DocumentService/DocumentService.Application/Common/Behaviors/LoggingBehavior.cs

using MediatR;
using Microsoft.Extensions.Logging;
using System.Diagnostics;

namespace DocumentService.Application.Common.Behaviors;

/// <summary>
/// MediatR Pipeline Behavior that logs requests and tracks performance
/// Executes AFTER ValidationBehavior, BEFORE Handler
/// </summary>
public class LoggingBehavior<TRequest, TResponse>(ILogger<LoggingBehavior<TRequest, TResponse>> Logger) : IPipelineBehavior<TRequest, TResponse>
    where TRequest : IRequest<TResponse>
{
    public async Task<TResponse> Handle(
        TRequest request,
        RequestHandlerDelegate<TResponse> next,
        CancellationToken cancellationToken)
    {
        var requestName = typeof(TRequest).Name;

        // Performance Tracking
        var stopwatch = Stopwatch.StartNew();

        try
        {
            // Handler ausführen
            var response = await next(cancellationToken);

            stopwatch.Stop();

            // Request Success
            Logger.LogInformation(
                "Handled {RequestName} in {ElapsedMs}ms",
                requestName,
                stopwatch.ElapsedMilliseconds
            );

            return response;
        }
        catch (Exception ex)
        {
            stopwatch.Stop();

            // Request Failed
            Logger.LogError(
                ex,
                "Error handling {RequestName} after {ElapsedMs}ms: {ErrorMessage}",
                requestName,
                stopwatch.ElapsedMilliseconds,
                ex.Message
            );

            throw; // Exception weiterwerfen (wird von Exception Middleware gefangen)
        }
    }
}