using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace StgSharp.Data
{
    public static partial class Serializer
    {
        public static byte[] Serialize(BitArray bits)
        {
            int size = bits.Count/4 +1;
            List<byte> ret = new List<byte>(size);
            int count = 0, total = 0; byte temp = new byte();
            for (int i = 0; i < bits.Count; i++) 
            {
                if (count == 4)
                {
                    ret.Add(temp);
                    count = 0;
                    temp = 0;
                    total++;
                }
                switch (count)
                {
                    case 0:
                        temp |= (byte)(bits[i] ? BoolMap.True_0 : BoolMap.False_0);
                        break;
                    case 1:
                        temp |= (byte)(bits[i] ? BoolMap.True_1 : BoolMap.False_1);
                        break;
                    case 2:
                        temp |= (byte)(bits[i] ? BoolMap.True_2 : BoolMap.False_2);
                        break;
                    case 3:
                        temp |= (byte)(bits[i] ? BoolMap.True_3 : BoolMap.False_3);
                        break;
                    default:
                        throw new Exception();
                }
                count++;
            }
            for (; count < 4; count++)
            {
                switch (count)
                {
                    case 1:
                        temp |= (byte)(BoolMap.None_1);
                        break;
                    case 2:
                        temp |= (byte)(BoolMap.None_2);
                        break;
                    case 3:
                        temp |= (byte)(BoolMap.None_3);
                        break;
                    default:
                        throw new Exception();
                }
                continue;
            }
            ret.Add( temp);
            return ret.ToArray();
        }

        public static void Deserialize(byte[] stream, out BitArray target)
        {
            List<bool> boolStream = new List<bool>( 4 * stream.Length);
            int i = 0, count = 0;
            foreach (byte b in stream) 
            {
                uint raw = b;
                for (i = 0; i < 4; i++)
                {
                    switch (raw & 0b11) 
                    {
                        case (uint)BoolMap.True_0:
                            boolStream.Add(true);
                            break;
                        case (uint)BoolMap.False_0:
                            boolStream.Add(false);
                            break;
                        case (uint)BoolMap.None_0:
                            goto end;
                        default:
                            throw new Exception();
                    }
                    raw >>= 2;
                    count++;
                    continue;
                    end:
                    {
                        break;
                    }
                }
            }
            while (boolStream.Count > count)
            {
                boolStream.RemoveAt(count);
            }
            target = new BitArray(boolStream.ToArray());
        }
    }


    internal enum BoolMap : byte
    {
        False_0 =   0b00000010,
        True_0 =    0b00000001,
        None_0 =    0b00000011,
        False_1 =   0b00001000,
        True_1=     0b00000100,
        None_1 =    0b00001100,
        False_2 =   0b00100000,
        True_2 =    0b00010000,
        None_2 =    0b00110000,
        False_3 =   0b10000000,
        True_3 =    0b01000000,
        None_3 =    0b11000000,
    }
}