import { describe, it, expect, beforeAll, afterAll } from 'vitest';
import type { FastifyInstance } from 'fastify';
import { buildApp } from '../src/app.js';
import { loadConfig } from '../src/config.js';

describe('Prometheus Metrics', () => {
  let app: FastifyInstance;

  beforeAll(async () => {
    const config = loadConfig({
      NODE_ENV: 'test',
      LOG_LEVEL: 'fatal',
      JWT_SECRET: 'test-secret-with-exactly-32chars',
      FEATURE_MESSAGING_ENABLED: 'false', // Disable WebSocket for metrics test
    });
    app = await buildApp({ config });
  });

  afterAll(async () => {
    await app.close();
  });

  it('should expose /metrics endpoint', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    expect(response.statusCode).toBe(200);
    expect(response.headers['content-type']).toContain('text/plain');
  });

  it('should expose agenthub_agents_connected metric', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    expect(response.body).toContain('# HELP agenthub_agents_connected');
    expect(response.body).toContain('# TYPE agenthub_agents_connected gauge');
    expect(response.body).toMatch(/agenthub_agents_connected \d+/);
  });

  it('should expose agenthub_rooms_active metric', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    expect(response.body).toContain('# HELP agenthub_rooms_active');
    expect(response.body).toContain('# TYPE agenthub_rooms_active gauge');
    expect(response.body).toMatch(/agenthub_rooms_active \d+/);
  });

  it('should expose agenthub_messages_total metric', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    expect(response.body).toContain('# HELP agenthub_messages_total');
    expect(response.body).toContain('# TYPE agenthub_messages_total counter');
    expect(response.body).toMatch(/agenthub_messages_total \d+/);
  });

  it('should expose agenthub_websocket_latency_seconds histogram', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    expect(response.body).toContain('# HELP agenthub_websocket_latency_seconds');
    expect(response.body).toContain('# TYPE agenthub_websocket_latency_seconds histogram');
    expect(response.body).toContain('agenthub_websocket_latency_seconds_bucket');
    expect(response.body).toContain('agenthub_websocket_latency_seconds_sum');
    expect(response.body).toContain('agenthub_websocket_latency_seconds_count');
  });

  it('should expose agenthub_http_requests_total metric', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    expect(response.body).toContain('# HELP agenthub_http_requests_total');
    expect(response.body).toContain('# TYPE agenthub_http_requests_total counter');
    // Should have tracked the /metrics request itself
    expect(response.body).toMatch(/agenthub_http_requests_total\{.*route="\/metrics".*\}/);
  });

  it('should expose agenthub_http_request_duration_seconds histogram', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    expect(response.body).toContain('# HELP agenthub_http_request_duration_seconds');
    expect(response.body).toContain('# TYPE agenthub_http_request_duration_seconds histogram');
    expect(response.body).toContain('agenthub_http_request_duration_seconds_bucket');
  });

  it('should expose default Node.js metrics', async () => {
    const response = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    // Check for some default metrics
    expect(response.body).toContain('agenthub_process_cpu_user_seconds_total');
    expect(response.body).toContain('agenthub_process_resident_memory_bytes');
    expect(response.body).toContain('agenthub_nodejs_eventloop_lag_seconds');
  });

  it('should increment HTTP request metrics on each call', async () => {
    // Make first call
    const response1 = await app.inject({
      method: 'GET',
      url: '/healthz',
    });
    expect(response1.statusCode).toBe(200);

    // Check metrics
    const metricsResponse = await app.inject({
      method: 'GET',
      url: '/metrics',
    });

    // Should have at least one request to /healthz
    expect(metricsResponse.body).toMatch(/agenthub_http_requests_total\{.*route="\/healthz".*status_code="200".*\} \d+/);
  });
});