#include <QCoreApplication>

#include <QTcpServer>
#include <QIODevice>
#include <QTcpSocket>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QTcpServer tcpServer;

    if (!tcpServer.listen(QHostAddress::LocalHost, 55666)) {
       qDebug() << QString("Unable to start the server: %1.")
                              .arg(tcpServer.errorString());
        return 0;
    }

    QObject::connect(&tcpServer, &QTcpServer::newConnection,
                     &tcpServer, [&](){
        auto tcpServerConnection = tcpServer.nextPendingConnection();
        tcpServerConnection->setReadBufferSize(65536);
        if (!tcpServerConnection) {
            qDebug() << "Error: got invalid pending connection!";
            return;
        }

        QObject::connect(tcpServerConnection, &QIODevice::readyRead,
                tcpServerConnection, [tcpServerConnection](){
            qDebug() << "Ready read = " << tcpServerConnection->bytesAvailable();
        });

        QObject::connect(tcpServerConnection, &QAbstractSocket::errorOccurred,
                         tcpServerConnection, [](QAbstractSocket::SocketError error){
            qDebug() << "Error = " << error;
        });

        QObject::connect(tcpServerConnection, &QTcpSocket::disconnected,
                tcpServerConnection, &QTcpSocket::deleteLater);
    });

    qDebug() << "Server port: " << tcpServer.serverPort();

    return a.exec();
}