import java.util.List;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ReplayingDecoder;

public class MessageDecoder extends ReplayingDecoder<DecoderState> {

    private int length;

    public MessageDecoder()
    {
        super(DecoderState.READ_LENGTH);
    }

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf buf, List<Object> out) throws Exception{
        System.out.println(buf.readableBytes());
        switch(state()){
            case READ_LENGTH:
                length=buf.readInt();
                System.out.println("length is: "+length);
                checkpoint(DecoderState.READ_CONTENT);
            case READ_CONTENT:
                ByteBuf frame = buf.readBytes(length);
                checkpoint(DecoderState.READ_LENGTH);
                out.add(frame);
                break;
            default:
                throw new Error("Shouldn't reach here");
        }
    }
}