namespace Holo
{
    using System;
    using System.Text;

    public static class Encoding
    {
        public static int decodeB64(string Val)
        {
            char[] val = Val.ToCharArray();
            int intTot = 0;
            int y = 0;
            for (int x = val.Length - 1; x >= 0; x--)
            {
                int intTmp = (byte) (val[x] - '@');
                if (y > 0)
                {
                    intTmp *= (int) Math.Pow(64.0, (double) y);
                }
                intTot += intTmp;
                y++;
            }
            return intTot;
        }

        public static int decodeVL64(char[] raw)
        {
            try
            {
                int pos = 0;
                int v = 0;
                bool negative = (raw[pos] & '\x0004') == 4;
                int totalBytes = (raw[pos] >> 3) & '\a';
                v = raw[pos] & '\x0003';
                pos++;
                int shiftAmount = 2;
                for (int b = 1; b < totalBytes; b++)
                {
                    v |= (raw[pos] & 0x3f) << shiftAmount;
                    shiftAmount = 2 + (6 * b);
                    pos++;
                }
                if (negative)
                {
                    v *= -1;
                }
                return v;
            }
            catch
            {
                return 0;
            }
        }

        public static int decodeVL64(string data)
        {
            return decodeVL64(data.ToCharArray());
        }

        public static string encodeB64(string Val)
        {
            int value = Val.Length;
            int length = 2;
            string stack = "";
            for (int x = 1; x <= length; x++)
            {
                int offset = 6 * (length - x);
                byte val = (byte) (0x40 + ((value >> offset) & 0x3f));
                stack = stack + ((char) val);
            }
            return stack;
        }

        public static string encodeB64(int value, int length)
        {
            string stack = "";
            for (int x = 1; x <= length; x++)
            {
                int offset = 6 * (length - x);
                byte val = (byte) (0x40 + ((value >> offset) & 0x3f));
                stack = stack + ((char) val);
            }
            return stack;
        }

        public static string encodeVL64(int i)
        {
            byte[] wf = new byte[6];
            int pos = 0;
            int startPos = pos;
            int bytes = 1;
            int negativeMask = (i >= 0) ? 0 : 4;
            i = Math.Abs(i);
            wf[pos++] = (byte) (0x40 + (i & 3));
            i = i >> 2;
            while (i != 0)
            {
                bytes++;
                wf[pos++] = (byte) (0x40 + (i & 0x3f));
                i = i >> 6;
            }
            wf[startPos] = (byte) ((wf[startPos] | (bytes << 3)) | negativeMask);
            ASCIIEncoding encoder = new ASCIIEncoding();
            return encoder.GetString(wf).Replace("\0", "");
        }
    }
}