/**
 * Vault — the bridge between app state, encryption, and storage adapters.
 */

import type { AppData, StorageMode } from '@/types';
import { encrypt, decrypt } from '@/lib/crypto/encryption';
import {
  CookieStorage,
  FileStorage,
  CloudStorage,
  type StorageAdapter,
} from './adapters';

export interface VaultConfig {
  mode: StorageMode;
  username: string;
  password: string;
  /** Required iff mode === 'cloud' */
  apiUrl?: string;
  getCloudToken?: () => string | null;
}

export class Vault {
  private adapter: StorageAdapter;
  private password: string;
  /** File adapter is held separately so the UI can call setFile() */
  public readonly fileAdapter: FileStorage;

  constructor(cfg: VaultConfig) {
    this.password = cfg.password;
    this.fileAdapter = new FileStorage();
    switch (cfg.mode) {
      case 'file':
        this.adapter = this.fileAdapter;
        break;
      case 'cloud':
        if (!cfg.apiUrl || !cfg.getCloudToken) {
          throw new Error('Cloud storage requires apiUrl and getCloudToken');
        }
        this.adapter = new CloudStorage(cfg.apiUrl, cfg.getCloudToken);
        break;
      case 'cookie':
      default:
        this.adapter = new CookieStorage(cfg.username);
        break;
    }
  }

  async save(data: AppData): Promise<void> {
    const json = JSON.stringify(data);
    const blob = await encrypt(json, this.password);
    await this.adapter.save(blob);
  }

  async load(): Promise<AppData | null> {
    const blob = await this.adapter.load();
    if (!blob) return null;
    const json = await decrypt(blob, this.password);
    return JSON.parse(json);
  }

  async clear(): Promise<void> {
    await this.adapter.clear();
  }

  /** Export current data as an encrypted file regardless of active storage mode */
  async exportToFile(data: AppData): Promise<void> {
    const json = JSON.stringify(data);
    const blob = await encrypt(json, this.password);
    await this.fileAdapter.save(blob);
  }
}

/** Check if a user already has encrypted data under their username (cookie mode) */
export async function cookieDataExists(username: string): Promise<boolean> {
  const cs = new CookieStorage(username);
  const blob = await cs.load();
  return blob != null;
}