/// <reference types="@sveltejs/kit" />
/// <reference no-default-lib="true"/>
/// <reference lib="esnext" />
/// <reference lib="webworker" />
import { build, files, version } from '$service-worker';
import { resolveStrategy } from '$lib/sw/cache-strategy';

declare const self: ServiceWorkerGlobalScope;

const SHELL_CACHE = `kochwas-shell-${version}`;
const DATA_CACHE = 'kochwas-data-v1';
const IMAGES_CACHE = 'kochwas-images-v1';

// App-Shell-Assets (Build-Output + statische Dateien, die SvelteKit kennt)
const SHELL_ASSETS = [...build, ...files];

self.addEventListener('install', (event) => {
  event.waitUntil(
    (async () => {
      const cache = await caches.open(SHELL_CACHE);
      await cache.addAll(SHELL_ASSETS);
      await self.skipWaiting();
    })()
  );
});

self.addEventListener('activate', (event) => {
  event.waitUntil(
    (async () => {
      // Alte Shell-Caches (vorherige Versionen) räumen
      const keys = await caches.keys();
      await Promise.all(
        keys
          .filter((k) => k.startsWith('kochwas-shell-') && k !== SHELL_CACHE)
          .map((k) => caches.delete(k))
      );
      await self.clients.claim();
    })()
  );
});

self.addEventListener('fetch', (event) => {
  const req = event.request;
  if (new URL(req.url).origin !== self.location.origin) return; // Cross-Origin unangetastet

  const strategy = resolveStrategy({ url: req.url, method: req.method });
  if (strategy === 'network-only') return;

  if (strategy === 'shell') {
    event.respondWith(cacheFirst(req, SHELL_CACHE));
  } else if (strategy === 'images') {
    event.respondWith(cacheFirst(req, IMAGES_CACHE));
  } else if (strategy === 'swr') {
    event.respondWith(staleWhileRevalidate(req, DATA_CACHE));
  }
});

async function cacheFirst(req: Request, cacheName: string): Promise<Response> {
  const cache = await caches.open(cacheName);
  const hit = await cache.match(req);
  if (hit) return hit;
  const fresh = await fetch(req);
  if (fresh.ok) cache.put(req, fresh.clone()).catch(() => {});
  return fresh;
}

async function staleWhileRevalidate(req: Request, cacheName: string): Promise<Response> {
  const cache = await caches.open(cacheName);
  const hit = await cache.match(req);
  const fetchPromise = fetch(req)
    .then((res) => {
      if (res.ok) cache.put(req, res.clone()).catch(() => {});
      return res;
    })
    .catch(() => hit ?? Response.error());
  return hit ?? fetchPromise;
}

export {};