.Init(newDeliveryset, currentDeliveryset).AssetsChanges();
 }
}

public class DeliverysetFileCopyHandlerFactory : IDeliverysetFileCopyHandlerFactory
{
 private readonly IDictionary<DeliverysetFileCopyHandler, IDeliverysetFileCopyHandler> _map;
 public DeliverysetFileCopyHandlerFactory(IDictionary<DeliverysetFileCopyHandler, IDeliverysetFileCopyHandler> map)
 {
 _map = map;
 }
 public IDeliverysetFileCopyHandler<T> GetDeliverysetFileCopyHandler<T>(DeliverysetFileCopyHandler copyMethod) where T : IFileEntity
 {
 var deliverySetFileCopyHandler = _map[copyMethod];
 return (IDeliverysetFileCopyHandler<T>)deliverySetFileCopyHandler;
 }
}

Interfaces IDeliverysetFileCopyHandler:

public interface IDeliverysetFileCopyHandler
{
}
public interface IDeliverysetFileCopyHandler<T> : IDeliverysetFileCopyHandler where T : IFileEntity
{
 IEnumerable<T> GetFilesToCopy(List<T> entities);
}

public class DeliverysetSubtitleFilesCopyHandler : IDeliverysetFileCopyHandler<SubtitleFiles>
{
 public IEnumerable<SubtitleFiles> GetFilesToCopy(List<SubtitleFiles>? entities)
 {
 if (entities == null) yield break;
 foreach (var entity in entities)
 {
 yield return new SubtitleFiles()
 {
 FileId = entity.FileId,
 Status = entity.Status,
 SubtitleType = entity.SubtitleType
 };
 }
 }
}

 public static class ConfigureServices
 {
 public static IServiceCollection AddLibraryServices(this IServiceCollection services)
 {
 var dummyConnString = "Server=127.0.0.1;Port=5432;Database=myDataBase;User Id=myUsername;Password=myPassword";
 services.AddDbContext<ApplicationDbContext>(options =>
 options.UseNpgsql(dummyConnString));
 services.AddValidatorsFromAssembly(Assembly.GetExecutingAssembly());
 services.AddScoped<IApplicationDbContext>(provider => provider.GetRequiredService<ApplicationDbContext>());
 services.AddScoped<AuditableEntitySaveChangesInterceptor>();
 services.AddDeliverysetServices();
 return services;
 }
 public static IServiceCollection AddDeliverysetServices(this IServiceCollection services)
 {
 services.AddScoped<IValidator<Deliveryset>, DeliverysetValidator>();
 services.AddScoped<IDeliverysetSaverService, DeliverysetSaverService>();
 services.AddScoped<IAssetStatusMapRetriever, AssetStatusMapRetriever>();
 services.AddScoped<IDeliverysetVersionInfoByIdRetrieve, DeliverysetVersionInfoByIdRetrieve>();
 services.AddScoped<IDeliverysetService, Services.DataServices.DeliverysetService>();
 services.AddScoped<IDeliverysetFileChangesCoordinator, DeliverysetFileChangesCoordinator>();
 services.AddSingleton<IDeliverysetFileCopyHandlerFactory, DeliverysetFileCopyHandlerFactory>(_ =>
 {
 var deliverySetFileCopyHandlers =
 new Dictionary<DeliverysetFileCopyHandler, IDeliverysetFileCopyHandler>
 {
 { DeliverysetFileCopyHandler.Video, new DeliverysetVideoFilesCopyHandler() },
 { DeliverysetFileCopyHandler.Sub, new DeliverysetSubtitleFilesCopyHandler() }
 };
 return new DeliverysetFileCopyHandlerFactory(deliverySetFileCopyHandlers);
 });
 services.AddSingleton<IDeliverysetFileDetectChangesHandlerFactory, DeliverysetFileDetectChangesHandlerFactory>(_ =>
 {
 var deliverySetFileDetectChangesHandlers =
 new Dictionary<DeliverysetChange, IDeliverysetFileDetectChangesHandler>
 {
 { DeliverysetChange.Video, new DeliverysetVideoFilesDetectChangesHandler() },
 { DeliverysetChange.Asset, new DeliverysetAssetsDetectChangesHandler() },
 { DeliverysetChange.Subtitle, new DeliverysetSubtitleFilesDetectChangesHandler() }
 };
 return new DeliverysetFileDetectChangesHandlerFactory(deliverySetFileDetectChangesHandlers);
 });
 return services;
 }
 }
}

