sw.js

const CACHE_NAME = 'medmcq-trainer-v4';
const ASSETS_TO_CACHE = [
    './',
    './index.html',
    './styles.css',
    './core.js',
    './ui.js',
    './modes.js',
    './main.js',
    './manifest.json'
];

self.addEventListener('install', (event) => {
    event.waitUntil(
        caches.open(CACHE_NAME)
            .then((cache) => cache.addAll(ASSETS_TO_CACHE))
            .then(() => self.skipWaiting())
    );
});

self.addEventListener('activate', (event) => {
    event.waitUntil(
        caches.keys().then((cacheNames) => {
            return Promise.all(
                cacheNames.map((cacheName) => {
                    if (cacheName !== CACHE_NAME) {
                        return caches.delete(cacheName);
                    }
                })
            );
        })
    );
    self.clients.claim();
});

self.addEventListener('fetch', (event) => {
    if (event.request.method !== 'GET') return;

    event.respondWith(
        caches.match(event.request).then((cachedResponse) => {
            if (cachedResponse) {
                return cachedResponse;
            }
            return fetch(event.request).then((response) => {
                if (!response || response.status !== 200 || response.type !== 'basic') {
                    return response;
                }
                const responseToCache = response.clone();
                caches.open(CACHE_NAME).then((cache) => {
                    cache.put(event.request, responseToCache);
                });
                return response;
            });
        }).catch(() => {
            // Offline fallback can go here if needed.
        })
    );
});