using System;
using System.Security.Cryptography;
using System.Text;

namespace EC.Utils.Security
{
	/// <summary>
	/// 加密、解密帮助类
	/// </summary>
	public static class DesEncrypt
	{
		/// <summary>
		/// 加密数据
		/// </summary>
		/// <param name="str">需要加密的内容</param>
		/// <param name="key">秘钥</param>
		/// <returns></returns>
		public static string Encrypt(string str, string key)
		{
			var des = new DESCryptoServiceProvider();
			des.Key = Encoding.ASCII.GetBytes(Md5Helper.Hash(key).ToUpper().Substring(0, 8));
			des.IV = Encoding.ASCII.GetBytes(Md5Helper.Hash(key).ToUpper().Substring(0, 8));

			var ms = new System.IO.MemoryStream();
			var cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
			var byteArray = Encoding.Default.GetBytes(str);
			cs.Write(byteArray, 0, byteArray.Length);
			cs.FlushFinalBlock();

			var builder = new StringBuilder();
			foreach (var b in ms.ToArray())
			{
				builder.Append(b.ToString("x2"));
			}

			return builder.ToString();
		}

		/// <summary>
		/// 解密数据
		/// </summary>
		/// <param name="str">需要解密的内容</param>
		/// <param name="key">秘钥</param>
		/// <returns></returns>
		public static string Decrypt(string str, string key)
		{
			var byteArray = new byte[str.Length / 2];
			for (var i = 0; i < byteArray.Length; i++)
			{
				byteArray[i] = (byte)Convert.ToInt32(str.Substring(i * 2, 2), 16);
			}

			var des = new DESCryptoServiceProvider();
			des.Key = Encoding.ASCII.GetBytes(Md5Helper.Hash(key).ToUpper().Substring(0, 8));
			des.IV = Encoding.ASCII.GetBytes(Md5Helper.Hash(key).ToUpper().Substring(0, 8));

			var ms = new System.IO.MemoryStream();
			var cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
			cs.Write(byteArray, 0, byteArray.Length);
			cs.FlushFinalBlock();

			return Encoding.Default.GetString(ms.ToArray());
		}
	}
}