using DeliverysetService.Library.Models.ValueObjects;
using DeliverysetService.Library.Persistence;
using DeliverysetService.Library.Persistence.Models;
using DeliverysetService.Library.Persistence.Models.Json;
using DeliverysetService.Library.Services;
using DeliverysetService.Library.Services.ChangesCoordinator;
using DeliverysetService.Library.Services.DataServices;
using FluentValidation;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
public class DeliverysetSaverService : IDeliverysetSaverService
 {
 private readonly IApplicationDbContext _context;
 private readonly IDeliverysetVersionInfoByIdRetrieve _deliverysetVersionInfoByIdRetrieve;
 private readonly IAssetStatusMapRetriever _assetStatusMapRetriever;
 private readonly ILogger<DeliverysetSaverService> _logger;
 private readonly IDeliverysetService _deliverySetService;
 private readonly IValidator<Deliveryset> _deliverySetValidator;
 private readonly IDeliverysetFileChangesCoordinator _deliverySetFileChangesCoordinator;
 
 public DeliverysetSaverService(IApplicationDbContext context, IDeliverysetVersionInfoByIdRetrieve deliverysetVersionInfoByIdRetrieve, IAssetStatusMapRetriever assetStatusMapRetriever, ILogger<DeliverysetSaverService> logger, IDeliverysetService deliverySetService, IValidator<Deliveryset> deliverySetValidator, IDeliverysetFileChangesCoordinator deliverySetFileChangesCoordinator)
 {
 _context = context;
 _deliverysetVersionInfoByIdRetrieve = deliverysetVersionInfoByIdRetrieve;
 _assetStatusMapRetriever = assetStatusMapRetriever;
 _logger = logger;
 _deliverySetService = deliverySetService;
 _deliverySetValidator = deliverySetValidator;
 _deliverySetFileChangesCoordinator = deliverySetFileChangesCoordinator;
 }
 
 public async Task<bool> SaveDeliveryset(Deliveryset? deliverySet, bool isDeletedFlag = false,
 CancellationToken cancellationToken = default)
 {
 if (deliverySet == null) return false;
 var validationResult = await _deliverySetValidator.ValidateAsync(deliverySet, cancellationToken);
 if (!validationResult.IsValid)
 {
 _logger.LogWarning("Deliveryset validation failed, reason: {reason}", validationResult.ToString());
 return false;
 }
 
 
 var id = new SomeIdValueObject(deliverySet.Tags.MhtId);
 
 var contentId = (await _context.Contents.SingleOrDefaultAsync(content =>
 content.ProductionNr == id.ProductionNr && content.ProgramNr == id.ProgramNr
 && content.Version == id.Version && content.Format == id.Format, cancellationToken: cancellationToken))?.Id;
 
 var (someTrafficId, _) = id;
 
 if (!contentId.HasValue)
 {
 _logger.LogWarning(
 "Content for id:{id} was not found when saving delivery set", someTrafficId);
 return false;
 }
 
 var deliverySetVersion =
 await _deliverysetVersionInfoByIdRetrieve.GetVersionInfo(contentId.Value, cancellationToken);
 
 var deliverySetChangesInfo = await _deliverySetFileChangesCoordinator.GetDeliverysetChangesInfo(deliverySetVersion, deliverySet, cancellationToken);
 if (!deliverySetChangesInfo.HasChanges)
 {
 return false;
 }
 
