const CACHE_NAME = 'seoul-shortcuts-v1';
const CORE_ASSETS = [
  './',
  './assets/favicon.svg',
  './assets/icon-32.png',
  './assets/icon-192.png',
  './assets/icon-512.png',
  './assets/apple-touch-icon.png',
  './manifest.webmanifest'
];

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

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

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

  const url = new URL(event.request.url);

  if (url.origin !== location.origin) {
    return;
  }

  event.respondWith(
    fetch(event.request)
      .then(response => {
        const copy = response.clone();
        caches.open(CACHE_NAME).then(cache => cache.put(event.request, copy));
        return response;
      })
      .catch(() => caches.match(event.request))
  );
});