pstream-backend/server/middleware/metrics.ts

import { recordHttpRequest } from '~/utils/metrics';
import { scopedLogger } from '~/utils/logger';

const log = scopedLogger('metrics-middleware');

// Paths we don't want to track metrics for
const EXCLUDED_PATHS = ['/metrics', '/ping.txt', '/favicon.ico', '/robots.txt', '/sitemap.xml'];

export default defineEventHandler(async event => {
  // Skip tracking excluded paths
  if (EXCLUDED_PATHS.includes(event.path)) {
    return;
  }

  const start = process.hrtime();

  try {
    // Wait for the request to complete
    await event._handled;
  } finally {
    // Calculate duration once the response is sent
    const [seconds, nanoseconds] = process.hrtime(start);
    const duration = seconds + nanoseconds / 1e9;

    // Get cleaned route path (remove dynamic segments)
    const method = event.method;
    const route = getCleanPath(event.path);
    const statusCode = event.node.res.statusCode || 200;

    // Record the request metrics
    recordHttpRequest(method, route, statusCode, duration);

    log.debug('Recorded HTTP request metrics', {
      evt: 'http_metrics',
      method,
      route,
      statusCode,
      duration,
    });
  }
});

// Helper to normalize routes with dynamic segments (e.g., /users/123 -> /users/:id)
function getCleanPath(path: string): string {
  // Common patterns for Nitro routes
  return path
    .replace(/\/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/g, '/:uuid')
    .replace(/\/\d+/g, '/:id')
    .replace(/@me/, ':uid')
    .replace(/\/[^\/]+\/progress\/[^\/]+/, '/:uid/progress/:tmdbid')
    .replace(/\/[^\/]+\/bookmarks\/[^\/]+/, '/:uid/bookmarks/:tmdbid')
    .replace(/\/sessions\/[^\/]+/, '/sessions/:sid');
}