/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.camel.component.syslog.netty;

import java.nio.charset.Charset;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandler.Sharable;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.oneone.OneToOneEncoder;

import static org.jboss.netty.buffer.ChannelBuffers.wrappedBuffer;

@Sharable
public class Rfc5425Encoder extends OneToOneEncoder {

    @Override
    protected Object encode(ChannelHandlerContext ctx, Channel channel, Object msg) throws Exception {
        if (!(msg instanceof ChannelBuffer)) {
            return msg;
        }

        ChannelBuffer src = (ChannelBuffer) msg;
        int length = src.readableBytes();

        String headerString = length + " ";

        ChannelBuffer header = channel.getConfig().getBufferFactory().getBuffer(src.order(), headerString.getBytes(Charset.forName("UTF8")).length);
        header.writeBytes(headerString.getBytes(Charset.forName("UTF8")));

        return wrappedBuffer(header, src);
    }
}
