sw.js

const CACHE_NAME = 'javahub-v1';
const STATIC_ASSETS = [
  '/',
  '/index.html',
  '/styles.css',
  '/app.js',
  '/lessons.js',
  '/groq-service.js',
  '/manifest.json'
];

const EXTERNAL_ASSETS = [
  'https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500;700&display=swap',
  'https://cdnjs.cloudflare.com/ajax/libs/codemirror/5.65.16/codemirror.min.css'
];

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

// Activate event - clean old caches
self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((cacheNames) => {
      return Promise.all(
        cacheNames
          .filter((name) => name !== CACHE_NAME)
          .map((name) => caches.delete(name))
      );
    })
  );
  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 non-GET requests
  if (request.method !== 'GET') return;

  // Skip API requests (Judge0, Groq) - they need network
  if (url.hostname.includes('judge0') || url.hostname.includes('groq') || url.hostname.includes('api')) {
    return;
  }

  // For same-origin requests, try cache first
  if (url.origin === location.origin) {
    event.respondWith(
      caches.match(request).then((cachedResponse) => {
        if (cachedResponse) {
          // Return cache but also update in background
          event.waitUntil(
            fetch(request).then((response) => {
              if (response.ok) {
                caches.open(CACHE_NAME).then((cache) => {
                  cache.put(request, response);
                });
              }
            }).catch(() => {})
          );
          return cachedResponse;
        }

        // Not in cache, fetch from network
        return fetch(request).then((response) => {
          if (response.ok) {
            const responseClone = response.clone();
            caches.open(CACHE_NAME).then((cache) => {
              cache.put(request, responseClone);
            });
          }
          return response;
        }).catch(() => {
          // Return offline page for navigation requests
          if (request.mode === 'navigate') {
            return caches.match('/index.html');
          }
          return new Response('Offline', { status: 503 });
        });
      })
    );
  }
});

// Handle messages from main thread
self.addEventListener('message', (event) => {
  if (event.data === 'skipWaiting') {
    self.skipWaiting();
  }
});