/**
 * Tiny IndexedDB sidecar for persisting FileSystemDirectoryHandle.
 *
 * SQLite can't store DOM objects (they require structured clone),
 * so we use a minimal IDB store exclusively for the folder handle.
 */

const DB_NAME = 'FolderSyncDB_handles';
const STORE_NAME = 'handles';
const DB_VERSION = 1;

function openHandleDB(): Promise<IDBDatabase> {
  return new Promise((resolve, reject) => {
    const req = indexedDB.open(DB_NAME, DB_VERSION);
    req.onupgradeneeded = () => {
      req.result.createObjectStore(STORE_NAME, { keyPath: 'key' });
    };
    req.onsuccess = () => resolve(req.result);
    req.onerror = () => reject(req.error);
  });
}

export async function storeHandle(
  key: string,
  handle: FileSystemDirectoryHandle,
): Promise<void> {
  const db = await openHandleDB();
  try {
    const tx = db.transaction(STORE_NAME, 'readwrite');
    tx.objectStore(STORE_NAME).put({ key, handle });
    await new Promise<void>((resolve, reject) => {
      tx.oncomplete = () => resolve();
      tx.onerror = () => reject(tx.error);
    });
  } finally {
    db.close();
  }
}

export async function loadHandle(
  key: string,
): Promise<FileSystemDirectoryHandle | null> {
  const db = await openHandleDB();
  try {
    const tx = db.transaction(STORE_NAME, 'readonly');
    const req = tx.objectStore(STORE_NAME).get(key);
    return await new Promise<FileSystemDirectoryHandle | null>(
      (resolve, reject) => {
        req.onsuccess = () => resolve(req.result?.handle ?? null);
        req.onerror = () => reject(req.error);
      },
    );
  } finally {
    db.close();
  }
}