const CACHE = 'microlearn-shell-v2'
const OFFLINE_URL = '/offline.html'
const SHELL = ['/', OFFLINE_URL, '/manifest.webmanifest', '/icons/app-icon.svg']

self.addEventListener('install', event => event.waitUntil(caches.open(CACHE).then(cache => cache.addAll(SHELL))))
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('message', event => { if (event.data?.type === 'SKIP_WAITING') void self.skipWaiting() })

function isCacheableAsset(url) {
  if (url.origin !== self.location.origin) return false
  return url.pathname.startsWith('/assets/') || url.pathname.startsWith('/icons/') || url.pathname.startsWith('/brand/') || url.pathname === '/manifest.webmanifest' || url.pathname.startsWith('/favicon') || url.pathname === '/apple-touch-icon.png'
}

self.addEventListener('fetch', event => {
  const request = event.request
  const url = new URL(request.url)
  if (request.method !== 'GET' || url.origin !== self.location.origin || url.pathname.startsWith('/api/') || url.pathname.startsWith('/storage/')) return
  if (request.mode === 'navigate') {
    event.respondWith(fetch(request).catch(async () => (await caches.match('/')) ?? (await caches.match(OFFLINE_URL))))
    return
  }
  if (!isCacheableAsset(url)) return
  event.respondWith(caches.match(request).then(cached => cached ?? fetch(request).then(response => {
    if (response.ok) void caches.open(CACHE).then(cache => cache.put(request, response.clone()))
    return response
  })))
})