 var contentDeliveryset = new ContentDeliveryset
 {
 ContentDeliverysetMetadata = new ContentDeliverysetMetadata()
 {
 AssetStatusId = _assetStatusMapRetriever.GetAssetStatusMap()["some_code"].Id
 },
 Deliveryset = deliverySet,
 ContentId = contentId,
 Version = deliverySetVersion.NextVersion,
 DeliverysetId = deliverySet.Id,
 SubtitleFiles = deliverySetChangesInfo.SubtitleFiles.ToList(),
 VideoFiles = deliverySetChangesInfo.VideoFiles.ToList(),
 IsDeleted = isDeletedFlag
 };
 
 await _deliverySetService.Save(contentDeliveryset, cancellationToken);
 return true;
 }
 }

using DeliverysetService.Library.Enums;
using DeliverysetService.Library.Models;
using DeliverysetService.Library.Persistence;
using DeliverysetService.Library.Persistence.Models;
using DeliverysetService.Library.Persistence.Models.Json;
using DeliverysetService.Library.Services.DeliverysetFileCopyHandlerStrategy;
using DeliverysetService.Library.Services.DeliverysetFileDetectChangesHandlerStrategy;
using Microsoft.EntityFrameworkCore;
public class DeliverysetFileChangesCoordinator : IDeliverysetFileChangesCoordinator
{
 private readonly IApplicationDbContext _context;
 private readonly IDeliverysetFileCopyHandlerFactory _deliverySetFileCopyHandlerFactory;
 private readonly IDeliverysetFileDetectChangesHandlerFactory _detectChangesHandlerFactory;
 private IEnumerable<VideoFiles> _videoFiles = Array.Empty<VideoFiles>();
 private IEnumerable<SubtitleFiles> _subtitleFiles = Array.Empty<SubtitleFiles>();
 private bool _anyChanges;

 public DeliverysetFileChangesCoordinator(IApplicationDbContext context, IDeliverysetFileCopyHandlerFactory deliverySetFileCopyHandlerFactory, IDeliverysetFileDetectChangesHandlerFactory detectChangesHandlerFactory)
 {
 _context = context;
 _deliverySetFileCopyHandlerFactory = deliverySetFileCopyHandlerFactory;
 _detectChangesHandlerFactory = detectChangesHandlerFactory;
 }
 public async Task<DeliverysetChangesInfo> GetDeliverysetChangesInfo(DeliverysetVersionInfo deliverySetVersionInfo, Deliveryset newDeliveryset, CancellationToken cancellationToken = default)
 {
 if (deliverySetVersionInfo.CurrentVersion == null)
 {
 return new DeliverysetChangesInfo(true, Array.Empty<VideoFiles>(), Array.Empty<SubtitleFiles>());
 }
 var currentNewestDeliveryset =
 await _context.ContentDeliveryset.AsNoTracking().Where(d => d.Id == deliverySetVersionInfo.CurrentVersion.Id)
 .Select(t => new
 {
 t.Deliveryset,
 t.VideoFiles,
 t.SubtitleFiles,
 t.Version
 }).SingleAsync(cancellationToken: cancellationToken);




 foreach (var deliverySetChange in Enum.GetValues<DeliverysetChange>())
 {
 var changesHandler = _detectChangesHandlerFactory.GetDeliverysetFileCopyHandler(deliverySetChange);
 var changesResult = changesHandler.GetDeliverysetChangesResult(currentNewestDeliveryset.Deliveryset, newDeliveryset);

 if (!changesResult.IsAllAreEqual)
 {
 _anyChanges = true;
 }
 if (changesResult.IsAllAreEqual && deliverySetChange == DeliverysetChange.Video)
 {
 var copyHandler = _deliverySetFileCopyHandlerFactory.GetDeliverysetFileCopyHandler<VideoFiles>(DeliverysetFileCopyHandler.Video);
 _videoFiles = copyHandler.GetFilesToCopy(currentNewestDeliveryset.VideoFiles);
 }

 if (deliverySetChange == DeliverysetChange.Subtitle)
 _subtitleFiles = GetSubtitlesToCopy(changesResult, currentNewestDeliveryset.SubtitleFiles);
 }

