/**
 * Device matching and Meraki client utilities.
 * Centralizes the fragile name/description matching logic used across reports.
 */

/**
 * Find the best matching Meraki client for a device using multiple strategies.
 *
 * identifiers can contain: mac, name, deviceName, adyenName, UserName,
 * DeviceFriendlyName, ip / ip_address. MAC, when present, is checked first
 * (and wins outright) because it's deterministic — useful for phones/DECT
 * basestations whose display names rarely line up with Meraki descriptions.
 */
function findMatchingClient(merakiClients = [], identifiers = {}) {
  if (!merakiClients.length) return null;

  // Strategy 0: MAC. Deterministic; runs ahead of any name/IP heuristic.
  const targetMac = normalizeMac(identifiers.mac);
  if (targetMac) {
    for (const client of merakiClients) {
      if (normalizeMac(client?.mac) === targetMac) return client;
    }
  }

  const names = [
    identifiers.name,
    identifiers.deviceName,
    identifiers.adyenName,
    identifiers.UserName,
    identifiers.DeviceFriendlyName,
    identifiers.printer_name,
    identifiers.register_display_name,
  ]
    .filter(Boolean)
    .map(n => String(n).toLowerCase().trim());

  // SIW often stores an FQDN in the `ip_address` field
  // (e.g. "VFI-807-005-168.us000782.stores.ae.com"). The hostname portion
  // before the first dot is what Meraki uses as its client `description`.
  const ipPrefix = extractHostname(identifiers.ip_address || identifiers.ip);

  for (const client of merakiClients) {
    if (!client?.description) continue;
    const desc = client.description.toLowerCase().trim();

    // Strategy 1: exact or substring match on any name
    if (names.some(n => n && (desc === n || desc.includes(n) || n.includes(desc)))) {
      return client;
    }

    // Strategy 2: FQDN hostname / IP prefix fallback
    if (ipPrefix && desc.includes(ipPrefix)) {
      return client;
    }

    // Strategy 3: check client.user field
    if (client.user) {
      const user = client.user.toLowerCase();
      if (names.some(n => n && user.includes(n))) {
        return client;
      }
    }
  }

  return null;
}

/**
 * Normalise a MAC address for equality comparison: strip every non-hex
 * character, lowercase, then validate length === 12. Returns null on bad
 * input so callers can safely use the result as a Map key.
 */
function normalizeMac(value) {
  if (!value) return null;
  const stripped = String(value)
    .replace(/[^0-9a-fA-F]/g, '')
    .toLowerCase();
  return stripped.length === 12 ? stripped : null;
}

/**
 * Pull the hostname out of an "ip_address" value. SIW endpoints frequently
 * return an FQDN (e.g. "VFI-807-005-168.us000782.stores.ae.com") in the
 * ip_address field; the portion before the first dot is the device's short
 * hostname, which is what Meraki advertises as the client description.
 * Returns null for empty/missing input.
 */
function extractHostname(value) {
  if (!value) return null;
  return String(value).split('.')[0].toLowerCase();
}

function getClientStatus(client) {
  if (!client) return '❓ Unknown';
  return client.status === 'Online' ? '✅ Online' : '❌ Offline';
}

function formatLastSeen(lastSeen) {
  if (!lastSeen) return 'N/A';
  const now = new Date();
  const seen = new Date(lastSeen);
  const diffMs = now - seen;
  const diffMin = Math.floor(diffMs / 60000);

  if (diffMin < 1) return 'Just now';
  if (diffMin < 60) return `${diffMin} min ago`;
  const hours = Math.floor(diffMin / 60);
  return `${hours} hr ago`;
}

/**
 * Build a best-effort link to the Meraki client detail page.
 * Note: This logic is environment-specific (dashboard URLs).
 */
function buildMerakiClientLink(merakiNetwork, client) {
  if (!client || !merakiNetwork?.url) return '';

  try {
    const networkCode = merakiNetwork.url.split('/n/')[1]?.split('/')[0] || merakiNetwork.id;
    const base = merakiNetwork.url.split('/n/')[0] || 'https://n976.dashboard.meraki.com';

    // Different sections for switches vs APs vs clients
    // Default to clients view
    return `${base}/${merakiNetwork.name.replace(/ /g, '-')}/n/${networkCode}/manage/clients/${client.id}/overview`;
  } catch (_e) {
    return '';
  }
}

module.exports = {
  findMatchingClient,
  getClientStatus,
  formatLastSeen,
  buildMerakiClientLink,
  extractHostname,
  normalizeMac,
};