sw.js

const CACHE_NAME = 'mathy-v1';

self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) =>
      cache.addAll(['./', './index.html'])
    )
  );
  self.skipWaiting();
});

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

self.addEventListener('fetch', (event) => {
  // Use network-first for navigation requests (picks up new deployments)
  if (event.request.mode === 'navigate') {
    event.respondWith(
      fetch(event.request)
        .then((response) => {
          const clone = response.clone();
          caches.open(CACHE_NAME).then((cache) => cache.put(event.request, clone));
          return response;
        })
        .catch(() =>
          caches.match(event.request).then((cached) =>
            cached || caches.match('./index.html').then((fallback) =>
              fallback || new Response('Offline', {
                status: 503,
                statusText: 'Service Unavailable',
                headers: { 'Content-Type': 'text/plain' },
              })
            )
          )
        )
    );
    return;
  }

  // Cache-first for assets
  event.respondWith(
    caches.match(event.request).then((cached) =>
      cached || fetch(event.request).then((response) => {
        if (response.ok && event.request.method === 'GET') {
          const clone = response.clone();
          caches.open(CACHE_NAME).then((cache) => cache.put(event.request, clone));
        }
        return response;
      }).catch(() =>
        new Response('Offline', {
          status: 503,
          statusText: 'Service Unavailable',
          headers: { 'Content-Type': 'text/plain' },
        })
      )
    )
  );
});