/**
 * Load test: Progressive ramp - stream server HLS
 * Ramp: 10 -> 50 -> 100 -> 200 VUs to find saturation point
 * Usage: k6 run loadtests/stream/ramp.js
 * Requires: STREAM_ORIGIN, AUTH_TOKEN, TRACK_ID (see hls.js)
 */
import http from 'k6/http';
import { check, sleep } from 'k6';
import { Rate, Trend } from 'k6/metrics';

const errorRate = new Rate('ramp_errors');
const manifestDuration = new Trend('ramp_manifest_duration');

const STREAM_ORIGIN = __ENV.STREAM_ORIGIN || 'http://localhost:8082';
const AUTH_TOKEN = __ENV.AUTH_TOKEN || '';
const TRACK_ID = __ENV.TRACK_ID || '';

export const options = {
  scenarios: {
    ramp: {
      executor: 'ramping-vus',
      startVUs: 0,
      stages: [
        { duration: '1m', target: 10 },
        { duration: '2m', target: 50 },
        { duration: '2m', target: 100 },
        { duration: '2m', target: 200 },
        { duration: '1m', target: 0 },
      ],
      gracefulRampDown: '30s',
      gracefulStop: '30s',
    },
  },
  thresholds: {
    http_req_duration: ['p(95)<2000', 'p(99)<5000'],
    ramp_errors: ['rate<0.05'],
    ramp_manifest_duration: ['p(95)<1000', 'p(99)<3000'],
  },
};

function getHeaders() {
  const h = { Accept: 'application/vnd.apple.mpegurl,*/*' };
  if (AUTH_TOKEN) {
    h['Authorization'] = `Bearer ${AUTH_TOKEN}`;
  }
  return h;
}

export function setup() {
  return { trackId: TRACK_ID || '00000000-0000-0000-0000-000000000000' };
}

export default function (data) {
  const { trackId } = data;
  const url = `${STREAM_ORIGIN}/hls/${trackId}/master.m3u8`;
  const start = Date.now();
  const res = http.get(url, { headers: getHeaders() });
  manifestDuration.add(Date.now() - start);
  errorRate.add(res.status !== 200 && res.status !== 404);
  sleep(0.5);
}