const CACHE = 'klassenportal-v2';
const PRECACHE = [
  '/',
  '/login.html',
  '/app.html',
  '/manifest.json',
  '/favicon.svg',
  '/icons/icon-192.png',
  '/icons/icon-512.png',
  '/icons/apple-touch-icon.png',
];

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

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

self.addEventListener('fetch', e => {
  const url = new URL(e.request.url);

  // Only handle same-origin GET requests
  if (url.origin !== self.location.origin) return;
  if (e.request.method !== 'GET') return;

  // API calls: always network, never cache
  if (url.pathname.startsWith('/api/')) return;

  // Page navigations: network-first, fallback to cache
  if (e.request.mode === 'navigate') {
    e.respondWith(
      fetch(e.request)
        .then(r => {
          const clone = r.clone();
          caches.open(CACHE).then(c => c.put(e.request, clone));
          return r;
        })
        .catch(() =>
          caches.match(e.request).then(r => r || caches.match('/login.html'))
        )
    );
    return;
  }

  // Static assets: cache-first, populate on miss
  e.respondWith(
    caches.match(e.request).then(cached => {
      if (cached) return cached;
      return fetch(e.request).then(r => {
        if (r.ok) {
          const clone = r.clone();
          caches.open(CACHE).then(c => c.put(e.request, clone));
        }
        return r;
      });
    })
  );
});