<?php

/**
 * Part of the Joomla Framework Crypt Package
 *
 * @copyright  Copyright (C) 2005 - 2021 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE
 */

namespace Joomla\Crypt\Cipher;

use Joomla\Crypt\CipherInterface;
use Joomla\Crypt\Exception\DecryptionException;
use Joomla\Crypt\Exception\EncryptionException;
use Joomla\Crypt\Exception\InvalidKeyException;
use Joomla\Crypt\Exception\InvalidKeyTypeException;
use Joomla\Crypt\Key;

/**
 * Joomla cipher for encryption, decryption and key generation via the openssl extension.
 *
 * @since  2.0.0
 */
class OpenSSL implements CipherInterface
{
    /**
     * Initialisation vector for key generator method.
     *
     * @var    string
     * @since  2.0.0
     */
    private $iv;

    /**
     * Method to use for encryption.
     *
     * @var    string
     * @since  2.0.0
     */
    private $method;

    /**
     * Instantiate the cipher.
     *
     * @param   string  $iv      The initialisation vector to use
     * @param   string  $method  The encryption method to use
     *
     * @since   2.0.0
     */
    public function __construct(string $iv, string $method)
    {
        $this->iv     = $iv;
        $this->method = $method;
    }

    /**
     * Method to decrypt a data string.
     *
     * @param   string  $data  The encrypted string to decrypt.
     * @param   Key     $key   The key object to use for decryption.
     *
     * @return  string  The decrypted data string.
     *
     * @since   2.0.0
     * @throws  DecryptionException if the data cannot be decrypted
     * @throws  InvalidKeyTypeException if the key is not valid for the cipher
     */
    public function decrypt($data, Key $key)
    {
        // Validate key.
        if ($key->getType() !== 'openssl') {
            throw new InvalidKeyTypeException('openssl', $key->getType());
        }

        $cleartext = openssl_decrypt($data, $this->method, $key->getPrivate(), 0, $this->iv);

        if ($cleartext === false) {
            throw new DecryptionException('Failed to decrypt data');
        }

        return $cleartext;
    }

    /**
     * Method to encrypt a data string.
     *
     * @param   string  $data  The data string to encrypt.
     * @param   Key     $key   The key object to use for encryption.
     *
     * @return  string  The encrypted data string.
     *
     * @since   2.0.0
     * @throws  EncryptionException if the data cannot be encrypted
     * @throws  InvalidKeyTypeException if the key is not valid for the cipher
     */
    public function encrypt($data, Key $key)
    {
        // Validate key.
        if ($key->getType() !== 'openssl') {
            throw new InvalidKeyTypeException('openssl', $key->getType());
        }

        $encrypted = openssl_encrypt($data, $this->method, $key->getPrivate(), 0, $this->iv);

        if ($encrypted === false) {
            throw new EncryptionException('Unable to encrypt data');
        }

        return $encrypted;
    }

    /**
     * Method to generate a new encryption key object.
     *
     * @param   array  $options  Key generation options.
     *
     * @return  Key
     *
     * @since   2.0.0
     * @throws  InvalidKeyException if the key cannot be generated
     */
    public function generateKey(array $options = [])
    {
        $passphrase = $options['passphrase'] ?? false;

        if ($passphrase === false) {
            throw new InvalidKeyException('Missing passphrase file');
        }

        return new Key('openssl', $passphrase, 'unused');
    }

    /**
     * Check if the cipher is supported in this environment.
     *
     * @return  boolean
     *
     * @since   2.0.0
     */
    public static function isSupported(): bool
    {
        return \extension_loaded('openssl');
    }
}