// src/services/voiceDiag/checks/wan/wanAppRtpLoss.js
//
// Per-application audio packet loss — measured on ACTUAL RTP voice
// traffic via Prisma DPI. Metric name on the v2.6 monitor/metrics
// endpoint is `AppPerfUDPAudioPacketLoss` (unit: percentage), 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 loss in the series. A 5-minute
// burst of 20% loss makes calls unusable during that window even
// if the 24h avg is 2% — always show the operator the worst-case
// number so they know a bad experience is real, not aggregated away.
//
// Skipped when the voice-app env is not configured.

import {
  maybeSkippedByKillSwitch,
  getAppAudio,
  evaluateAppAudioMetric,
  getAppLossWarnPct,
  getAppLossErrorPct,
} from './_helpers.js';

export const WAN_APP_RTP_LOSS_STANDARDS = Object.freeze({
  maxWarnPct:  5,
  maxErrorPct: 15,
  unit: '%',
  reference: 'ITU-T G.113 (voice loss tolerance)',
  gradeAgainst: 'worst-window',
});

export const wanAppRtpLossCheck = {
  id: 'wanAppRtpLoss',
  label: 'SD-WAN Voice Traffic Packet Loss (worst window)',
  requires: ['sdwanSite'],
  scope: null,
  standards: WAN_APP_RTP_LOSS_STANDARDS,

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

    const audio = getAppAudio(ctx, 'loss');
    const warnThresh  = getAppLossWarnPct();
    const errorThresh = getAppLossErrorPct();
    return evaluateAppAudioMetric({
      audio,
      label: 'packet loss',
      unit: '%',
      warnThresh,
      errorThresh,
      lowIsBad: false,
      standardLabel: `warn > ${warnThresh}%, error > ${errorThresh}%`,
    });
  },
};