const config = require('../config');
const { fetchWithPolicy } = require('../http');
const { createBrowserSession, shouldUseBrowser } = require('./browserCrawler');
const { classifyPageWithLlm } = require('./crawlerClassifier');
const { getRssSources } = require('./sourceCatalog');

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

const TRACKING_PARAM_PATTERNS = [
  /^utm_/i,
  /^fbclid$/i,
  /^gclid$/i,
  /^mkt_tok$/i,
  /^mc_cid$/i,
  /^mc_eid$/i,
  /^ref$/i,
  /^ref_src$/i,
  /^s$/i,
  /^cmpid$/i,
  /^guccounter$/i,
  /^guce_referrer$/i,
  /^guce_referrer_sig$/i,
];
const LISTING_PATH_HINT = /(archive|archives|latest|topic|topics|section|sections|category|categories|news|world|business|politics|technology|tech|markets|economy|page|tag|tags)/i;
const ARTICLE_DATE_PATH = /\/\d{4}\/\d{2}\/\d{2}(?:\/|$)|\/\d{4}\/\d{2}(?:\/|$)/;
const ARTICLE_PATH_HINT = /(\/article\/|\/articles\/|\/news\/|\/story\/|\/stories\/)/i;
const ARTICLE_PATH_STRONG_HINT = /\/\d{4}\/\d{2}\/\d{2}\//;
const LISTING_ARTICLE_FALSE_POSITIVE_PATH = /(\/category\/|\/tag\/|\/latest(?:\/|$)|\/topics?(?:\/|$)|\/sections?(?:\/|$))/i;
const BLOCKED_PATH_HINT = /(\/search(?:\/|$)|\/login(?:\/|$)|\/account(?:\/|$)|\/video(?:\/|$)|\/videos(?:\/|$)|\/podcast(?:\/|$)|\/podcasts(?:\/|$)|\/live(?:\/|$)|\/subscribe(?:\/|$)|\/subscription(?:\/|$)|\/newsletters?(?:\/|$)|\/privacy(?:\/|$)|\/terms(?:\/|$)|\/about(?:\/|$)|\/contact(?:\/|$))/i;
const EXPLORATION_PATH_HINT = /(\/page\/\d+(?:\/|$)|[?&]page=\d+|\/archive(?:s)?(?:\/|$)|\/latest(?:\/|$)|\/news(?:\/|$)|\/world(?:\/|$)|\/business(?:\/|$)|\/politics(?:\/|$)|\/technology(?:\/|$)|\/tech(?:\/|$)|\/markets(?:\/|$)|\/economy(?:\/|$)|\/topic(?:s)?(?:\/|$)|\/section(?:s)?(?:\/|$)|\/category(?:ies)?(?:\/|$)|\/tag(?:s)?(?:\/|$))/i;

function decodeHtmlEntities(value) {
  return String(value || '')
    .replace(/&#x([0-9a-f]+);/gi, (_, hex) => String.fromCodePoint(parseInt(hex, 16)))
    .replace(/&#(\d+);/g, (_, dec) => String.fromCodePoint(parseInt(dec, 10)))
    .replace(/"/g, '"')
    .replace(/'/g, "'")
    .replace(/'/g, "'")
    .replace(/&/g, '&')
    .replace(/&lt;/g, '<')
    .replace(/&gt;/g, '>')
    .replace(/&nbsp;/g, ' ');
}

function stripTags(value) {
  return decodeHtmlEntities(String(value || '').replace(/<[^>]*>/g, ' ')).replace(/\s+/g, ' ').trim();
}

function normalizeText(value) {
  return stripTags(value).replace(/\s+/g, ' ').trim();
}

function isAllowedHost(hostname, allowedHosts) {
  const normalized = String(hostname || '').toLowerCase();
  return allowedHosts.some((allowedHost) => {
    const candidate = String(allowedHost || '').toLowerCase();
    return normalized === candidate || normalized.endsWith(`.${candidate}`);
  });
}

