import crypto from 'crypto';

const ENCRYPTION_KEY = process.env.ENCRYPTION_SECRET || 'fallback_secret_do_not_use_in_production_12345'; // Must be 32 chars for aes-256-gcm
const IV_LENGTH = 16;
const ALGORITHM = 'aes-256-gcm';

/**
 * Encrypts a piece of sensitive text (like a private key)
 */
export function encrypt(text: string): string {
    // Ensure key is 32 bytes
    const key = crypto.createHash('sha256').update(ENCRYPTION_KEY).digest();
    const iv = crypto.randomBytes(IV_LENGTH);
    const cipher = crypto.createCipheriv(ALGORITHM, key, iv);
    
    let encrypted = cipher.update(text, 'utf8', 'hex');
    encrypted += cipher.final('hex');
    
    const authTag = cipher.getAuthTag().toString('hex');
    
    // Format: iv:authTag:encrypted
    return `${iv.toString('hex')}:${authTag}:${encrypted}`;
}

/**
 * Decrypts an encrypted string back to its original form
 */
export function decrypt(encryptedText: string): string {
    try {
        const parts = encryptedText.split(':');
        if (parts.length !== 3) throw new Error('Invalid encrypted text format');
        
        const iv = Buffer.from(parts[0], 'hex');
        const authTag = Buffer.from(parts[1], 'hex');
        const encrypted = parts[2];
        
        const key = crypto.createHash('sha256').update(ENCRYPTION_KEY).digest();
        const decipher = crypto.createDecipheriv(ALGORITHM, key, iv);
        decipher.setAuthTag(authTag);
        
        let decrypted = decipher.update(encrypted, 'hex', 'utf8');
        decrypted += decipher.final('utf8');
        
        return decrypted;
    } catch (error) {
        console.error('Decryption failed:', error);
        throw new Error('Critical: Could not decrypt sensitive data. Check ENCRYPTION_SECRET.');
    }
}