<?php

declare(strict_types=1);

/**
 * AES.php
 *
 * @since     2011-05-23
 * @category  Library
 * @package   PdfEncrypt
 * @author    Nicola Asuni <info@tecnick.com>
 * @copyright 2011-2026 Nicola Asuni - Tecnick.com LTD
 * @license   https://www.gnu.org/copyleft/lesser.html GNU-LGPL v3 (see LICENSE)
 * @link      https://github.com/tecnickcom/tc-lib-pdf-encrypt
 *
 * This file is part of tc-lib-pdf-encrypt software library.
 */

namespace Com\Tecnick\Pdf\Encrypt\Type;

use Com\Tecnick\Pdf\Encrypt\Exception as EncException;

/**
 * Com\Tecnick\Pdf\Encrypt\Type\AES
 *
 * AES
 *
 * @since     2011-05-23
 * @category  Library
 * @package   PdfEncrypt
 * @author    Nicola Asuni <info@tecnick.com>
 * @copyright 2011-2026 Nicola Asuni - Tecnick.com LTD
 * @license   https://www.gnu.org/copyleft/lesser.html GNU-LGPL v3 (see LICENSE)
 * @link      https://github.com/tecnickcom/tc-lib-pdf-encrypt
 */
class AES
{
    /**
     * Encrypt the data using OpenSSL
     *
     * @param string $data Data string to encrypt
     * @param string $key  Encryption key
     * @param string $mode Cipher
     *
     * @return string encrypted text
     *
     * @throws \Com\Tecnick\Pdf\Encrypt\Exception
     */
    public function encrypt(string $data, string $key, string $mode = ''): string
    {
        if ($mode === '') {
            $mode = \strlen($key) > 16 ? 'aes-256-cbc' : 'aes-128-cbc';
        }

        $aesnopad = new AESnopad();
        $aesnopad->checkCipher($mode);
        $aesnopad->checkKeyLength($key, $mode);

        $len = \openssl_cipher_iv_length($mode);
        if ($len === false || $len <= 0) {
            throw new EncException('openssl_cipher_iv_length failed');
        }

        try {
            $ivect = \random_bytes($len);
        } catch (\Random\RandomException $e) {
            throw new EncException('unable to generate the initialization vector', 0, $e);
        }

        $enc = \openssl_encrypt($data, $mode, $key, OPENSSL_RAW_DATA, $ivect);

        if ($enc === false) {
            throw new EncException('encryption error: ' . (string) \openssl_error_string());
        }

        return $ivect . $enc;
    }
}
