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

namespace GCHR.Model
{
    class CTripleDes
    {
        // define the triple des provider

        private readonly TripleDESCryptoServiceProvider _des =
                 new TripleDESCryptoServiceProvider();

        // define the string handler

        private readonly UTF8Encoding _utf8 = new UTF8Encoding();

        // define the local property arrays

        private readonly byte[] _key;
        private readonly byte[] _iv;

        public CTripleDes(byte[] key, byte[] iv)
        {
            _key = key;
            _iv = iv;
        }

        public byte[] Encrypt(byte[] input)
        {
            return Transform(input,
                   _des.CreateEncryptor(_key, _iv));
        }

        public byte[] Decrypt(byte[] input)
        {
            return Transform(input,
                   _des.CreateDecryptor(_key, _iv));
        }

        public string Encrypt(string text)
        {
            var input = _utf8.GetBytes(text);
            var output = Transform(input,
                            _des.CreateEncryptor(_key, _iv));
            return Convert.ToBase64String(output);
        }

        public string Decrypt(string text)
        {
            var input = Convert.FromBase64String(text);
            var output = Transform(input,
                            _des.CreateDecryptor(_key, _iv));
            return _utf8.GetString(output);
        }

        private static byte[] Transform(byte[] input,
                       ICryptoTransform cryptoTransform)
        {
            // create the necessary streams

            var memStream = new MemoryStream();
            var cryptStream = new CryptoStream(memStream,
                         cryptoTransform, CryptoStreamMode.Write);
            // transform the bytes as requested

            cryptStream.Write(input, 0, input.Length);
            cryptStream.FlushFinalBlock();
            // Read the memory stream and

            // convert it back into byte array

            memStream.Position = 0;
            var result = memStream.ToArray();
            // close and release the streams

            memStream.Close();
            cryptStream.Close();
            // hand back the encrypted buffer

            return result;
        }
    }
}