package com.runescape.net.packet.encryption;

import java.nio.ByteBuffer;

import org.jboss.netty.buffer.BigEndianHeapChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.FrameDecoder;

import com.runescape.net.packet.RSCPacket;

public final class PacketDecoder extends FrameDecoder {

    @Override
    protected Object decode(ChannelHandlerContext chc, Channel channel,
            ChannelBuffer channelBuffer) throws Exception {

        if (channelBuffer instanceof BigEndianHeapChannelBuffer) {
            BigEndianHeapChannelBuffer buffer = (BigEndianHeapChannelBuffer) channelBuffer;
            ByteBuffer in = ByteBuffer.wrap(buffer.array());
            if (in.remaining() >= 2) {
                byte[] buf = new byte[] { in.get(), in.get() };
                int length = ((short) ((buf[0] & 0xff) << 8) | (short) (buf[1] & 0xff));
                if (length <= in.remaining()) {
                    if (length - 1 < 0) {
                        chc.getChannel().close();
                        return true;
                    }
                    byte[] payload = new byte[length - 1];
                    int id = in.get() & 0xff;
                    in.get(payload);
                    in.rewind();
                    channelBuffer.readByte();
                    return new RSCPacket(chc, id, payload);
                } else {
                    in.rewind();
                    channelBuffer.readByte();
                    return ChannelBuffers.EMPTY_BUFFER;
                }
            }
        }
        return channelBuffer;
    }

}