function shouldDropParam(key) {
  return TRACKING_PARAM_PATTERNS.some((pattern) => pattern.test(key));
}

function canonicalizeUrl(rawUrl, baseUrl, allowedHosts) {
  try {
    const url = new URL(rawUrl, baseUrl);

    if (!['http:', 'https:'].includes(url.protocol)) {
      return null;
    }

    if (allowedHosts && allowedHosts.length && !isAllowedHost(url.hostname, allowedHosts)) {
      return null;
    }

    url.hash = '';
    url.username = '';
    url.password = '';

    const params = [...url.searchParams.entries()]
      .filter(([key]) => !shouldDropParam(key))
      .sort(([left], [right]) => left.localeCompare(right));

    url.search = '';
    for (const [key, value] of params) {
      url.searchParams.append(key, value);
    }

    if (url.pathname !== '/') {
      url.pathname = url.pathname.replace(/\/+$/, '') || '/';
    }

    return url.toString();
  } catch {
    return null;
  }
}

function extractAttribute(tag, name) {
  const match = tag.match(new RegExp(`${name}\\s*=\\s*(["'])(.*?)\\1`, 'i'));
  return match ? decodeHtmlEntities(match[2]).trim() : '';
}

function extractMetaMap(html) {
  const metas = new Map();
  const metaTags = html.match(/<meta\b[^>]*>/gi) || [];

  for (const tag of metaTags) {
    const key = extractAttribute(tag, 'property') || extractAttribute(tag, 'name');
    const content = extractAttribute(tag, 'content');

    if (!key || !content) {
      continue;
    }

    metas.set(key.toLowerCase(), content);
  }

  return metas;
}

function extractCanonicalHref(html) {
  const links = html.match(/<link\b[^>]*>/gi) || [];

  for (const tag of links) {
    const rel = extractAttribute(tag, 'rel').toLowerCase();
    if (!rel || !rel.split(/\s+/).includes('canonical')) {
      continue;
    }

    const href = extractAttribute(tag, 'href');
    if (href) {
      return href;
    }
  }

  return null;
}

function extractTitleTag(html) {
  const match = html.match(/<title[^>]*>([\s\S]*?)<\/title>/i);
  return match ? normalizeText(match[1]) : null;
}

function extractH1(html) {
  const match = html.match(/<h1\b[^>]*>([\s\S]*?)<\/h1>/i);
  return match ? normalizeText(match[1]) : null;
}

function extractTimeDatetime(html) {
  const match = html.match(/<time\b[^>]*datetime\s*=\s*(["'])(.*?)\1/i);
  return match ? decodeHtmlEntities(match[2]).trim() : null;
}

function extractParagraphStats(html) {
  const paragraphs = html.match(/<p\b[^>]*>[\s\S]*?<\/p>/gi) || [];
  const normalizedParagraphs = paragraphs.slice(0, 12).map((paragraph) => normalizeText(paragraph)).filter(Boolean);

  return {
    textLength: normalizedParagraphs.reduce((total, paragraph) => total + paragraph.length, 0),
    substantialCount: normalizedParagraphs.filter((paragraph) => paragraph.length >= 80).length,
  };
}

function extractJsonLdBlocks(html) {
  const blocks = [];
  const regex = /<script\b[^>]*type\s*=\s*(["'])application\/ld\+json\1[^>]*>([\s\S]*?)<\/script>/gi;
  let match;

  while ((match = regex.exec(html)) !== null) {
    const raw = String(match[2] || '').trim();
    if (!raw) {
      continue;
    }

    try {
      blocks.push(JSON.parse(raw));
    } catch {
      continue;
    }
  }

  return blocks;
}

function isArticleType(type) {
  if (Array.isArray(type)) {
    return type.some((entry) => isArticleType(entry));
  }

  return ['article', 'newsarticle'].includes(String(type || '').toLowerCase());
}

function extractArticleJsonLd(html) {
  const blocks = extractJsonLdBlocks(html);

  for (const block of blocks) {
    if (!block || typeof block !== 'object') {
      continue;
    }

