/*
 * Copyright 2015 Open Networking Laboratory
 *
 * 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.onosproject.pcep.controller.impl;

import java.util.LinkedList;
import java.util.List;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.handler.codec.frame.FrameDecoder;
import org.onosproject.pcepio.protocol.PcepFactories;
import org.onosproject.pcepio.protocol.PcepMessage;
import org.onosproject.pcepio.protocol.PcepMessageReader;
import org.onosproject.pcepio.util.HexDump;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Decode an pcep message from a Channel, for use in a netty pipeline.
 */
public class PcepMessageDecoder extends FrameDecoder {

    protected static final Logger log = LoggerFactory.getLogger(PcepMessageDecoder.class);

    @Override
    protected Object decode(ChannelHandlerContext ctx, Channel channel,
            ChannelBuffer buffer) throws Exception {
        log.debug("Message received.");
        if (!channel.isConnected()) {
            log.info("Channel is not connected.");
            // In testing, I see decode being called AFTER decode last.
            // This check avoids that from reading corrupted frames
            return null;
        }

        HexDump.pcepHexDump(buffer);

        // Note that a single call to decode results in reading a single
        // PcepMessage from the channel buffer, which is passed on to, and processed
        // by, the controller (in PcepChannelHandler).
        // This is different from earlier behavior (with the original pcepIO),
        // where we parsed all the messages in the buffer, before passing on
        // a list of the parsed messages to the controller.
        // The performance *may or may not* not be as good as before.
        PcepMessageReader<PcepMessage> reader = PcepFactories.getGenericReader();
        List<PcepMessage> msgList = new LinkedList<>();

        while (buffer.readableBytes() > 0) {
            PcepMessage message = reader.readFrom(buffer);
            msgList.add(message);
        }
        return msgList;
    }
}