//#define ENCRYPTION

using UnityEngine;
using System.Collections;
using System.Security.Cryptography;
using System.Text;
using System.IO;
using ULinq;

using JsonFx.Json;
using System.Collections.Generic;

public class SecurityUtil
{
    private static int IntKey;
    private static MD5 md5;

    static SecurityUtil()
    {
        System.Random rnd = new System.Random();
        IntKey = Mathf.Abs( rnd.Next() );

        md5 = MD5.Create();
    }

    public static int Decrypt( int v )
    {
        return v ^ IntKey;
    }

    public static int Encrypt( int v )
    {
        return v ^ IntKey;
    }

    public static string Sign( string source )
    {
        return Digest( source + Backend.Instance.Session.digest );
    }

    public static bool CheckSignature( string source, string targetSignature )
    {
        return Digest( source + Backend.Instance.Session.digest ).Equals( targetSignature );
    }

    public static string CreateSessionHandShake( SessionModel session )
    {
        StringBuilder sb = new StringBuilder();
        sb.Append( session.p );
        sb.Append( "|" );
        sb.Append( session.g );
        sb.Append( "|" );
        sb.Append( session.pub_key );

        DiffieHellman.DiffieHellman dh = new DiffieHellman.DiffieHellman( 256 ).GenerateResponse( sb.ToString() );
        session.digest = System.Convert.ToBase64String( dh.Key, System.Base64FormattingOptions.None );

        string publicKey = dh.ToString();
        dh.Dispose();

        return publicKey;
    }

    public static string RsaEncrypt( string text )
    {
        byte[] publicRsaKey = {
            157, 192, 109, 109,  93, 251, 115, 241,  30, 112, 202, 107, 177,  17, 125, 183,  68, 238, 168,
            206, 246,  64, 252,   2, 190,  71,  53,  68, 198, 163,  37,  76, 253, 215, 162,  17,  55, 158, 112,
            128,  12, 221, 215, 179, 245,  34, 254, 129, 134, 206,  52,  19, 212, 142,  66, 131, 116,  48, 122,
            119, 123,   8, 221, 231, 132,  38, 163, 205, 144, 105,  53, 143, 249, 161, 236, 169, 217, 105, 151,
            142,  15, 120, 149, 150,  54,  48, 144,  78, 128,  33,  76, 133, 238,  88, 236, 147, 192, 240, 159,
            248,  49, 121, 109,   9,  35, 145, 239,  73, 251,  93, 156, 180,  84,  22,  62, 131, 126, 146,  73,
             73, 119,  34, 201,  25, 220,  48,  34, 106, 188, 169,  76,  54,  33,   0, 167, 190, 250,   5,  74,
             25, 128, 189, 216, 114, 179,  81,  96, 154, 146, 225,  22, 141, 126,  63, 211, 251, 151,  37,  64,
             78,  48,  81, 246,  63,  53,   4, 201,   7, 138,   3,  67, 235, 142, 177, 163, 119, 142, 150,  56,
            220,  15, 177, 124, 111, 243,  54, 128,  59, 160, 177, 247, 134, 188, 216,  73,  80,  18,  97, 191,
             17, 182,  12,   1,  43, 130, 170,  24,  79, 101, 140, 129, 185, 212, 137,  65, 223,   9, 145, 179,
            198,  47, 102, 239, 148,  22, 208, 169, 133, 166, 223,  14,   6, 230,  41, 165, 116,  93,  73, 191,
             90,   5, 146,  78,  85, 115, 224,  44, 110, 190, 189, 185, 204, 164,  80,  66,  63
        };

        byte[] exponent = { 1, 0, 1 };

        string encryptedText = "";

        using( RSACryptoServiceProvider rsa = new RSACryptoServiceProvider() )
        {
            RSAParameters rsaKeyInfo = new RSAParameters();
            rsaKeyInfo.Modulus = publicRsaKey;
            rsaKeyInfo.Exponent = exponent;

            rsa.ImportParameters( rsaKeyInfo );

            byte[] textData = UTF8Encoding.UTF8.GetBytes( text );
            byte[] encryptedData = rsa.Encrypt( textData, false );

            encryptedText = System.Convert.ToBase64String( encryptedData, System.Base64FormattingOptions.None );
            var temp = encryptedText.Replace( '+', '-' ).Replace( '/', '_' ).TrimEnd( '=' );

            encryptedText = temp;
        }

        return encryptedText;
    }

    public static WWW SecureWWW( string url, string action )
    {
#if ENCRYPTION
        action = RsaEncrypt( action );
#endif

        return new WWW( url + action );
    }

    public static WWW SecureWWW( string url, string action, Dictionary<string, object> form )
    {
        var wwwForm = new WWWForm();
        foreach( var pair in form )
        {
            var key = pair.Key;
            var val = pair.Value;

            if( val is string )
                wwwForm.AddField( key, val as string );
            else if( val is int )
                wwwForm.AddField( key, ( int ) val );
            else
                wwwForm.AddField( key, val.ToString() );
        }

#if ENCRYPTION
        action = RsaEncrypt( action );
#endif

        return new WWW( url + action, wwwForm );
    }

    public static string Digest( string source )
    {
        byte[] hash = md5.ComputeHash( Encoding.ASCII.GetBytes( source ) );
        return System.Convert.ToBase64String( hash, System.Base64FormattingOptions.None );
    }
}