/*!
 * 
 * Copyright (c) 2019-2020 Diality Inc. - All Rights Reserved.
 * \copyright
 * THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
 * WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
 * 
 * \file singleton.h
 * \author (last) Behrouz NematiPour
 * \date (last) 02-Jan-2020
 * \author (original) Behrouz NematiPour
 * \date (original) 02-Jan-2020
 * 
 */
#pragma once

// Qt
#include <QDebug>
#include <QObject>
#include <QThread>
#include <QApplication>
// Project


#define SINGLETON(vCLASS)                           \
private:                                            \
    explicit vCLASS(QObject *parent = nullptr);     \
    vCLASS(vCLASS const &);                         \
    vCLASS & operator = (vCLASS const &) = delete;  \
public:                                             \
    static vCLASS &I() {                            \
        static vCLASS _instance;                    \
        return _instance;                           \
    }


class Singleton : public QObject
{
    Q_OBJECT

    static QVector<QThread *> _threads;

    Singleton (Singleton const &);
    Singleton & operator = (Singleton const &) = delete;

protected:
    bool _initialized = false;

    explicit Singleton(QObject *parent = nullptr) : QObject(parent) {}
    virtual ~Singleton() {
        _quit_();
    }

    static Singleton &I() {
        static Singleton _instance;
        return           _instance;
    }

    void initThread(QThread *vThread) {
        qDebug() << this->metaObject()->className();
        if (! vThread) return;
        vThread->setObjectName(QString("%1_Thread").arg(this->metaObject()->className()));
        moveToThread(vThread);
        QObject::connect(qApp, &QApplication::aboutToQuit, vThread, [vThread]() {
            vThread->quit();
            vThread->wait();
        });
        QObject::connect(vThread, &QThread::finished, this, [this](){
            moveToThread(qApp->thread());
        });
        vThread->start();
    }

    virtual bool _init_() {
        return true;

    }

    virtual void _quit_() {
        _initialized = false;
    }

    virtual void initConnections() {

    }

public:
    virtual bool init(QThread *thread = nullptr) final {
        _init_();
        initConnections();
        initThread(thread);
        _initialized = true;
        return true;
    }
};