sw.js

const CACHE_NAME = 'lensing-viz-v1.1';
const ASSETS_TO_CACHE = [
    './index.html',
    './css/styles.css',
    './js/utils.js',
    './js/galaxy-factory.js',
    './js/textures.js',
    './js/shaders.js',
    './js/ui.js',
    './js/app.js',
    './manifest.json',
    './icons/icon-192x192.png',
    './icons/icon-512x512.png',
    'https://cdnjs.cloudflare.com/ajax/libs/three.js/r128/three.min.js'
];

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

// Activate event - clean up 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))
                );
            })
            .then(() => {
                // Take control of all pages immediately
                return self.clients.claim();
            })
    );
});

// Fetch event - serve from cache, fall back to network
self.addEventListener('fetch', (event) => {
    // Skip non-GET requests
    if (event.request.method !== 'GET') {
        return;
    }

    event.respondWith(
        fetch(event.request)
            .then((networkResponse) => {
                // 1. Network Succeeded:
                // Check if we received a valid response
                if (!networkResponse || networkResponse.status !== 200 || networkResponse.type !== 'basic') {
                    return networkResponse;
                }

                // 2. Update the cache with the new file
                const responseToCache = networkResponse.clone();
                caches.open(CACHE_NAME)
                    .then((cache) => {
                        cache.put(event.request, responseToCache);
                    });

                return networkResponse;
            })
            .catch(() => {
                // 3. Network Failed (Offline):
                // Fallback to cache
                return caches.match(event.request)
                    .then((cachedResponse) => {
                        if (cachedResponse) {
                            return cachedResponse;
                        }
                        // Optional: Return a specific offline page if the file isn't found
                        if (event.request.mode === 'navigate') {
                            return caches.match('./index.html');
                        }
                    });
            })
    );
});