/**
 * Crypto Service for Stack.Gallery Registry
 * Handles AES-256-GCM encryption/decryption of secrets
 */

export class CryptoService {
  private masterKey: CryptoKey | null = null;
  private initialized = false;

  /**
   * Initialize the crypto service with the master key
   * The key should be a 64-character hex string (32 bytes = 256 bits)
   */
  public async initialize(): Promise<void> {
    if (this.initialized) return;

    const keyHex = Deno.env.get('AUTH_ENCRYPTION_KEY');
    if (!keyHex) {
      console.warn(
        '[CryptoService] AUTH_ENCRYPTION_KEY not set. Generating ephemeral key (NOT for production!)'
      );
      const randomBytes = crypto.getRandomValues(new Uint8Array(32));
      this.masterKey = await this.importKey(this.bytesToHex(randomBytes));
    } else {
      if (keyHex.length !== 64) {
        throw new Error('AUTH_ENCRYPTION_KEY must be a 64-character hex string (32 bytes)');
      }
      this.masterKey = await this.importKey(keyHex);
    }

    this.initialized = true;
  }

  /**
   * Encrypt a plaintext string
   * Returns format: base64(iv):base64(ciphertext)
   */
  public async encrypt(plaintext: string): Promise<string> {
    await this.initialize();

    if (!this.masterKey) {
      throw new Error('CryptoService not initialized');
    }

    // Generate random IV (12 bytes for AES-GCM)
    const iv = crypto.getRandomValues(new Uint8Array(12));

    // Encode plaintext to bytes
    const encoded = new TextEncoder().encode(plaintext);

    // Encrypt
    const encrypted = await crypto.subtle.encrypt(
      { name: 'AES-GCM', iv },
      this.masterKey,
      encoded
    );

    // Format: iv:ciphertext (both base64)
    const ivBase64 = this.bytesToBase64(iv);
    const ciphertextBase64 = this.bytesToBase64(new Uint8Array(encrypted));

    return `${ivBase64}:${ciphertextBase64}`;
  }

  /**
   * Decrypt an encrypted string
   * Expects format: base64(iv):base64(ciphertext)
   */
  public async decrypt(ciphertext: string): Promise<string> {
    await this.initialize();

    if (!this.masterKey) {
      throw new Error('CryptoService not initialized');
    }

    const parts = ciphertext.split(':');
    if (parts.length !== 2) {
      throw new Error('Invalid ciphertext format');
    }

    const [ivBase64, encryptedBase64] = parts;

    // Decode from base64
    const iv = this.base64ToBytes(ivBase64);
    const encrypted = this.base64ToBytes(encryptedBase64);

    // Decrypt
    const decrypted = await crypto.subtle.decrypt(
      { name: 'AES-GCM', iv },
      this.masterKey,
      encrypted
    );

    // Decode to string
    return new TextDecoder().decode(decrypted);
  }

  /**
   * Check if a string is already encrypted (contains the iv:ciphertext format)
   */
  public isEncrypted(value: string): boolean {
    if (!value || typeof value !== 'string') return false;
    const parts = value.split(':');
    if (parts.length !== 2) return false;

    // Check if both parts look like base64
    try {
      this.base64ToBytes(parts[0]);
      this.base64ToBytes(parts[1]);
      return true;
    } catch {
      return false;
    }
  }

  /**
   * Import a hex key as CryptoKey
   */
  private async importKey(keyHex: string): Promise<CryptoKey> {
    const keyBytes = this.hexToBytes(keyHex);
    return await crypto.subtle.importKey(
      'raw',
      keyBytes,
      { name: 'AES-GCM' },
      false,
      ['encrypt', 'decrypt']
    );
  }

  /**
   * Convert bytes to hex string
   */
  private bytesToHex(bytes: Uint8Array): string {
    return Array.from(bytes)
      .map((b) => b.toString(16).padStart(2, '0'))
      .join('');
  }

  /**
   * Convert hex string to bytes
   */
  private hexToBytes(hex: string): Uint8Array {
    const bytes = new Uint8Array(hex.length / 2);
    for (let i = 0; i < hex.length; i += 2) {
      bytes[i / 2] = parseInt(hex.substring(i, i + 2), 16);
    }
    return bytes;
  }

  /**
   * Convert bytes to base64
   */
  private bytesToBase64(bytes: Uint8Array): string {
    return btoa(String.fromCharCode(...bytes));
  }

  /**
   * Convert base64 to bytes
   */
  private base64ToBytes(base64: string): Uint8Array {
    const binary = atob(base64);
    return Uint8Array.from(binary, (c) => c.charCodeAt(0));
  }

  /**
   * Generate a new encryption key (for setup)
   * Returns a 64-character hex string
   */
  public static generateKey(): string {
    const bytes = crypto.getRandomValues(new Uint8Array(32));
    return Array.from(bytes)
      .map((b) => b.toString(16).padStart(2, '0'))
      .join('');
  }
}

// Singleton instance
export const cryptoService = new CryptoService();