PositionProvider.h

/***************************************************************************
 *   Copyright (C) 2019-2025 by Stefan Kebekus                             *
 *   stefan.kebekus@gmail.com                                              *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 3 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
 
#pragma once
 
#include <QBindable>
#include <QElapsedTimer>
#include <QQmlEngine>
#include <QSet>
 
#include "GlobalObject.h"
#include "positioning/PositionInfoSource_Satellite.h"
 
 
namespace Positioning {

 
class PositionProvider : public QObject
{
    Q_OBJECT
    QML_ELEMENT
    QML_SINGLETON
 
 
public:
    explicit PositionProvider(QObject* parent = nullptr);
 
    // No default constructor, important for QML singleton
    explicit PositionProvider() = delete;

    ~PositionProvider() override;
 
 
    // factory function for QML singleton
    static Positioning::PositionProvider* create(QQmlEngine* /*unused*/, QJSEngine* /*unused*/)
    {
        return GlobalObject::positionProvider();
    }
 
 
    //
    // PROPERTIES
    //

    Q_PROPERTY(QGeoCoordinate approximateLastValidCoordinate READ approximateLastValidCoordinate BINDABLE bindableApproximateLastValidCoordinate)
 
    
    Q_PROPERTY(QString icon READ icon BINDABLE bindableIcon)

    Q_PROPERTY(QGeoCoordinate lastValidCoordinate READ lastValidCoordinate BINDABLE bindableLastValidCoordinate)

    Q_PROPERTY(QGeoCoordinate mapCenter READ mapCenter WRITE setMapCenter BINDABLE bindableMapCenter NOTIFY mapCenterChanged)

    Q_PROPERTY(Units::Angle lastValidTT READ lastValidTT BINDABLE bindableLastValidTT)

    Q_PROPERTY(Positioning::PositionInfo positionInfo READ positionInfo BINDABLE bindablePositionInfo NOTIFY positionInfoChanged)

    Q_PROPERTY(Units::Distance pressureAltitude READ pressureAltitude BINDABLE bindablePressureAltitude)

    Q_PROPERTY(bool pressureAltitudeImplausible READ pressureAltitudeImplausible BINDABLE bindablePressureAltitudeImplausible NOTIFY pressureAltitudeImplausibleChanged)

    Q_PROPERTY(bool receivingPositionInfo READ receivingPositionInfo BINDABLE bindableReceivingPositionInfo)

    Q_PROPERTY(QString statusString READ statusString BINDABLE bindableStatusString)
 
 
    //
    // Getter Methods
    //

    [[nodiscard]] QGeoCoordinate approximateLastValidCoordinate() const {return m_approximateLastValidCoordinate.value();}

    [[nodiscard]] QBindable<QGeoCoordinate> bindableApproximateLastValidCoordinate() const {return &m_approximateLastValidCoordinate;}

    [[nodiscard]] QString icon() const {return m_icon.value();}

    [[nodiscard]] QBindable<QString> bindableIcon() const {return &m_icon;}

    [[nodiscard]] static QGeoCoordinate lastValidCoordinate();

    [[nodiscard]] QBindable<QGeoCoordinate> bindableLastValidCoordinate() {return &m_lastValidCoordinate;}

    [[nodiscard]] static Units::Angle lastValidTT();

    [[nodiscard]] QBindable<Units::Angle> bindableLastValidTT() {return &m_lastValidTT;}

    [[nodiscard]] QGeoCoordinate mapCenter() const {return m_mapCenter.value();}

    [[nodiscard]] QBindable<QGeoCoordinate> bindableMapCenter() {return &m_mapCenter;}

    void setMapCenter(const QGeoCoordinate& newMapCenter) {m_mapCenter = newMapCenter;}

    [[nodiscard]] Positioning::PositionInfo positionInfo() const {return m_positionInfo.value();}

    [[nodiscard]] QBindable<Positioning::PositionInfo> bindablePositionInfo() const {return &m_positionInfo;}

    [[nodiscard]] Units::Distance pressureAltitude() const {return m_pressureAltitude.value();}

    [[nodiscard]] QBindable<Units::Distance> bindablePressureAltitude() const {return &m_pressureAltitude;}

    [[nodiscard]] bool pressureAltitudeImplausible() const {return m_pressureAltitudeImplausible.value();}

    [[nodiscard]] QBindable<bool> bindablePressureAltitudeImplausible() const {return &m_pressureAltitudeImplausible;}

    [[nodiscard]] bool receivingPositionInfo() const {return m_receivingPositionInfo.value();}

    [[nodiscard]] QBindable<bool> bindableReceivingPositionInfo() {return &m_receivingPositionInfo;}

