// Depends on: data/tlds.js (REAL_TLDS, REAL_SLD_TLDS)

/**
 * Validate a virtual host hostname.
 * Rules:
 *  1. Must have at least 2 dots (3 labels minimum: host.second.tld)
 *  2. Each label: only [a-z0-9-], no leading/trailing hyphen, non-empty
 *  3. The last two labels (base domain, e.g. "hole.sail") must not be a
 *     real public TLD or second-level public suffix
 * Returns { ok: true } or { ok: false, error: string }
 */
function isValidVhostHostname(hostname) {
  if (!hostname) return { ok: false, error: 'Hostname is required' };
  const labels = hostname.split('.');
  if (labels.length < 3) {
    return { ok: false, error: 'Hostname must have the form host.second.tld (e.g. myapp.hole.sail) — single-dot names are not allowed' };
  }
  for (const label of labels) {
    if (!label) return { ok: false, error: 'Hostname contains empty labels' };
    if (!/^[a-z0-9-]+$/.test(label)) return { ok: false, error: 'Hostname contains invalid characters — only letters, digits and hyphens allowed' };
    if (label.startsWith('-') || label.endsWith('-')) return { ok: false, error: 'Hostname labels must not start or end with a hyphen' };
  }
  const tld = labels[labels.length - 1];
  const baseDomain = labels.slice(-2).join('.');
  if (REAL_TLDS.has(tld) || REAL_SLD_TLDS.has(baseDomain)) {
    return { ok: false, error: 'The TLD ".' + baseDomain + '" is a real registered domain — use a private TLD like .hole.sail or .my.internal' };
  }
  return { ok: true };
}

/** Extract the two-label base domain from a hostname (e.g. "hole.sail" from "myapp.hole.sail") */
function extractBaseDomain(hostname) {
  const parts = hostname.split('.');
  return parts.slice(-2).join('.');
}

/** Extract unique two-label base domains from a list of virtual host objects */
function extractActiveTlds(virtualHosts) {
  const seen = new Set();
  seen.add('hole.sail'); // always include baseline
  for (const v of (virtualHosts || [])) {
    if (v.hostname) seen.add(extractBaseDomain(v.hostname));
  }
  return Array.from(seen).map(b => '.' + b);
}