(() => {
  // Optional live updates on dashboard
  if (!document.getElementById('tbl-displays')) return;

  const socket = io({ transports: ['websocket'], upgrade: false });
  socket.on('connect', () => {
    socket.emit('admin_join');
  });

  function updateRow(publicId, patch) {
    const row = document.querySelector(`tr[data-public-id="${publicId}"]`);
    if (!row) return;
    if (patch.is_online !== undefined) row.querySelector('.st').textContent = patch.is_online ? 'online' : 'offline';
    if (patch.last_seen) row.querySelector('.ls').textContent = patch.last_seen;
    if (patch.latency_ms !== undefined) row.querySelector('.lat').textContent = patch.latency_ms ? `${patch.latency_ms.toFixed(1)}ms` : '';
    if (patch.offset_ms !== undefined) row.querySelector('.off').textContent = patch.offset_ms ? `${patch.offset_ms.toFixed(1)}ms` : '';
  }

  socket.on('admin_snapshot', (msg) => {
    const live = msg.live || {};
    Object.keys(live).forEach(pid => updateRow(pid, { ...live[pid], is_online: true }));
  });

  socket.on('admin_display_update', (msg) => {
    updateRow(msg.public_id, msg);
  });

  socket.on('admin_event_triggered', (msg) => {
    const el = document.getElementById('active-event');
    if (!el) return;
    el.innerHTML = `<div><strong>${msg.event_name}</strong> (#${msg.event_id})</div><div>Start: <code>${msg.start_time_ms.toFixed(3)}</code></div>`;
  });
})();