const CACHE_PREFIX = "office-tools-shell-";
const CACHE_NAME = `${CACHE_PREFIX}0.2.0`;
const CORE = ["./", "./manifest.webmanifest", "./favicon.svg"];

self.addEventListener("install", (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then(async (cache) => {
      await cache.addAll(CORE);
      const response = await fetch("./");
      const html = await response.text();
      const assets = [...html.matchAll(/(?:src|href)="(\.\/assets\/[^"]+)"/g)]
        .map((match) => match[1])
        .filter(Boolean);
      await cache.addAll(assets);
    }),
  );
  self.skipWaiting();
});

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

self.addEventListener("fetch", (event) => {
  if (event.request.method !== "GET") return;
  const url = new URL(event.request.url);
  if (url.origin !== self.location.origin) return;
  const scope = new URL(self.registration.scope);
  if (!url.pathname.startsWith(scope.pathname)) return;

  if (event.request.mode === "navigate") {
    event.respondWith(
      fetch(event.request)
        .then((response) => {
          if (response.ok) {
            const copy = response.clone();
            void caches
              .open(CACHE_NAME)
              .then((cache) => cache.put(event.request, copy));
          }
          return response;
        })
        .catch(async () => {
          const cached = await caches.match(event.request);
          if (cached) return cached;
          const shellUrl = new URL("./", self.registration.scope).href;
          return (await caches.match(shellUrl)) ?? Response.error();
        }),
    );
    return;
  }

  event.respondWith(
    caches.match(event.request).then(
      (cached) =>
        cached ??
        fetch(event.request).then((response) => {
          if (response.ok) {
            const copy = response.clone();
            void caches
              .open(CACHE_NAME)
              .then((cache) => cache.put(event.request, copy));
          }
          return response;
        }),
    ),
  );
});