// src/services/voiceDiag/checks/wan/wanLoss.js
//
// Per-path WAN packet loss (LQM %, 0-100). Voice codec loss
// tolerance:
//   - <= 1%  : good (PLC hides it)
//   - 1-3%   : warn (audible artifacts on longer calls)
//   - > 3%   : error (words dropping, users repeating themselves)
//
// Both thresholds are env-configurable via WAN_STANDARD_LOSS_*.

import {
  maybeSkippedByKillSwitch,
  getLinks,
  getLossWarnPct,
  getLossErrorPct,
  evaluatePerLinkMetric,
} from './_helpers.js';

export const WAN_LOSS_STANDARDS = Object.freeze({
  maxWarnPct: 1,
  maxErrorPct: 3,
  unit: '%',
  reference: 'G.711 PLC tolerance envelope',
});

export const wanLossCheck = {
  id: 'wanLoss',
  label: 'SD-WAN Packet Loss (per path)',
  requires: ['sdwanSite'],
  scope: null,
  standards: WAN_LOSS_STANDARDS,

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

    const warnThresh = getLossWarnPct();
    const errorThresh = getLossErrorPct();
    return evaluatePerLinkMetric({
      links: getLinks(ctx),
      metricKey: 'lossPct',
      label: 'packet loss',
      unit: '%',
      warnThresh,
      errorThresh,
      lowIsBad: false,
      standardLabel: `warn > ${warnThresh}%, error > ${errorThresh}%`,
    });
  },
};