    if (isArticleType(block['@type'])) {
      return block;
    }

    const graph = Array.isArray(block['@graph']) ? block['@graph'] : [];
    const directChildren = [
      ...graph,
      ...(Array.isArray(block.mainEntity) ? block.mainEntity : [block.mainEntity]),
      ...(Array.isArray(block.mainEntityOfPage) ? block.mainEntityOfPage : [block.mainEntityOfPage]),
    ].filter((value) => value && typeof value === 'object');

    const article = directChildren.find((value) => isArticleType(value['@type']));
    if (article) {
      return article;
    }
  }

  return null;
}

function extractLinks(html, pageUrl, allowedHosts) {
  const links = [];
  const seen = new Set();
  const regex = /<a\b[^>]*href\s*=\s*(["'])(.*?)\1[^>]*>([\s\S]*?)<\/a>/gi;
  let match;

  while ((match = regex.exec(html)) !== null) {
    const url = canonicalizeUrl(match[2], pageUrl, allowedHosts);
    if (!url || seen.has(url)) {
      continue;
    }

    const text = normalizeText(match[3]);
    seen.add(url);
    links.push({ url, text });
  }

  return links;
}

function selectTitle(meta, jsonLdArticle, html) {
  return [
    meta.get('og:title'),
    meta.get('twitter:title'),
    jsonLdArticle && jsonLdArticle.headline,
    extractH1(html),
    extractTitleTag(html),
  ].find((value) => String(value || '').trim()) || null;
}

function selectDescription(meta, jsonLdArticle) {
  return [
    meta.get('og:description'),
    meta.get('description'),
    jsonLdArticle && jsonLdArticle.description,
  ].find((value) => String(value || '').trim()) || null;
}

function selectPubDate(meta, jsonLdArticle, html) {
  return [
    jsonLdArticle && jsonLdArticle.datePublished,
    meta.get('article:published_time'),
    meta.get('og:article:published_time'),
    extractTimeDatetime(html),
  ].find((value) => String(value || '').trim()) || null;
}

function scorePage(pageUrl, meta, html, jsonLdArticle, links) {
  let articleScore = 0;
  let listingScore = 0;
  const pathname = new URL(pageUrl).pathname;
  const hasArticleDatePath = ARTICLE_DATE_PATH.test(pageUrl);
  const hasArticlePathHint = ARTICLE_PATH_HINT.test(pageUrl);
  const hasStrongArticlePath = ARTICLE_PATH_STRONG_HINT.test(pathname);
  const hasListingFalsePositivePath = LISTING_ARTICLE_FALSE_POSITIVE_PATH.test(pathname);
  const { textLength: paragraphTextLength, substantialCount: substantialParagraphCount } = extractParagraphStats(html);
  const headlineLinks = links.filter(({ text }) => text.length >= 25 && text.length <= 180).length;
  const h1 = extractH1(html);
  const titleTag = extractTitleTag(html);
  const ogTitle = normalizeText(meta.get('og:title') || '');
  const twitterTitle = normalizeText(meta.get('twitter:title') || '');
  const titleSignalsLower = [h1, titleTag, ogTitle, twitterTitle].filter(Boolean).map((value) => value.toLowerCase());
  const looksLikeSectionTitle = titleSignalsLower.some((value) => /^(category:|section:)/.test(value)
    || /(market[s]?|business|technology|tech|science|health|gaming|culture|news|world|economy)/.test(value) && value.length <= 80);
  const looksLikeCommercialPage = titleSignalsLower.some((value) => /(subscribe|subscription|sign in|log in|newsletter|advertis)/.test(value));
  const jsonLdHeadline = normalizeText(jsonLdArticle && jsonLdArticle.headline);
  const titleSignals = [h1, ogTitle, twitterTitle, titleTag].filter(Boolean);
  const matchingTitleSignals = titleSignals.filter((value) => jsonLdHeadline && (value.includes(jsonLdHeadline) || jsonLdHeadline.includes(value)));
  const hasJsonLdArticle = Boolean(jsonLdArticle && matchingTitleSignals.length > 0);
  const hasPublishTime = Boolean(meta.get('article:published_time') || meta.get('og:article:published_time') || extractTimeDatetime(html));
  const hasOgArticle = String(meta.get('og:type') || '').toLowerCase() === 'article';
  const hasArticleTag = /<article\b/i.test(html);
  const hasLongBody = paragraphTextLength >= 600 && substantialParagraphCount >= 3;
  const hasArticleStructure = Boolean(h1) && (hasArticleTag || hasLongBody);
  const hasMetadataArticleSignal = hasOgArticle || hasPublishTime || hasJsonLdArticle;
  const hasUrlArticleSignal = hasArticleDatePath || hasStrongArticlePath || hasArticlePathHint;
  const hasPrimaryArticleSignal = hasMetadataArticleSignal || hasUrlArticleSignal;
  const hasSecondaryArticleSignal = hasArticlePathHint || hasArticleStructure;

