sw.js

// Service Worker for PWA and Offline Support

const CACHE_NAME = 'pdf-image-editor-v1';
const urlsToCache = [
  '/',
  '/index.html',
  '/css/styles.css',
  '/js/app.js',
  '/js/utils.js',
  '/js/pdf-editor.js',
  '/js/image-editor.js',
  '/manifest.json'
];

// External CDN resources (cached with network-first strategy)
const cdnResources = [
  'https://cdnjs.cloudflare.com/ajax/libs/pdf.js/3.11.174/pdf.min.js',
  'https://cdnjs.cloudflare.com/ajax/libs/pdf.js/3.11.174/pdf.worker.min.js',
  'https://unpkg.com/pdf-lib@1.17.1/dist/pdf-lib.min.js',
  'https://cdnjs.cloudflare.com/ajax/libs/fabric.js/5.3.0/fabric.min.js'
];

// Install event - cache resources
self.addEventListener('install', (event) => {
  console.log('Service Worker: Installing...');
  
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then((cache) => {
        console.log('Service Worker: Caching files');
        return cache.addAll(urlsToCache);
      })
      .then(() => {
        console.log('Service Worker: Installed');
        return self.skipWaiting();
      })
      .catch((error) => {
        console.error('Service Worker: Cache failed', error);
      })
  );
});

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

// Fetch event - serve from cache, fallback to network
self.addEventListener('fetch', (event) => {
  const { request } = event;
  const url = new URL(request.url);
  
  // Skip cross-origin requests that are not CDN resources
  if (url.origin !== location.origin && !cdnResources.some(cdn => request.url.startsWith(cdn))) {
    return;
  }
  
  // Network-first strategy for CDN resources
  if (cdnResources.some(cdn => request.url.startsWith(cdn))) {
    event.respondWith(
      fetch(request)
        .then((response) => {
          // Clone the response before caching
          const responseClone = response.clone();
          caches.open(CACHE_NAME).then((cache) => {
            cache.put(request, responseClone);
          });
          return response;
        })
        .catch(() => {
          // Fallback to cache if network fails
          return caches.match(request);
        })
    );
    return;
  }
  
  // Cache-first strategy for app resources
  event.respondWith(
    caches.match(request)
      .then((response) => {
        if (response) {
          return response;
        }
        
        return fetch(request)
          .then((response) => {
            // Don't cache if not a success response
            if (!response || response.status !== 200 || response.type === 'error') {
              return response;
            }
            
            // Clone the response before caching
            const responseClone = response.clone();
            
            caches.open(CACHE_NAME).then((cache) => {
              cache.put(request, responseClone);
            });
            
            return response;
          });
      })
      .catch((error) => {
        console.error('Service Worker: Fetch failed', error);
        
        // Return offline page or error response
        if (request.destination === 'document') {
          return caches.match('/index.html');
        }
      })
  );
});

// Handle messages from the client
self.addEventListener('message', (event) => {
  if (event.data && event.data.type === 'SKIP_WAITING') {
    self.skipWaiting();
  }
  
  if (event.data && event.data.type === 'CACHE_URLS') {
    event.waitUntil(
      caches.open(CACHE_NAME).then((cache) => {
        return cache.addAll(event.data.urls);
      })
    );
  }
});

// Background sync for future features
self.addEventListener('sync', (event) => {
  console.log('Service Worker: Background sync', event.tag);
  
  if (event.tag === 'sync-edits') {
    event.waitUntil(
      // Handle background sync operations
      Promise.resolve()
    );
  }
});

// Push notification support for future features
self.addEventListener('push', (event) => {
  console.log('Service Worker: Push notification received');
  
  const options = {
    body: event.data ? event.data.text() : 'New notification',
    icon: '/assets/icons/icon-192.png',
    badge: '/assets/icons/icon-72.png',
    vibrate: [200, 100, 200]
  };
  
  event.waitUntil(
    self.registration.showNotification('PDF & Image Editor', options)
  );
});

// Notification click handler
self.addEventListener('notificationclick', (event) => {
  console.log('Service Worker: Notification clicked');
  event.notification.close();
  
  event.waitUntil(
    clients.openWindow('/')
  );
});