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

/// <summary>
/// C# AES256 by jackz98
/// </summary>
public static class ClipboardFusionHelper
{
    private static readonly int Iterations = 10025;

    private static byte[] CompressBytes(byte[] bytes)
    {
        using (MemoryStream compressStream = new MemoryStream())
        {
            using (var zipStream = new GZipStream(compressStream, CompressionMode.Compress))
                zipStream.Write(bytes, 0, bytes.Length);
            return compressStream.ToArray();
        }
    }

    private static byte[] DecompressBytes(byte[] bytes)
    {
        using (var compressStream = new MemoryStream(bytes))
        {
            using (var zipStream = new GZipStream(compressStream, CompressionMode.Decompress))
            {
                using (var resultStream = new MemoryStream())
                {
                    zipStream.CopyTo(resultStream);
                    return resultStream.ToArray();
                }
            }
        }
    }

    public static byte[] D(byte[] input, string password, bool enc)
    {
        using (var aes = new AesManaged()
        {
            KeySize = 256,
            BlockSize = 128,
            Mode = CipherMode.CBC,
            Padding = PaddingMode.PKCS7
        })
        {
            byte[] salt = new byte[16];
            if(enc)
                new RNGCryptoServiceProvider().GetBytes(salt);
            else
                Array.Copy(input, 0, salt, 0, salt.Length);
            using (var generator = new Rfc2898DeriveBytes(password, salt, Iterations))
            {
                aes.IV = generator.GetBytes(16);
                aes.Key = generator.GetBytes(32);
                
                ICryptoTransform eng;
                if (enc)
                    eng = aes.CreateEncryptor();
                else
                    eng = aes.CreateDecryptor();
    

                using (var outStream = new MemoryStream())
                {
                    if(enc)
                        outStream.Write(salt, 0, salt.Length);
                    using (var cryptoStream = new CryptoStream(outStream, eng, CryptoStreamMode.Write))
                    using (var binaryWriter = new BinaryWriter(cryptoStream))
                    {
                        if(enc)
                            binaryWriter.Write(CompressBytes(input));
                        else
                            binaryWriter.Write(input, salt.Length, input.Length - salt.Length);
                    }
                    if(enc)
                        return outStream.ToArray();
                    else
                        return DecompressBytes(outStream.ToArray());
                }
            }
        }
    }

    private static string AddNewLine(string s)
    {
        var sb = new StringBuilder(s);
        for (int i = (s.Length / 64) * 64; i >= 64; i -= 64)
            sb.Insert(i, Environment.NewLine);
        return sb.ToString();
    }

    public static string ProcessText(string text)
    {
        // your code goes here
        text = BFS.Clipboard.CopyText();

        BFS.ClipboardFusion.PauseClipboardListener();

        if (text != null && text.Length >= 0)
        {
            string res;
            string a = BFS.Dialog.GetUserInputListViewWithFilter("AES Encryption/Decryption", new string[2] { "Encryption", "Decryption" });
            if (a == "Encryption")
            {
                string pass = BFS.Dialog.GetUserInput("Encryption: Input your password here!", "");
                if (pass != "")
                {
                    res = AddNewLine(System.Convert.ToBase64String(D(System.Text.Encoding.UTF8.GetBytes(text), pass, true)));
                    BFS.Clipboard.PasteText(res);
                }
            }
            else if (a != "")
            {
                string pass = BFS.Dialog.GetUserInput("Decryption: Input your password here!", "");
                if (pass != "")
                {
                    try
                    {
                        res = Encoding.UTF8.GetString(D(System.Convert.FromBase64String(text), pass, false));
                        BFS.Clipboard.PasteText(res);
                    }
                    catch (Exception)
                    {
                        BFS.Dialog.ShowMessageError("Decryption Failed: malformated text, corrupted message or wrong password!");
                    }
                }
            }
        }

        BFS.Clipboard.Clear();

        BFS.ClipboardFusion.ResumeClipboardListener();

        return null;
    }
}