/**
 * Root-level /metrics endpoint tests — DC-097b
 *
 * Verifies that:
 *   - GET /metrics returns Prometheus text format (not JSON, not HTML)
 *   - The Content-Type is text/plain with Prometheus version
 *   - The response includes HELP/TYPE annotations and metric names
 *   - The endpoint is listed in PUBLIC_ROUTES (no auth required)
 *   - The endpoint is in the rate-limiter skip list
 *
 * Documentation tells users to scrape /metrics (the Prometheus convention),
 * but the route previously only existed at /api/v1/metrics/prometheus. The
 * root-level alias makes doc examples work without modification.
 */
const fs = require('fs');
const path = require('path');

const MIDDLEWARE_PATH = path.join(__dirname, '../src/utilities/middleware.js');
const APP_PATH = path.join(__dirname, '../src/app.js');

describe('Root-level /metrics endpoint — DC-097b', () => {
  describe('PUBLIC_ROUTES includes /metrics', () => {
    let mwSource;
    beforeAll(() => {
      mwSource = fs.readFileSync(MIDDLEWARE_PATH, 'utf8');
    });

    test('/metrics is in PUBLIC_ROUTES', () => {
      // Match the route entry: { path: '/metrics', ... method: 'GET' }
      expect(mwSource).toMatch(/['"]\/metrics['"]/);
    });

    test('/metrics is in the rate-limiter skip list', () => {
      expect(mwSource).toMatch(/req\.path\s*===\s*['"]\/metrics['"]/);
    });
  });

  describe('app.js registers GET /metrics', () => {
    let appSource;
    beforeAll(() => {
      appSource = fs.readFileSync(APP_PATH, 'utf8');
    });

    test('app.get("/metrics", ...) is registered', () => {
      expect(appSource).toMatch(/app\.get\(\s*['"]\/metrics['"]/);
    });

    test('/metrics handler sets Prometheus Content-Type', () => {
      // The handler should set Content-Type to text/plain with prometheus version
      expect(appSource).toMatch(/text\/plain.*version=0\.0\.4/);
    });
  });

  describe('Parity with /api/v1/metrics/prometheus', () => {
    let appSource;
    beforeAll(() => {
      appSource = fs.readFileSync(APP_PATH, 'utf8');
    });

    test('both endpoints call metrics.toPrometheus()', () => {
      const matches = appSource.match(/metrics\.toPrometheus\(\)/g);
      expect(matches).toBeTruthy();
      // At least two call sites: /api/v1/metrics/prometheus and /metrics
      expect(matches.length).toBeGreaterThanOrEqual(2);
    });
  });
});