package org.moparscape.msc.gs.connection;

import org.apache.mina.common.ByteBuffer;
import org.apache.mina.common.IoSession;
import org.apache.mina.filter.codec.ProtocolEncoder;
import org.apache.mina.filter.codec.ProtocolEncoderOutput;
import org.moparscape.msc.gs.util.Logger;

/**
 * Encodes the high level <code>LSPacket</code> class into the proper protocol
 * data required for transmission.
 */
public class LSProtocolEncoder implements ProtocolEncoder {
	/**
	 * Releases all resources used by this encoder.
	 * 
	 * @param session
	 *            The IO session
	 */
	public void dispose(IoSession session) {
	}

	/**
	 * Converts a <code>LSPacket</code> object into the raw data needed for
	 * transmission.
	 * 
	 * @param session
	 *            The IO session associated with the packet
	 * @param message
	 *            A <code>LSPacket</code> to encode
	 * @param out
	 *            The output stream to which to write the data
	 */
	public void encode(IoSession session, Object message,
			ProtocolEncoderOutput out) {
		if (!(message instanceof LSPacket)) {
			Logger.error(new Exception("Wrong packet type! "
					+ message.toString()));
			return;
		}
		LSPacket p = (LSPacket) message;
		byte[] data = p.getData();
		int packetLength = data.length;
		ByteBuffer buffer;
		if (!p.isBare()) {
			buffer = ByteBuffer.allocate(data.length + 13);
			packetLength += 9;

			buffer.putInt(packetLength);
			buffer.put((byte) p.getID());
			buffer.putLong(p.getUID());

		} else {
			buffer = ByteBuffer.allocate(data.length);
		}
		buffer.put(data, 0, data.length);
		buffer.flip();
		out.write(buffer);
	}
}