// src/services/voiceDiag/checks/wan/wanLinkState.js
//
// Per-path administrative + operational up/down state. Any single
// path being down at a Prisma SD-WAN site is an error-severity
// signal: SD-WAN by design tolerates one path being down (traffic
// shifts to a surviving path), but a DOWN path is still lost
// capacity + a lost failover buffer, and voice-quality problems
// are much more likely on the remaining paths under load.
//
// A path with `up === null` (LinkState metric didn't come back)
// isn't counted as down — surfaced as "unknown" in details so the
// operator can see the visibility gap.
//
// No remediation — bringing a WAN link back up is a physical /
// carrier task, not something the bot should try to automate.

import {
  maybeSkippedByKillSwitch,
  getLinks,
  labelForLink,
} from './_helpers.js';

export const WAN_LINK_STATE_STANDARDS = Object.freeze({
  perLinkUp: true,
});

export const wanLinkStateCheck = {
  id: 'wanLinkState',
  label: 'SD-WAN Link State',
  requires: ['sdwanSite'],
  scope: null,
  standards: WAN_LINK_STATE_STANDARDS,

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

    const links = getLinks(ctx);
    if (links.length === 0) {
      return {
        status: 'skipped',
        message: 'No WAN paths reported for this site.',
        details: null,
        remediation: null,
      };
    }

    const down = links.filter((l) => l.up === false);
    const unknown = links.filter((l) => l.up === null || l.up === undefined);
    const up = links.filter((l) => l.up === true);

    const details = {
      total: links.length,
      up: up.length,
      down: down.length,
      unknown: unknown.length,
      offenders: down.map(labelForLink),
      unknownLabels: unknown.map(labelForLink),
    };

    if (down.length > 0) {
      return {
        status: 'error',
        message:
          `${down.length} of ${links.length} WAN path(s) DOWN: ` +
          down.map(labelForLink).join(', ') +
          `. Voice quality on surviving paths may degrade under load.`,
        details,
        remediation: null,
      };
    }

    if (unknown.length > 0 && up.length === 0) {
      // Prisma returned NO LinkState samples at all — treat as a
      // reporting warning, not a health error.
      return {
        status: 'warn',
        message: `Link state unknown for all ${unknown.length} WAN path(s) (no samples from Prisma).`,
        details,
        remediation: null,
      };
    }

    return {
      status: 'ok',
      message: `All ${up.length} WAN path(s) up.` +
        (unknown.length > 0 ? ` (${unknown.length} with no state samples.)` : ''),
      details,
      remediation: null,
    };
  },
};