/// <reference types="@sveltejs/kit" />
/// <reference no-default-lib="true"/>
/// <reference lib="esnext" />
/// <reference lib="WebWorker" />

declare let self: ServiceWorkerGlobalScope;

import { build, files, version } from "$service-worker";

// Create a unique cache name for this deployment
const CACHE = `cache-${version}`;

const ASSETS = [
  ...build, // the app itself
  ...files, // everything in `static`
];

self.addEventListener("install", (event) => {
  // Create a new cache and add all files to it
  async function addFilesToCache() {
    const cache = await caches.open(CACHE);
    await cache.addAll(ASSETS);
  }

  event.waitUntil(addFilesToCache());
});

self.addEventListener("activate", (event) => {
  // Remove previous cached data from disk
  async function deleteOldCaches() {
    for (const key of await caches.keys()) {
      if (key !== CACHE) await caches.delete(key);
    }
  }

  event.waitUntil(deleteOldCaches());
});

self.addEventListener("fetch", (event: FetchEvent) => {
  const url = new URL(event.request.url);
  // ignore POST requests etc
  if (event.request.method !== "GET") return;
  // ignore oauth pages
  if (url.pathname.startsWith("/oauth")) return;

  async function respond() {
    const cache = await caches.open(CACHE);

    // `build`/`files` can always be served from the cache
    if (ASSETS.includes(url.pathname)) {
      return cache.match(url.pathname);
    }

    // for everything else, try the network first, but
    // fall back to the cache if we're offline
    try {
      const response = await fetch(event.request);

      if (response.status === 200) {
        cache.put(event.request, response.clone());
      }

      return response;
    } catch {
      return cache.match(event.request);
    }
  }

  event.respondWith(
    (async () => {
      const resp = await respond();
      return resp ? resp : new Response(undefined, { status: 404 });
    })(),
  );
});