self.addEventListener("push", (event) => {
  if (!event.data) return;
  const message = event.data.json();
  event.waitUntil(self.registration.showNotification(message.title, {
    body: message.body,
    icon: "/icon.png",
    tag: message.id,
    data: { url: message.url },
  }));
});

self.addEventListener("notificationclick", (event) => {
  event.notification.close();
  const url = new URL(event.notification.data.url, self.location.origin);
  if (url.origin !== self.location.origin) return;
  event.waitUntil((async () => {
    const windows = await self.clients.matchAll({ type: "window", includeUncontrolled: true });
    const existing = windows.find((client) => client.url === url.href);
    if (existing) return existing.focus();
    return self.clients.openWindow(url.href);
  })());
});