watchparty/client/js/party.js

// Party REST + realtime WebSocket - same origin as everything else, auth is
// the session cookie (see embyApi.js), so no headers/tokens to pass around
// here at all.

async function apiFetch(path, options = {}) {
  const res = await fetch(path, {
    credentials: 'same-origin',
    ...options,
    headers: { 'Content-Type': 'application/json', ...(options.headers || {}) }
  });
  if (!res.ok) {
    const body = await res.json().catch(() => ({}));
    throw new Error(body.error || `Request failed: ${res.status}`);
  }
  return res.json();
}

export async function listActiveParties() {
  const data = await apiFetch('/api/parties');
  return data.parties || [];
}

export function createParty(itemId) {
  return apiFetch('/api/parties', { method: 'POST', body: JSON.stringify({ itemId }) });
}

export function joinParty(joinCode) {
  return apiFetch(`/api/parties/${encodeURIComponent(joinCode)}/join`, { method: 'POST' });
}

export function leaveParty(partyId) {
  return apiFetch(`/api/parties/${partyId}/leave`, { method: 'POST' });
}

export function getParty(partyId) {
  return apiFetch(`/api/parties/${partyId}`);
}

/**
 * Opens the realtime connection for a party. Auth rides along on the
 * WebSocket's HTTP upgrade handshake as the session cookie (browsers attach
 * cookies to that handshake automatically for a same-origin URL) - so all
 * this needs to send is which party to join.
 */
export function connectParty(partyId, { onMembers, onPlaystate, onError, onClose } = {}) {
  const proto = location.protocol === 'https:' ? 'wss://' : 'ws://';
  const ws = new WebSocket(proto + location.host + '/ws');

  ws.addEventListener('open', () => {
    ws.send(JSON.stringify({ type: 'join', partyId }));
  });

  ws.addEventListener('message', (evt) => {
    let msg;
    try { msg = JSON.parse(evt.data); } catch (err) { return; }
    if (msg.type === 'members' && onMembers) onMembers(msg.members);
    if (msg.type === 'playstate' && onPlaystate) onPlaystate(msg);
    if (msg.type === 'error' && onError) onError(msg.message);
  });

  ws.addEventListener('close', () => { if (onClose) onClose(); });

  return {
    sendPlaystate(isPaused, positionTicks) {
      if (ws.readyState === WebSocket.OPEN) {
        ws.send(JSON.stringify({ type: 'playstate', isPaused, positionTicks }));
      }
    },
    leave() {
      if (ws.readyState === WebSocket.OPEN) {
        ws.send(JSON.stringify({ type: 'leave' }));
      }
      ws.close();
    }
  };
}