using System.IO;
using System.Net;
using System;

namespace Com.Xagasoft.Gats
{
    public class GatsStream
    {
        private Stream s;
        private MemoryStream ReadBuf;
        private int size = -1;
        private int version;
        private BinaryWriter bw = null;
        private BinaryReader br = null;

        public GatsStream( Stream s )
        {
            this.s = s;
            this.ReadBuf = new MemoryStream();
        }

        public GatsObject ReadObject()
        {
            if( size == -1 )
            {
                for(;;)
                {
                    version = s.ReadByte();
                    if( version == -1 )
                        return null;
                    if( version > 0 )
                        break;
                }
            }

            if( br == null )
                this.br = new BinaryReader( s );

            switch( version )
            {
                case 1:
                    // Verion 1 of gats
                    if( size == -1 )
                        size = IPAddress.NetworkToHostOrder( br.ReadInt32() )-5;
                    byte[] buf = new byte[4096];
                    while( ReadBuf.Length < size )
                    {
                        int goal = (int)(size-ReadBuf.Length);
                        if( goal > 4096 )
                            goal = 4096;
                        int amnt = s.Read( buf, 0, goal );
                        if( amnt <= 0 )
                            return null;
                        ReadBuf.Write( buf, 0, amnt );
                    }
                    ReadBuf.Seek( 0, SeekOrigin.Begin );
                    GatsObject ret = GatsObject.Read( ReadBuf );
                    ReadBuf.SetLength( 0 );
                    size = version = -1;
                    return ret;
            }

            return null;
        }

        public void WriteObject( GatsObject obj )
        {
            MemoryStream ms = new MemoryStream();
            obj.Write( ms );

            if( bw == null )
                this.bw = new BinaryWriter( s );
            bw.Write( (byte)1 );
            bw.Write( IPAddress.HostToNetworkOrder( (int)ms.Length+5 ) );
            bw.Write( ms.GetBuffer(), 0, (int)ms.Length );
        }
    }
}