/*
 * Copyright 2019 The Netty Project
 *
 * The Netty Project licenses this file to you 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 io.netty.example.mqtt.heartBeat;

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.mqtt.MqttConnectMessage;
import io.netty.handler.codec.mqtt.MqttConnectPayload;
import io.netty.handler.codec.mqtt.MqttConnectVariableHeader;
import io.netty.handler.codec.mqtt.MqttFixedHeader;
import io.netty.handler.codec.mqtt.MqttMessage;
import io.netty.handler.codec.mqtt.MqttMessageType;
import io.netty.handler.codec.mqtt.MqttQoS;
import io.netty.handler.timeout.IdleStateEvent;
import io.netty.util.ReferenceCountUtil;

public class MqttHeartBeatClientHandler implements ChannelHandler {

    private static final String PROTOCOL_NAME_MQTT_3_1_1 = "MQTT";
    private static final int PROTOCOL_VERSION_MQTT_3_1_1 = 4;

    private final String clientId;
    private final String userName;
    private final byte[] password;

    public MqttHeartBeatClientHandler(String clientId, String userName, String password) {
        this.clientId = clientId;
        this.userName = userName;
        this.password = password.getBytes();
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        // discard all messages
        ReferenceCountUtil.release(msg);
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        MqttFixedHeader connectFixedHeader =
                new MqttFixedHeader(MqttMessageType.CONNECT, false, MqttQoS.AT_MOST_ONCE, false, 0);
        MqttConnectVariableHeader connectVariableHeader =
                new MqttConnectVariableHeader(PROTOCOL_NAME_MQTT_3_1_1, PROTOCOL_VERSION_MQTT_3_1_1, true, true, false,
                                              0, false, false, 20);
        MqttConnectPayload connectPayload = new MqttConnectPayload(clientId, null, null, userName, password);
        MqttConnectMessage connectMessage =
                new MqttConnectMessage(connectFixedHeader, connectVariableHeader, connectPayload);
        ctx.writeAndFlush(connectMessage);
        System.out.println("Sent CONNECT");
    }

    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof IdleStateEvent) {
            MqttFixedHeader pingreqFixedHeader =
                    new MqttFixedHeader(MqttMessageType.PINGREQ, false, MqttQoS.AT_MOST_ONCE, false, 0);
            MqttMessage pingreqMessage = new MqttMessage(pingreqFixedHeader);
            ctx.writeAndFlush(pingreqMessage);
            System.out.println("Sent PINGREQ");
        } else {
            ctx.fireUserEventTriggered(evt);
        }
    }

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