const CACHE = 'sm-v1';
const STATIC_ASSETS = [
  '/assets/css/style.css',
  '/assets/js/app.js',
  '/assets/js/main.js',
  '/assets/img/server.svg',
  '/assets/img/icon-192.png',
  '/assets/img/icon-512.png',
  '/manifest.json',
  '/offline',
];

self.addEventListener('install', function(e) {
  e.waitUntil(
    caches.open(CACHE).then(function(cache) {
      return cache.addAll(STATIC_ASSETS);
    }).then(function() {
      return self.skipWaiting();
    })
  );
});

self.addEventListener('activate', function(e) {
  e.waitUntil(
    caches.keys().then(function(keys) {
      return Promise.all(
        keys.filter(function(k) { return k !== CACHE; }).map(function(k) { return caches.delete(k); })
      );
    }).then(function() {
      return self.clients.claim();
    })
  );
});

self.addEventListener('fetch', function(e) {
  var url = new URL(e.request.url);

  if (url.pathname.startsWith('/api/')) {
    return;
  }

  if (
    url.pathname.startsWith('/assets/') ||
    url.pathname === '/manifest.json'
  ) {
    e.respondWith(
      caches.open(CACHE).then(function(cache) {
        return cache.match(e.request).then(function(cached) {
          var fetchPromise = fetch(e.request).then(function(response) {
            cache.put(e.request, response.clone());
            return response;
          });
          return cached || fetchPromise;
        });
      })
    );
    return;
  }

  e.respondWith(
    fetch(e.request).catch(function() {
      return caches.match(e.request).then(function(cached) {
        if (cached) return cached;
        if (e.request.mode === 'navigate') {
          return caches.match('/offline');
        }
        return new Response('Offline', { status: 503 });
      });
    })
  );
});