const CACHE_NAME = 'quartiles-pwa-v1';

const STATIC_ASSETS = [
  '/',
  '/index.html',
  '/manifest.webmanifest',
  '/icon.svg'
];

// Install: Cache initial shell assets
self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(CACHE_NAME).then(cache => {
      return cache.addAll(STATIC_ASSETS);
    }).then(() => self.skipWaiting())
  );
});

// Activate: Clean up old cache versions
self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys().then(keys => {
      return Promise.all(
        keys.map(key => {
          if (key !== CACHE_NAME) {
            return caches.delete(key);
          }
        })
      );
    }).then(() => self.clients.claim())
  );
});

// Fetch: Stale-While-Revalidate for local assets, Network-First for HTML navigation
self.addEventListener('fetch', event => {
  const request = event.request;
  const url = new URL(request.url);

  // Only handle GET requests
  if (request.method !== 'GET') return;

  // Version checks must always hit the network (never cached)
  if (url.origin === location.origin && url.pathname === '/version.json') return;

  // Handle HTML navigation requests (Offline support)
  if (request.mode === 'navigate') {
    event.respondWith(
      fetch(request)
        .then(response => {
          if (response && response.status === 200) {
            const responseClone = response.clone();
            caches.open(CACHE_NAME).then(cache => cache.put(request, responseClone));
          }
          return response;
        })
        .catch(() => caches.match('/index.html') || caches.match('/'))
    );
    return;
  }

  // Same-origin static assets or Google Fonts: Stale-While-Revalidate
  if (url.origin === location.origin || url.hostname.includes('googleapis.com') || url.hostname.includes('gstatic.com')) {
    event.respondWith(
      caches.match(request).then(cachedResponse => {
        const fetchPromise = fetch(request)
          .then(networkResponse => {
            if (networkResponse && networkResponse.status === 200) {
              const responseClone = networkResponse.clone();
              caches.open(CACHE_NAME).then(cache => cache.put(request, responseClone));
            }
            return networkResponse;
          })
          .catch(() => cachedResponse);

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