/* BM WATCH TRACKER v1 (ops, Aug 29 2026)
   One module, two consumers: localStorage watch history (feeds the rails)
   and GA4 custom events (replaces enhanced-measurement video, which misses facade players).
   Usage on an episode page, after the lite-youtube facade upgrades to a real player:
     const player = await document.querySelector('lite-youtube').getYTPlayer();
     BMTracker.attach(player, EPISODE_ID, CATALOG_ENTRY); // entry = its object from catalog.json
   On up-next swap (same player, new video): BMTracker.attach(player, nextId, nextEntry) again.
*/
(function () {
  var KEY = 'bm_watch_v1';
  var MILESTONES = [10, 25, 50, 75, 90];
  var COMPLETE_PCT = 95;
  var THEME_CREDIT_PCT = 70;

  function load() {
    try { return JSON.parse(localStorage.getItem(KEY)) || { v: 1, episodes: {}, lastWatched: null, themeCounts: {} }; }
    catch (e) { return { v: 1, episodes: {}, lastWatched: null, themeCounts: {} }; }
  }
  function save(s) { try { localStorage.setItem(KEY, JSON.stringify(s)); } catch (e) { /* private mode: session-only */ } }
  function ga(name, params) { if (typeof gtag === 'function') gtag('event', name, params); }

  var current = null; // { player, id, entry, timer, played, lastT, milestonesFired, themeCredited }

  function tick() {
    if (!current) return;
    var p = current.player;
    var t, d;
    try { t = p.getCurrentTime(); d = p.getDuration(); } catch (e) { return; }
    if (!d) return;
    var delta = t - current.lastT;
    if (delta > 0 && delta < 3) current.played += delta; // seeks don't inflate
    current.lastT = t;
    var pct = Math.min(100, Math.round((t / d) * 100));

    var s = load();
    var e = s.episodes[current.id] || {};
    e.t = Math.floor(t); e.d = Math.floor(d);
    e.pct = Math.max(e.pct || 0, pct);
    e.last = Date.now();
    if (pct >= COMPLETE_PCT) e.done = true;
    s.episodes[current.id] = e;
    s.lastWatched = current.id;

    if (!current.themeCredited && pct >= THEME_CREDIT_PCT && current.entry && current.entry.tags) {
      current.entry.tags.forEach(function (tag) { s.themeCounts[tag] = (s.themeCounts[tag] || 0) + 1; });
      current.themeCredited = true;
    }
    save(s);

    MILESTONES.forEach(function (m) {
      if (pct >= m && current.milestonesFired.indexOf(m) === -1) {
        current.milestonesFired.push(m);
        ga('video_progress', { video_id: current.id, video_title: current.entry ? current.entry.title : '', percent: m });
      }
    });
  }

  function flushWatchTime(reason) {
    if (!current || current.played < 1) return;
    ga('video_watch_time', { video_id: current.id, seconds: Math.round(current.played), reason: reason });
    current.played = 0;
  }

  window.BMTracker = {
    attach: function (player, id, entry) {
      if (current) { flushWatchTime('swap'); clearInterval(current.timer); }
      current = { player: player, id: id, entry: entry || null, timer: null, played: 0, lastT: 0, milestonesFired: [], themeCredited: false };
      var resume = (load().episodes[id] || {});
      if (resume.t && resume.pct < COMPLETE_PCT && resume.t > 10) { try { player.seekTo(resume.t, true); } catch (e) {} }
      player.addEventListener('onStateChange', function (ev) {
        if (ev.data === 1) { // playing
          if (!current.startedFired) { current.startedFired = true; ga('video_start', { video_id: id, video_title: entry ? entry.title : '' }); }
          if (!current.timer) current.timer = setInterval(tick, 1000);
        } else {
          if (current.timer) { clearInterval(current.timer); current.timer = null; }
          if (ev.data === 2) flushWatchTime('pause');
          if (ev.data === 0) { // ended
            tick(); flushWatchTime('ended');
            var s = load(); var e = s.episodes[id] || {}; e.done = true; e.pct = 100; s.episodes[id] = e; save(s);
            ga('video_complete', { video_id: id });
            document.dispatchEvent(new CustomEvent('bm:ended', { detail: { id: id } })); // up-next overlay listens for this
          }
        }
      });
      document.addEventListener('visibilitychange', function () { if (document.hidden) { tick(); flushWatchTime('hidden'); } });
      window.addEventListener('pagehide', function () { tick(); flushWatchTime('unload'); });
    },
    nextAuto: function (fromId, toId) { ga('next_video_auto', { from: fromId, to: toId }); },
    history: load // rails call BMTracker.history() to build continue-watching etc.
  };
})();