const CACHE_NAME = 'radiocast-core-v2';
const CORE_ASSETS = [
  '.',
  'index.html',
  'main.js',
  'styles.css',
  'stations.json',
  'assets/favicon_io/android-chrome-192x192.png',
  'assets/favicon_io/android-chrome-512x512.png',
  'assets/favicon_io/apple-touch-icon.png'
];

self.addEventListener('install', (event) => {
  // Activate updated SW as soon as it's installed.
  self.skipWaiting();
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => cache.addAll(CORE_ASSETS))
  );
});

self.addEventListener('activate', (event) => {
  event.waitUntil(
    Promise.all([
      self.clients.claim(),
      caches.keys().then((keys) => Promise.all(
        keys.map((k) => { if (k !== CACHE_NAME) return caches.delete(k); return null; })
      )),
    ])
  );
});

self.addEventListener('fetch', (event) => {
  // Only handle GET requests
  if (event.request.method !== 'GET') return;

  event.respondWith(
    caches.match(event.request).then((cached) => {
      if (cached) return cached;
      return fetch(event.request).then((networkResp) => {
        // Optionally cache new resources (best-effort)
        try {
          const respClone = networkResp.clone();
          caches.open(CACHE_NAME).then((cache) => cache.put(event.request, respClone)).catch(()=>{});
        } catch (e) {}
        return networkResp;
      }).catch(() => {
        // If offline and HTML navigation, return cached index.html
        if (event.request.mode === 'navigate') return caches.match('index.html');
        return new Response('', { status: 503, statusText: 'Service Unavailable' });
      });
    })
  );
});