using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace PEP_Tool
{
    public static class Crypto
    {
        static string CryptoString = @"]VQr$gOKG_19m~p:9y0+DD{6?hL}##l_'^?M)>}OI&EIC~8thwY7YG<\d2[NdKA";

        public static async Task<string> EncryptString(string Message)
        {
            await Task.Delay(100);
            byte[] Results = null;
            System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();
            MD5CryptoServiceProvider HashProvider = new MD5CryptoServiceProvider();
            byte[] TDESKey = HashProvider.ComputeHash(UTF8.GetBytes(CryptoString));
            TripleDESCryptoServiceProvider TDESAlgorithm = new TripleDESCryptoServiceProvider();
            TDESAlgorithm.Key = TDESKey;
            TDESAlgorithm.Mode = CipherMode.ECB;
            TDESAlgorithm.Padding = PaddingMode.PKCS7;
            byte[] DataToEncrypt = UTF8.GetBytes(Message);
            try
            {
                ICryptoTransform Encryptor = TDESAlgorithm.CreateEncryptor();
                Results = Encryptor.TransformFinalBlock(DataToEncrypt, 0, DataToEncrypt.Length);
            }
            catch (Exception ex)        
            {
                System.Diagnostics.Debug.WriteLine(ex);
            }
            finally
            {
                TDESAlgorithm.Clear();
                HashProvider.Clear();

            }

                return Convert.ToBase64String(Results);

        }

        public static async Task<string> DecryptString(string Message)
        {
            await Task.Delay(100);
            byte[] Results;
            System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();
            MD5CryptoServiceProvider HashProvider = new MD5CryptoServiceProvider();
            byte[] TDESKey = HashProvider.ComputeHash(UTF8.GetBytes(CryptoString));
            TripleDESCryptoServiceProvider TDESAlgorithm = new TripleDESCryptoServiceProvider();
            TDESAlgorithm.Key = TDESKey;
            TDESAlgorithm.Mode = CipherMode.ECB;
            TDESAlgorithm.Padding = PaddingMode.PKCS7;
            byte[] DataToDecrypt = Convert.FromBase64String(Message);
            try
            {
                ICryptoTransform Decryptor = TDESAlgorithm.CreateDecryptor();
                Results = Decryptor.TransformFinalBlock(DataToDecrypt, 0, DataToDecrypt.Length);
            }
            catch(Exception ex)
            {
                LogFile.WriteLine(ex.Message.ToString() + $"  Datenlänge: {DataToDecrypt.Length}");
                return "%%";
            }
            finally
            {
                TDESAlgorithm.Clear();
                HashProvider.Clear();
            }
            return UTF8.GetString(Results);
        }
    }
}