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

namespace Alipay.AopSdk.Core.Util
{
	internal class AlipayEncrypt
	{
		/// <summary>
		///     128位0向量
		/// </summary>
		private static readonly byte[] AES_IV = initIv(16);

		/// <summary>
		///     AES 加密
		/// </summary>
		/// <param name="encryptKey"></param>
		/// <param name="bizContent"></param>
		/// <param name="charset"></param>
		/// <returns></returns>
		public static string AesEncrypt(string encryptKey, string bizContent, string charset)
		{
			var keyArray = Convert.FromBase64String(encryptKey);
			byte[] toEncryptArray = null;

			if (string.IsNullOrEmpty(charset))
				toEncryptArray = Encoding.UTF8.GetBytes(bizContent);
			else
				toEncryptArray = Encoding.GetEncoding(charset).GetBytes(bizContent);

			var rDel = new RijndaelManaged();
			rDel.Key = keyArray;
			rDel.Mode = CipherMode.CBC;
			rDel.Padding = PaddingMode.PKCS7;
			rDel.IV = AES_IV;

			var cTransform = rDel.CreateEncryptor(rDel.Key, rDel.IV);
			var resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);


			return Convert.ToBase64String(resultArray);
		}

		/// <summary>
		///     AES解密
		/// </summary>
		/// <param name="encryptKey"></param>
		/// <param name="bizContent"></param>
		/// <param name="charset"></param>
		/// <returns></returns>
		public static string AesDencrypt(string encryptKey, string bizContent, string charset)
		{
			var keyArray = Convert.FromBase64String(encryptKey);
			var toEncryptArray = Convert.FromBase64String(bizContent);

			var rDel = new RijndaelManaged();
			rDel.Key = keyArray;
			rDel.Mode = CipherMode.CBC;
			rDel.Padding = PaddingMode.PKCS7;
			rDel.IV = AES_IV;

			var cTransform = rDel.CreateDecryptor(rDel.Key, rDel.IV);
			var resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);


			if (string.IsNullOrEmpty(charset))
				return Encoding.UTF8.GetString(resultArray);
			return Encoding.GetEncoding(charset).GetString(resultArray);
		}

		/// <summary>
		///     初始化向量
		/// </summary>
		/// <param name="blockSize"></param>
		/// <returns></returns>
		private static byte[] initIv(int blockSize)
		{
			var iv = new byte[blockSize];
			for (var i = 0; i < blockSize; i++)
				iv[i] = 0x0;
			return iv;
		}
	}
}