// src/services/voiceDiag/checks/wan/wanAppRtpJitter.js
//
// Per-application audio jitter — measured on ACTUAL RTP voice
// traffic via Prisma DPI. Metric name on the v2.6 monitor/metrics
// endpoint is `AppPerfUDPAudioJitter` (unit: milliseconds), takes
// filter.direction="Ingress" AND filter.path_type=[all].
//
// See wanAppRtpMos.js for the app-selection contract — the check is
// app-agnostic; the tenant picks which voice app to grade via env.
//
// Grades against the WORST-window jitter — same reasoning as the
// MOS + loss checks: a brief burst that ruins in-flight calls is
// exactly what needs surfacing.
//
// Skipped when the voice-app env is not configured.

import {
  maybeSkippedByKillSwitch,
  getAppAudio,
  evaluateAppAudioMetric,
  getAppJitterWarnMs,
  getAppJitterErrorMs,
} from './_helpers.js';

export const WAN_APP_RTP_JITTER_STANDARDS = Object.freeze({
  maxWarnMs:  30,
  maxErrorMs: 50,
  unit: 'ms',
  reference: 'RFC 3550 (jitter buffer tolerance)',
  gradeAgainst: 'worst-window',
});

export const wanAppRtpJitterCheck = {
  id: 'wanAppRtpJitter',
  label: 'SD-WAN Voice Traffic Jitter (worst window)',
  requires: ['sdwanSite'],
  scope: null,
  standards: WAN_APP_RTP_JITTER_STANDARDS,

  async run(ctx) {
    const skip = maybeSkippedByKillSwitch(wanAppRtpJitterCheck);
    if (skip) return skip;

    const audio = getAppAudio(ctx, 'jitter');
    const warnThresh  = getAppJitterWarnMs();
    const errorThresh = getAppJitterErrorMs();
    return evaluateAppAudioMetric({
      audio,
      label: 'jitter',
      unit: 'ms',
      warnThresh,
      errorThresh,
      lowIsBad: false,
      standardLabel: `warn > ${warnThresh}ms, error > ${errorThresh}ms`,
    });
  },
};