const CACHE_NAME = 'piclets-v4';
const urlsToCache = [
  '/',
  '/manifest.json',
  '/assets/logo.PNG'
];

// Install event - cache key resources
self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then(cache => {
        console.log('Opened cache');
        return cache.addAll(urlsToCache);
      })
  );
});

// Activate event - clean up old caches
self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys().then(cacheNames => {
      return Promise.all(
        cacheNames.map(cacheName => {
          if (cacheName !== CACHE_NAME) {
            console.log('Deleting old cache:', cacheName);
            return caches.delete(cacheName);
          }
        })
      );
    })
  );
});

// Fetch event - serve from cache when offline
self.addEventListener('fetch', event => {
  event.respondWith(
    caches.match(event.request)
      .then(response => {
        // Cache hit - return response
        if (response) {
          return response;
        }

        // Clone the request
        const fetchRequest = event.request.clone();

        return fetch(fetchRequest).then(response => {
          // Check if valid response
          if (!response || response.status !== 200 || response.type !== 'basic') {
            return response;
          }

          // Clone the response
          const responseToCache = response.clone();

          // Cache the fetched response for future use
          caches.open(CACHE_NAME)
            .then(cache => {
              // Don't cache API calls or external resources
              if (event.request.url.startsWith(self.location.origin)) {
                cache.put(event.request, responseToCache);
              }
            });

          return response;
        });
      })
      .catch(() => {
        // Offline fallback
        if (event.request.mode === 'navigate') {
          return caches.match('/');
        }
      })
  );
});