const CACHE_NAME = 'rhetorikmaster-v11';
const STATIC_ASSETS = [
  '/',
  '/index.html',
  '/rhetorik_trainer_quiz.html',
  '/qrcode.min.js',
  '/favicon.svg',
  '/manifest.json',
  '/icon-192.png',
  '/icon-512.png',
  'https://cdn.tailwindcss.com',
  'https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.4.0/css/all.min.css',
  'https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@400;500;600;700;800&display=swap'
];

self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => {
      return cache.addAll(STATIC_ASSETS).catch((err) => {
        console.warn('Precache partial failure:', err);
      });
    })
  );
  self.skipWaiting();
});

self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((cacheNames) => {
      return Promise.all(
        cacheNames.map((name) => {
          if (name !== CACHE_NAME) {
            console.log('Cleaning old cache:', name);
            return caches.delete(name);
          }
        })
      );
    }).then(() => self.clients.claim())
  );
});

self.addEventListener('fetch', (event) => {
  const request = event.request;
  const isHtmlNavigation = request.mode === 'navigate' || 
    (request.method === 'GET' && request.headers.get('accept') && request.headers.get('accept').includes('text/html'));

  if (isHtmlNavigation) {
    // Network-First for HTML/Navigation: Always fetch fresh HTML from server, fallback to cache if offline
    event.respondWith(
      fetch(request)
        .then((networkResponse) => {
          if (networkResponse && networkResponse.status === 200) {
            const copy = networkResponse.clone();
            caches.open(CACHE_NAME).then((cache) => cache.put(request, copy));
          }
          return networkResponse;
        })
        .catch(() => {
          return caches.match(request).then((cached) => cached || caches.match('/rhetorik_trainer_quiz.html') || caches.match('/'));
        })
    );
    return;
  }

  // Stale-While-Revalidate for other static assets (CSS, fonts, images)
  event.respondWith(
    caches.match(request).then((cachedResponse) => {
      const fetchPromise = fetch(request).then((networkResponse) => {
        if (networkResponse && networkResponse.status === 200) {
          const responseToCache = networkResponse.clone();
          caches.open(CACHE_NAME).then((cache) => {
            cache.put(request, responseToCache);
          });
        }
        return networkResponse;
      }).catch(() => cachedResponse);

      return cachedResponse || fetchPromise;
    })
  );
});