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

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

const sw = self as unknown as ServiceWorkerGlobalScope;

const APP_CACHE = `kochwas-app-${version}`;
const IMAGE_CACHE = `kochwas-images-v1`;
const APP_ASSETS = [...build, ...files];

sw.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(APP_CACHE).then((cache) => cache.addAll(APP_ASSETS))
  );
  // Activate new worker without waiting for old clients to close.
  void sw.skipWaiting();
});

sw.addEventListener('activate', (event) => {
  event.waitUntil(
    (async () => {
      const keys = await caches.keys();
      await Promise.all(
        keys
          .filter((k) => k.startsWith('kochwas-app-') && k !== APP_CACHE)
          .map((k) => caches.delete(k))
      );
      await sw.clients.claim();
    })()
  );
});

sw.addEventListener('fetch', (event) => {
  const req = event.request;
  if (req.method !== 'GET') return;

  const url = new URL(req.url);
  if (url.origin !== location.origin) return;

  // Images served from /images/* — cache-first with background update
  if (url.pathname.startsWith('/images/')) {
    event.respondWith(
      (async () => {
        const cache = await caches.open(IMAGE_CACHE);
        const cached = await cache.match(req);
        const network = fetch(req)
          .then((res) => {
            if (res.ok) void cache.put(req, res.clone());
            return res;
          })
          .catch(() => undefined);
        return cached ?? (await network) ?? new Response('Offline', { status: 503 });
      })()
    );
    return;
  }

  // App shell assets (build/* and static files) — cache-first
  if (APP_ASSETS.includes(url.pathname)) {
    event.respondWith(
      (async () => {
        const cache = await caches.open(APP_CACHE);
        const cached = await cache.match(req);
        return cached ?? fetch(req);
      })()
    );
    return;
  }

  // API and HTML pages — network-first, fall back to cache for HTML
  if (req.destination === 'document') {
    event.respondWith(
      (async () => {
        try {
          const res = await fetch(req);
          const cache = await caches.open(APP_CACHE);
          if (res.ok) void cache.put(req, res.clone());
          return res;
        } catch {
          const cached = await caches.match(req);
          return cached ?? new Response('Offline', { status: 503 });
        }
      })()
    );
  }
});