const CACHE = 'stackchain-shell-v1';
const SHELL = ['/manifest.webmanifest', '/static/icons/stackchain-192.png', '/static/icons/stackchain-512.png'];

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

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

self.addEventListener('fetch', event => {
  const request = event.request;
  if (request.method !== 'GET' || request.url.includes('/api/')) return;
  const url = new URL(request.url);
  if (request.mode === 'navigate') {
    event.respondWith(fetch(request));
    return;
  }
  if (url.origin === self.location.origin && SHELL.includes(url.pathname)) {
    event.respondWith(caches.match(request).then(cached => cached || fetch(request)));
  }
});