using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;
using System.IO;
using MyCode.Project.Infrastructure.Exceptions;

namespace MyCode.Project.Infrastructure.Common
{
	public class EncryptHelper
	{
		//DES加密秘钥，要求为8位  
		private const string desKey = "zhitamal";
		//默认密钥向量  
		private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

		//秘钥过期的秒数
		private static int expireSecond = 36000;

        #region Encrypt(加密，带过期时间)
        /// <summary>  
        /// DES加密  
        /// </summary>  
        /// <param name="encryptString">待加密的字符串，未加密成功返回原串</param>  
        /// <returns></returns>  
        public static string Encrypt(string encryptString)
		{
			var totalSecond = Convert.ToInt64((DateTime.Now - DateTime.Parse("2000-01-01")).TotalSeconds);

			encryptString = encryptString + "$$$" + totalSecond;

			byte[] rgbKey = Encoding.UTF8.GetBytes(desKey);
			byte[] rgbIV = Keys;
			byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
			DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
			MemoryStream mStream = new MemoryStream();
			CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
			cStream.Write(inputByteArray, 0, inputByteArray.Length);
			cStream.FlushFinalBlock();
			string returnStr = Convert.ToBase64String(mStream.ToArray());
			returnStr = returnStr.Replace('+', '@');
			return System.Web.HttpUtility.UrlEncode(returnStr);
		}
        #endregion

        #region Decrypt(解密，带过期时间)
        /// <summary>  
        /// DES解密  
        /// </summary>  
        /// <param name="decryptString">待解密的字符串，未解密成功返回原串</param>  
        /// <returns></returns>  
        public static string Decrypt(string decryptString)
		{
			decryptString = System.Web.HttpUtility.UrlDecode(decryptString);
			decryptString = decryptString.Replace('@', '+');
			byte[] rgbKey = Encoding.UTF8.GetBytes(desKey);
			byte[] rgbIV = Keys;
			byte[] inputByteArray = Convert.FromBase64String(decryptString);
			DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();
			MemoryStream mStream = new MemoryStream();
			CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
			cStream.Write(inputByteArray, 0, inputByteArray.Length);
			cStream.FlushFinalBlock();

			var returnStr = Encoding.UTF8.GetString(mStream.ToArray());
			var arrStr = returnStr.Split(new char[3] { '$', '$', '$' }, StringSplitOptions.RemoveEmptyEntries);

			if (arrStr.Length < 2)
			{
				throw new BaseException("非法加密字符串：" + decryptString);
			}
			var totalSecond = Convert.ToInt64(arrStr[1]);
			var currentTotalSecond = Convert.ToInt64((DateTime.Now - DateTime.Parse("2000-01-01")).TotalSeconds);
			if (currentTotalSecond - totalSecond > expireSecond)
			{
				throw new BaseException("该加密字符串已过期");
			}
			return arrStr[0];
		}
        #endregion

        #region GetMD5(获取大写的MD5签名结果)
        /// <summary>
        /// 获取大写的MD5签名结果
        /// </summary>
        /// <param name="encypStr"></param>
        /// <param name="charset"></param>
        /// <returns></returns>
        public static string GetMD5(string encypStr, string charset)
        {
            string retStr;
            MD5CryptoServiceProvider m5 = new MD5CryptoServiceProvider();

            //创建md5对象
            byte[] inputBye;
            byte[] outputBye;

            //使用GB2312编码方式把字符串转化为字节数组．
            try
            {
                inputBye = Encoding.GetEncoding(charset).GetBytes(encypStr);
            }
            catch (Exception ex)
            {
                inputBye = Encoding.GetEncoding("GB2312").GetBytes(encypStr);
            }
            outputBye = m5.ComputeHash(inputBye);

            retStr = System.BitConverter.ToString(outputBye);
            retStr = retStr.Replace("-", "").ToUpper();
            return retStr;
        }
        #endregion

