<?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;

use Joomla\Crypt\Cipher\Crypto;
use Joomla\Crypt\Exception\DecryptionException;
use Joomla\Crypt\Exception\EncryptionException;
use Joomla\Crypt\Exception\InvalidKeyException;
use Joomla\Crypt\Exception\InvalidKeyTypeException;
use Joomla\Crypt\Exception\UnsupportedCipherException;

/**
 * Crypt is a Joomla Framework class for handling basic encryption/decryption of data.
 *
 * @since  1.0
 */
class Crypt
{
    /**
     * The encryption cipher object.
     *
     * @var    CipherInterface
     * @since  1.0
     */
    private $cipher;

    /**
     * The encryption key[/pair)].
     *
     * @var    Key
     * @since  1.0
     */
    private $key;

    /**
     * Object Constructor takes an optional key to be used for encryption/decryption. If no key is given then the
     * secret word from the configuration object is used.
     *
     * @param   ?CipherInterface  $cipher  The encryption cipher object.
     * @param   ?Key              $key     The encryption key[/pair)].
     *
     * @since   1.0
     */
    public function __construct(?CipherInterface $cipher = null, ?Key $key = null)
    {
        // Set the encryption cipher.
        $this->cipher = $cipher ?: new Crypto();

        // Set the encryption key[/pair)].
        $this->key = $key ?: $this->generateKey();
    }

    /**
     * Method to decrypt a data string.
     *
     * @param   string  $data  The encrypted string to decrypt.
     *
     * @return  string  The decrypted data string.
     *
     * @since   1.0
     * @throws  DecryptionException if the data cannot be decrypted
     * @throws  InvalidKeyTypeException if the key is not valid for the cipher
     * @throws  UnsupportedCipherException if the cipher is not supported on the current environment
     */
    public function decrypt($data)
    {
        return $this->cipher->decrypt($data, $this->key);
    }

    /**
     * Method to encrypt a data string.
     *
     * @param   string  $data  The data string to encrypt.
     *
     * @return  string  The encrypted data string.
     *
     * @since   1.0
     * @throws  EncryptionException if the data cannot be encrypted
     * @throws  InvalidKeyTypeException if the key is not valid for the cipher
     * @throws  UnsupportedCipherException if the cipher is not supported on the current environment
     */
    public function encrypt($data)
    {
        return $this->cipher->encrypt($data, $this->key);
    }

    /**
     * Method to generate a new encryption key[/pair] object.
     *
     * @param   array  $options  Key generation options.
     *
     * @return  Key
     *
     * @since   1.0
     * @throws  InvalidKeyException if the key cannot be generated
     * @throws  UnsupportedCipherException if the cipher is not supported on the current environment
     */
    public function generateKey(array $options = [])
    {
        return $this->cipher->generateKey($options);
    }

    /**
     * Method to set the encryption key[/pair] object.
     *
     * @param   Key  $key  The key object to set.
     *
     * @return  Crypt  Instance of $this to allow chaining.
     *
     * @since   1.0
     */
    public function setKey(Key $key)
    {
        $this->key = $key;

        return $this;
    }

    /**
     * Generate random bytes.
     *
     * @param   integer  $length  Length of the random data to generate
     *
     * @return  string  Random binary data
     *
     * @since   1.0
     */
    public static function genRandomBytes($length = 16)
    {
        return random_bytes($length);
    }
}