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

namespace Application.Behaviors;

public sealed class LoggingBehavior<TRequest, TResponse>(ILogger<LoggingBehavior<TRequest, TResponse>> logger) : IPipelineBehavior<TRequest, TResponse> where TRequest : notnull
{
    private const long SlowThresholdMs = 500;

    public async Task<TResponse> Handle(
        TRequest request,
        RequestHandlerDelegate<TResponse> next,
        CancellationToken ct
    ) {
        var requestName = typeof(TRequest).Name;
        var sw = Stopwatch.StartNew();

        try
        {
            var result = await next(ct);
            sw.Stop();

            if (sw.ElapsedMilliseconds > SlowThresholdMs)
            {
                logger.LogWarning("[Slow] {Request} took {Elapsed}ms", requestName, sw.ElapsedMilliseconds);
            }
            else if (logger.IsEnabled(LogLevel.Debug))
            {
                logger.LogDebug("[Done] {Request} {Elapsed}ms", requestName, sw.ElapsedMilliseconds);
            }

            return result;
        }
        catch (Exception ex)
        {
            sw.Stop();
            logger.LogError(ex, "[Failed] {Request} after {Elapsed}ms", requestName, sw.ElapsedMilliseconds);
            throw;
        }
    }
}