/**
 * 
 */
package com.waylau.netty.demo.protocol;

import java.nio.charset.Charset;


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

/**
 * 说明：编码器
 *
 * @author <a href="http://www.waylau.com">waylau.com</a> 2015年11月10日 
 */
public class ProtocolEncoder extends MessageToByteEncoder<ProtocolMsg> {

	/**
	 * 
	 */
	public ProtocolEncoder() {
		// TODO Auto-generated constructor stub
	}

	/**
	 * @param outboundMessageType
	 */
	public ProtocolEncoder(Class<? extends ProtocolMsg> outboundMessageType) {
		super(outboundMessageType);
		// TODO Auto-generated constructor stub
	}

	/**
	 * @param preferDirect
	 */
	public ProtocolEncoder(boolean preferDirect) {
		super(preferDirect);
		// TODO Auto-generated constructor stub
	}

	/**
	 * @param outboundMessageType
	 * @param preferDirect
	 */
	public ProtocolEncoder(Class<? extends ProtocolMsg> outboundMessageType,
			boolean preferDirect) {
		super(outboundMessageType, preferDirect);
		// TODO Auto-generated constructor stub
	}

	/* (non-Javadoc)
	 * @see io.netty.handler.codec.MessageToByteEncoder#encode(io.netty.channel.ChannelHandlerContext, java.lang.Object, io.netty.buffer.ByteBuf)
	 */
	@Override
	protected void encode(ChannelHandlerContext ctx, ProtocolMsg msg,
			ByteBuf out) throws Exception {
		if (msg == null | msg.getProtocolHeader() == null) {
			throw new Exception("The encode message is null");
		}
		ProtocolHeader header = msg.getProtocolHeader();
		String body = msg.getBody();
		byte[] bodyBytes = body.getBytes(Charset.forName("utf-8"));
		int bodySize = bodyBytes.length;
		
		out.writeByte(header.getMagic());
		out.writeByte(header.getMsgType());
		out.writeShort(header.getReserve());
		out.writeShort(header.getSn());
		out.writeInt(bodySize);
		out.writeBytes(bodyBytes);
	}

}