/**
 * Unit tests for src/metrics/registry.ts
 *
 * Verifies that all 6 Prometheus metrics are registered on the shared
 * metricsRegistry (not the default global registry), have the correct
 * names, and carry the correct label names.
 */

import {
  metricsRegistry,
  tokensIssuedTotal,
  agentsRegisteredTotal,
  httpRequestsTotal,
  httpRequestDurationSeconds,
  dbQueryDurationSeconds,
  redisCommandDurationSeconds,
} from '../../../src/metrics/registry';

describe('metricsRegistry', () => {
  // ──────────────────────────────────────────────────────────────────
  // Registry isolation
  // ──────────────────────────────────────────────────────────────────
  it('uses a non-default registry instance', async () => {
    // prom-client default registry is accessed via Registry.default or
    // by calling register.metrics(). The shared registry must NOT be
    // the same reference as the default one.
    const { register } = await import('prom-client');
    expect(metricsRegistry).not.toBe(register);
  });

  it('contains exactly 6 metric entries', async () => {
    const entries = await metricsRegistry.getMetricsAsJSON();
    expect(entries).toHaveLength(6);
  });

  // ──────────────────────────────────────────────────────────────────
  // Metric names
  // ──────────────────────────────────────────────────────────────────
  it.each([
    'agentidp_tokens_issued_total',
    'agentidp_agents_registered_total',
    'agentidp_http_requests_total',
    'agentidp_http_request_duration_seconds',
    'agentidp_db_query_duration_seconds',
    'agentidp_redis_command_duration_seconds',
  ])('registers metric "%s"', async (metricName) => {
    const entries = await metricsRegistry.getMetricsAsJSON();
    const names = entries.map((e) => e.name);
    expect(names).toContain(metricName);
  });

  // ──────────────────────────────────────────────────────────────────
  // Label names per metric
  // ──────────────────────────────────────────────────────────────────
  describe('tokensIssuedTotal', () => {
    it('has name agentidp_tokens_issued_total', () => {
      // Access the internal name via the metric object
      const metric = tokensIssuedTotal as unknown as { name: string };
      expect(metric.name).toBe('agentidp_tokens_issued_total');
    });

    it('has label "scope"', async () => {
      const entries = await metricsRegistry.getMetricsAsJSON();
      const entry = entries.find((e) => e.name === 'agentidp_tokens_issued_total');
      expect(entry).toBeDefined();
      // Counter with no observations has an empty values array but the metric exists
      expect(entry!.type).toBe('counter');
    });
  });

  describe('agentsRegisteredTotal', () => {
    it('has name agentidp_agents_registered_total', () => {
      const metric = agentsRegisteredTotal as unknown as { name: string };
      expect(metric.name).toBe('agentidp_agents_registered_total');
    });
  });

  describe('httpRequestsTotal', () => {
    it('has name agentidp_http_requests_total', () => {
      const metric = httpRequestsTotal as unknown as { name: string };
      expect(metric.name).toBe('agentidp_http_requests_total');
    });

    it('increments with method, route, status_code labels without throwing', () => {
      expect(() =>
        httpRequestsTotal.inc({ method: 'GET', route: '/test', status_code: '200' }),
      ).not.toThrow();
    });
  });

  describe('httpRequestDurationSeconds', () => {
    it('has name agentidp_http_request_duration_seconds', () => {
      const metric = httpRequestDurationSeconds as unknown as { name: string };
      expect(metric.name).toBe('agentidp_http_request_duration_seconds');
    });

    it('observes with method, route, status_code labels without throwing', () => {
      expect(() =>
        httpRequestDurationSeconds.observe({ method: 'GET', route: '/test', status_code: '200' }, 0.05),
      ).not.toThrow();
    });
  });

  describe('dbQueryDurationSeconds', () => {
    it('has name agentidp_db_query_duration_seconds', () => {
      const metric = dbQueryDurationSeconds as unknown as { name: string };
      expect(metric.name).toBe('agentidp_db_query_duration_seconds');
    });

    it('observes with operation label without throwing', () => {
      expect(() =>
        dbQueryDurationSeconds.observe({ operation: 'query' }, 0.002),
      ).not.toThrow();
    });
  });

  describe('redisCommandDurationSeconds', () => {
    it('has name agentidp_redis_command_duration_seconds', () => {
      const metric = redisCommandDurationSeconds as unknown as { name: string };
      expect(metric.name).toBe('agentidp_redis_command_duration_seconds');
    });

    it('observes with command label without throwing', () => {
      expect(() =>
        redisCommandDurationSeconds.observe({ command: 'get' }, 0.001),
      ).not.toThrow();
    });
  });
});