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Quick MQTT Example

// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

#include "qmlmqttclient.h"
#include <QDebug>

QmlMqttSubscription::QmlMqttSubscription(QMqttSubscription *s, QmlMqttClient *c)
    : sub(s)
    , client(c)
{
    connect(sub, &QMqttSubscription::messageReceived, this, &QmlMqttSubscription::handleMessage);
    m_topic = sub->topic();
}

QmlMqttSubscription::~QmlMqttSubscription()
{
}

QmlMqttClient::QmlMqttClient(QObject *parent)
    : QObject(parent)
{
    connect(&m_client, &QMqttClient::hostnameChanged, this, &QmlMqttClient::hostnameChanged);
    connect(&m_client, &QMqttClient::portChanged, this, &QmlMqttClient::portChanged);
    connect(&m_client, &QMqttClient::stateChanged, this, &QmlMqttClient::stateChanged);
}

void QmlMqttClient::connectToHost()
{
    m_client.connectToHost();
}

void QmlMqttClient::disconnectFromHost()
{
    m_client.disconnectFromHost();
}

QmlMqttSubscription* QmlMqttClient::subscribe(const QString &topic)
{
    auto sub = m_client.subscribe(topic, 0);
    auto result = new QmlMqttSubscription(sub, this);
    return result;
}

void QmlMqttSubscription::handleMessage(const QMqttMessage &qmsg)
{
    emit messageReceived(qmsg.payload());
}

const QString QmlMqttClient::hostname() const
{
    return m_client.hostname();
}

void QmlMqttClient::setHostname(const QString &newHostname)
{
    m_client.setHostname(newHostname);
}

int QmlMqttClient::port() const
{
    return m_client.port();
}

void QmlMqttClient::setPort(int newPort)
{
    if (newPort < 0 || newPort > std::numeric_limits<quint16>::max()) {
        qWarning() << "Trying to set invalid port number";
        return;
    }
    m_client.setPort(static_cast<quint16>(newPort));

    m_client.state();
}

const QMqttClient::ClientState QmlMqttClient::state() const
{
    return m_client.state();
}

void QmlMqttClient::setState(const QMqttClient::ClientState &newState)