  if (hasJsonLdArticle) {
    articleScore += 3;
  }

  if (hasOgArticle && !hasListingFalsePositivePath) {
    articleScore += 2;
  }

  if (hasPublishTime && !hasListingFalsePositivePath) {
    articleScore += 2;
  }

  if (hasArticleTag) {
    articleScore += 1;
  }

  if (hasArticleDatePath || hasArticlePathHint) {
    articleScore += 2;
  }

  if (hasLongBody) {
    articleScore += 2;
  }

  if (links.length >= 20) {
    listingScore += 2;
  }

  if (headlineLinks >= 8) {
    listingScore += 2;
  }

  if (LISTING_PATH_HINT.test(pathname)) {
    listingScore += 1;
  }

  if (hasListingFalsePositivePath) {
    listingScore += 3;
  }

  if (looksLikeSectionTitle) {
    listingScore += 3;
  }

  if (looksLikeCommercialPage) {
    listingScore += 4;
  }

  if ((pathname === '/' || LISTING_PATH_HINT.test(pathname)) && headlineLinks >= 8 && links.length >= 20) {
    listingScore += 4;
  }

  if (headlineLinks >= 15 && !hasPrimaryArticleSignal && !hasLongBody) {
    listingScore += 3;
  }

  if (!hasPrimaryArticleSignal && headlineLinks >= 12 && links.length >= 25) {
    listingScore += 2;
  }

  const shouldAskLlm = !looksLikeCommercialPage && (
    articleScore >= 2
    || hasPrimaryArticleSignal
    || hasSecondaryArticleSignal
    || (headlineLinks <= 10 && links.length <= 40)
  );

  return {
    articleScore,
    listingScore,
    shouldAskLlm,
    headlineLinks,
    paragraphCount: substantialParagraphCount,
    paragraphTextLength,
  };
}

function shouldQueueLink(url) {
  const parsed = new URL(url);
  const pathname = parsed.pathname.toLowerCase();
  const hostname = parsed.hostname.toLowerCase();

  if (BLOCKED_PATH_HINT.test(pathname)) {
    return false;
  }

  if (hostname.includes('consent.yahoo.com') || pathname.startsWith('/v2/') || pathname.startsWith('/redirect')) {
    return false;
  }

  return !/\.(?:jpg|jpeg|png|gif|webp|svg|pdf|zip|xml|mp4|mp3|avi|mov|wmv|m4v)$/i.test(pathname);
}

function shouldContinueExploring(current, listingScore, links) {
  if (current.depth === 0) {
    return true;
  }

  if (listingScore >= 1) {
    return true;
  }

  if (current.depth <= 1 && links.length >= 8) {
    return true;
  }

  return EXPLORATION_PATH_HINT.test(current.url);
}

function slugifyLabel(label) {
  return String(label || '')
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '_')
    .replace(/^_+|_+$/g, '');
}

function unique(values) {
  return [...new Set(values.filter(Boolean))];
}

function buildAllowedHosts(hostname) {
  if (!hostname) {
    return [];
  }

  const hosts = [hostname.toLowerCase()];
  if (hostname.startsWith('www.')) {
    hosts.push(hostname.slice(4).toLowerCase());
  } else {
    hosts.push(`www.${hostname}`.toLowerCase());
  }

