// This is the service worker with the combined offline experience (Offline page + Offline copy of pages)
import workbox from 'workbox-sw'

const CACHE = 'pwabuilder-offline-page'

importScripts('https://storage.googleapis.com/workbox-cdn/releases/5.1.4/workbox-sw.js')

// TODO: replace the following with the correct offline fallback page i.e.: const offlineFallbackPage = "offline.html";
const offlineFallbackPage = '/offline.html'

self.addEventListener('message', (event) => {
  if (event.data && event.data.type === 'SKIP_WAITING') {
    self.skipWaiting()
  }
})

self.addEventListener('install', async (event) => {
  event.waitUntil(
    caches.open(CACHE)
      .then((cache) => cache.add(offlineFallbackPage))
  )
})

if (workbox.navigationPreload.isSupported()) {
  workbox.navigationPreload.enable()
}

workbox.routing.registerRoute(
  /\/*/,
  new workbox.strategies.StaleWhileRevalidate({
    cacheName: CACHE
  })
)

self.addEventListener('fetch', (event) => {
  if (event.request.mode === 'navigate') {
    event.respondWith((async () => {
      try {
        const preloadResp = await event.preloadResponse

        if (preloadResp) {
          return preloadResp
        }

        const networkResp = await fetch(event.request)
        return networkResp
      } catch (error) {
        const cache = await caches.open(CACHE)
        const cachedResp = await cache.match(offlineFallbackPage)
        return cachedResp
      }
    })())
  }
})