import type { IStorageAdapter } from '../core/IStorageAdapter';

/**
 * IndexedDB-based storage adapter for browser environments.
 * Provides persistent storage that survives page reloads.
 */
export class IndexedDBAdapter implements IStorageAdapter {
  private dbName: string;
  private storeName: string;

  constructor(dbName: string = 'wcli-storage', storeName: string = 'data') {
    this.dbName = dbName;
    this.storeName = storeName;
  }

  private async openDB(): Promise<IDBDatabase> {
    return new Promise((resolve, reject) => {
      const request = indexedDB.open(this.dbName, 1);

      request.onerror = () => reject(request.error);
      request.onsuccess = () => resolve(request.result);

      request.onupgradeneeded = (event) => {
        const db = (event.target as IDBOpenDBRequest).result;
        if (!db.objectStoreNames.contains(this.storeName)) {
          db.createObjectStore(this.storeName);
        }
      };
    });
  }

  async save(key: string, data: any): Promise<void> {
    try {
      const db = await this.openDB();
      const transaction = db.transaction([this.storeName], 'readwrite');
      const store = transaction.objectStore(this.storeName);

      store.put(data, key);

      return new Promise((resolve, reject) => {
        transaction.oncomplete = () => {
          db.close();
          resolve();
        };
        transaction.onerror = () => {
          db.close();
          reject(transaction.error);
        };
      });
    } catch (error) {
      throw new Error(`Failed to save data: ${error instanceof Error ? error.message : String(error)}`);
    }
  }

  async load(key: string): Promise<any> {
    try {
      const db = await this.openDB();
      const transaction = db.transaction([this.storeName], 'readonly');
      const store = transaction.objectStore(this.storeName);
      const request = store.get(key);

      return new Promise((resolve, reject) => {
        request.onsuccess = () => {
          db.close();
          resolve(request.result || null);
        };
        request.onerror = () => {
          db.close();
          reject(request.error);
        };
      });
    } catch (error) {
      throw new Error(`Failed to load data: ${error instanceof Error ? error.message : String(error)}`);
    }
  }

  async remove(key: string): Promise<void> {
    try {
      const db = await this.openDB();
      const transaction = db.transaction([this.storeName], 'readwrite');
      const store = transaction.objectStore(this.storeName);

      store.delete(key);

      return new Promise((resolve, reject) => {
        transaction.oncomplete = () => {
          db.close();
          resolve();
        };
        transaction.onerror = () => {
          db.close();
          reject(transaction.error);
        };
      });
    } catch (error) {
      throw new Error(`Failed to remove data: ${error instanceof Error ? error.message : String(error)}`);
    }
  }

  async list(): Promise<string[]> {
    try {
      const db = await this.openDB();
      const transaction = db.transaction([this.storeName], 'readonly');
      const store = transaction.objectStore(this.storeName);
      const request = store.getAllKeys();

      return new Promise((resolve, reject) => {
        request.onsuccess = () => {
          db.close();
          resolve(request.result as string[]);
        };
        request.onerror = () => {
          db.close();
          reject(request.error);
        };
      });
    } catch (error) {
      throw new Error(`Failed to list keys: ${error instanceof Error ? error.message : String(error)}`);
    }
  }
}