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

namespace Ant.Service.Utility
{
    public class EncodeHelper
    {
        #region 对称加密算法AES RijndaelManaged加密解密
        private static readonly string Default_AES_Key = "@#kim123";
        private static byte[] Keys = { 0x41, 0x72, 0x65, 0x79, 0x6F, 0x75, 0x6D, 0x79,
                                             0x53,0x6E, 0x6F, 0x77, 0x6D, 0x61, 0x6E, 0x3F };
        private static byte[] keyase = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };

        private static byte[] inputData = { 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f };
        /// <summary>
        /// 对称加密算法AES RijndaelManaged加密(RijndaelManaged（AES）算法是块式加密算法)
        /// </summary>
        /// <param name="encryptString">待加密字符串</param>
        /// <returns>加密结果字符串</returns>
        public static string AES_Encrypt(string encryptString)
        {
            return null;
        }

        /// <summary>
        /// 对称加密算法AES RijndaelManaged加密(RijndaelManaged（AES）算法是块式加密算法)
        /// </summary>
        /// <param name="encryptString">待加密字符串</param>
        /// <param name="encryptKey">加密密钥，须半角字符</param>
        /// <returns>加密结果字符串</returns>
        public static string AES_Encrypt()
        {


            RijndaelManaged rijndaelProvider = new RijndaelManaged();
            rijndaelProvider.Key = keyase;
            rijndaelProvider.IV = Keys;
            ICryptoTransform rijndaelEncrypt = rijndaelProvider.CreateEncryptor();

            byte[] inputData = { 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f };
            byte[] encryptedData = rijndaelEncrypt.TransformFinalBlock(inputData, 0, inputData.Length);

            return Convert.ToBase64String(encryptedData);
        }
        /// <summary>  
        /// AES加密(无向量)  
        /// </summary>  
        /// <param name="plainBytes">被加密的明文</param>  
        /// <param name="key">密钥</param>  
        /// <returns>密文</returns>  
        public static string AESEncrypttest()
        {
            MemoryStream mStream = new MemoryStream();
            RijndaelManaged aes = new RijndaelManaged();

            byte[] plainBytes = inputData;
            //Byte[] bKey = new Byte[16];
            //Array.Copy(keyase, bKey, bKey.Length);

            aes.Mode = CipherMode.ECB;
            aes.Padding = PaddingMode.PKCS7;
            aes.KeySize = 128;
            //aes.Key = _key;  
            aes.Key = keyase;
            //aes.IV = _iV;  
            CryptoStream cryptoStream = new CryptoStream(mStream, aes.CreateEncryptor(), CryptoStreamMode.Write);
            try
            {
                cryptoStream.Write(plainBytes, 0, plainBytes.Length);
                cryptoStream.FlushFinalBlock();
                Byte[] str = new Byte[16];
                str = mStream.ToArray();
                return Convert.ToBase64String(str);
            }
            finally
            {
                cryptoStream.Close();
                mStream.Close();
                aes.Clear();
            }
        }


        /// <summary>
        /// 对称加密算法AES RijndaelManaged解密字符串
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <returns>解密成功返回解密后的字符串,失败返源串</returns>
        public static string AES_Decrypt(string decryptString)
        {
            return AES_Decrypt(decryptString, Default_AES_Key);
        }

        /// <summary>
        /// 对称加密算法AES RijndaelManaged解密字符串
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <param name="decryptKey">解密密钥,和加密密钥相同</param>
        /// <returns>解密成功返回解密后的字符串,失败返回空</returns>
        public static string AES_Decrypt(string decryptString, string decryptKey)
        {
            try
            {
                decryptKey = GetSubString(decryptKey, 32, "");
                decryptKey = decryptKey.PadRight(32, ' ');

                RijndaelManaged rijndaelProvider = new RijndaelManaged();
                rijndaelProvider.Key = Encoding.UTF8.GetBytes(decryptKey);
                rijndaelProvider.IV = Keys;
                ICryptoTransform rijndaelDecrypt = rijndaelProvider.CreateDecryptor();

                byte[] inputData = Convert.FromBase64String(decryptString);
                byte[] decryptedData = rijndaelDecrypt.TransformFinalBlock(inputData, 0, inputData.Length);

                return Encoding.UTF8.GetString(decryptedData);
            }
            catch
            {
                return string.Empty;
            }
        }

        /// <summary>
        /// 按字节长度(按字节,一个汉字为2个字节)取得某字符串的一部分
        /// </summary>
        /// <param name="sourceString">源字符串</param>
        /// <param name="length">所取字符串字节长度</param>
        /// <param name="tailString">附加字符串(当字符串不够长时，尾部所添加的字符串，一般为"...")</param>
        /// <returns>某字符串的一部分</returns>
        private static string GetSubString(string sourceString, int length, string tailString)
        {
            return GetSubString(sourceString, 0, length, tailString);
        }

        /// <summary>
        /// 按字节长度(按字节,一个汉字为2个字节)取得某字符串的一部分
        /// </summary>
        /// <param name="sourceString">源字符串</param>
        /// <param name="startIndex">索引位置，以0开始</param>
        /// <param name="length">所取字符串字节长度</param>
        /// <param name="tailString">附加字符串(当字符串不够长时，尾部所添加的字符串，一般为"...")</param>
        /// <returns>某字符串的一部分</returns>
        private static string GetSubString(string sourceString, int startIndex, int length, string tailString)
        {
            string myResult = sourceString;