  return unique(hosts);
}

function cleanFeedPath(pathname) {
  const withoutIndex = pathname
    .replace(/\/index\.[a-z0-9]+$/i, '/')
    .replace(/\.[a-z0-9]+$/i, '')
    .replace(/\/rss(?:$|\/.*$)/i, '/')
    .replace(/\/feed(?:$|\/.*$)/i, '/')
    .replace(/\/feeds?(?:$|\/.*$)/i, '/')
    .replace(/\/xml(?:$|\/.*$)/i, '/')
    .replace(/\/arc\/outboundfeeds\//i, '/')
    .replace(/\/dynamo\//i, '/')
    .replace(/\/id\/\d+\/device\/rss\//i, '/')
    .replace(/\/contentexport\//i, '/')
    .replace(/\/rssfeedstopstories$/i, '/')
    .replace(/\/latest$/i, '/')
    .replace(/\/+$|^$/g, '');

  if (!withoutIndex) {
    return '/';
  }

  const segments = withoutIndex
    .split('/')
    .filter(Boolean)
    .filter((segment) => !/^(rss|feed|feeds|xml)$/i.test(segment))
    .slice(0, 3);

  if (!segments.length) {
    return '/';
  }

  return `/${segments.join('/')}`;
}

function buildDefaultSeeds(feedUrl) {
  try {
    const parsed = new URL(feedUrl);
    const origin = `${parsed.protocol}//${parsed.hostname}`;
    const cleanedPath = cleanFeedPath(parsed.pathname);

    return unique([
      canonicalizeUrl(origin, origin),
      cleanedPath === '/' ? null : canonicalizeUrl(`${origin}${cleanedPath}`, origin),
    ]);
  } catch {
    return [];
  }
}

function normalizeLimit(value, fallback, minimum, maximum) {
  const numeric = Number(value);

  if (numeric === -1) {
    return Number.POSITIVE_INFINITY;
  }

  if (!Number.isFinite(numeric)) {
    return fallback;
  }

  return Math.max(minimum, Math.min(numeric, maximum));
}

function normalizeSite(site) {
  const allowedHosts = unique((site.allowedHosts || []).map((host) => String(host || '').toLowerCase()).filter(Boolean));
  const seeds = unique((site.seeds || [])
    .map((seed) => canonicalizeUrl(seed, seed, allowedHosts))
    .filter(Boolean));
  const renderMode = String(site.renderMode || 'http').trim().toLowerCase() === 'browser' ? 'browser' : 'http';
  const maxPages = normalizeLimit(site.maxPages, 15, 1, 500);

  return {
    name: String(site.name || '').trim(),
    label: String(site.label || '').trim(),
    allowedHosts,
    seeds,
    renderMode,
    maxPages,
    maxDepth: normalizeLimit(site.maxDepth, 1, 0, 5),
    pageConcurrency: normalizeLimit(site.pageConcurrency, renderMode === 'browser' ? 2 : 4, 1, renderMode === 'browser' ? 4 : 12),
    maxQueuedPages: normalizeLimit(site.maxQueuedPages, Math.min(maxPages * 3, 1000), maxPages, 2000),
    memorySoftLimitMb: normalizeLimit(site.memorySoftLimitMb, 800, 128, 8192),
    memoryHardLimitMb: normalizeLimit(site.memoryHardLimitMb, 1400, 256, 16384),
    memoryThrottleDelayMs: normalizeLimit(site.memoryThrottleDelayMs, 1500, 100, 10000),
    llmPatternMinHits: normalizeLimit(site.llmPatternMinHits, 3, 1, 20),
    requestTimeout: Math.max(1000, Math.min(Number(site.requestTimeout) || 15000, 30000)),
  };
}

function getCrawlerSiteOverrides(label) {
  return config.newsCrawler?.overrides?.[label] || null;
}

