// IndexedDB cache for the whole-Bible search index.
const BIBLE_IDB_NAME = 'study-app-bible-index';
const BIBLE_IDB_STORE = 'bible-index';
export const BIBLE_IDB_TTL = 7 * 24 * 60 * 60 * 1000; // 7 days

function openBibleIndexDB() {
  return new Promise((resolve, reject) => {
    const req = indexedDB.open(BIBLE_IDB_NAME, 1);
    req.onupgradeneeded = (e) => {
      const db = e.target.result;
      if (!db.objectStoreNames.contains(BIBLE_IDB_STORE)) {
        db.createObjectStore(BIBLE_IDB_STORE, { keyPath: 'id' });
      }
    };
    req.onsuccess = (e) => resolve(e.target.result);
    req.onerror = () => reject(req.error);
  });
}

export async function getBibleIndexFromIDB(translation) {
  try {
    const db = await openBibleIndexDB();
    return new Promise((resolve, reject) => {
      const tx = db.transaction(BIBLE_IDB_STORE, 'readonly');
      const req = tx.objectStore(BIBLE_IDB_STORE).get(translation);
      req.onsuccess = () => resolve(req.result ?? null);
      req.onerror = () => reject(req.error);
    });
  } catch {
    return null;
  }
}

export async function saveBibleIndexToIDB(translation, flat) {
  try {
    const db = await openBibleIndexDB();
    await new Promise((resolve, reject) => {
      const tx = db.transaction(BIBLE_IDB_STORE, 'readwrite');
      const req = tx.objectStore(BIBLE_IDB_STORE).put({ id: translation, flat, cachedAt: Date.now() });
      req.onsuccess = () => resolve();
      req.onerror = () => reject(req.error);
    });
  } catch {
    // Non-fatal; in-memory cache still works for this session
  }
}