/* ============================================================================
 * device-db.js — this device's own file registry (IndexedDB "ytp-device")
 *
 * One record per saved video, next to the bytes in OPFS:
 *   { videoId, cid, size, savedAt, lastCheckedAt, state }
 *     cid    SHA-256 of the stored file (P2P content id) or null
 *     state  'verified'   hash computed on save and equal to the server's
 *            'unverified' hash computed, but the server sent none to compare
 *            'unhashed'   saved before hashing existed / main-thread fallback
 * The P2P client (p2p-client.js) reads this to report holdings; OPFS stays the
 * source of truth for what is playable (a record without a file is ignored).
 * Every call resolves (null / [] on failure) — private windows can block IDB.
 * See docs/p2p-architecture.md.
 * ========================================================================== */
(function () {
  'use strict';

  const DB_NAME = 'ytp-device';
  const VERSION = 1;
  let _open = null;

  function open() {
    if (!_open) {
      _open = new Promise((resolve, reject) => {
        const r = indexedDB.open(DB_NAME, VERSION);
        r.onupgradeneeded = () => {
          const d = r.result;
          if (!d.objectStoreNames.contains('files')) {
            const s = d.createObjectStore('files', { keyPath: 'videoId' });
            s.createIndex('cid', 'cid', { unique: false });
          }
        };
        r.onsuccess = () => resolve(r.result);
        r.onerror = () => reject(r.error);
        r.onblocked = () => reject(new Error('device-db blocked'));
      });
      _open.catch(() => { _open = null; });
    }
    return _open;
  }

  const done = (req) => new Promise((resolve, reject) => {
    req.onsuccess = () => resolve(req.result);
    req.onerror = () => reject(req.error);
  });

  async function store(mode) {
    const d = await open();
    return d.transaction('files', mode).objectStore('files');
  }

  async function safe(fn, fallback) {
    try { return await fn(); } catch { return fallback; }
  }

  window.DeviceDB = {
    isSupported: () => typeof indexedDB !== 'undefined',
    putFile: (rec) => safe(async () => {
      if (!rec || !rec.videoId) return null;
      await done((await store('readwrite')).put({
        videoId: String(rec.videoId),
        cid: rec.cid || null,
        size: Number(rec.size) || 0,
        savedAt: Number(rec.savedAt) || Date.now(),
        lastCheckedAt: Number(rec.lastCheckedAt) || Date.now(),
        state: rec.state || 'unhashed',
      }));
      return true;
    }, null),
    getFile: (videoId) => safe(async () => (await done((await store('readonly')).get(String(videoId)))) || null, null),
    getByCid: (cid) => safe(async () => (await done((await store('readonly')).index('cid').get(String(cid)))) || null, null),
    listFiles: () => safe(async () => (await done((await store('readonly')).getAll())) || [], []),
    deleteFile: (videoId) => safe(async () => { await done((await store('readwrite')).delete(String(videoId))); return true; }, null),
    clear: () => safe(async () => { await done((await store('readwrite')).clear()); return true; }, null),
  };
}());