// musicshare service worker.
// Deliberately small: live data must always come from the network, so we only
// cache Next.js's immutable build assets, and show an offline page when a
// navigation fails. It also shows push notifications (reactions, follows, songs sent to you).
const VERSION = 'v2';
const STATIC_CACHE = `static-${VERSION}`;
const OFFLINE_URL = '/offline.html';

self.addEventListener('install', (event) => {
  event.waitUntil(caches.open(STATIC_CACHE).then((cache) => cache.addAll([OFFLINE_URL, '/icon-192.png'])));
  self.skipWaiting();
});

self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches
      .keys()
      .then((keys) => Promise.all(keys.filter((k) => k !== STATIC_CACHE).map((k) => caches.delete(k))))
      .then(() => self.clients.claim()),
  );
});

self.addEventListener('fetch', (event) => {
  const { request } = event;
  if (request.method !== 'GET') return;
  const url = new URL(request.url);
  if (url.origin !== self.location.origin) return; // API calls, artwork, etc.: straight to the network

  // Hashed build assets never change: cache first.
  if (url.pathname.startsWith('/_next/static/')) {
    event.respondWith(
      caches.match(request).then(
        (hit) =>
          hit ||
          fetch(request).then((res) => {
            const copy = res.clone();
            caches.open(STATIC_CACHE).then((cache) => cache.put(request, copy));
            return res;
          }),
      ),
    );
    return;
  }

  // Pages: always fresh; offline page if the network is gone.
  if (request.mode === 'navigate') {
    event.respondWith(fetch(request).catch(() => caches.match(OFFLINE_URL)));
  }
});

// Push: { id, title, body, path, icon } from the server, already decrypted by the browser.
self.addEventListener('push', (event) => {
  let data = {};
  try {
    data = event.data ? event.data.json() : {};
  } catch {
    return;
  }
  event.waitUntil(
    self.registration.showNotification(data.title || 'musicshare', {
      body: data.body || '',
      icon: data.icon || '/icon-192.png',
      badge: '/icon-192.png',
      tag: data.id,
      data: { path: data.path || '/' },
    }),
  );
});

// Tap: focus an open tab and go there, or open a new one.
self.addEventListener('notificationclick', (event) => {
  event.notification.close();
  const url = new URL(event.notification.data?.path || '/', self.location.origin).href;
  event.waitUntil(
    self.clients.matchAll({ type: 'window', includeUncontrolled: true }).then((tabs) => {
      const tab = tabs.find((t) => new URL(t.url).origin === self.location.origin);
      if (tab) return tab.focus().then(() => tab.navigate(url));
      return self.clients.openWindow(url);
    }),
  );
});