/*******************************************************************************
 * Copyright © 2017-2020 Znyc.Cloudcar.Admin.Framework 版权所有
 * Author: Znyc
 * Description: Znyc快速开发平台
 * Website：http://www.Znyc.Cloudcar.Admin.com
*********************************************************************************/

using Newtonsoft.Json;
using System.IO;
using System.Security.Cryptography;

namespace Znyc.Cloudcar.Admin.Commons.Encrypt
{
    /// <summary>
    ///     RSA加解密工具
    /// </summary>
    public static class RSAUtils
    {
        /// <summary>
        ///     从本地文件中读取用来签发Token的 RSA Key。
        /// </summary>
        /// <param name="filePath">存放密钥的文件夹路径</param>
        /// <param name="withPrivate"></param>
        /// <param name="keyParameters"></param>
        /// <returns></returns>
        public static bool TryGetKeyParameters(string filePath, bool withPrivate, out RSAParameters keyParameters)
        {
            string filename = withPrivate ? "key.json" : "key.public.json";
            keyParameters = default;
            if (Directory.Exists(filePath) == false)
            {
                return false;
            }

            keyParameters =
                JsonConvert.DeserializeObject<RSAParameters>(File.ReadAllText(Path.Combine(filePath, filename)));
            return true;
        }

        /// <summary>
        ///     生成并保存 RSA 公钥与私钥。
        /// </summary>
        /// <param name="filePath">存放密钥的文件夹路径</param>
        /// <returns></returns>
        public static RSAParameters GenerateAndSaveKey(string filePath)
        {
            RSAParameters publicKeys, privateKeys;
            using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(2048))
            {
                try
                {
                    privateKeys = rsa.ExportParameters(true);
                    publicKeys = rsa.ExportParameters(false);
                }
                finally
                {
                    rsa.PersistKeyInCsp = false;
                }
            }

            File.WriteAllText(Path.Combine(filePath, "key.json"), JsonConvert.SerializeObject(privateKeys));
            File.WriteAllText(Path.Combine(filePath, "key.public.json"), JsonConvert.SerializeObject(publicKeys));
            return privateKeys;
        }
    }
}