const HARD_EXPIRED_PATTERNS = [
  /job (is )?no longer available/i,
  /job.*no longer open/i,
  /position has been filled/i,
  /this job has expired/i,
  /job posting has expired/i,
  /no longer accepting applications/i,
  /this (position|role|job) (is )?no longer/i,
  /this job (listing )?is closed/i,
  /job (listing )?not found/i,
  /the page you are looking for doesn.t exist/i,
  /applications?\s+(?:(?:have|are|is)\s+)?closed/i,
  /closed on \d{1,2}\s+(?:jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)/i,
  /closed on (?:jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\w*\s+\d{1,2}/i,
  /diese stelle (ist )?(nicht mehr|bereits) besetzt/i,
  /offre (expirée|n'est plus disponible)/i,
];

const LISTING_PAGE_PATTERNS = [
  /\d+\s+jobs?\s+found/i,
  /search for jobs page is loaded/i,
];

// Anti-bot interstitials (Cloudflare "Just a moment...", hCaptcha walls, etc.)
// render a tiny challenge page instead of the posting. Headless Playwright trips
// these on portals like pracuj.pl. They must NOT be read as expired: the body is
// short and lacks an apply control, so without this guard they fall through to
// `insufficient_content` → expired, and scan --verify would write live jobs to
// scan-history and permanently filter them out. Treat as uncertain instead.
const BOT_CHALLENGE_PATTERNS = [
  /just a moment/i,
  /performing security verification/i,
  /checking your browser before/i,
  /verify you are (a |not a )?human/i,
  /enable javascript and cookies to continue/i,
  /attention required.*cloudflare/i,
  /\bray id\b/i,
  /\bcf-ray\b/i,
  /please complete the security check/i,
];

const EXPIRED_URL_PATTERNS = [
  /[?&]error=true/i,
];

const APPLY_PATTERNS = [
  /\bapply\b/i,
  /\bsolicitar\b/i,
  /\bbewerben\b/i,
  /\bpostuler\b/i,
  /submit application/i,
  /easy apply/i,
  /start application/i,
  /ich bewerbe mich/i,
  // Polish (pracuj.pl, justjoin.it, bulldogjob.pl): "Aplikuj" / "Aplikuj teraz" /
  // "Wyślij CV" / "Przejdź do panelu aplikowania". Without these, a fully-loaded
  // Polish posting has no recognized apply control and falls to no_apply_control.
  /\baplikuj\b/i,
  /panelu aplikowania/i,
  /wyślij (cv|aplikacj)/i,
];

const MIN_CONTENT_CHARS = 300;

// A job-detail URL almost always carries the posting's identity: a numeric req id
// (Greenhouse, Workday pid, Microsoft) or a UUID (Lever, Ashby). If the requested
// URL had one and the final URL lost it, the browser landed somewhere else.
const JOB_ID_TOKEN = /[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}|\d{5,}/gi;

function jobIdToken(url = '') {
  const matches = url.match(JOB_ID_TOKEN);
  return matches ? matches[matches.length - 1].toLowerCase() : null;
}

function firstMatch(patterns, text = '') {
  return patterns.find((pattern) => pattern.test(text));
}

function hasApplyControl(controls = []) {
  return controls.some((control) => APPLY_PATTERNS.some((pattern) => pattern.test(control)));
}

export function classifyLiveness({ status = 0, requestedUrl = '', finalUrl = '', bodyText = '', applyControls = [] } = {}) {
  if (status === 404 || status === 410) {
    return { result: 'expired', code: 'http_gone', reason: `HTTP ${status}` };
  }

  // Bot/anti-scraping walls — never expired. Check before the content-length and
  // listing-page heuristics, which would otherwise misread the short challenge
  // body as a dead posting. 403/503 are access-blocked signals, not "gone"
  // (a genuinely removed posting returns 404/410 or a hard-expired banner).
  const botChallenge = firstMatch(BOT_CHALLENGE_PATTERNS, bodyText);
  if (botChallenge) {
    return { result: 'uncertain', code: 'bot_challenge', reason: `anti-bot challenge: ${botChallenge.source}` };
  }
  if (status === 403 || status === 503) {
    return { result: 'uncertain', code: 'access_blocked', reason: `HTTP ${status} (access blocked, likely anti-bot)` };
  }

  const expiredUrl = firstMatch(EXPIRED_URL_PATTERNS, finalUrl);
  if (expiredUrl) {
    return { result: 'expired', code: 'expired_url', reason: `redirect to ${finalUrl}` };
  }

  const expiredBody = firstMatch(HARD_EXPIRED_PATTERNS, bodyText);
  if (expiredBody) {
    return { result: 'expired', code: 'expired_body', reason: `pattern matched: ${expiredBody.source}` };
  }

  // A dead permalink that 301s to a generic search/listing page still shows
  // "Apply" buttons — on OTHER jobs' cards (seen when jobs.careers.microsoft.com
  // permalinks migrated to apply.careers.microsoft.com). When the requested URL
  // carried a job identifier and the final URL lost it, the page being read is
  // not the posting, so apply controls are not evidence of liveness. Uncertain,
  // not expired: a portal migration can 301 live postings too, and a false
  // "expired" permanently filters a real job out of scans.
  const jobId = jobIdToken(requestedUrl);
  if (jobId && finalUrl && !finalUrl.toLowerCase().includes(jobId)) {
    return {
      result: 'uncertain',
      code: 'redirected_off_posting',
      reason: `redirected to ${finalUrl} — job id "${jobId}" missing from final URL`,
    };
  }

  if (hasApplyControl(applyControls)) {
    return { result: 'active', code: 'apply_control_visible', reason: 'visible apply control detected' };
  }

  const listingPage = firstMatch(LISTING_PAGE_PATTERNS, bodyText);
  if (listingPage) {
    return { result: 'expired', code: 'listing_page', reason: `pattern matched: ${listingPage.source}` };
  }

  if (bodyText.trim().length < MIN_CONTENT_CHARS) {
    return { result: 'expired', code: 'insufficient_content', reason: 'insufficient content — likely nav/footer only' };
  }

  return { result: 'uncertain', code: 'no_apply_control', reason: 'content present but no visible apply control found' };
}