(function () {
  'use strict';

  /* ── Background player ───────────────────────────────────── */
  const bgAudio   = new Audio();
  let bgPlaying   = false;
  let bgBar: HTMLElement | null = null;
  let bgTitle: HTMLElement | null = null;
  let bgPlayBtn: HTMLButtonElement | null = null;

  function createBgBar(): void {
    if (bgBar) return;
    bgBar = document.createElement('div');
    bgBar.id = 'bg-bar';
    bgBar.innerHTML =
      '<span id="bg-title"></span>' +
      '<button id="bg-play" aria-label="Abspielen">▶</button>' +
      '<button id="bg-close" aria-label="Schließen">✕</button>';
    document.body.appendChild(bgBar);

    bgTitle   = document.getElementById('bg-title');
    bgPlayBtn = document.getElementById('bg-play') as HTMLButtonElement;

    bgPlayBtn.addEventListener('click', function () {
      if (bgAudio.paused) void bgAudio.play(); else bgAudio.pause();
    });
    document.getElementById('bg-close')?.addEventListener('click', function () {
      bgAudio.pause();
      if (bgBar) bgBar.style.display = 'none';
    });
    bgAudio.addEventListener('play',  function () { if (bgPlayBtn) bgPlayBtn.textContent = '⏸'; });
    bgAudio.addEventListener('pause', function () { if (bgPlayBtn) bgPlayBtn.textContent = '▶'; });
    bgAudio.addEventListener('ended', function () { if (bgPlayBtn) bgPlayBtn.textContent = '▶'; });
  }

  function sendToBg(src: string, title: string): void {
    createBgBar();
    if (bgBar) bgBar.style.display = 'flex';
    bgAudio.src = src;
    if (bgTitle) bgTitle.textContent = title;
    void bgAudio.play();
  }

  // Attach "♪" button to every inline audio player
  document.querySelectorAll<HTMLAudioElement>('audio.media-audio').forEach(function (a) {
    const btn = document.createElement('button');
    btn.className = 'btn-bg-music';
    btn.textContent = '♪ Hintergrundmusik';
    btn.type = 'button';
    const title = a.title || a.src.split('/').pop() || a.src;
    btn.addEventListener('click', function () { sendToBg(a.src, title); });
    a.insertAdjacentElement('afterend', btn);
  });

  /* ── Video autoplay + coordination ──────────────────────── */
  const obs = new IntersectionObserver(function (entries: IntersectionObserverEntry[]) {
    entries.forEach(function (e) {
      const v = e.target as HTMLVideoElement;
      if (e.isIntersecting) {
        void v.play();
      } else {
        v.pause();
      }
    });
  }, { threshold: 0.3 });

  document.querySelectorAll<HTMLVideoElement>('video.media-embed').forEach(function (v) {
    v.muted = true;
    v.loop  = true;
    v.setAttribute('playsinline', '');
    obs.observe(v);

    // User unmutes → pause background music
    v.addEventListener('volumechange', function () {
      if (!v.muted && !v.paused) {
        bgPlaying = !bgAudio.paused;
        bgAudio.pause();
      }
      // Video muted again → resume background
      if (v.muted && bgPlaying) {
        void bgAudio.play();
        bgPlaying = false;
      }
    });

    // Video pauses or ends → resume background if it was playing
    v.addEventListener('pause', function () {
      if (bgPlaying) { void bgAudio.play(); bgPlaying = false; }
    });
    v.addEventListener('ended', function () {
      if (bgPlaying) { void bgAudio.play(); bgPlaying = false; }
    });
  });

})();