/*
 * Copyright 2016-present 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.lisp.ctl;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
import io.netty.util.ReferenceCountUtil;
import org.onosproject.lisp.msg.protocols.LispEncapsulatedControl;
import org.onosproject.lisp.msg.protocols.LispMapNotify;
import org.onosproject.lisp.msg.protocols.LispMapRegister;
import org.onosproject.lisp.msg.protocols.LispMapRequest;
import org.onosproject.lisp.msg.protocols.LispMessage;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Channel handler deals with the xTR connection and dispatches xTR messages
 * to the appropriate locations.
 */
public class LispChannelHandler extends ChannelInboundHandlerAdapter {

    private final Logger log = LoggerFactory.getLogger(getClass());

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        // first we need to check whether this is an ECM
        if (msg instanceof LispEncapsulatedControl) {
            LispMessage innerMsg = extractLispMessage((LispEncapsulatedControl) msg);
            if (innerMsg instanceof LispMapRequest) {
                LispMapResolver mapResolver = new LispMapResolver();
                LispMessage lispMessage = mapResolver.processMapRequest((LispEncapsulatedControl) msg);

                // try to remove the received map-request message from buffer
                ReferenceCountUtil.release(msg);

                ctx.writeAndFlush(lispMessage);
            }
        }

        if (msg instanceof LispMapRegister) {
            LispMapServer mapServer = new LispMapServer();
            LispMapNotify mapNotify = mapServer.processMapRegister((LispMapRegister) msg);

            // try to remove the received map-register message from buffer
            ReferenceCountUtil.release(msg);

            ctx.writeAndFlush(mapNotify);
        }
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt)
            throws Exception {

        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            if (event.state() == IdleState.READER_IDLE) {
                log.info("READER_IDLE read timeout");
                ctx.disconnect();
            } else if (event.state() == IdleState.WRITER_IDLE) {
                log.info("WRITER_IDLE write timeout");
                ctx.disconnect();
            } else if (event.state() == IdleState.ALL_IDLE) {
                log.info("ALL_IDLE total timeout");
                ctx.disconnect();
            }
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
            throws Exception {
        log.warn(cause.getMessage());
        ctx.close();
    }

    /**
     * Extracts LISP message from encapsulated control message.
     *
     * @param ecm Encapsulated Control Message
     * @return extracted LISP message
     */
    private LispMessage extractLispMessage(LispEncapsulatedControl ecm) {
        LispMessage message = ecm.getControlMessage();
        message.configSender(ecm.getSender());
        return message;
    }
}