//using FluentValidation;
//using Microsoft.Extensions.Logging;
//using System;
//using System.Collections.Concurrent;
//using System.Linq;
//using System.Linq.Expressions;
//using System.Threading.Tasks;
//using zero.Core.Entities;
//using zero.Core.Options;

//namespace zero.Core.Collections
//{
//  public class CollectionInterceptorHandler : ICollectionInterceptorHandler
//  {
//    protected ConcurrentDictionary<Type, object> Interceptors { get; private set; } = new();

//    protected IZeroOptions Options { get; set; }

//    protected IServiceProvider Services { get; set; }

//    protected ILogger<ICollectionInterceptorHandler> Logger { get; set; }


//    public CollectionInterceptorHandler(IZeroOptions options, IServiceProvider serviceProvider, ILogger<ICollectionInterceptorHandler> logger)
//    {
//      Logger = logger;
//      Options = options;
//      Services = serviceProvider;
//    }


//    /// <inheritdoc />
//    public InterceptorInstruction<T, TParameters> Create<T, TParameters>(string operationName, TParameters parameters)
//      where T : ZeroEntity
//      where TParameters : CollectionInterceptor<T>.Parameters
//    {
//      InterceptorInstruction<T, TParameters> instruction = new(parameters);
//      instruction.Operation = operationName;
//      instruction.BeforeOperationHandler = async expression => await HandleBefore(expression, instruction);
//      instruction.AfterOperationHandler = async expression => await HandleAfter(expression, instruction);

//      return instruction;
//    }



//    /// <summary>
//    /// Calls all matching interceptors with the specified expression
//    /// </summary>
//    internal async Task HandleBefore<T, TParameters>(Expression<Func<ICollectionInterceptor<T>, Task<InterceptorResult<T>>>> expression, InterceptorInstruction<T, TParameters> instruction)
//      where T : ZeroEntity
//      where TParameters : CollectionInterceptor<T>.Parameters
//    {
//      string typeName = (typeof(T)).Name;
//      Func<ICollectionInterceptor<T>, Task<InterceptorResult<T>>> func = default;

//      foreach (InterceptorRegistration registration in ForType(typeof(T)))
//      {
//        if (!TryResolve(registration, out ICollectionInterceptor<T> interceptor))
//        {
//          continue;
//        }

//        if (!interceptor.CanRun(instruction.Parameters))
//        {
//          continue;
//        }

//        if (func == default)
//        {
//          func = expression.Compile();
//        }

//        // we do not log save operations as they are always called for update/create which are already logged beforehand
//        if (instruction.Operation != "save")
//        {
//          Logger.LogDebug("Run interceptor {interceptor} for {type}:{operation}", registration.Name, typeName, instruction.Operation);
//        }

//        InterceptorResult<T> result = await func(interceptor);

//        if (result == default)
//        {
//          result = new();
//        }

//        result.InterceptorHash = registration.Hash;
//        instruction.Results.Add(result);

//        if (result.Result != null)
//        {
//          instruction.EntityResult = result.Result;
//          break;
//        }
//        if (result.Prevent)
//        {
//          break;
//        }
//      }
//    }



//    /// <summary>
//    /// Calls all matching interceptors with the specified expression
//    /// </summary>
//    internal async Task HandleAfter<T, TParameters>(Expression<Func<ICollectionInterceptor<T>, Task>> expression, InterceptorInstruction<T, TParameters> instruction)
//      where T : ZeroEntity
//      where TParameters : CollectionInterceptor<T>.Parameters
//    {
//      Func<ICollectionInterceptor<T>, Task> func = default;
//      instruction ??= new();

//      foreach (InterceptorRegistration registration in ForType(typeof(T)))
//      {
//        if (!TryResolve(registration, out ICollectionInterceptor<T> interceptor))
//        {
//          continue;
//        }

//        if (!interceptor.CanRun(instruction.Parameters))
//        {
//          continue;
//        }

//        InterceptorResult<T> beforeResult = instruction?.Results.FirstOrDefault(res => res.InterceptorHash == registration.Hash);

//        if (func == default)
//        {
//          func = expression.Compile();
//        }

//        await func(interceptor);
//      }
//    }


//    /// <summary>
//    /// Get all interceptors for a certain type
//    /// </summary>
//    IOrderedEnumerable<InterceptorRegistration> ForType(Type targetType)
//    {
//      return Options.Interceptors.GetAllItems().Where(x => x.CanHandle(targetType)).OrderByDescending(x => x.Gravity);
//     // return Interceptors.Where(item => item.Types.Count == 0 || item.Types.Any(type => targetType.IsAssignableFrom(type)));
//    }


//    /// <summary>
//    /// Resolves an interceptor from the service provider
//    /// </summary>
//    bool TryResolve<T>(InterceptorRegistration registration, out ICollectionInterceptor<T> interceptor) where T : ZeroEntity
//    {
//      Type type = registration.InterceptorType;

//      if (Interceptors.TryGetValue(type, out object interceptorObj))
//      {
//        interceptor = interceptorObj as ICollectionInterceptor<T>;
//        return interceptor != null;
//      }

//      object service = Services.GetService(type);
//      interceptor = service as ICollectionInterceptor<T>;

//      if (interceptor == null && service != null && service is ICollectionInterceptor)
//      {
//        interceptor = new CollectionInterceptorShim<T>(service as ICollectionInterceptor);
//      }

//      if (interceptor == null)
//      {
//        Logger.LogWarning("Could not resolve interceptor {interceptor}", registration.Name);
//      }

//      Interceptors.TryAdd(type, interceptor);

//      return interceptor != null;
//    }
//  }


//  public interface ICollectionInterceptorHandler
//  {
//    /// <summary>
//    /// Creates a new interceptor instruction
//    /// </summary>
//    InterceptorInstruction<T, TParameters> Create<T, TParameters>(string operationName, TParameters parameters)
//      where T : ZeroEntity
//      where TParameters : CollectionInterceptor<T>.Parameters;
//  }
//}