/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

// OFFLINE_VERSION is used as an update marker so that on subsequent installations
// the newer version of the file gets updated.
// eslint-disable-next-line header/header, no-unused-vars
const OFFLINE_VERSION = 1;
const CACHE_NAME = 'offline';
const OFFLINE_URL = 'offline.html';

self.addEventListener('install', (event) => {
    console.log('Flipper service worker installed');

    event.waitUntil((async () => {
      const cache = await caches.open(CACHE_NAME);
      // Setting {cache: 'reload'} in the new request will ensure that the response
      // isn't fulfilled from the HTTP cache; i.e., it will be from the network.
      await cache.add(new Request(OFFLINE_URL, {cache: 'reload'}));
    })());
    // Force the waiting service worker to become the active service worker.
    self.skipWaiting();
});

self.addEventListener('activate', (event) => {
  console.log('Flipper service worker activate');
  event.waitUntil((async () => {
    // Enable navigation preload if it's supported.
    // See https://developers.google.com/web/updates/2017/02/navigation-preload
    if ('navigationPreload' in self.registration) {
      await self.registration.navigationPreload.enable();
    }
  })());

  // Tell the active service worker to take control of the page immediately.
  self.clients.claim();
});

self.addEventListener('fetch', (event) => {
  // We only want to call event.respondWith() if this is a navigation request
  // for an HTML page.
  if (event.request.mode === 'navigate') {
    event.respondWith((async () => {
      try {
        // First, try to use the navigation preload response if it's supported.
        const preloadResponse = await event.preloadResponse;
        if (preloadResponse) {
          return preloadResponse;
        }

        // Always try the network first (try flipper server)
        const networkResponse = await fetch(event.request);
        return networkResponse;
      } catch (error) {
        // Catch is only triggered if an exception is thrown, which is likely
        // due to a network error.
        // If fetch() returns a valid HTTP response with a response code in
        // the 4xx or 5xx range, the catch() will NOT be called.
        console.log('Fetch failed; returning offline page instead.', error);

        const cache = await caches.open(CACHE_NAME);
        const cachedResponse = await cache.match(OFFLINE_URL);
        return cachedResponse;
      }
    })());
  }
});