const CACHE_VERSION = "simple-llm-chat-ui-v2"
const APP_SHELL_URLS = [
  "/",
  "/manifest.webmanifest",
  "/icons/icon-192.png",
  "/icons/icon-512.png",
  "/icons/maskable-512.png",
  "/icons/apple-touch-icon.png",
]
const CACHEABLE_DESTINATIONS = new Set(["font", "image", "script", "style"])

self.addEventListener("install", (event) => {
  event.waitUntil(
    caches
      .open(CACHE_VERSION)
      .then((cache) => cache.addAll(APP_SHELL_URLS))
      .then(() => self.skipWaiting())
  )
})

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

self.addEventListener("fetch", (event) => {
  const { request } = event
  const url = new URL(request.url)

  if (request.method !== "GET" || url.origin !== self.location.origin) {
    return
  }

  if (request.mode === "navigate") {
    event.respondWith(networkFirst(request))
    return
  }

  if (CACHEABLE_DESTINATIONS.has(request.destination)) {
    event.respondWith(cacheFirst(request))
  }
})

async function networkFirst(request) {
  const cache = await caches.open(CACHE_VERSION)

  try {
    const response = await fetch(request)

    if (response.ok) {
      await cache.put(request, response.clone())
    }

    return response
  } catch {
    return (await cache.match(request)) ?? (await cache.match("/"))
  }
}

async function cacheFirst(request) {
  const cache = await caches.open(CACHE_VERSION)
  const cached = await cache.match(request)

  if (cached) {
    return cached
  }

  const response = await fetch(request)

  if (response.ok) {
    await cache.put(request, response.clone())
  }

  return response
}