/// <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';
import { diffManifest } from '$lib/sw/diff-manifest';

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);
      // Kein self.skipWaiting() hier — der Client (pwaStore) fragt den
      // User via UpdateToast, ob der neue SW sofort übernehmen soll, und
      // schickt dann eine SKIP_WAITING-Message. Ohne diese Trennung
      // würde pwaStore beim Install-Event fälschlich "Neue Version"
      // zeigen (weil statechange='installed' + controller=alter SW), und
      // der neue SW würde einen Tick später ungefragt übernehmen.
    })()
  );
});

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 === 'network-first') {
    event.respondWith(networkFirstWithTimeout(req, DATA_CACHE, NETWORK_TIMEOUT_MS));
  }
});

const NETWORK_TIMEOUT_MS = 3000;

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;
}

// Network-first mit Timeout-Fallback: frische Daten gewinnen, wenn das Netz
// innerhalb von NETWORK_TIMEOUT_MS antwortet. Sonst wird der Cache geliefert
// (falls vorhanden), während der Netz-Fetch noch im Hintergrund weiterläuft
// und den Cache für den nächsten Request aktualisiert. Ohne Cache wartet der
// Client trotzdem aufs Netz, weil ein Error-Response hier nichts nützt.
async function networkFirstWithTimeout(
  req: Request,
  cacheName: string,
  timeoutMs: number
): Promise<Response> {
  const cache = await caches.open(cacheName);
  const networkPromise: Promise<Response | null> = fetch(req)
    .then((res) => {
      if (res.ok) cache.put(req, res.clone()).catch(() => {});
      return res;
    })
    .catch(() => null);

  const timeoutPromise = new Promise<'timeout'>((resolve) =>
    setTimeout(() => resolve('timeout'), timeoutMs)
  );

  const winner = await Promise.race([networkPromise, timeoutPromise]);
  if (winner instanceof Response) return winner;

  // Timeout oder Netzwerk-Fehler: Cache bevorzugen, sonst auf Netz warten.
  const hit = await cache.match(req);
  if (hit) return hit;
  const late = await networkPromise;
  return late ?? Response.error();
}

const META_CACHE = 'kochwas-meta';
const MANIFEST_KEY = '/__cache-manifest__';
const PAGE_SIZE = 50; // /api/recipes/all limitiert auf 50
const CONCURRENCY = 4;

type RecipeSummary = { id: number; image_path: string | null };

self.addEventListener('message', (event) => {
  const data = event.data as { type?: string } | undefined;
  if (!data) return;
  if (data.type === 'sync-start') {
    event.waitUntil(runSync(false));
  } else if (data.type === 'sync-check') {
    event.waitUntil(runSync(true));
  } else if (data.type === 'SKIP_WAITING') {
    // Wird vom pwaStore nach User-Klick auf "Neu laden" geschickt.
    void self.skipWaiting();
  } else if (data.type === 'GET_VERSION') {
    // Zombie-Schutz: Chromium hält nach einem SKIP_WAITING-Zyklus
    // mitunter einen bit-identischen waiting-SW im Registration-Slot
    // (Race zwischen SW-Update-Check während activate). Ohne diesen
    // Version-Handshake zeigt init() den „Neue Version"-Toast bei jedem
    // Reload erneut, obwohl es nichts zu aktualisieren gibt.
    const port = event.ports[0] as MessagePort | undefined;
    port?.postMessage({ version });
  }
});

async function runSync(isUpdate: boolean): Promise<void> {
  try {
    // Storage-Quota-Check vor dem Pre-Cache
    if (navigator.storage?.estimate) {
      const est = await navigator.storage.estimate();
      const freeBytes = (est.quota ?? 0) - (est.usage ?? 0);
      if (freeBytes < 100 * 1024 * 1024) {
        await broadcast({
          type: 'sync-error',
          message: `Nicht genug Speicher für Offline-Modus (${Math.round(freeBytes / 1024 / 1024)} MB frei)`
        });
        return;
      }
    }

    const summaries = await fetchAllSummaries();
    const currentIds = summaries.map((s) => s.id);
    const cachedIds = await loadCachedIds();
    const { toAdd, toRemove } = diffManifest(currentIds, cachedIds);
    const worklist = isUpdate ? toAdd : currentIds; // initial: alles laden

    await broadcast({ type: 'sync-start', total: worklist.length });

    const successful = new Set<number>();
    let done = 0;
    const tasks = worklist.map((id) => async () => {
      const summary = summaries.find((s) => s.id === id);
      const ok = await cacheRecipe(id, summary?.image_path ?? null);
      if (ok) successful.add(id);
      done += 1;
      await broadcast({ type: 'sync-progress', current: done, total: worklist.length });
    });
    await runPool(tasks, CONCURRENCY);

    if (isUpdate && toRemove.length > 0) {
      await removeRecipes(toRemove);
    }

