/*
 * Copyright 2014 Anton Tananaev (anton.tananaev@gmail.com)
 *
 * Licensed 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.traccar.protocol;

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.DelimiterBasedFrameDecoder;
import org.traccar.helper.ChannelBufferTools;

public class Stl060FrameDecoder extends DelimiterBasedFrameDecoder {

    private static final byte delimiter[] = { (byte) '#' };
    
    public Stl060FrameDecoder(int maxFrameLength) {
        super(maxFrameLength, ChannelBuffers.wrappedBuffer(delimiter));
    }
    
    @Override
    protected Object decode(
            ChannelHandlerContext ctx,
            Channel channel,
            ChannelBuffer buf) throws Exception {
        
        ChannelBuffer result = (ChannelBuffer) super.decode(ctx, channel, buf);
        
        if (result != null) {
            
            Integer beginIndex = ChannelBufferTools.find(
                    result, 0, result.readableBytes(), "$");
            if (beginIndex == null) {
                return result;
            } else {
                result.skipBytes(beginIndex);
                return result.readBytes(result.readableBytes());
            }

        }

        return null;
    }

}