/* Copyright (C) 2017
 * swift Project Community / Contributors
 *
 * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
 * directory of this distribution. No part of swift project, including this file, may be copied, modified, propagated,
 * or distributed except according to the terms contained in the LICENSE file.
 */

//! \file

#ifndef BLACKMISC_SHAREDSTATE_PASSIVEOBSERVER_H
#define BLACKMISC_SHAREDSTATE_PASSIVEOBSERVER_H

#include "blackmisc/variant.h"
#include "blackmisc/valueobject.h"
#include "blackmisc/blackmiscexport.h"
#include <QObject>
#include <QSharedPointer>
#include <QMutex>

namespace BlackMisc
{
    namespace SharedState
    {
        class CActiveObserver;

        /*!
         * Endpoint which can subscribe to events emitted by CPassiveMutator.
         * \ingroup SharedState
         */
        class BLACKMISC_EXPORT CPassiveObserver : public QObject, public QEnableSharedFromThis<CPassiveObserver>
        {
            Q_OBJECT
            friend CActiveObserver;
            friend QSharedPointer<CPassiveObserver>;

            template <typename T, typename F>
            CPassiveObserver(T *parent, F eventHandler) :
                QObject(parent),
                m_eventHandler([ = ](const CVariant &param) { Private::invokeMethod(parent, eventHandler, param); })
            {}

        public:
            //! Factory method.
            template <typename T, typename F>
            static auto create(T *parent, F eventHandler) { return QSharedPointer<CPassiveObserver>::create(parent, eventHandler); }

            //! Set the object that determines which events are subscribed to.
            void setEventSubscription(const CVariant &param);

            //! Get the object that determines which events are subscribed to.
            CVariant eventSubscription() const;

            //! Called when a subscribed event is emitted.
            void handleEvent(const CVariant& param) const;

            //! Get a QWeakPointer pointing to this object.
            QWeakPointer<const CPassiveObserver> weakRef() const { return sharedFromThis(); }

        signals:
            //! Emitted by setEventSubscription.
            void eventSubscriptionChanged(const BlackMisc::CVariant &param);

        private:
            const std::function<void(const CVariant &param)> m_eventHandler;

            mutable QMutex m_eventSubscriptionMutex;
            CVariant m_eventSubscription;
        };

        /*!
         * Dummy value class that matches any event.
         * \ingroup SharedState
         */
        class BLACKMISC_EXPORT CAnyMatch : public CValueObject<CAnyMatch>
        {
        public:
            //! Returns true.
            bool matches(const CVariant &) const { return true; }

            //! To string.
            QString convertToQString(bool = false) const { return QStringLiteral("any"); }

        private:
            int m_dummy = 0;

            BLACK_METACLASS(CAnyMatch, BLACK_METAMEMBER(dummy));
        };
    }
}

Q_DECLARE_METATYPE(BlackMisc::SharedState::CAnyMatch)

#endif