import * as crypto from 'crypto';

const algorithm = 'aes-256-cbc';
const secretKey = crypto.scryptSync('your-secret-password', 'salt', 32);
const ivLength = 16;

// Encrypt function
export function encryptUserId(id: string): string {
	const iv = crypto.randomBytes(ivLength);
	const cipher = crypto.createCipheriv(algorithm, secretKey, iv);
	let encrypted = cipher.update(id, 'utf8', 'hex');
	encrypted += cipher.final('hex');
	return `${iv.toString('hex')}:${encrypted}`;
}

// Decrypt function
export function decryptUserId(encryptedId: string): string | null {
	try {
		const parts = encryptedId.split(':');
		if (parts.length !== 2) {
			console.error('Invalid encryptedId format:', encryptedId);
			return null;
		}

		const iv = Buffer.from(parts[0], 'hex');
		const encryptedText = Buffer.from(parts[1], 'hex');

		const decipher = crypto.createDecipheriv(algorithm, secretKey, iv);
		let decrypted = decipher.update(encryptedText);
		decrypted = Buffer.concat([decrypted, decipher.final()]);

		return decrypted.toString('utf8');
	} catch (error) {
		console.error('Decryption failed:', error);
		return null;
	}
}