using System;
using System.IO;
using System.Net;
using System.Security.Cryptography;
using System.Text;

namespace learun.wechat
{
	/// <summary>
	/// 版 本 EasyCode EC管理后台
	/// Copyright (c) 2019-present EC管理有限公司
	/// 创建人：tobin
	/// 日 期：2019.11.06
	/// 描 述：密码处理
	/// </summary>
	public class Cryptography
	{
		private const int V = 1;

		/// <summary>
		/// 获取主机到网络的订单值
		/// </summary>
		/// <param name="inval">输入值</param>
		/// <returns></returns>
		public static UInt32 HostToNetworkOrder(UInt32 inval)
		{
			UInt32 outval = 0;
			for (int i = 0; i < 4; i++)
				outval = (outval << 8) + ((inval >> (i * 8)) & 255);
			return outval;
		}

		/// <summary>
		/// 获取主机到网络的订单值
		/// </summary>
		/// <param name="inval">输入值</param>
		/// <returns></returns>
		public static Int32 HostToNetworkOrder(Int32 inval)
		{
			Int32 outval = 0;
			for (int i = 0; i < 4; i++)
				outval = (outval << 8) + ((inval >> (i * 8)) & 255);
			return outval;
		}

		/// <summary>
		/// 解密方法
		/// </summary>
		/// <param name="Input">密文</param>
		/// <param name="EncodingAESKey">秘钥</param>
		/// <param name="corpid">企业id</param>
		/// <returns></returns>
		///
		public static string AES_decrypt(String Input, string EncodingAESKey, ref string corpid)
		{
			byte[] Key;
			Key = Convert.FromBase64String(EncodingAESKey + "=");

			foreach (var b in Key)
			{
				Console.WriteLine(b);
			}

			byte[] Iv = new byte[16];
			Array.Copy(Key, Iv, 16);
			byte[] btmpMsg = AES_decrypt(Input, Iv, Key);

			int len = BitConverter.ToInt32(btmpMsg, 16);
			len = IPAddress.NetworkToHostOrder(len);

			byte[] bMsg = new byte[len];
			byte[] bCorpid = new byte[btmpMsg.Length - 20 - len];
			Array.Copy(btmpMsg, 20, bMsg, 0, len);
			Array.Copy(btmpMsg, 20 + len, bCorpid, 0, btmpMsg.Length - 20 - len);
			string oriMsg = Encoding.UTF8.GetString(bMsg);
			corpid = Encoding.UTF8.GetString(bCorpid);

			return oriMsg;
		}

		/// <summary>
		/// 加密方法
		/// </summary>
		/// <param name="Input">密文</param>
		/// <param name="EncodingAESKey">秘钥</param>
		/// <param name="corpid">企业id</param>
		/// <returns></returns>
		public static String AES_encrypt(String Input, string EncodingAESKey, string corpid)
		{
			byte[] Key;
			Key = Convert.FromBase64String(EncodingAESKey + "=");
			byte[] Iv = new byte[16];
			Array.Copy(Key, Iv, 16);
			string Randcode = CreateRandCode(16);
			byte[] bRand = Encoding.UTF8.GetBytes(Randcode);
			byte[] bCorpid = Encoding.UTF8.GetBytes(corpid);
			byte[] btmpMsg = Encoding.UTF8.GetBytes(Input);
			byte[] bMsgLen = BitConverter.GetBytes(HostToNetworkOrder(btmpMsg.Length));
			byte[] bMsg = new byte[bRand.Length + bMsgLen.Length + bCorpid.Length + btmpMsg.Length];

			Array.Copy(bRand, bMsg, bRand.Length);
			Array.Copy(bMsgLen, 0, bMsg, bRand.Length, bMsgLen.Length);
			Array.Copy(btmpMsg, 0, bMsg, bRand.Length + bMsgLen.Length, btmpMsg.Length);
			Array.Copy(bCorpid, 0, bMsg, bRand.Length + bMsgLen.Length + btmpMsg.Length, bCorpid.Length);

			return AES_encrypt(bMsg, Iv, Key);
		}

		/// <summary>
		/// 创建随机码
		/// </summary>
		/// <param name="codeLen">码长度</param>
		/// <returns></returns>
		private static string CreateRandCode(int codeLen)
		{
			string codeSerial = "2,3,4,5,6,7,a,c,d,e,f,h,i,j,k,m,n,p,r,s,t,A,C,D,E,F,G,H,J,K,M,N,P,Q,R,S,U,V,W,X,Y,Z";
			if (codeLen == 0)
			{
				codeLen = 16;
			}
			string[] arr = codeSerial.Split(',');
			string code = "";
			int randValue = -1;
			Random rand = new Random(unchecked((int)DateTime.Now.Ticks));
			for (int i = 0; i < codeLen; i++)
			{
				randValue = rand.Next(0, arr.Length - 1);
				code += arr[randValue];
			}
			return code;
		}

