const CACHE_NAME = 'inknote-v2';

// Install — cache app shell on first load
self.addEventListener('install', (e) => {
  e.waitUntil(
    caches.open(CACHE_NAME).then(async (cache) => {
      // Cache the main page and manifest
      const urls = ['/', '/manifest.json', '/icon-192.png', '/icon-512.png'];
      for (const url of urls) {
        try { await cache.add(url); } catch (err) { console.warn('[SW] Failed to cache:', url); }
      }
    })
  );
  self.skipWaiting();
});

// Activate — clean old caches
self.addEventListener('activate', (e) => {
  e.waitUntil(
    caches.keys().then(keys => Promise.all(keys.filter(k => k !== CACHE_NAME).map(k => caches.delete(k))))
  );
  self.clients.claim();
});

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

  // Skip API/WebSocket requests entirely — handled by app + IndexedDB
  if (url.pathname.startsWith('/api/') || url.pathname.startsWith('/ws')) return;

  // Skip non-GET requests
  if (e.request.method !== 'GET') return;

  // Navigation (HTML pages) — network-first, fallback to cache
  if (e.request.mode === 'navigate') {
    e.respondWith(
      fetch(e.request)
        .then(r => { const c = r.clone(); caches.open(CACHE_NAME).then(cache => cache.put('/', c)); return r; })
        .catch(() => caches.match('/'))
    );
    return;
  }

  // JS/CSS/images — stale-while-revalidate
  e.respondWith(
    caches.match(e.request).then(cached => {
      const fetchP = fetch(e.request).then(r => {
        if (r.ok && r.type === 'basic') {
          caches.open(CACHE_NAME).then(cache => cache.put(e.request, r.clone()));
        }
        return r;
      }).catch(() => cached);
      return cached || fetchP;
    })
  );
});

// Background sync
self.addEventListener('sync', (e) => {
  if (e.tag === 'sync-changes') {
    e.waitUntil(self.clients.matchAll().then(clients => {
      clients.forEach(c => c.postMessage({ type: 'FLUSH_QUEUE' }));
    }));
  }
});