 return new DeliverysetChangesInfo(_anyChanges, _videoFiles, _subtitleFiles);
 }



 private IEnumerable<SubtitleFiles> GetSubtitlesToCopy(DeliverysetChangesResult changesResult, List<SubtitleFiles> currentDeliverysetSubFiles)
 {
 var copy = _deliverySetFileCopyHandlerFactory.GetDeliverysetFileCopyHandler<SubtitleFiles>(DeliverysetFileCopyHandler.Sub);

 bool FilterNotChangedSubtitleTypes(SubtitleFiles t) => changesResult.NotChangedByKeyList.Contains(t.SubtitleType);

 var subtitleFilesList = changesResult.IsAllAreEqual
 ? currentDeliverysetSubFiles
 : currentDeliverysetSubFiles.Where(FilterNotChangedSubtitleTypes).ToList();

 var subtitleFilesEnumerable = copy.GetFilesToCopy(subtitleFilesList);
 return subtitleFilesEnumerable;
 }
}

using DeliverysetService.Library.Enums;
 public class DeliverysetFileDetectChangesHandlerFactory : IDeliverysetFileDetectChangesHandlerFactory
{
 private readonly IDictionary<DeliverysetChange, IDeliverysetFileDetectChangesHandler> _map;

 public DeliverysetFileDetectChangesHandlerFactory(IDictionary<DeliverysetChange, IDeliverysetFileDetectChangesHandler> map)
 {
 _map = map;
 }

 public IDeliverysetFileDetectChangesHandler GetDeliverysetFileCopyHandler(DeliverysetChange deliverySetChange)
 {
 return _map[deliverySetChange];
 }
}

Interface IDeliverysetFileDetectChangesHandler:

using DeliverysetService.Library.Models;
using DeliverysetService.Library.Persistence.Models.Json;
 public interface IDeliverysetFileDetectChangesHandler
{
 DeliverysetChangesResult GetDeliverysetChangesResult(Deliveryset currentDeliveryset, Deliveryset newDeliveryset);
}

using DeliverysetService.Library.Models;
using DeliverysetService.Library.Persistence.Models.Json;
using DeliverysetService.Library.Services.Comparers;
 public class DeliverysetAssetsDetectChangesHandler : IDeliverysetFileDetectChangesHandler
{
 public DeliverysetChangesResult GetDeliverysetChangesResult(Deliveryset currentDeliveryset, Deliveryset newDeliveryset)
 {
 return DeliverysetComparer.Init(newDeliveryset, currentDeliveryset).AssetsChanges();
 }
}

using DeliverysetService.Library.Enums;
using DeliverysetService.Library.Persistence.Models.Common.Interfaces;
 public class DeliverysetFileCopyHandlerFactory : IDeliverysetFileCopyHandlerFactory
{
 private readonly IDictionary<DeliverysetFileCopyHandler, IDeliverysetFileCopyHandler> _map;

 public DeliverysetFileCopyHandlerFactory(IDictionary<DeliverysetFileCopyHandler, IDeliverysetFileCopyHandler> map)
 {
 _map = map;
 }

 public IDeliverysetFileCopyHandler<T> GetDeliverysetFileCopyHandler<T>(DeliverysetFileCopyHandler copyMethod) where T : IFileEntity
 {
 var deliverySetFileCopyHandler = _map[copyMethod];
 return (IDeliverysetFileCopyHandler<T>)deliverySetFileCopyHandler;
 }
}

