using System.Diagnostics;
using HrynCo.NotificationService.DAL.Abstract;
using MediatR;
using Microsoft.Extensions.Logging;

namespace HrynCo.NotificationService.Services.Behaviors;

public class TransactionBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
    where TRequest : notnull
{
    private readonly IUnitOfWork _unitOfWork;
    private readonly ILogger<TransactionBehavior<TRequest, TResponse>> _logger;

    public TransactionBehavior(IUnitOfWork unitOfWork, ILogger<TransactionBehavior<TRequest, TResponse>> logger)
    {
        _unitOfWork = unitOfWork;
        _logger = logger;
    }

    public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
    {
        string handlerName = typeof(TRequest).Name;
        _logger.LogDebug("Handling {Handler}", handlerName);

        Stopwatch sw = Stopwatch.StartNew();
        try
        {
            TResponse result = await _unitOfWork.ExecuteInTransactionAsync(async () =>
            {
                TResponse response = await next();
                await _unitOfWork.SaveChangesAsync(cancellationToken);
                return response;
            });

            _logger.LogDebug("Handled {Handler} in {ElapsedMs}ms", handlerName, sw.ElapsedMilliseconds);
            return result;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Handler {Handler} failed after {ElapsedMs}ms", handlerName, sw.ElapsedMilliseconds);
            throw;
        }
    }
}