using log4net;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

namespace CnasSynchronousCommon
{
    public class EncryptionOperation
    {
        #region MD5加密
        /// <summary>
        /// MD5加密
        /// </summary>
        /// <param name="input"></param>
        /// <returns></returns>
        public static string GetMD5Hash(String input)
        {
            string cl = input;
            string pwd = "";
            MD5 md5 = MD5.Create();//实例化一个md5对像
            // 加密后是一个字节类型的数组，这里要注意编码UTF8/Unicode等的选择　
            byte[] s = md5.ComputeHash(Encoding.Default.GetBytes(cl));
            // 通过使用循环，将字节类型的数组转换为字符串，此字符串是常规字符格式化所得
            for (int i = 0; i < s.Length; i++)
            {
                // 将得到的字符串使用十六进制类型格式。格式后的字符是小写的字母，如果使用大写（X）则格式后的字符是大写字符

                pwd = pwd + s[i].ToString("X");

            }
            return pwd;
        }
        #endregion


        // 对称加密算法提供器
        private ICryptoTransform encryptor;     // 加密器对象
        private ICryptoTransform decryptor;     // 解密器对象
        private const int BufferSize = 1024;

        public EncryptionOperation(string algorithmName, string key)
        {
            try
            {
                SymmetricAlgorithm provider = SymmetricAlgorithm.Create(algorithmName);
                provider.Key = Encoding.UTF8.GetBytes(key);
                provider.IV = new byte[] { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

                encryptor = provider.CreateEncryptor();
                decryptor = provider.CreateDecryptor();
            }
            catch (Exception ex)
            {
                string s = ex.Message.ToString();
   
            }
        }

        public EncryptionOperation(string key) : this("TripleDES", key) { }

        // 加密算法
        public string Encrypt(string clearText)
        {
            try
            {
                // 创建明文流
                byte[] clearBuffer = Encoding.UTF8.GetBytes(clearText);
                MemoryStream clearStream = new MemoryStream(clearBuffer);

                // 创建空的密文流
                MemoryStream encryptedStream = new MemoryStream();

                CryptoStream cryptoStream =
                    new CryptoStream(encryptedStream, encryptor, CryptoStreamMode.Write);

                // 将明文流写入到buffer中
                // 将buffer中的数据写入到cryptoStream中
                int bytesRead = 0;
                byte[] buffer = new byte[BufferSize];
                do
                {
                    bytesRead = clearStream.Read(buffer, 0, BufferSize);
                    cryptoStream.Write(buffer, 0, bytesRead);
                } while (bytesRead > 0);

                cryptoStream.FlushFinalBlock();

                // 获取加密后的文本
                buffer = encryptedStream.ToArray();
                string encryptedText = Convert.ToBase64String(buffer);
                return encryptedText;
            }
            catch (Exception ex)
            {
                AppLog.Error(ex.Message);
                return "";
            }
        }

        // 解密算法
        public string Decrypt(string encryptedText)
        {
            try
            {
                byte[] encryptedBuffer = Convert.FromBase64String(encryptedText);
                Stream encryptedStream = new MemoryStream(encryptedBuffer);

                MemoryStream clearStream = new MemoryStream();
                CryptoStream cryptoStream =
                    new CryptoStream(encryptedStream, decryptor, CryptoStreamMode.Read);

                int bytesRead = 0;
                byte[] buffer = new byte[BufferSize];

                do
                {
                    bytesRead = cryptoStream.Read(buffer, 0, BufferSize);
                    clearStream.Write(buffer, 0, bytesRead);
                } while (bytesRead > 0);

                buffer = clearStream.GetBuffer();
                string clearText =
                    Encoding.UTF8.GetString(buffer, 0, (int)clearStream.Length);

                return clearText;
            }
            catch (Exception ex)
            {
                AppLog.Error(ex.Message);
                return "";
            }
        }

        public static string Encrypt(string clearText, string key)
        {
            EncryptionOperation helper = new EncryptionOperation(key);
            return helper.Encrypt(clearText);
            //return clearText;
        }

        public static string Decrypt(string encryptedText, string key)
        {
            EncryptionOperation helper = new EncryptionOperation(key);
            return helper.Decrypt(encryptedText);
            //return encryptedText;
        }
    }
}