let applyingRemote = false;

function getMediaElement() {
  const els = Array.from(document.querySelectorAll('video, audio'));
  if (!els.length) return null;
  const playing = els.find((el) => !el.paused && !el.ended);
  if (playing) return playing;
  const videos = els.filter((el) => el.tagName === 'VIDEO');
  return videos.length ? videos[0] : els[0];
}

function onPlay(e) {
  if (applyingRemote) return;
  chrome.runtime.sendMessage({ type: 'media_event', action: 'play', time: e.target.currentTime });
}

function onPause(e) {
  if (applyingRemote) return;
  chrome.runtime.sendMessage({ type: 'media_event', action: 'pause', time: e.target.currentTime });
}

function onSeeked(e) {
  if (applyingRemote) return;
  chrome.runtime.sendMessage({ type: 'media_event', action: 'seek', time: e.target.currentTime });
}

function attachToMedia(el) {
  if (el._syncwatchAttached) return;
  el._syncwatchAttached = true;
  el.addEventListener('play', onPlay);
  el.addEventListener('pause', onPause);
  el.addEventListener('seeked', onSeeked);
}

function attachAll() {
  document.querySelectorAll('video, audio').forEach(attachToMedia);
}

attachAll();

const observer = new MutationObserver(attachAll);
observer.observe(document.documentElement, { childList: true, subtree: true });

chrome.runtime.onMessage.addListener((msg) => {
  if (msg.type !== 'apply_sync') return;

  const el = getMediaElement();
  if (!el) return;

  applyingRemote = true;

  // Re-sync time on any action; only seek if drift is significant
  const drift = Math.abs(el.currentTime - msg.time);

  if (msg.action === 'play') {
    if (drift > 1) el.currentTime = msg.time;
    el.play().catch(() => {});
  } else if (msg.action === 'pause') {
    el.pause();
    if (drift > 1) el.currentTime = msg.time;
  } else if (msg.action === 'seek') {
    el.currentTime = msg.time;
  }

  setTimeout(() => { applyingRemote = false; }, 500);
});