using System;
using System.Web;
using System.Web.UI;
using System.Web.Security;
using System.Text;
using System.IO;
using System.Security.Cryptography;
using System.Configuration;
using System.Linq;

namespace EnVisage.Code.UserVoice
{
  public class UserVoiceGenerator 
  {  
      public static string create(string userDetails) 
      { 
        // If you're acme.uservoice.com then this value would be 'acme'
        string uservoiceSubdomain = "planitppm";
        // Get this from your UserVoice General Settings page
        string ssoKey = "036ccf37723654d432855e17635cbc08";        
        string initVector = "OpenSSL for Ruby"; // DO NOT CHANGE

        byte[] initVectorBytes = Encoding.UTF8.GetBytes(initVector);
        byte[] keyBytesLong;

        //---- this needs a TODO: refactor to either system preference or ClientControl - swappable ticket systems/URLs
        string uservoiceConfigSubDomain = string.Empty;
        bool activateUserVoice = true;

        if (ConfigurationManager.AppSettings.AllKeys.Contains("ActivateUserVoice"))
            activateUserVoice = Convert.ToBoolean(ConfigurationManager.AppSettings["ActivateUserVoice"]);

        //---- If UserVoice is not active, do an empty string return.
        if (activateUserVoice == false)
            return string.Empty;


        if (ConfigurationManager.AppSettings.AllKeys.Contains("UserVoiceSubDomain"))
            uservoiceConfigSubDomain = ConfigurationManager.AppSettings["UserVoiceSubDomain"];

        if (uservoiceConfigSubDomain.Length > 0)
            uservoiceSubdomain = uservoiceConfigSubDomain;
        //----
        //----  
        using ( SHA1CryptoServiceProvider sha = new SHA1CryptoServiceProvider() ) 
        {
            keyBytesLong = sha.ComputeHash( Encoding.UTF8.GetBytes( ssoKey + uservoiceSubdomain ) );
        }
        byte[] keyBytes = new byte[16];
        Array.Copy(keyBytesLong, keyBytes, 16);

        byte[] textBytes = Encoding.UTF8.GetBytes(userDetails);
        for (int i = 0; i < 16; i++) 
        {
            textBytes[i] ^= initVectorBytes[i];
        }

        // Encrypt the string to an array of bytes
        byte[] encrypted = encryptStringToBytes_AES(textBytes, keyBytes, initVectorBytes);
        string encoded = Convert.ToBase64String(encrypted);	
        
          return HttpUtility.UrlEncode(encoded);
      }

      static byte[] encryptStringToBytes_AES(byte[] textBytes, byte[] Key, byte[] IV) 
      {
        // Declare the stream used to encrypt to an in memory
        // array of bytes and the RijndaelManaged object
        // used to encrypt the data.
        using( MemoryStream msEncrypt = new MemoryStream() )
        using( RijndaelManaged aesAlg = new RijndaelManaged() )
        {
            // Provide the RijndaelManaged object with the specified key and IV.
            aesAlg.Mode = CipherMode.CBC;
            aesAlg.Padding = PaddingMode.PKCS7;
            aesAlg.KeySize = 128;
            aesAlg.BlockSize = 128;
            aesAlg.Key = Key;
            aesAlg.IV = IV;
            // Create an encrytor to perform the stream transform.
            ICryptoTransform encryptor = aesAlg.CreateEncryptor();

            // Create the streams used for encryption.
            using( CryptoStream csEncrypt = new CryptoStream( msEncrypt, encryptor, CryptoStreamMode.Write ) ) 
            {
                csEncrypt.Write( textBytes, 0, textBytes.Length );
                csEncrypt.FlushFinalBlock();
            }

            byte[] encrypted = msEncrypt.ToArray(); 
            // Return the encrypted bytes from the memory stream.
            return encrypted;
        }
      }   
  }
}