/**
 * Forage Chrome Extension — Content Script
 *
 * Injected into every page at document_idle. Reads page metadata and sends
 * it to the background service worker, which POSTs to the Forage server.
 * Also fires a dwell signal after 30 seconds of continuous page presence.
 */
(function () {
  const url = location.href;

  // Skip internal browser pages and the Forage UI itself to avoid
  // self-referential signals and phantom items in the feed.
  if (
    url.startsWith('chrome://') ||
    url.startsWith('chrome-extension://') ||
    url.startsWith('moz-extension://') ||
    /https?:\/\/(localhost|127\.0\.0\.1)(:\d+)?/.test(url)
  ) {
    return;
  }

  const canonical_url =
    document.querySelector('link[rel="canonical"]')?.href || '';
  const title = document.title || url;
  const words = (document.body?.innerText || '').trim().split(/\s+/).length;
  const reading_time_min = Math.max(1, Math.round(words / 200));
  const description =
    document.querySelector('meta[name="description"]')?.content ||
    document.querySelector('meta[property="og:description"]')?.content ||
    '';
  const source = (() => {
    try {
      return new URL(url).hostname.replace(/^www\./, '');
    } catch {
      return '';
    }
  })();

  let itemId = null;

  // Send capture to background worker
  chrome.runtime.sendMessage(
    { type: 'capture', url, canonical_url, title, source, description, reading_time_min },
    response => {
      if (response?.item_id) itemId = response.item_id;
    }
  );

  // 30s dwell timer — cancelled if the user navigates away
  const DWELL_MS = 30_000;
  let dwellTimer = setTimeout(() => {
    if (itemId == null) return;
    chrome.runtime.sendMessage({ type: 'dwell', item_id: itemId, duration_ms: DWELL_MS });
  }, DWELL_MS);

  window.addEventListener('beforeunload', () => {
    clearTimeout(dwellTimer);
  });
})();