/* Opt-in, same-browser synchronization. The regular deck has no channel or session. */
(() => {
  const params = new URLSearchParams(location.search);
  const session = params.get('session');
  const role = params.get('view');
  if (!session || !['preview', 'audience'].includes(role)) return;
  const channel = new BroadcastChannel(`aritmolab-presenter:${session}`);
  const sender = crypto.randomUUID();
  const storageKey = `aritmolab-state:${session}`;
  let applying = false;
  let pending = false;
  const send = (type, extra = {}) => channel.postMessage({ type, role, sender, ...extra });
  const api = window.PresentationControls;
  const valid = state => state && Number.isInteger(state.index) && state.index >= 0 && state.index < Reveal.getTotalSlides();
  function save(state) { try { localStorage.setItem(storageKey, JSON.stringify(state)); } catch {} }
  function publish() {
    if (applying || pending) return;
    pending = true;
    queueMicrotask(() => {
      pending = false;
      const state = api.snapshot();
      save(state);
      send('state', { state });
    });
  }
  function apply(state) {
    if (!valid(state)) return;
    applying = true;
    Reveal.slide(state.index);
    api.closePopup();
    if (state.popup) api.openPopup(state.popup);
    applying = false;
    save(api.snapshot());
  }
  function command(message) {
    if (message.action === 'next') Reveal.next();
    if (message.action === 'previous') Reveal.prev();
    if (message.action === 'slide' && valid({ index: message.index })) Reveal.slide(message.index);
    if (message.action === 'popup' && message.popup) api.openPopup(message.popup);
    if (message.action === 'close') api.closePopup();
    publish();
  }
  function ready() {
    Reveal.configure({ overview: false, pause: false });
    if (role === 'preview') {
      // Remove only the presenter's footer and its 34px, preserving the slide body geometry.
      document.documentElement.classList.add('presenter-preview');
      Reveal.configure({ height: 686 });
    }
    try { apply(JSON.parse(localStorage.getItem(storageKey))); } catch {}
    addEventListener('presentationchange', publish);
    Reveal.on('slidechanged', publish);
    channel.onmessage = ({ data }) => {
      if (!data || data.sender === sender) return;
      if (data.type === 'state') apply(data.state);
      if (data.type === 'command' && role === 'preview') command(data);
      if (data.type === 'request' && role === 'preview') publish();
    };
    if (role === 'preview') publish();
    else send('request');
    send('presence');
    setInterval(() => send('presence'), 1000);
    addEventListener('pagehide', () => send('departed'));
    if (role === 'audience') {
      document.title = 'AritmoLab | Audience';
      const button = document.createElement('button');
      button.textContent = 'Full screen';
      button.setAttribute('aria-label', 'Enter audience full screen');
      Object.assign(button.style, { position: 'fixed', right: '16px', top: '16px', zIndex: '200', padding: '10px 18px', borderRadius: '6px', border: '1px solid #b9afb1', background: '#faf7f7', color: '#482d34', cursor: 'pointer', font: '15px system-ui' });
      button.onclick = () => document.documentElement.requestFullscreen().catch(() => { button.textContent = 'Use the browser full-screen command'; });
      document.addEventListener('fullscreenchange', () => { button.hidden = Boolean(document.fullscreenElement); });
      document.body.append(button);
    }
  }
  if (Reveal.isReady()) ready(); else Reveal.on('ready', ready);
})();