function getConfiguredCrawlerSites() {
  const defaults = config.newsCrawler || {};
  const disabledLabels = new Set((defaults.disabledLabels || []).map((label) => String(label || '').trim()));
  const explicitSites = (defaults.sites || []).map((site) => normalizeSite(site));
  const explicitLabels = new Set(explicitSites.map((site) => site.label).filter(Boolean));
  const derivedSites = [];

  for (const feed of getRssSources()) {
    const label = String(feed.label || '').trim();
    if (!label || disabledLabels.has(label) || explicitLabels.has(label)) {
      continue;
    }

    let hostname = '';
    try {
      hostname = new URL(feed.feedUrl).hostname;
    } catch {
      continue;
    }

    const override = getCrawlerSiteOverrides(label) || {};
    const site = normalizeSite({
      label,
      name: override.name || `crawler_${slugifyLabel(label)}`,
      allowedHosts: override.allowedHosts || buildAllowedHosts(hostname),
      seeds: override.seeds || buildDefaultSeeds(feed.feedUrl),
      renderMode: override.renderMode || defaults.renderMode,
      maxPages: override.maxPages || defaults.maxPages,
      maxDepth: override.maxDepth || defaults.maxDepth,
      pageConcurrency: override.pageConcurrency,
      maxQueuedPages: override.maxQueuedPages,
      memorySoftLimitMb: override.memorySoftLimitMb || defaults.memorySoftLimitMb,
      memoryHardLimitMb: override.memoryHardLimitMb || defaults.memoryHardLimitMb,
      memoryThrottleDelayMs: override.memoryThrottleDelayMs || defaults.memoryThrottleDelayMs,
      llmPatternMinHits: override.llmPatternMinHits || defaults.llmPatternMinHits,
      requestTimeout: override.requestTimeout || defaults.requestTimeout,
    });

    if (site.name && site.allowedHosts.length && site.seeds.length) {
      derivedSites.push(site);
    }
  }

  return [...explicitSites.filter((site) => site.name && site.allowedHosts.length && site.seeds.length), ...derivedSites];
}

async function fetchHtml(url, site, browserSession) {
  if (browserSession) {
    return browserSession.fetchRenderedHtml(url);
  }

  const response = await fetchWithPolicy(url, {
    timeout: site.requestTimeout,
    retries: 1,
  });

  if (!response.ok) {
    return null;
  }

  const contentType = String(response.headers.get('content-type') || '').toLowerCase();
  if (!contentType.includes('text/html') && !contentType.includes('application/xhtml+xml')) {
    return null;
  }

  return response.text();
}

async function crawlSite(site) {
  const normalizedSite = normalizeSite(site);

  if (!normalizedSite.name || !normalizedSite.allowedHosts.length || !normalizedSite.seeds.length) {
    return [];
  }

  const browserSession = shouldUseBrowser(normalizedSite)
    ? await createBrowserSession(normalizedSite)
    : null;
  const queue = normalizedSite.seeds.map((url) => ({ url, depth: 0 }));
  const queuedUrls = new Set(normalizedSite.seeds);
  const visitedUrls = new Set();
  const discoveredArticleUrls = new Set();
  const articles = [];

  function getResidentSetMb() {
    return Math.round(process.memoryUsage().rss / (1024 * 1024));
  }

  async function throttleForMemory() {
    let residentSetMb = getResidentSetMb();

    while (residentSetMb >= normalizedSite.memorySoftLimitMb) {
      if (residentSetMb >= normalizedSite.memoryHardLimitMb) {
        console.error(`Crawler memory hard limit reached for ${normalizedSite.name}: ${residentSetMb}MB >= ${normalizedSite.memoryHardLimitMb}MB`);
        queue.length = 0;
        return false;
      }

      console.warn(`Crawler memory throttle for ${normalizedSite.name}: ${residentSetMb}MB >= ${normalizedSite.memorySoftLimitMb}MB`);
      await sleep(normalizedSite.memoryThrottleDelayMs);
      residentSetMb = getResidentSetMb();
    }