    // Manifest: für Update = (cached - toRemove) + neue successes
    // Für Initial = nur die diesmal erfolgreich gecachten
    const finalManifest = isUpdate
      ? Array.from(
          new Set([...cachedIds.filter((id) => !toRemove.includes(id)), ...successful])
        )
      : Array.from(successful);

    await saveCachedIds(finalManifest);
    await broadcast({ type: 'sync-done', lastSynced: Date.now() });
  } catch (e) {
    await broadcast({
      type: 'sync-error',
      message: (e as Error).message ?? 'Unbekannter Sync-Fehler'
    });
  }
}

async function fetchAllSummaries(): Promise<RecipeSummary[]> {
  const result: RecipeSummary[] = [];
  let offset = 0;
  for (;;) {
    const res = await fetch(`/api/recipes/all?sort=name&limit=${PAGE_SIZE}&offset=${offset}`);
    if (!res.ok) throw new Error(`/api/recipes/all HTTP ${res.status}`);
    const body = (await res.json()) as { hits: { id: number; image_path: string | null }[] };
    result.push(...body.hits.map((h) => ({ id: h.id, image_path: h.image_path })));
    if (body.hits.length < PAGE_SIZE) break;
    offset += PAGE_SIZE;
  }
  return result;
}

async function cacheRecipe(id: number, imagePath: string | null): Promise<boolean> {
  const data = await caches.open(DATA_CACHE);
  const images = await caches.open(IMAGES_CACHE);
  const [htmlOk, apiOk] = await Promise.all([
    addToCache(data, `/recipes/${id}`),
    addToCache(data, `/api/recipes/${id}`)
  ]);
  if (imagePath && !/^https?:\/\//i.test(imagePath)) {
    // Image-Fehler soll den Recipe-Eintrag nicht invalidieren (bei
    // manchen Rezepten gibt es schlicht kein Bild)
    await addToCache(images, `/images/${imagePath}`);
  }
  return htmlOk && apiOk;
}

async function addToCache(cache: Cache, url: string): Promise<boolean> {
  try {
    const res = await fetch(url);
    if (!res.ok) {
      console.warn(`[sw] cache miss ${url}: HTTP ${res.status}`);
      return false;
    }
    await cache.put(url, res);
    return true;
  } catch (e) {
    console.warn(`[sw] cache error ${url}:`, e);
    return false;
  }
}

async function removeRecipes(ids: number[]): Promise<void> {
  const data = await caches.open(DATA_CACHE);
  for (const id of ids) {
    await data.delete(`/recipes/${id}`);
    await data.delete(`/api/recipes/${id}`);
  }
  // Orphan-Bilder: wir räumen nicht aktiv — neuer Hash = neuer Entry,
  // alte Einträge stören nicht.
}

async function loadCachedIds(): Promise<number[]> {
  const meta = await caches.open(META_CACHE);
  const res = await meta.match(MANIFEST_KEY);
  if (!res) return [];
  try {
    return (await res.json()) as number[];
  } catch {
    return [];
  }
}

async function saveCachedIds(ids: number[]): Promise<void> {
  const meta = await caches.open(META_CACHE);
  await meta.put(
    MANIFEST_KEY,
    new Response(JSON.stringify(ids), { headers: { 'content-type': 'application/json' } })
  );
}

async function runPool<T>(tasks: (() => Promise<T>)[], limit: number): Promise<void> {
  const executing: Promise<void>[] = [];
  for (const task of tasks) {
    const p: Promise<void> = task().then(() => {
      executing.splice(executing.indexOf(p), 1);
    });
    executing.push(p);
    if (executing.length >= limit) await Promise.race(executing);
  }
  await Promise.all(executing);
}

async function broadcast(msg: unknown): Promise<void> {
  const clients = await self.clients.matchAll();
  for (const client of clients) client.postMessage(msg);
}

export {};