using System.Diagnostics;
using System.Net;
using System.Web.Http.Controllers;
using System.Web.Http.Filters;
using Prometheus;

namespace VECV_WebApi.Filters
{
    public class MetricsFilterAttribute : ActionFilterAttribute
    {
        private static readonly Counter RequestCounter = Metrics.CreateCounter(
            "app_http_requests_total", "Total HTTP requests", new[] { "method", "endpoint", "status_code" });

        private static readonly Histogram ResponseTime = Metrics.CreateHistogram(
            "app_http_response_duration_seconds", "API response time", new[] { "endpoint" });

        private Stopwatch _timer;

        public override void OnActionExecuting(HttpActionContext actionContext)
        {
            _timer = Stopwatch.StartNew();
        }

        public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
        {
            _timer.Stop();
            var request = actionExecutedContext.Request;
            var response = actionExecutedContext.Response;
            var endpoint = request.RequestUri.AbsolutePath;
            var method = request.Method.Method;
            var status = ((int)(response?.StatusCode ?? HttpStatusCode.InternalServerError)).ToString();

            RequestCounter.Labels(method, endpoint, status).Inc();
            ResponseTime.Labels(endpoint).Observe(_timer.Elapsed.TotalSeconds);
        }
    }
}