const CACHE = 'ns-v17';
const PRECACHE = ['/', 'index.html', 'styles.css', 'app.js', 'sw.js', 'manifest.json', 'icon.svg'];
const SKIP_URLS = ['/rest/stream', '/rest/download', '/config.js'];

self.addEventListener('install', e => {
  e.waitUntil(caches.open(CACHE).then(c => c.addAll(PRECACHE)));
  self.skipWaiting();
});

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

self.addEventListener('fetch', e => {
  if (SKIP_URLS.some(u => e.request.url.includes(u))) return;
  e.respondWith(
    caches.match(e.request).then(cached =>
      cached || fetch(e.request).then(res => {
        if (res.status === 200 && e.request.method === 'GET') {
          const clone = res.clone();
          caches.open(CACHE).then(c => c.put(e.request, clone));
        }
        return res;
      }).catch(() => cached)
    )
  );
});