/*
 * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.netconf.nettyutil;

import io.netty.channel.Channel;
import io.netty.util.concurrent.Promise;
import org.opendaylight.netconf.api.NetconfSession;
import org.opendaylight.netconf.codec.EOMFrameDecoder;
import org.opendaylight.netconf.codec.FrameDecoder;
import org.opendaylight.netconf.codec.HelloMessageWriter;
import org.opendaylight.netconf.codec.MessageDecoder;
import org.opendaylight.netconf.codec.MessageEncoder;
import org.opendaylight.netconf.nettyutil.handler.HelloXMLMessageDecoder;

// FIXME: This is not related Netty's'ChannelInitializer' and is pretty much unused.
//        Perhaps a NetconfConnectionFactory? It would:
//        - take a TransportChannel
//        - initialize the pipeline with MessageEncoder
//        - produce a NetconfConnection, which has:
//          -  TransportChannel transport()
//          -  MessageEncoder messageEncoder()
public abstract class AbstractChannelInitializer<S extends NetconfSession> {
    public static final String NETCONF_SESSION_NEGOTIATOR = "negotiator";

    // FIXME: this should be taking only a TransportChannel and should be factory method producing NetconfConnections,
    //        without the 'attach a negotiator with some promise' part
    public void initialize(final Channel ch, final Promise<S> promise) {
        ch.pipeline().addLast(FrameDecoder.HANDLER_NAME, new EOMFrameDecoder());
        initializeMessageDecoder(ch);
        // Special encoding handler for hello message to include additional header if available, it is thrown away after
        // successful negotiation
        ch.pipeline().addLast("netconfMessageEncoder", new MessageEncoder(HelloMessageWriter.pretty()));

        initializeSessionNegotiator(ch, promise);
    }

    protected void initializeMessageDecoder(final Channel ch) {
        // Special decoding handler for hello message to parse additional header if available,
        // it is thrown away after successful negotiation
        ch.pipeline().addLast(MessageDecoder.HANDLER_NAME, new HelloXMLMessageDecoder());
    }

    /**
     * Insert session negotiator into the pipeline. It must be inserted after message decoder
     * identified by {@link MessageDecoder#HANDLER_NAME}, (or any other custom decoder processor)
     */
    // FIXME: This should be somewhere else. It should take an already-initialized NetconfConnection and perform
    //        the listener magic of eventually giving out the negotiated NetconfSession.
    protected abstract void initializeSessionNegotiator(Channel ch, Promise<S> promise);
}