    [[nodiscard]] QString statusString() const {return m_statusString.value();}

    [[nodiscard]] QBindable<QString> bindableStatusString() const {return &m_statusString;}
 
 
    //
    // Constants
    //

    static constexpr Units::Distance pressureAltitudeImplausibleThreshold = Units::Distance::fromFT(5000.0);
 
 
    //
    // Methods
    //

    Q_INVOKABLE void startUpdates() { satelliteSource.startUpdates(); }

    Q_INVOKABLE void setBackgroundUpdates(const QString& caller, bool enable);
 
signals:
    // Notifier signal
    void approximateLastValidCoordinateChanged();
 
    // Notifier signal
    void mapCenterChanged();
 
    // Notifier signal
    void positionInfoChanged(const Positioning::PositionInfo& info);
 
    // Notifier signal
    void pressureAltitudeImplausibleChanged();
 
    // Notifier signal
    void receivingPositionInfoChanged(bool);

    void backgroundLocationUnavailable();
 
private slots:
    // Intializations that are moved out of the constructor, in order to avoid
    // nested uses of constructors in Global.
    void deferredInitialization();
 
    // Saves last valid position and track
    void savePositionAndTrack();
 
private:
    Q_DISABLE_COPY_MOVE(PositionProvider)
 
#ifdef Q_OS_IOS
    QSet<QString> m_backgroundUpdateCallers;
    void updateBackgroundLocation();
#endif
 
    // Computation method for property with the same name
    QString computeStatusString();
 
    // Aircraft is considered flying if speed is at least this high
    static constexpr double minFlightSpeedInKT = 30.0;
    // Hysteresis for flight speed
    static constexpr double flightSpeedHysteresis = 5.0;
 
    // Coordinates of EDTF airfield
    static constexpr double EDTF_lat = 48.022653;
    static constexpr double EDTF_lon = 7.832583;
    static constexpr double EDTF_ele = 244;
 
    PositionInfoSource_Satellite satelliteSource;
 
    // The incoming position info is set by a binding that monitors
    // the satelliteSource and the TrafficDataSource
    QProperty<Positioning::PositionInfo> m_incomingPositionInfo;
    Positioning::PositionInfo computeIncomingPositionInfo();
 
    // This method updates m_approximateLastValidCoordinate, m_lastValidCoordinate and m_lastValidTT
    // whenever m_incomingPositionInfo changes.
    void onIncomingPositionInfoUpdated();
    QPropertyNotifier m_incomingPositionInfoNotifier;
 
    Q_OBJECT_BINDABLE_PROPERTY(Positioning::PositionProvider, Positioning::PositionInfo, m_positionInfo, &Positioning::PositionProvider::positionInfoChanged);
    Q_OBJECT_BINDABLE_PROPERTY(Positioning::PositionProvider, QGeoCoordinate, m_approximateLastValidCoordinate, &Positioning::PositionProvider::approximateLastValidCoordinateChanged);
    QProperty<QGeoCoordinate> m_lastValidCoordinate {QGeoCoordinate(EDTF_lat, EDTF_lon, EDTF_ele)};
    QProperty<Units::Angle> m_lastValidTT;
    Q_OBJECT_BINDABLE_PROPERTY(Positioning::PositionProvider, QGeoCoordinate, m_mapCenter, &Positioning::PositionProvider::mapCenterChanged);
 
    Q_OBJECT_BINDABLE_PROPERTY(Positioning::PositionProvider, bool, m_receivingPositionInfo, &Positioning::PositionProvider::receivingPositionInfoChanged);
    QProperty<QString> m_icon;
    QProperty<QString> m_statusString;
 
    QProperty<Units::Distance> m_pressureAltitude;
    static Units::Distance computePressureAltitude();
 
    // This method updates m_pressureAltitudeImplausible. It is called whenever
    // m_positionInfo or m_pressureAltitude change.
    void updatePressureAltitudeImplausible();
    QPropertyNotifier m_pressureAltitudeNotifier;
 
    // Hysteresis for the pressure altitude plausibility check: once the warning
    // is active, it clears only when the difference drops below this value.
    static constexpr Units::Distance pressureAltitudePlausibleThreshold = Units::Distance::fromFT(3000.0);
    // The difference must persist for at least this long before the warning is raised.
    static constexpr qint64 pressureAltitudeImplausibleDwellTime_ms = 30LL*1000;
    // Measures for how long pressure altitude and geometric altitude have been
    // differing by more than pressureAltitudeImplausibleThreshold.
    QElapsedTimer m_pressureAltitudeDivergenceTimer;
    Q_OBJECT_BINDABLE_PROPERTY(Positioning::PositionProvider, bool, m_pressureAltitudeImplausible, &Positioning::PositionProvider::pressureAltitudeImplausibleChanged);
};
 
} // namespace Positioning