        #region MD5Encrypt(MD5加密)
        /// <summary>
        /// MD5加密
        /// </summary>
        /// <param name="encypStr">需要加密文本</param>
        /// <param name="charset">字符编码默认UTF8</param>
        /// <returns></returns>
        public static string MD5Encrypt(string encypStr, string charset = "UTF-8")
        {
            return BitConverter.ToString(MD5.Create().ComputeHash(Encoding.Default.GetBytes(encypStr))).Replace("-", "");

            //string retStr;
            //MD5CryptoServiceProvider m5 = new MD5CryptoServiceProvider();

            ////创建md5对象
            //byte[] inputBye;
            //byte[] outputBye;

            ////使用GB2312编码方式把字符串转化为字节数组．
            //try
            //{
            //    inputBye = Encoding.GetEncoding(charset).GetBytes(encypStr);
            //}
            //catch (Exception ex)
            //{
            //    inputBye = Encoding.GetEncoding("UTF-8").GetBytes(encypStr);
            //}
            //outputBye = m5.ComputeHash(inputBye);
            //retStr = System.BitConverter.ToString(outputBye);
            //return retStr;
        }
        #endregion

        #region SHA1Hash(SHA加密)
        /// <summary>
        /// 加密方法，通过SHA1加密后再转Base64
        /// 注意，这个加密属于不可逆的加密，一般用于密码加密使用
        /// </summary>
        /// <param name="input">需要加密的文本</param>
        /// <returns></returns>
        public static string SHA1Hash(string input)
        {
            HashAlgorithm algorithm = SHA1.Create();
            return Convert.ToBase64String(algorithm.ComputeHash(Encoding.UTF8.GetBytes(input)));
        }
        #endregion

        #region EncryptToSHA1()
        /// <summary>
        /// SHA1
        /// </summary>
        /// <param name="text"></param>
        /// <returns></returns>
        public static string EncryptToSHA1(string text)
        {
            byte[] cleanBytes = Encoding.Default.GetBytes(text);
            byte[] hashedBytes = System.Security.Cryptography.SHA1.Create().ComputeHash(cleanBytes);
            return BitConverter.ToString(hashedBytes).Replace("-", "");
        }
        #endregion

        #region Base64Encrypt
        /// <summary>
        /// Base64加密方法
        /// </summary>
        /// <param name="input">需要加密的文本</param>
        /// <returns></returns>
        public static string Base64Encrypt(string input)
        {
            if (string.IsNullOrWhiteSpace(input)) { return ""; }

            return Convert.ToBase64String(Encoding.UTF8.GetBytes(input));
        }
        #endregion

        #region Base64Decrypt
        /// <summary>
        /// Base64解密方法
        /// </summary>
        /// <param name="input">需要解密的文本</param>
        /// <returns></returns>
        public static string Base64Decrypt(string input)
        {
            if (string.IsNullOrWhiteSpace(input)) { return ""; }

            return Encoding.UTF8.GetString(Convert.FromBase64String(input));
        }
        #endregion

        #region GetParamSrc
        private static string GetParamSrc(Dictionary<string, string> paramsMap)
        {
            var vDic = (from objDic in paramsMap orderby objDic.Key ascending select objDic);
            StringBuilder str = new StringBuilder();
            foreach (KeyValuePair<string, string> kv in vDic)
            {
                string pkey = kv.Key;
                string pvalue = kv.Value;
                str.Append(pkey + "=" + pvalue + "&");
            }

            String result = str.ToString().Substring(0, str.ToString().Length - 1);
            return result;
        }

        public static string GetSign(Dictionary<string, string> paramsMap, string signKey)
        {
            var paramstr = GetParamSrc(paramsMap);

            paramstr = paramstr + $"&signKey={signKey}";

            return MD5Encrypt(paramstr).Replace("-","").ToLower();
        }
        #endregion

