// src/services/enrichment/alarmSemantics.js
//
// Shared alarm-code semantics for Prisma SD-WAN events. Two things
// live here so both the check runner (services/voiceDiag/checks/wan
// /wanAlarms.js) and the follow-up renderer (services/renderers/
// wanDiagnosticsRenderer.js) present the same story:
//
//   1. categorizeAlarm(code)   — buckets a raw alarm code into one of:
//        - 'overlay'   SD-WAN VPN tunnels between peer elements. These
//                      DO NOT correspond to the physical WAN interfaces
//                      shown in the Link State / LQM checks; a store
//                      can have all physical circuits green while the
//                      overlay flaps repeatedly.
//        - 'physical'  A specific WAN circuit / interface is affected.
//                      Should generally line up with what Link State
//                      reports.
//        - 'device'    Element / ION appliance itself (heartbeat, boot).
//        - 'other'     Everything else (LAN, DHCP, config, etc.).
//
//   2. humanizeAlarmCode(code) — one-line English label so the check
//                      message and the recent-samples list don't dump
//                      raw Prisma constants at the operator.
//
//   3. rollupAlarms(samples) — groups near-identical alarm samples
//                      by (code + severity) so 20 successive
//                      NETWORK_ANYNETLINK_DOWN flaps show as a single
//                      line with "×20" instead of a 20-line wall.
//                      Sorted critical → major → minor, then by count.
//
// The category / humanizer tables err on the side of "unknown code
// falls through to a sensible default" — Prisma introduces new codes
// with tenant updates and we do NOT want a new code to blow up the
// diagnostic.

/**
 * Alarm category → operator meaning.
 *
 *   overlay   → SD-WAN VPN link between peer elements; will NOT
 *               appear as a physical link-down in the Link State
 *               check. Common when a hub site or a peer is temporarily
 *               unreachable.
 *   physical  → An actual WAN circuit / interface is down or
 *               degraded. Should correlate with Link State / LQM.
 *   device    → Element itself (ION appliance) missed heartbeats,
 *               rebooted, or entered a bad state.
 *   other     → LAN / DHCP / configuration / anything else.
 */
const CATEGORY_TABLE = {
  // ── overlay (VPN tunnel / SD-WAN mesh) ──────────────────────────
  NETWORK_ANYNETLINK_DOWN:      'overlay',
  NETWORK_VPNLINK_DOWN:         'overlay',
  NETWORK_VPNLINK_FLAP:         'overlay',
  NETWORK_VPNLINK_UNREACHABLE:  'overlay',
  NETWORK_DIRECTPRIVATE_DOWN:   'overlay',
  NETWORK_STANDBY_LINK_DOWN:    'overlay',
  NETWORK_SITE_UNREACHABLE:     'overlay',

  // ── physical (WAN circuit / interface) ──────────────────────────
  NETWORK_INTERNET_DOWN:              'physical',
  NETWORK_PUBLICWAN_UNREACHABLE:      'physical',
  NETWORK_PRIVATEWAN_UNREACHABLE:     'physical',
  NETWORK_DIRECTINTERNET_UNREACHABLE: 'physical',
  DEVICE_INTERFACE_STATE_CHANGED:     'physical',
  DEVICE_INTERFACE_DOWN:              'physical',
  DEVICE_INTERFACE_FLAP:              'physical',
  NETWORK_LTE_LINK_DOWN:              'physical',

  // ── device (element / ION itself) ───────────────────────────────
  DEVICE_HB_MISSED:                 'device',
  DEVICE_UNREACHABLE:               'device',
  DEVICE_REBOOT:                    'device',
  DEVICE_HIGH_CPU:                  'device',
  DEVICE_HIGH_MEMORY:               'device',
  DEVICE_DISK_UTILIZATION_HIGH:     'device',
  DEVICE_SOFTWARE_UPGRADE_FAILED:   'device',
  DEVICE_HA_STATE_CHANGE:           'device',

  // ── other (LAN / DHCP / config) ─────────────────────────────────
  DHCP_POOL_UTILIZATION_HIGH:       'other',
  DHCP_FAILURE:                     'other',
  CONFIG_SYNC_FAILED:               'other',
  LAN_INTERFACE_DOWN:               'other',
  BGP_PEER_DOWN:                    'other',
};

