globalThis.Wegwichtel ??= {};
(function (ns) {
  'use strict';

  const CONTROL = 'wegwichtel-offline-control-v1';
  const PREFIX = 'wegwichtel-offline-data-';
  const STATE_URL = '/__wegwichtel_offline_state__';
  const ROUTES_URL = '/__wegwichtel_offline_routes__';
  const DIRECTORY = 'wegwichtel-offline-v1';

  function key(value) {
    const url = new URL(value, globalThis.location.origin);
    if (url.origin !== globalThis.location.origin) throw new TypeError(ns.I18n.t("offline-storage.error.foreign-origin"));
    url.searchParams.delete('v');
    if (url.pathname.startsWith('/api/')) url.searchParams.delete('_');
    url.hash = '';
    return url.href;
  }

  async function state() {
    const cache = await caches.open(CONTROL);
    const response = await cache.match(STATE_URL);
    return response ? response.json() : null;
  }

  async function routes() {
    const response = await (await caches.open(CONTROL)).match(ROUTES_URL);
    return response ? response.json() : [];
  }

  async function writeRoutes(saved) {
    await (await caches.open(CONTROL)).put(ROUTES_URL, new Response(JSON.stringify(saved), { headers: { 'Content-Type': 'application/json' } }));
  }

  async function folder(id, create = false) {
    const root = await navigator.storage.getDirectory();
    const directory = await root.getDirectoryHandle(DIRECTORY, { create });
    return directory.getDirectoryHandle(id, { create });
  }

  async function writeFile(directory, name, contents) {
    const handle = await directory.getFileHandle(name, { create: true });
    const stream = await handle.createWritable();
    try {
      await stream.write(contents);
      await stream.close();
    } catch (error) {
      await stream.abort().catch(() => {});
      throw error;
    }
  }

  async function create() {
    const id = `${PREFIX}${crypto.randomUUID()}`;
    let directory = null;
    if (typeof navigator.storage?.getDirectory === 'function') {
      try { directory = await folder(id, true); } catch { /* Use CacheStorage when OPFS is unavailable. */ }
    }
    return { id, mode: directory ? 'filesystem' : 'cache', directory, resources: {}, count: 0 };
  }

  async function put(stage, url, response) {
    if (!response.ok || response.type === 'opaque') throw new Error(ns.I18n.t("offline-storage.error.response"));
    const normalized = key(url);
    if (stage.mode === 'cache') {
      const cache = await caches.open(stage.id);
      await cache.put(normalized, response.clone());
    } else {
      const filename = `${stage.count}.bin`;
      const headers = [...response.headers].filter(([name]) => !['content-encoding', 'content-length', 'transfer-encoding'].includes(name));
      await writeFile(stage.directory, filename, await response.blob());
      stage.resources[normalized] = { filename, headers, status: response.status, statusText: response.statusText };
    }
    stage.count += 1;
  }

  async function remove(id) {
    if (!id?.startsWith(PREFIX)) return;
    await caches.delete(id);
    if (typeof navigator.storage?.getDirectory === 'function') {
      try {
        const root = await navigator.storage.getDirectory();
        const directory = await root.getDirectoryHandle(DIRECTORY);
        await directory.removeEntry(id, { recursive: true });
      } catch { /* Missing directory or disabled OPFS needs no cleanup. */ }
    }
  }

  async function commit(stage, route = null) {
    if (stage.mode === 'filesystem') {
      await writeFile(stage.directory, 'index.json', JSON.stringify(stage.resources));
    }
    const savedRoutes = route ? await routes() : [];
    const previous = route ? savedRoutes.find(item => String(item.route.id) === String(route.id)) : await state();
    const current = { id: stage.id, mode: stage.mode, count: stage.count, savedAt: new Date().toISOString(), appOnly: !route };
    if (route) {
      const summary = { ...route };
      delete summary.pois;
      delete summary.points;
      current.route = summary;
      await writeRoutes([...savedRoutes.filter(item => String(item.route.id) !== String(route.id)), current]);
    } else {
      const cache = await caches.open(CONTROL);
      await cache.put(STATE_URL, new Response(JSON.stringify(current), { headers: { 'Content-Type': 'application/json' } }));
    }
    if (previous?.id !== current.id) await remove(previous?.id).catch(() => {});
    return current;
  }

  async function matchSnapshot(current, normalized) {
    if (!current) return null;
    if (current.mode === 'cache') return (await caches.open(current.id)).match(normalized);
    try {
      const directory = await folder(current.id);
      const index = JSON.parse(await (await (await directory.getFileHandle('index.json')).getFile()).text());
      const entry = index[normalized];
      if (!entry) return null;
      const file = await (await directory.getFileHandle(entry.filename)).getFile();
      return new Response(file, { status: entry.status, statusText: entry.statusText, headers: entry.headers });
    } catch {
      return null;
    }
  }

  async function match(url) {
    const normalized = key(url);
    const snapshots = [await state(), ...await routes()];
    for (const snapshot of snapshots) {
      const response = await matchSnapshot(snapshot, normalized);
      if (response) return response;
    }
    return null;
  }

  async function clearRoute(routeId) {
    const saved = await routes();
    const previous = saved.find(item => String(item.route.id) === String(routeId));
    await writeRoutes(saved.filter(item => String(item.route.id) !== String(routeId)));
    await remove(previous?.id);
  }

  async function clear() {
    // Disable serving first; remove only our offline resources, never route drafts/media.
    const cache = await caches.open(CONTROL);
    const previous = await state();
    await cache.delete(STATE_URL);
    await remove(previous?.id);
  }

  ns.OfflineStore = Object.freeze({ key, state, routes, create, put, commit, match, remove, clear, clearRoute });
}(globalThis.Wegwichtel));