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


namespace Util
{
    class DecryptionUtil
    {
        public static byte[] AES_IV = Encoding.UTF8.GetBytes("AES_IV");

       
        public static string Encrypt(string data)
        {
            using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
            {
                aesAlg.Key = Encoding.UTF8.GetBytes("key");
                aesAlg.IV = AES_IV;
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            swEncrypt.Write(data);
                        }
                        byte[] bytes = msEncrypt.ToArray();
                        return Convert.ToBase64String(bytes);
                    }
                }
            }

        }
     
        public static string Decrypt(string data)
        {
            try {
                string dummyData = data.Trim().Replace("%", "").Replace(",", "").Replace(" ", "+");
                if (dummyData.Length % 4 > 0)
                {
                    dummyData = dummyData.PadRight(dummyData.Length + 4 - dummyData.Length % 4, '=');
                }
                {
                    byte[] inputBytes = Convert.FromBase64String(dummyData);

                    using (AesCryptoServiceProvider aesAlg = new AesCryptoServiceProvider())
                    {
                        aesAlg.Key = Encoding.UTF8.GetBytes("key");
                        aesAlg.IV = AES_IV;

                        ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
                        using (MemoryStream msEncrypt = new MemoryStream(inputBytes))
                        {
                            using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, decryptor, CryptoStreamMode.Read))
                            {
                                using (StreamReader srEncrypt = new StreamReader(csEncrypt))
                                {
                                    return srEncrypt.ReadToEnd();
                                }
                            }
                        }
                    }
                }

            }
            catch (Exception) {
                return null;
            }


        }

        internal static bool Decrypt()
        {
            throw new NotImplementedException();
        }
    }


}