using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.RemoteDesktop.Quantization;

namespace Tango.RemoteDesktop.Encoders
{
    public class GifEncoder : JpegEncoder
    {
        public GifEncoder(IFrame frame) : base(frame)
        {
            
        }

        public override MemoryStream ToStream()
        {
            return ToStream(100);
        }

        public override MemoryStream ToStream(long quality)
        {
            MemoryStream ms = new MemoryStream();
            var quantizer = new OctreeQuantizer(256, true);
            var quantized = quantizer.Quantize(Frame.ToBitmap());
            quantized.Save(ms, ImageFormat.Gif);
            ms.Position = 0;
            quantized.Dispose();
            return ms;
        }

        public static Bitmap MakeTransparentGif(Bitmap bitmap, Color color)
        {
            byte R = color.R;
            byte G = color.G;
            byte B = color.B;
            MemoryStream fin = new MemoryStream();
            bitmap.Save(fin, System.Drawing.Imaging.ImageFormat.Gif);
            MemoryStream fout = new MemoryStream((int)fin.Length);
            int count = 0;
            byte[] buf = new byte[256];
            byte transparentIdx = 0;
            fin.Seek(0, SeekOrigin.Begin);
            //header  
            count = fin.Read(buf, 0, 13);
            if ((buf[0] != 71) || (buf[1] != 73) || (buf[2] != 70)) return null; //GIF  
            fout.Write(buf, 0, 13);
            int i = 0;
            if ((buf[10] & 0x80) > 0)
            {
                i = 1 << ((buf[10] & 7) + 1) == 256 ? 256 : 0;
            }
            for (; i != 0; i--)
            {
                fin.Read(buf, 0, 3);
                if ((buf[0] == R) && (buf[1] == G) && (buf[2] == B))
                {
                    transparentIdx = (byte)(256 - i);
                }
                fout.Write(buf, 0, 3);
            }
            bool gcePresent = false;
            while (true)
            {
                fin.Read(buf, 0, 1);
                fout.Write(buf, 0, 1);
                if (buf[0] != 0x21) break;
                fin.Read(buf, 0, 1);
                fout.Write(buf, 0, 1);
                gcePresent = (buf[0] == 0xf9);
                while (true)
                {
                    fin.Read(buf, 0, 1);
                    fout.Write(buf, 0, 1);
                    if (buf[0] == 0) break;
                    count = buf[0];
                    if (fin.Read(buf, 0, count) != count) return null;
                    if (gcePresent)
                    {
                        if (count == 4)
                        {
                            buf[0] |= 0x01;
                            buf[3] = transparentIdx;
                        }
                    }
                    fout.Write(buf, 0, count);
                }
            }
            while (count > 0)
            {
                count = fin.Read(buf, 0, 1);
                fout.Write(buf, 0, 1);
            }
            fin.Close();
            fout.Flush();
            return new Bitmap(fout);
        }
    }
}