            //当是日文或韩文时(注:中文的范围:\u4e00 - \u9fa5, 日文在\u0800 - \u4e00, 韩文为\xAC00-\xD7A3)
            if (System.Text.RegularExpressions.Regex.IsMatch(sourceString, "[\u0800-\u4e00]+") ||
                System.Text.RegularExpressions.Regex.IsMatch(sourceString, "[\xAC00-\xD7A3]+"))
            {
                //当截取的起始位置超出字段串长度时
                if (startIndex >= sourceString.Length)
                {
                    return string.Empty;
                }
                else
                {
                    return sourceString.Substring(startIndex,
                                                   ((length + startIndex) > sourceString.Length) ? (sourceString.Length - startIndex) : length);
                }
            }

            //中文字符，如"中国人民abcd123"
            if (length <= 0)
            {
                return string.Empty;
            }
            byte[] bytesSource = Encoding.Default.GetBytes(sourceString);

            //当字符串长度大于起始位置
            if (bytesSource.Length > startIndex)
            {
                int endIndex = bytesSource.Length;

                //当要截取的长度在字符串的有效长度范围内
                if (bytesSource.Length > (startIndex + length))
                {
                    endIndex = length + startIndex;
                }
                else
                {   //当不在有效范围内时,只取到字符串的结尾
                    length = bytesSource.Length - startIndex;
                    tailString = "";
                }

                int[] anResultFlag = new int[length];
                int nFlag = 0;
                //字节大于127为双字节字符
                for (int i = startIndex; i < endIndex; i++)
                {
                    if (bytesSource[i] > 127)
                    {
                        nFlag++;
                        if (nFlag == 3)
                        {
                            nFlag = 1;
                        }
                    }
                    else
                    {
                        nFlag = 0;
                    }
                    anResultFlag[i] = nFlag;
                }
                //最后一个字节为双字节字符的一半
                if ((bytesSource[endIndex - 1] > 127) && (anResultFlag[length - 1] == 1))
                {
                    length = length + 1;
                }

                byte[] bsResult = new byte[length];
                Array.Copy(bytesSource, startIndex, bsResult, 0, length);
                myResult = Encoding.Default.GetString(bsResult);
                myResult = myResult + tailString;

                return myResult;
            }

            return string.Empty;

        }

        /// <summary>
        /// 加密文件流
        /// </summary>
        /// <param name="fs"></param>
        /// <returns></returns>
        public static CryptoStream AES_EncryptStrream(FileStream fs, string decryptKey)
        {
            decryptKey = GetSubString(decryptKey, 32, "");
            decryptKey = decryptKey.PadRight(32, ' ');

            RijndaelManaged rijndaelProvider = new RijndaelManaged();
            rijndaelProvider.Key = Encoding.UTF8.GetBytes(decryptKey);
            rijndaelProvider.IV = Keys;

            ICryptoTransform encrypto = rijndaelProvider.CreateEncryptor();
            CryptoStream cytptostreamEncr = new CryptoStream(fs, encrypto, CryptoStreamMode.Write);
            return cytptostreamEncr;
        }

        /// <summary>
        /// 解密文件流
        /// </summary>
        /// <param name="fs"></param>
        /// <returns></returns>
        public static CryptoStream AES_DecryptStream(FileStream fs, string decryptKey)
        {
            decryptKey = GetSubString(decryptKey, 32, "");
            decryptKey = decryptKey.PadRight(32, ' ');

            RijndaelManaged rijndaelProvider = new RijndaelManaged();
            rijndaelProvider.Key = Encoding.UTF8.GetBytes(decryptKey);
            rijndaelProvider.IV = Keys;
            ICryptoTransform Decrypto = rijndaelProvider.CreateDecryptor();
            CryptoStream cytptostreamDecr = new CryptoStream(fs, Decrypto, CryptoStreamMode.Read);
            return cytptostreamDecr;
        }

        /// <summary>
        /// 对指定文件加密
        /// </summary>
        /// <param name="InputFile"></param>
        /// <param name="OutputFile"></param>
        /// <returns></returns>
        public static bool AES_EncryptFile(string InputFile, string OutputFile)
        {
            try
            {
                string decryptKey = "www.iqidi.com";

                FileStream fr = new FileStream(InputFile, FileMode.Open);
                FileStream fren = new FileStream(OutputFile, FileMode.Create);
                CryptoStream Enfr = AES_EncryptStrream(fren, decryptKey);
                byte[] bytearrayinput = new byte[fr.Length];
                fr.Read(bytearrayinput, 0, bytearrayinput.Length);
                Enfr.Write(bytearrayinput, 0, bytearrayinput.Length);
                Enfr.Close();
                fr.Close();
                fren.Close();
            }
            catch
            {
                //文件异常
                return false;
            }
            return true;
        }

        /// <summary>
        /// 对指定的文件解压缩
        /// </summary>
        /// <param name="InputFile"></param>
        /// <param name="OutputFile"></param>
        /// <returns></returns>
        public static bool AES_DecryptFile(string InputFile, string OutputFile)
        {
            try
            {
                string decryptKey = "www.iqidi.com";
                FileStream fr = new FileStream(InputFile, FileMode.Open);
                FileStream frde = new FileStream(OutputFile, FileMode.Create);
                CryptoStream Defr = AES_DecryptStream(fr, decryptKey);
                byte[] bytearrayoutput = new byte[1024];
                int m_count = 0;

                do
                {
                    m_count = Defr.Read(bytearrayoutput, 0, bytearrayoutput.Length);
                    frde.Write(bytearrayoutput, 0, m_count);
                    if (m_count < bytearrayoutput.Length)
                        break;
                } while (true);

                Defr.Close();
                fr.Close();
                frde.Close();
            }
            catch
            {
                //文件异常
                return false;
            }
            return true;
        }

        #endregion
    }
}