<?php
/**
 * Tour Operator Pro System
 *
 * Copyright (C) 2005 - 2019 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later; see LICENSE.txt
 */

namespace WpBookingEvent\Crypt\Cipher;

defined('_WPBOOKINGEVENT_EXEC') or die;

use WpBookingEvent\Crypt\CipherInterface;
use WpBookingEvent\Crypt\Key;
use ParagonIE\Sodium\Compat;

/**
 * JCrypt cipher for sodium algorithm encryption, decryption and key generation.
 *
 * @since  3.8.0
 */
class SodiumCipher implements CipherInterface
{
    /**
     * The message nonce to be used with encryption/decryption
     *
     * @var    string
     * @since  3.8.0
     */
    private $nonce;

    /**
     * Method to decrypt a data string.
     *
     * @param string $data The encrypted string to decrypt.
     * @param Key $key The key object to use for decryption.
     *
     * @return  string  The decrypted data string.
     *
     * @throws  \RuntimeException
     * @since   3.8.0
     */
    public function decrypt($data, Key $key)
    {
        // Validate key.
        if ($key->type !== 'sodium') {
            throw new \InvalidArgumentException('Invalid key of type: ' . $key->type . '.  Expected sodium.');
        }

        if (!$this->nonce) {
            throw new \RuntimeException('Missing nonce to decrypt data');
        }

        $decrypted = Compat::crypto_box_open(
            $data,
            $this->nonce,
            Compat::crypto_box_keypair_from_secretkey_and_publickey($key->private, $key->public)
        );

        if ($decrypted === false) {
            throw new \RuntimeException('Malformed message or invalid MAC');
        }

        return $decrypted;
    }

    /**
     * Method to encrypt a data string.
     *
     * @param string $data The data string to encrypt.
     * @param Key $key The key object to use for encryption.
     *
     * @return  string  The encrypted data string.
     *
     * @throws  \RuntimeException
     * @since   3.8.0
     */
    public function encrypt($data, Key $key)
    {
        // Validate key.
        if ($key->type !== 'sodium') {
            throw new \InvalidArgumentException('Invalid key of type: ' . $key->type . '.  Expected sodium.');
        }

        if (!$this->nonce) {
            throw new \RuntimeException('Missing nonce to decrypt data');
        }

        return Compat::crypto_box(
            $data,
            $this->nonce,
            Compat::crypto_box_keypair_from_secretkey_and_publickey($key->private, $key->public)
        );
    }

    /**
     * Method to generate a new encryption key object.
     *
     * @param array $options Key generation options.
     *
     * @return  Key
     *
     * @throws  RuntimeException
     * @since   3.8.0
     */
    public function generateKey(array $options = array())
    {
        // Create the new encryption key object.
        $key = new Key('sodium');

        // Generate the encryption key.
        $pair = Compat::crypto_box_keypair();

        $key->public = Compat::crypto_box_publickey($pair);
        $key->private = Compat::crypto_box_secretkey($pair);

        return $key;
    }

    /**
     * Set the nonce to use for encrypting/decrypting messages
     *
     * @param string $nonce The message nonce
     *
     * @return  void
     *
     * @since   3.8.0
     */
    public function setNonce($nonce)
    {
        $this->nonce = $nonce;
    }
}