Interface IDeliverysetFileCopyHandler:

using DeliverysetService.Library.Persistence.Models.Common.Interfaces;
 public interface IDeliverysetFileCopyHandler
{
}
public interface IDeliverysetFileCopyHandler<T> : IDeliverysetFileCopyHandler where T : IFileEntity
{
 IEnumerable<T> GetFilesToCopy(List<T> entities);
}

using DeliverysetService.Library.Persistence.Models;
 public class DeliverysetSubtitleFilesCopyHandler : IDeliverysetFileCopyHandler<SubtitleFiles>
{
 public IEnumerable<SubtitleFiles> GetFilesToCopy(List<SubtitleFiles>? entities)
 {
 if (entities == null) yield break;

 foreach (var entity in entities)
 {
 yield return new SubtitleFiles()
 {
 FileId = entity.FileId,
 Status = entity.Status,
 SubtitleType = entity.SubtitleType
 };
 }
 }
}

using DeliverysetService.Library.Enums;
using DeliverysetService.Library.Persistence.Models.Json;
using DeliverysetService.Library.Validators;
using FluentValidation;
using Microsoft.Extensions.DependencyInjection;
using System.Reflection;
using DeliverysetService.Library.Persistence;
using DeliverysetService.Library.Services.DataServices;
using Microsoft.EntityFrameworkCore;
using DeliverysetService.Library.Services.DeliverysetFileCopyHandlerStrategy;
using DeliverysetService.Library.Services.DeliverysetFileDetectChangesHandlerStrategy;
using DeliverysetService.Library.Services.ChangesCoordinator;
using DeliverysetService.Library.Services;
 public static class ConfigureServices
 {
 public static IServiceCollection AddLibraryServices(this IServiceCollection services)
 {
 var dummyConnString = "Server=127.0.0.1;Port=5432;Database=myDataBase;User Id=myUsername;Password=myPassword";

 services.AddDbContext<ApplicationDbContext>(options =>
 options.UseNpgsql(dummyConnString));
 services.AddValidatorsFromAssembly(Assembly.GetExecutingAssembly());
 services.AddScoped<IApplicationDbContext>(provider => provider.GetRequiredService<ApplicationDbContext>());
 services.AddScoped<AuditableEntitySaveChangesInterceptor>();

 services.AddDeliverysetServices();


 return services;
 }
 public static IServiceCollection AddDeliverysetServices(this IServiceCollection services)
 {
 services.AddScoped<IValidator<Deliveryset>, DeliverysetValidator>();
 services.AddScoped<IDeliverysetSaverService, DeliverysetSaverService>();
 services.AddScoped<IAssetStatusMapRetriever, AssetStatusMapRetriever>();
 services.AddScoped<IDeliverysetVersionInfoByIdRetrieve, DeliverysetVersionInfoByIdRetrieve>();
 services.AddScoped<IDeliverysetService, Services.DataServices.DeliverysetService>();
 services.AddScoped<IDeliverysetFileChangesCoordinator, DeliverysetFileChangesCoordinator>();
 services.AddSingleton<IDeliverysetFileCopyHandlerFactory, DeliverysetFileCopyHandlerFactory>(_ =>
 {
 var deliverySetFileCopyHandlers =
 new Dictionary<DeliverysetFileCopyHandler, IDeliverysetFileCopyHandler>
 {
 { DeliverysetFileCopyHandler.Video, new DeliverysetVideoFilesCopyHandler() },
 { DeliverysetFileCopyHandler.Sub, new DeliverysetSubtitleFilesCopyHandler() }
 };
 return new DeliverysetFileCopyHandlerFactory(deliverySetFileCopyHandlers);
 });
 services.AddSingleton<IDeliverysetFileDetectChangesHandlerFactory, DeliverysetFileDetectChangesHandlerFactory>(_ =>
 {
 var deliverySetFileDetectChangesHandlers =
 new Dictionary<DeliverysetChange, IDeliverysetFileDetectChangesHandler>
 {
 { DeliverysetChange.Video, new DeliverysetVideoFilesDetectChangesHandler() },
 { DeliverysetChange.Asset, new DeliverysetAssetsDetectChangesHandler() },
 { DeliverysetChange.Subtitle, new DeliverysetSubtitleFilesDetectChangesHandler() }
 };
 return new DeliverysetFileDetectChangesHandlerFactory(deliverySetFileDetectChangesHandlers);
 });
 return services;
 }
 }
}