using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

namespace VRS.Util
{
    public static class AESHelper
    {
        /// <summary>
        ///  AES 加密
        /// </summary>
        /// <param name="content">待加密的字符串</param>
        /// <param name="key">密文</param>
        /// <returns></returns>
        public static string AesEncrypt(string str, string key)
        {
            if (string.IsNullOrEmpty(str)) return null;
            Byte[] toEncryptArray = Encoding.UTF8.GetBytes(str);

            RijndaelManaged rm = new RijndaelManaged
            {
                Key = Encoding.UTF8.GetBytes(key),
                Mode = CipherMode.ECB,
                Padding = PaddingMode.PKCS7
            };

            ICryptoTransform cTransform = rm.CreateEncryptor();
            Byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
            return BitConverter.ToString(resultArray).Replace("-", "");
        }

        /// <summary>
        /// 校内密码加密
        /// </summary>
        /// <param name="plainText"></param>
        /// <returns></returns>
        public static string EncryptPassword(string plainText)
        {
            // AES 密钥（必须是 16、24 或 32 字节）
            var key = Encoding.UTF8.GetBytes("kGBxaThxMCMGaysp");
            // 初始化向量 IV（必须是 16 字节）
            var iv = Encoding.UTF8.GetBytes("VXFxgTgcvSDEXHpC");
            using (Aes aesAlg = Aes.Create())
            {
                aesAlg.Key = key;
                aesAlg.IV = iv;
                aesAlg.Mode = CipherMode.CBC;
                aesAlg.Padding = PaddingMode.PKCS7;

                // 创建加密器对象
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            // 写入加密后的数据到内存流中
                            swEncrypt.Write(plainText);
                        }
                    }
                    // 返回加密后的数据的 Base64 字符串
                    return Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
        }

        /// <summary>
        ///  AES 解密
        /// </summary>
        /// <param name="content">待解密的字符串</param>
        /// <param name="key">密文</param>
        /// <returns></returns>
        public static string AesDecrypt(string content, string key)
        {
            if (string.IsNullOrEmpty(content)) return null;
            Byte[] toEncryptArray = ConvertToByteArray(content);

            RijndaelManaged rm = new RijndaelManaged
            {
                Key = Encoding.UTF8.GetBytes(key),
                Mode = CipherMode.ECB,
                Padding = PaddingMode.PKCS7
            };

            ICryptoTransform cTransform = rm.CreateDecryptor();
            Byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

            return Encoding.UTF8.GetString(resultArray);
        }

        /// <summary>
        /// hex字符串转为byte[]数组
        /// </summary>
        /// <param name="hexString">hex字符串</param>
        /// <returns></returns>
        private static byte[] ConvertToByteArray(string hexString)
        {
            int length = hexString.Length / 2;
            byte[] bytes = new byte[length];

            for (int i = 0; i < length; ++i)
            {
                bytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
            }

            return bytes;
        }
    }
}