using System;
using System.Text;
using System.Collections;

namespace Woodpecker.Net.Game.Encoding
{
    /// <summary>
    /// Provides 'wire' encoding and decoding for numbers, better known as 'VL64' or 'LV64'. 
    /// </summary>
    public static class wireEncoding
    {
        /// <summary>
        /// Encodes an integer to a VL64 string.
        /// </summary>
        /// <param name="i">The integer to encode.</param>
        public static string Encode(int i)
        {
            try
            {
                byte[] res = new byte[6];
                int p = 0;
                int sP = 0;
                int bytes = 1;
                int negativeMask = i >= 0 ? 0 : 4;

                i = Math.Abs(i);
                res[p++] = (byte)(64 + (i & 3));
                for (i >>= 2; i != 0; i >>= 6)
                {
                    bytes++;
                    res[p++] = (byte)(64 + (i & 0x3f));
                }

                res[sP] = (byte)(res[sP] | bytes << 3 | negativeMask);
                return new ASCIIEncoding().GetString(res).Replace("\0", "");
            }
            catch { return ""; }
        }
        /// <summary>
        /// Encodes each integer in the input array and adds it to the 'wire'. Returns the result.
        /// </summary>
        /// <param name="i">The integer array to wire up the values of.</param>
        public static string Encode(int[] i)
        {
            string s = "";
            foreach (int j in i)
                s += Encode(j);

            return s;
        }
        /// <summary>
        /// Encodes a boolean to a VL64 char.
        /// </summary>
        /// <param name="b">The boolean to encode.</param>
        public static char Encode(bool b)
        {
            if (b)
                return 'I';
            else
                return 'H';
        }
        /// <summary>
        /// Decodes a wire encoded string to the first encoded number in the wire.
        /// </summary>
        /// <param name="s">The write to decode.</param>
        public static int Decode(string s)
        {
            try
            {
                char[] u = s.ToCharArray();
                int i = u[0] & 3;
                int p = 1;
                int g = 2;

                for (int b = 1; b < (u[p] >> 3 & 7); b++)
                {
                    i |= (u[p] & 0x3f) << g;
                    g = 2 + 6 * b;
                    p++;
                }

                if ((u[0] & 4) == 4)
                    i *= -1;

                return i;
            }
            catch { return 0; }
        }
        /// <summary>
        /// Decodes a wire encoded string to a boolean. This is fancy.
        /// </summary>
        /// <param name="s">The wire encoded boolean to decode.</param>
        public static bool decodeBoolean(string s)
        {
            return (s == "I");
        }
        public static int[] decodeWire(string s)
        {
            try
            {
                ArrayList res = new ArrayList();
                while (s != "")
                {
                    int i = Decode(s);
                    res.Add(i);
                    s = s.Substring(Encode(i).Length);
                }

                return (int[])res.ToArray(typeof(int));
            }
            catch { return new int[0]; }
        }
    }
}