/**
 * SecureKeyManager - Gestion sécurisée des clés privées
 * Chiffre les clés privées avant stockage et les déchiffre à la demande
 */
export class SecureKeyManager {
  private keyStore: CryptoKey | null = null;
  private salt: Uint8Array;
  private isInitialized: boolean = false;

  constructor() {
    this.salt = crypto.getRandomValues(new Uint8Array(16));
  }

  /**
   * Initialise le gestionnaire de clés avec un mot de passe
   */
  async initialize(password: string): Promise<void> {
    try {
      const derivedKey = await this.deriveKey(password);
      this.keyStore = derivedKey;
      this.isInitialized = true;
      console.log('🔐 SecureKeyManager initialized');
    } catch (error) {
      console.error('❌ Failed to initialize SecureKeyManager:', error);
      throw new Error('Failed to initialize secure key manager');
    }
  }

  /**
   * Stocke une clé privée de manière chiffrée
   */
  async storePrivateKey(key: string, password: string): Promise<void> {
    if (!this.isInitialized) {
      await this.initialize(password);
    }

    try {
      const derivedKey = await this.deriveKey(password);
      const iv = crypto.getRandomValues(new Uint8Array(12));

      const encryptedKey = await crypto.subtle.encrypt(
        { name: 'AES-GCM', iv },
        derivedKey,
        new TextEncoder().encode(key)
      );

      // Stocker la clé chiffrée avec l'IV
      const encryptedData = new Uint8Array(iv.length + encryptedKey.byteLength);
      encryptedData.set(iv);
      encryptedData.set(new Uint8Array(encryptedKey), iv.length);

      // Stocker dans IndexedDB de manière sécurisée
      await this.storeEncryptedData(encryptedData);

      console.log('🔐 Private key stored securely');
    } catch (error) {
      console.error('❌ Failed to store private key:', error);
      throw new Error('Failed to store private key securely');
    }
  }

  /**
   * Récupère et déchiffre une clé privée
   */
  async getPrivateKey(password: string): Promise<string | null> {
    try {
      const encryptedData = await this.getEncryptedData();
      if (!encryptedData) {return null;}

      const derivedKey = await this.deriveKey(password);
      const iv = encryptedData.slice(0, 12);
      const encryptedKey = encryptedData.slice(12);

      const decrypted = await crypto.subtle.decrypt(
        { name: 'AES-GCM', iv },
        derivedKey,
        encryptedKey
      );

      return new TextDecoder().decode(decrypted);
    } catch (error) {
      console.error('❌ Failed to retrieve private key:', error);
      return null;
    }
  }

  /**
   * Supprime toutes les clés stockées
   */
  async clearKeys(): Promise<void> {
    try {
      await this.clearEncryptedData();
      this.keyStore = null;
      this.isInitialized = false;
      console.log('🔐 All keys cleared');
    } catch (error) {
      console.error('❌ Failed to clear keys:', error);
    }
  }

  /**
   * Vérifie si une clé est stockée
   */
  async hasStoredKey(): Promise<boolean> {
    try {
      const encryptedData = await this.getEncryptedData();
      return encryptedData !== null;
    } catch {
      return false;
    }
  }

  /**
   * Dérive une clé de chiffrement à partir du mot de passe
   */
  private async deriveKey(password: string): Promise<CryptoKey> {
    const keyMaterial = await crypto.subtle.importKey(
      'raw',
      new TextEncoder().encode(password),
      'PBKDF2',
      false,
      ['deriveKey']
    );

    return crypto.subtle.deriveKey(
      {
        name: 'PBKDF2',
        salt: new Uint8Array(this.salt),
        iterations: 100000,
        hash: 'SHA-256'
      },
      keyMaterial,
      { name: 'AES-GCM', length: 256 },
      false,
      ['encrypt', 'decrypt']
    );
  }

  /**
   * Stocke les données chiffrées dans IndexedDB
   */
  private async storeEncryptedData(data: Uint8Array): Promise<void> {
    return new Promise((resolve, reject) => {
      const request = indexedDB.open('SecureKeyStore', 1);

      request.onerror = () => reject(new Error('Failed to open IndexedDB'));

      request.onsuccess = () => {
        const db = request.result;
        const transaction = db.transaction(['keys'], 'readwrite');
        const store = transaction.objectStore('keys');

        const putRequest = store.put(data, 'encryptedKey');
        putRequest.onsuccess = () => resolve();
        putRequest.onerror = () => reject(new Error('Failed to store encrypted data'));
      };

      request.onupgradeneeded = () => {
        const db = request.result;
        if (!db.objectStoreNames.contains('keys')) {
          db.createObjectStore('keys');
        }
      };
    });
  }

  /**
   * Récupère les données chiffrées depuis IndexedDB
   */
  private async getEncryptedData(): Promise<Uint8Array | null> {
    return new Promise((resolve, reject) => {
      const request = indexedDB.open('SecureKeyStore', 1);

      request.onerror = () => reject(new Error('Failed to open IndexedDB'));

      request.onsuccess = () => {
        const db = request.result;
        const transaction = db.transaction(['keys'], 'readonly');
        const store = transaction.objectStore('keys');

        const getRequest = store.get('encryptedKey');
        getRequest.onsuccess = () => {
          const result = getRequest.result;
          resolve(result ? new Uint8Array(result) : null);
        };
        getRequest.onerror = () => reject(new Error('Failed to retrieve encrypted data'));
      };

      request.onupgradeneeded = () => {
        const db = request.result;
        if (!db.objectStoreNames.contains('keys')) {
          db.createObjectStore('keys');
        }
      };
    });
  }

  /**
   * Supprime les données chiffrées
   */
  private async clearEncryptedData(): Promise<void> {
    return new Promise((resolve, reject) => {
      const request = indexedDB.open('SecureKeyStore', 1);

      request.onerror = () => reject(new Error('Failed to open IndexedDB'));

      request.onsuccess = () => {
        const db = request.result;
        const transaction = db.transaction(['keys'], 'readwrite');
        const store = transaction.objectStore('keys');

        const deleteRequest = store.delete('encryptedKey');
        deleteRequest.onsuccess = () => resolve();
        deleteRequest.onerror = () => reject(new Error('Failed to clear encrypted data'));
      };
    });
  }
}

// Instance singleton pour l'application
export const secureKeyManager = new SecureKeyManager();