		/// <summary>
		/// 加密方法
		/// </summary>
		/// <param name="Input">密文</param>
		/// <param name="Iv">Iv</param>
		/// <param name="Key">Key</param>
		/// <returns></returns>
		private static String AES_encrypt(String Input, byte[] Iv, byte[] Key)
		{
			var aes = new RijndaelManaged
			{
				//秘钥的大小，以位为单位
				KeySize = 256,
				//支持的块大小
				BlockSize = 128,
				//填充模式
				Padding = PaddingMode.PKCS7,
				Mode = CipherMode.CBC,
				Key = Key,
				IV = Iv
			};
			var encrypt = aes.CreateEncryptor(aes.Key, aes.IV);
			byte[] xBuff = null;

			using (var ms = new MemoryStream())
			{
				using (var cs = new CryptoStream(ms, encrypt, CryptoStreamMode.Write))
				{
					byte[] xXml = Encoding.UTF8.GetBytes(Input);
					cs.Write(xXml, 0, xXml.Length);
				}
				xBuff = ms.ToArray();
			}
			String Output = Convert.ToBase64String(xBuff);
			return Output;
		}

		/// <summary>
		/// 加密方法
		/// </summary>
		/// <param name="Input">Input</param>
		/// <param name="Iv">Iv</param>
		/// <param name="Key">Key</param>
		/// <returns></returns>
		private static String AES_encrypt(byte[] Input, byte[] Iv, byte[] Key)
		{
			var aes = new RijndaelManaged
			{
				//秘钥的大小，以位为单位
				KeySize = 256,
				//支持的块大小
				BlockSize = 128,
				//填充模式
				//aes.Padding = PaddingMode.PKCS7;
				Padding = PaddingMode.None,
				Mode = CipherMode.CBC,
				Key = Key,
				IV = Iv
			};
			var encrypt = aes.CreateEncryptor(aes.Key, aes.IV);
			byte[] xBuff = null;

			#region 自己进行PKCS7补位，用系统自己带的不行

			byte[] msg = new byte[Input.Length + 32 - Input.Length % 32];
			Array.Copy(Input, msg, Input.Length);
			byte[] pad = KCS7Encoder(Input.Length);
			Array.Copy(pad, 0, msg, Input.Length, pad.Length);

			#endregion 自己进行PKCS7补位，用系统自己带的不行

			#region 注释的也是一种方法，效果一样

			//ICryptoTransform transform = aes.CreateEncryptor();
			//byte[] xBuff = transform.TransformFinalBlock(msg, 0, msg.Length);

			#endregion 注释的也是一种方法，效果一样

			using (var ms = new MemoryStream())
			{
				using (var cs = new CryptoStream(ms, encrypt, CryptoStreamMode.Write))
				{
					cs.Write(msg, 0, msg.Length);
				}
				xBuff = ms.ToArray();
			}

			String Output = Convert.ToBase64String(xBuff);
			return Output;
		}

		/// <summary>
		///
		/// </summary>
		/// <param name="text_length"></param>
		/// <returns></returns>
		private static byte[] KCS7Encoder(int text_length)
		{
			int block_size = 32;
			// 计算需要填充的位数
			int amount_to_pad = block_size - (text_length % block_size);
			if (amount_to_pad == 0)
			{
				amount_to_pad = block_size;
			}
			// 获得补位所用的字符
			char pad_chr = Chr(amount_to_pad);
			string tmp = "";
			for (int index = 0; index < amount_to_pad; index++)
			{
				tmp += pad_chr;
			}
			return Encoding.UTF8.GetBytes(tmp);
		}

		/**
         * 将数字转化成ASCII码对应的字符，用于对明文进行补码
         *
         * @param a 需要转化的数字
         * @return 转化得到的字符
         */

		private static char Chr(int a)
		{
			byte target = (byte)(a & 0xFF);
			return (char)target;
		}

		/// <summary>
		///
		/// </summary>
		/// <param name="Input"></param>
		/// <param name="Iv"></param>
		/// <param name="Key"></param>
		/// <returns></returns>
		private static byte[] AES_decrypt(String Input, byte[] Iv, byte[] Key)
		{
			RijndaelManaged aes = new RijndaelManaged
			{
				KeySize = 256,
				BlockSize = 128,
				Mode = CipherMode.CBC,
				Padding = PaddingMode.None,
				Key = Key,
				IV = Iv
			};
			var decrypt = aes.CreateDecryptor(aes.Key, aes.IV);
			byte[] xBuff = null;
			using (var ms = new MemoryStream())
			{
				using (var cs = new CryptoStream(ms, decrypt, CryptoStreamMode.Write))
				{
					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);
				}
				xBuff = Decode2(ms.ToArray());
			}
			return xBuff;
		}

		/// <summary>
		///
		/// </summary>
		/// <param name="decrypted"></param>
		/// <returns></returns>
		private static byte[] Decode2(byte[] decrypted)
		{
			int pad = decrypted[^V];
			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;
		}
	}
}