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

namespace Extentions
{
    public static class ExtFileInfo
    {
        public static MD5 MD5Crypto;

        public static String GetMD5Hash(this FileInfo f)
        {
            if (!File.Exists(f.FullName)) return "0";

            if (MD5Crypto == null) MD5Crypto = MD5.Create();

            Byte[] data = File.ReadAllBytes(f.FullName);
            Byte[] bHash = MD5Crypto.ComputeHash(data);
            StringBuilder sBuilder = new StringBuilder();
            foreach (Byte b in bHash) sBuilder.AppendFormat("{0:x2}", b);
            return sBuilder.ToString();
        }
    }

    public static class ExtString
    {
        /// <summary>Encodes the string into Base64 and returns the result.</summary>
        public static String EncodeBase64(this String s)
        {
            try
            {
                return Convert.ToBase64String(Encoding.UTF8.GetBytes(s));
            }
            catch (Exception)
            {
                return null;
            }
        }

        /// <summary>Decodes the string from Base64 and returns the result.</summary>
        public static String DecodeBase64(this String s)
        {
            try
            {
                return Encoding.Default.GetString(Convert.FromBase64String(s));
            }
            catch (Exception)
            {
                return null;
            }
        }

        /// <summary>Encrypts the string and returns the result.</summary>
        public static Byte[] Encrypt(this String s)
        {
            try
            {
                Byte[] buffer = new byte[s.Length];

                for (int i = 0; i < s.Length; i++)
                {
                    buffer[i] = (byte)(s[i] ^ (0x54 ^ (i & 0xFF)));
                }

                return buffer;
            }
            catch (Exception)
            {
                return null;
            }
        }

        /// <summary>Decrypts the string and returns the result.</summary>
        public static String Decrypt(this Byte[] b)
        {
            try
            {
                StringBuilder sBuilder = new StringBuilder();

                for (int i = 0; i < b.Length; i++)
                {
                    sBuilder.Append((Char)(b[i] ^ (0x54 ^ (i & 0xFF))));
                }

                return sBuilder.ToString();
            }
            catch (Exception)
            {
                return null;
            }
        }
    }
}