/**
 * Human-readable one-liner per alarm code. Kept short — operators
 * scan the message field, they don't need a paragraph. Falls back to
 * a Title-Cased version of the raw code when we don't know it.
 */
const HUMANIZE_TABLE = {
  NETWORK_ANYNETLINK_DOWN:      'SD-WAN overlay tunnel down',
  NETWORK_VPNLINK_DOWN:         'VPN link to peer site down',
  NETWORK_VPNLINK_FLAP:         'VPN link flapping',
  NETWORK_VPNLINK_UNREACHABLE:  'VPN link unreachable',
  NETWORK_DIRECTPRIVATE_DOWN:   'Direct private link down',
  NETWORK_STANDBY_LINK_DOWN:    'Standby link down',
  NETWORK_SITE_UNREACHABLE:     'Peer site unreachable',
  NETWORK_INTERNET_DOWN:              'Internet WAN circuit down',
  NETWORK_PUBLICWAN_UNREACHABLE:      'Public WAN unreachable',
  NETWORK_PRIVATEWAN_UNREACHABLE:     'Private WAN unreachable',
  NETWORK_DIRECTINTERNET_UNREACHABLE: 'Direct internet unreachable',
  NETWORK_LTE_LINK_DOWN:              'LTE link down',
  DEVICE_INTERFACE_STATE_CHANGED:     'Physical interface state change',
  DEVICE_INTERFACE_DOWN:              'Physical interface down',
  DEVICE_INTERFACE_FLAP:              'Physical interface flap',
  DEVICE_HB_MISSED:                   'ION heartbeat missed',
  DEVICE_UNREACHABLE:                 'ION unreachable',
  DEVICE_REBOOT:                      'ION reboot',
  DEVICE_HIGH_CPU:                    'ION high CPU',
  DEVICE_HIGH_MEMORY:                 'ION high memory',
  DEVICE_DISK_UTILIZATION_HIGH:       'ION disk full',
  DEVICE_SOFTWARE_UPGRADE_FAILED:     'Software upgrade failed',
  DEVICE_HA_STATE_CHANGE:             'HA state change',
  DHCP_POOL_UTILIZATION_HIGH:         'DHCP pool nearly full',
  DHCP_FAILURE:                       'DHCP failure',
  CONFIG_SYNC_FAILED:                 'Configuration sync failed',
  LAN_INTERFACE_DOWN:                 'LAN interface down',
  BGP_PEER_DOWN:                      'BGP peer down',
};

/**
 * Return one of 'overlay' | 'physical' | 'device' | 'other' for the
 * given raw alarm code. Case-insensitive on the code. Unknown codes
 * bucket to 'other' — Prisma adds new codes over time and we prefer
 * a benign fallback to a hard failure.
 */
export function categorizeAlarm(code) {
  if (!code) return 'other';
  return CATEGORY_TABLE[String(code).toUpperCase()] || 'other';
}

/**
 * Return a short human label for the alarm code. Falls back to a
 * Title-Cased split of the raw constant when we don't recognise it,
 * so `SOMETHING_NEW_DOWN` becomes "Something New Down" instead of
 * being dumped raw.
 */
export function humanizeAlarmCode(code) {
  if (!code) return 'Unknown alarm';
  const key = String(code).toUpperCase();
  if (HUMANIZE_TABLE[key]) return HUMANIZE_TABLE[key];
  return key
    .toLowerCase()
    .split('_')
    .filter(Boolean)
    .map((w) => w.charAt(0).toUpperCase() + w.slice(1))
    .join(' ');
}

/**
 * Roll alarm samples up by (code + severity). Preserves the newest
 * timestamp per rollup and orders results critical → major → minor,
 * then by count descending. This turns a wall of 20 near-identical
 * NETWORK_ANYNETLINK_DOWN JSON blobs into one scannable line.
 *
 * Shape of the returned rollups:
 *   { code, severity, count, newestTs }
 *
 * (Kept minimal — the caller decorates with humanized label + category
 * so we don't force every downstream to import both tables.)
 */
export function rollupAlarms(samples) {
  if (!Array.isArray(samples)) return [];
  const byKey = new Map();
  for (const s of samples) {
    if (!s) continue;
    const key = `${s.severity}::${s.code}`;
    const prev = byKey.get(key);
    if (prev) {
      prev.count += 1;
      if (!prev.newestTs || (s.ts && String(s.ts) > String(prev.newestTs))) {
        prev.newestTs = s.ts;
      }
    } else {
      byKey.set(key, {
        code: s.code,
        severity: s.severity,
        count: 1,
        newestTs: s.ts,
      });
    }
  }
  const sevRank = { critical: 0, major: 1, minor: 2, unknown: 3 };
  return [...byKey.values()].sort((a, b) => {
    const ra = sevRank[a.severity] ?? 9;
    const rb = sevRank[b.severity] ?? 9;
    if (ra !== rb) return ra - rb;
    return b.count - a.count;
  });
}

/**
 * Count alarms by category from a set of samples.
 * Returns `{ overlay, physical, device, other, total }`.
 */
export function countByCategory(samples) {
  const counts = { overlay: 0, physical: 0, device: 0, other: 0, total: 0 };
  if (!Array.isArray(samples)) return counts;
  for (const s of samples) {
    if (!s) continue;
    counts.total += 1;
    counts[categorizeAlarm(s.code)] += 1;
  }
  return counts;
}

/**
 * Given an alarm timestamp (ISO string), return a coarse "how long
 * ago" label. Handles ms drift on both sides — "now", "5m ago",
 * "2h ago", "3d ago". Falls back to the raw ts on parse failure.
 */
export function humanizeAge(ts, now = Date.now()) {
  if (!ts) return '';
  const t = Date.parse(ts);
  if (!Number.isFinite(t)) return '';
  const deltaSec = Math.max(0, Math.floor((now - t) / 1000));
  if (deltaSec < 60)         return 'just now';
  if (deltaSec < 3600)       return `${Math.floor(deltaSec / 60)}m ago`;
  if (deltaSec < 86_400)     return `${Math.floor(deltaSec / 3600)}h ago`;
  return `${Math.floor(deltaSec / 86_400)}d ago`;
}

/**
 * Human-friendly minutes label (mirrors the renderer helpers).
 * Exported so the alarm check can label windows consistently without
 * a separate helper import.
 */
export function humanizeWindow(minutes) {
  if (!Number.isFinite(minutes) || minutes <= 0) return `${minutes}m`;
  if (minutes >= 1440 && minutes % 1440 === 0) return `${minutes / 1440}d`;
  if (minutes >= 60 && minutes % 60 === 0) return `${minutes / 60}h`;
  return `${minutes}m`;
}