        #region AES_Decrypt(解密)
        private static byte[] AES_Decrypt(String Input, byte[] Iv, byte[] Key)
        {
#if NET45
            RijndaelManaged aes = new RijndaelManaged();
#else
            SymmetricAlgorithm aes = Aes.Create();
#endif
            aes.KeySize = 128;//原始：256
            aes.BlockSize = 128;
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;
            aes.Key = Key;
            aes.IV = Iv;
            var decrypt = aes.CreateDecryptor(aes.Key, aes.IV);
            byte[] xBuff = null;

            //using (ICryptoTransform decrypt = aes.CreateDecryptor(aes.Key, aes.IV) /*aes.CreateDecryptor()*/)
            //{
            //    var src = Convert.FromBase64String(Input); 
            //    byte[] dest = decrypt.TransformFinalBlock(src, 0, src.Length);
            //    return dest;
            //    //return Encoding.UTF8.GetString(dest);
            //}


            try
            {
                using (var ms = new MemoryStream())
                {
                    using (var cs = new CryptoStream(ms, decrypt, CryptoStreamMode.Write))
                    {
                        //cs.Read(decryptBytes, 0, decryptBytes.Length);
                        //cs.Close();
                        //ms.Close();

                        //cs.FlushFinalBlock();//用于解决第二次获取小程序Session解密出错的情况


                        byte[] xXml = Convert.FromBase64String(Input);
                        byte[] msg = new byte[xXml.Length + 32 - xXml.Length % 32];
                        Array.Copy(xXml, msg, xXml.Length);
                        cs.Write(xXml, 0, xXml.Length);
                    }
                    //cs.Dispose();
                    xBuff = decode2(ms.ToArray());
                }
            }
            catch (System.Security.Cryptography.CryptographicException e)
            {
                //Padding is invalid and cannot be removed.
                Console.WriteLine("===== CryptographicException =====");

                using (var ms = new MemoryStream())
                {
                    //cs 不自动释放，用于避免“Padding is invalid and cannot be removed”的错误    —— 2019.07.27 Jeffrey
                    var cs = new CryptoStream(ms, decrypt, CryptoStreamMode.Write);
                    {
                        //cs.Read(decryptBytes, 0, decryptBytes.Length);
                        //cs.Close();
                        //ms.Close();

                        //cs.FlushFinalBlock();//用于解决第二次获取小程序Session解密出错的情况

                        byte[] xXml = Convert.FromBase64String(Input);
                        byte[] msg = new byte[xXml.Length + 32 - xXml.Length % 32];
                        Array.Copy(xXml, msg, xXml.Length);
                        cs.Write(xXml, 0, xXml.Length);
                    }
                    //cs.Dispose();
                    xBuff = decode2(ms.ToArray());
                }
            }
            return xBuff;
        }

        private static byte[] decode2(byte[] decrypted)
        {
            int pad = (int)decrypted[decrypted.Length - 1];
            if (pad < 1 || pad > 32)
            {
                pad = 0;
            }
            byte[] res = new byte[decrypted.Length - pad];
            Array.Copy(decrypted, 0, res, 0, decrypted.Length - pad);
            return res;
        }

        #endregion

        #region DecodeEncryptedData(解密小程序的加密方式)
        /// <summary>
        /// 解密所有消息的基础方法
        /// </summary>
        /// <param name = "sessionKey" > 储存在 SessionBag 中的当前用户 会话 SessionKey</param>
        /// <param name = "encryptedData" > 接口返回数据中的 encryptedData 参数</param>
        /// <param name = "iv" > 接口返回数据中的 iv 参数，对称解密算法初始向量</param>
        //    / <returns></returns>
        public static string DecodeEncryptedData(string sessionKey, string encryptedData, string iv)
        {
            var aesCipher = Convert.FromBase64String(encryptedData);
            var aesKey = Convert.FromBase64String(sessionKey);
            var aesIV = Convert.FromBase64String(iv);

            var result = AES_Decrypt(encryptedData, aesIV, aesKey);
            var resultStr = Encoding.UTF8.GetString(result);
            return resultStr;
        }
        #endregion
    }

}