    return true;
  }

  async function processPage(current) {
    let html;
    try {
      html = await fetchHtml(current.url, normalizedSite, browserSession);
    } catch (error) {
      console.error(`Crawler fetch failed for ${normalizedSite.name}: ${current.url}`, error);
      return;
    }

    if (!html) {
      return;
    }

    const meta = extractMetaMap(html);
    const jsonLdArticle = extractArticleJsonLd(html);
    const canonicalHref = extractCanonicalHref(html);
    const canonicalUrl = canonicalHref
      ? canonicalizeUrl(canonicalHref, current.url, normalizedSite.allowedHosts) || current.url
      : current.url;
    const links = extractLinks(html, canonicalUrl, normalizedSite.allowedHosts);
    const heuristic = scorePage(canonicalUrl, meta, html, jsonLdArticle, links);
    let isArticleCandidate = false;
    let effectiveListingScore = heuristic.listingScore;

    if (heuristic.shouldAskLlm) {
      try {
        const llmDecision = await classifyPageWithLlm({
          siteName: normalizedSite.name,
          url: canonicalUrl,
          html,
          meta,
          jsonLdArticle,
          heuristic,
          links,
          minPatternHits: normalizedSite.llmPatternMinHits,
        });

        if (llmDecision.classification === 'article') {
          isArticleCandidate = true;
          effectiveListingScore = Math.max(0, heuristic.listingScore - 2);
        } else if (llmDecision.classification === 'listing') {
          effectiveListingScore = Math.max(heuristic.listingScore, 3);
        } else if (llmDecision.classification === 'other') {
          effectiveListingScore = Math.max(0, heuristic.listingScore - 1);
        }
      } catch (error) {
        console.error(`Crawler LLM classification failed for ${normalizedSite.name}: ${canonicalUrl}`, error);
      }
    }

    if (isArticleCandidate && !discoveredArticleUrls.has(canonicalUrl)) {
      const title = normalizeText(selectTitle(meta, jsonLdArticle, html));
      if (title) {
        discoveredArticleUrls.add(canonicalUrl);
        articles.push({
          title,
          description: normalizeText(selectDescription(meta, jsonLdArticle)) || null,
          url: canonicalUrl,
          source: normalizedSite.name,
          pubDate: selectPubDate(meta, jsonLdArticle, html),
          isIndexPage: false,
        });
      }
    }

    if (current.depth >= normalizedSite.maxDepth || !shouldContinueExploring(current, effectiveListingScore, links)) {
      return;
    }

    for (const link of links) {
      if (queuedUrls.size >= normalizedSite.maxQueuedPages) {
        break;
      }

      if (!shouldQueueLink(link.url) || visitedUrls.has(link.url) || queuedUrls.has(link.url)) {
        continue;
      }

      queuedUrls.add(link.url);
      queue.push({ url: link.url, depth: current.depth + 1 });
    }
  }

  try {
    while (queue.length && visitedUrls.size < normalizedSite.maxPages) {
      if (!await throttleForMemory()) {
        break;
      }

      const batch = [];

      while (queue.length && batch.length < normalizedSite.pageConcurrency && visitedUrls.size + batch.length < normalizedSite.maxPages) {
        const current = queue.shift();
        if (!current || visitedUrls.has(current.url)) {
          continue;
        }

        visitedUrls.add(current.url);
        batch.push(current);
      }

      if (!batch.length) {
        continue;
      }

      await Promise.all(batch.map(processPage));
    }

    return articles;
  } finally {
    if (browserSession) {
      await browserSession.close();
    }
  }
}

async function fetchCrawlerArticles() {
  const articles = [];

  for (const site of getConfiguredCrawlerSites()) {
    try {
      articles.push(...await crawlSite(site));
    } catch (error) {
      console.error(`Crawler failed for ${site && site.name ? site.name : 'unknown_site'}`, error);
    }
  }

  return articles;
}

module.exports = {
  fetchCrawlerArticles,
  crawlSite,
  canonicalizeUrl,
  getConfiguredCrawlerSites,
};