new Cookies(cookieStr?: string, isSetCookie?: boolean): Cookies;

cookies.get(name?: string): null | Cookie | Array<Cookie>;

cookies.set(name: string, value: string, options?: Cookie): boolean;

cookies.append(name: string, value: string, options?: Cookie): boolean;

cookies.remove(name: string, options?: Cookie): boolean;

function handleEvent(event) {
  const request = event.request;

  // Parse the Cookie request header (invalid fragments are automatically ignored)
  const cookies = new Cookies(request.headers.get('Cookie') || '');

  // Read the login state marker cookie
  // get may return null / a single Cookie / an array of Cookies (duplicates with the same name)
  const loginState = cookies.get('login_state');
  const loggedIn = loginState !== null &&
                   !Array.isArray(loginState) &&
                   loginState.value === '1';

  if (!loggedIn) {
    // Not logged in: redirect to the login page with the return URL
    const backUrl = encodeURIComponent(request.url);
    return event.respondWith(Response.redirect(`https://www.example.com/login?back_url=${backUrl}`, 302));
  }

  // Logged in: allow origin-pull
  return;
}