/*
 Copyright 2014 Trustees of Indiana University

   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 edu.iu.grnoc.flowspace_firewall;

import java.util.concurrent.TimeUnit;

import net.floodlightcontroller.core.internal.HandshakeTimeoutException;

import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.util.Timeout;
import org.jboss.netty.util.Timer;
import org.jboss.netty.util.TimerTask;

/**
 * Trigger a timeout if a switch fails to complete handshake soon enough
 */
public class ControllerHandshakeTimeoutHandler 
    extends SimpleChannelUpstreamHandler {
    static final HandshakeTimeoutException EXCEPTION = 
            new HandshakeTimeoutException();
    
    final OFControllerChannelHandler channelHandler;
    final Timer timer;
    final long timeoutNanos;
    volatile Timeout timeout;
    
    public ControllerHandshakeTimeoutHandler(OFControllerChannelHandler channelHandler,
                                   Timer timer,
                                   long timeoutSeconds) {
        super();
        this.channelHandler = channelHandler;
        this.timer = timer;
        this.timeoutNanos = TimeUnit.SECONDS.toNanos(timeoutSeconds);

    }
    
    @Override
    public void channelOpen(ChannelHandlerContext ctx, ChannelStateEvent e)
            throws Exception {
        if (timeoutNanos > 0) {
            timeout = timer.newTimeout(new HandshakeTimeoutTask(ctx), 
                                       timeoutNanos, TimeUnit.NANOSECONDS);
        }
        ctx.sendUpstream(e);
    }
    
    @Override
    public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e)
            throws Exception {
        if (timeout != null) {
            timeout.cancel();
            timeout = null;
        }
    }
    
    private final class HandshakeTimeoutTask implements TimerTask {

        private final ChannelHandlerContext ctx;

        HandshakeTimeoutTask(ChannelHandlerContext ctx) {
            this.ctx = ctx;
        }

        @Override
        public void run(Timeout timeout) throws Exception {
            if (timeout.isCancelled()) {
                return;
            }

            if (!ctx.getChannel().isOpen()) {
                return;
            }
            if (!channelHandler.isHandshakeComplete())
                Channels.fireExceptionCaught(ctx, EXCEPTION);
        }
    }
}