BtServer QCoreApplication issue

////////////////////////////////////////// main.cpp //////////////////////////////////////////
#include "btechoserver.h"

#include <QDebug>
#include <QBluetoothLocalDevice>
#include <QBluetoothHostInfo>
#include <QGuiApplication>


int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);

    qDebug() << Q_FUNC_INFO;
    auto localAdapters = QBluetoothLocalDevice::allDevices();
    QBluetoothLocalDevice adapter(localAdapters.at(0).address());
    adapter.setHostMode(QBluetoothLocalDevice::HostDiscoverable);

    BtEchoServer *m_pServer = new BtEchoServer();
    m_pServer->startServer();

    return app.exec();
}

////////////////////////////////////////// btechoserver.h //////////////////////////////////////////

#ifndef BTECHOSERVER_H
#define BTECHOSERVER_H

#include <QObject>
#include <QBluetoothAddress>
#include <QBluetoothServiceInfo>
#include <QBluetoothSocket>
#include <QBluetoothHostInfo>

class QBluetoothServer;

class BtEchoServer : public QObject
{
    Q_OBJECT

public:
    explicit BtEchoServer(QObject *parent = 0);
    ~BtEchoServer();
    void startServer(const QBluetoothAddress &localAdapter = QBluetoothAddress());
    void stopServer();

public slots:
    void onClientConnected();
    void onClientDisconnected();
    void readIncomingData();
    void onBtSocketError(QBluetoothSocket::SocketError error);


private:
    QBluetoothServer *m_pRfcommServer;
    QBluetoothServiceInfo m_serviceInfo;
    QList<QBluetoothSocket *> m_pClients;
    QList<QBluetoothHostInfo> m_localAdapters;
};

#endif // BTECHOSERVER_H

////////////////////////////////////////// btechoserver.cpp //////////////////////////////////////////

#include "btechoserver.h"

#include <QBluetoothServer>
#include <QBluetoothSocket>
#include <QBluetoothLocalDevice>
#include <QDebug>
#include <QString>

static const QLatin1String btServiceUuid("e8e10f95-1a70-4b27-9ccf-02010264e9c8");

BtEchoServer::BtEchoServer(QObject *parent)
    : QObject(parent)
    , m_pRfcommServer(nullptr)
{
}

BtEchoServer::~BtEchoServer()
{
    qDebug() << Q_FUNC_INFO;
    stopServer();
}

void BtEchoServer::startServer(const QBluetoothAddress &localAdapter)
{
    qDebug() << Q_FUNC_INFO;

    if (m_pRfcommServer)
        return;

    m_pRfcommServer = new QBluetoothServer(QBluetoothServiceInfo::RfcommProtocol, this);
    connect(m_pRfcommServer, SIGNAL(newConnection()), this, SLOT(onClientConnected()));

    m_pRfcommServer->listen(localAdapter);

    QBluetoothServiceInfo::Sequence classId;
    classId << QVariant::fromValue(QBluetoothUuid(QBluetoothUuid::SerialPort));
    m_serviceInfo.setAttribute(QBluetoothServiceInfo::BluetoothProfileDescriptorList, classId);

    classId.prepend(QVariant::fromValue(QBluetoothUuid(btServiceUuid)));

    m_serviceInfo.setAttribute(QBluetoothServiceInfo::ServiceClassIds, classId);
    m_serviceInfo.setAttribute(QBluetoothServiceInfo::BluetoothProfileDescriptorList, classId);

    m_serviceInfo.setAttribute(QBluetoothServiceInfo::ServiceName, tr("My Dummy Bt Server"));
    m_serviceInfo.setAttribute(QBluetoothServiceInfo::ServiceDescription, tr("Dummy Description"));
    m_serviceInfo.setAttribute(QBluetoothServiceInfo::ServiceProvider, tr("bla-service.com"));
    m_serviceInfo.setServiceUuid(QBluetoothUuid(btServiceUuid));

    QBluetoothServiceInfo::Sequence publicBrowse;
    publicBrowse << QVariant::fromValue(QBluetoothUuid(QBluetoothUuid::PublicBrowseGroup));
    m_serviceInfo.setAttribute(QBluetoothServiceInfo::BrowseGroupList, publicBrowse);

    QBluetoothServiceInfo::Sequence protocolDescriptorList;
    QBluetoothServiceInfo::Sequence protocol;
    protocol << QVariant::fromValue(QBluetoothUuid(QBluetoothUuid::L2cap));
    protocolDescriptorList.append(QVariant::fromValue(protocol));
    protocol.clear();

    protocol << QVariant::fromValue(QBluetoothUuid(QBluetoothUuid::Rfcomm))
             << QVariant::fromValue(quint8(m_pRfcommServer->serverPort()));
    protocolDescriptorList.append(QVariant::fromValue(protocol));
    m_serviceInfo.setAttribute(QBluetoothServiceInfo::ProtocolDescriptorList, protocolDescriptorList);

    qDebug() << Q_FUNC_INFO << m_serviceInfo.registerService(localAdapter);
    qDebug() << Q_FUNC_INFO << "Server Started!";

}

void BtEchoServer::stopServer()
{
    qDebug() << Q_FUNC_INFO;
    // Unregister service
    m_serviceInfo.unregisterService();

    // Close server
    delete m_pRfcommServer;
    m_pRfcommServer = 0;
}

void BtEchoServer::onClientConnected()
{
    qDebug() << Q_FUNC_INFO;
    QBluetoothSocket *socket = m_pRfcommServer->nextPendingConnection();
    if (!socket)
        return;

    connect(socket, SIGNAL(readyRead()), this, SLOT(readIncomingData()));
    connect(socket, SIGNAL(disconnected()), this, SLOT(onClientDisconnected()));
}

void BtEchoServer::onClientDisconnected()
{
    qDebug() << Q_FUNC_INFO;
    QBluetoothSocket *socket = qobject_cast<QBluetoothSocket *>(sender());
    if (!socket)
        return;

    socket->deleteLater();
}

void BtEchoServer::readIncomingData()
{
    QBluetoothSocket *socket = qobject_cast<QBluetoothSocket *>(sender());
    if (!socket)
        return;

    while (socket->canReadLine()) {
        QByteArray line = socket->readLine().trimmed();
        qDebug() << Q_FUNC_INFO << QString::fromUtf8(line.constData(), line.length());
    }
}

void BtEchoServer::onBtSocketError(QBluetoothSocket::SocketError error)
{
    qDebug() << "ERROR:" << error;
}


////////////////////////////////////////// btServer.pro //////////////////////////////////////////

QT += core bluetooth
QT += gui //this should be QT -= gui when using QCoreApplication

CONFIG += c++11

TARGET = btServer
#CONFIG += console
CONFIG += app_bundle

TEMPLATE = app

SOURCES += main.cpp \
    btechoserver.cpp

HEADERS += \
    btechoserver.h