// Copyright (C) 2021 The Qt Company Ltd.

// Copyright (C) 2021 Intel Corporation.

// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only

#ifndef QDATETIME_H

#define QDATETIME_H

#include <QtCore/qcalendar.h>

#include <QtCore/qcompare.h>

#include <QtCore/qlocale.h>

#include <QtCore/qnamespace.h>

#include <QtCore/qshareddata.h>

#include <QtCore/qstring.h>

#include <limits>

#include <chrono>

#if defined(Q_OS_DARWIN) || defined(Q_QDOC)

Q_FORWARD_DECLARE_CF_TYPE(CFDate);

Q_FORWARD_DECLARE_OBJC_CLASS(NSDate);

#endif

QT_BEGIN_NAMESPACE

class QTimeZone;

class QDateTime;

class Q_CORE_EXPORT QDate

{

    explicit constexpr QDate(qint64 julianDay) : jd(julianDay) {}

public:

    constexpr QDate() : jd(nullJd()) {}

    QDate(int y, int m, int d);

    QDate(int y, int m, int d, QCalendar cal);

// INTEGRITY incident-85878 (timezone and clock_cast are not supported)

#if (__cpp_lib_chrono >= 201907L && !defined(Q_OS_INTEGRITY)) || defined(Q_QDOC)

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    Q_IMPLICIT constexpr QDate(std::chrono::year_month_day date) noexcept

        : jd(date.ok() ? stdSysDaysToJulianDay(date) : nullJd())

    {}

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    Q_IMPLICIT constexpr QDate(std::chrono::year_month_day_last date) noexcept

        : jd(date.ok() ? stdSysDaysToJulianDay(date) : nullJd())

    {}

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    Q_IMPLICIT constexpr QDate(std::chrono::year_month_weekday date) noexcept

        : jd(date.ok() ? stdSysDaysToJulianDay(date) : nullJd())

    {}

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    Q_IMPLICIT constexpr QDate(std::chrono::year_month_weekday_last date) noexcept

        : jd(date.ok() ? stdSysDaysToJulianDay(date) : nullJd())

    {}

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    static constexpr QDate fromStdSysDays(const std::chrono::sys_days &days) noexcept

    {

        return QDate(stdSysDaysToJulianDay(days));

    }

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    constexpr std::chrono::sys_days toStdSysDays() const noexcept

    {

        const qint64 days = isValid() ? jd - unixEpochJd() : 0;

        return std::chrono::sys_days(std::chrono::days(days));

    }

#endif

    constexpr bool isNull() const { return !isValid(); }

    constexpr bool isValid() const { return jd >= minJd() && jd <= maxJd(); }

    // Gregorian-optimized:

    int year() const;

    int month() const;

    int day() const;

    int dayOfWeek() const;

    int dayOfYear() const;

    int daysInMonth() const;

    int daysInYear() const;

    int weekNumber(int *yearNum = nullptr) const; // ISO 8601, always Gregorian

    int year(QCalendar cal) const;

    int month(QCalendar cal) const;

    int day(QCalendar cal) const;

    int dayOfWeek(QCalendar cal) const;

    int dayOfYear(QCalendar cal) const;

    int daysInMonth(QCalendar cal) const;

    int daysInYear(QCalendar cal) const;

#if QT_DEPRECATED_SINCE(6, 9)

    QT_DEPRECATED_VERSION_X_6_9("Pass QTimeZone instead")

    QDateTime startOfDay(Qt::TimeSpec spec, int offsetSeconds = 0) const;

    QT_DEPRECATED_VERSION_X_6_9("Pass QTimeZone instead")

    QDateTime endOfDay(Qt::TimeSpec spec, int offsetSeconds = 0) const;

#endif

    QDateTime startOfDay(const QTimeZone &zone) const;

    QDateTime endOfDay(const QTimeZone &zone) const;

    QDateTime startOfDay() const;

    QDateTime endOfDay() const;

#if QT_CONFIG(datestring)

    QString toString(Qt::DateFormat format = Qt::TextDate) const;

    QString toString(const QString &format) const;

    QString toString(const QString &format, QCalendar cal) const

    { return toString(qToStringViewIgnoringNull(format), cal); }

    QString toString(QStringView format) const;

    QString toString(QStringView format, QCalendar cal) const;

#endif

    bool setDate(int year, int month, int day); // Gregorian-optimized

    bool setDate(int year, int month, int day, QCalendar cal);

    void getDate(int *year, int *month, int *day) const;

    [[nodiscard]] QDate addDays(qint64 days) const;

// INTEGRITY incident-85878 (timezone and clock_cast are not supported)

#if (__cpp_lib_chrono >= 201907L && !defined(Q_OS_INTEGRITY)) || defined(Q_QDOC)

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    [[nodiscard]] QDate addDuration(std::chrono::days days) const

    {

        return addDays(days.count());

    }

#endif

    // Gregorian-optimized:

    [[nodiscard]] QDate addMonths(int months) const;

    [[nodiscard]] QDate addYears(int years) const;

    [[nodiscard]] QDate addMonths(int months, QCalendar cal) const;

    [[nodiscard]] QDate addYears(int years, QCalendar cal) const;

    qint64 daysTo(QDate d) const;

    static QDate currentDate();

#if QT_CONFIG(datestring)

    // No DateFormat accepts a two-digit year, so no need for baseYear:

    static QDate fromString(QStringView string, Qt::DateFormat format = Qt::TextDate);

    static QDate fromString(const QString &string, Qt::DateFormat format = Qt::TextDate)

    { return fromString(qToStringViewIgnoringNull(string), format); }

    // Accept calendar without over-ride of base year:

    static QDate fromString(QStringView string, QStringView format, QCalendar cal)

    { return fromString(string.toString(), format, QLocale::DefaultTwoDigitBaseYear, cal); }

    QT_CORE_INLINE_SINCE(6, 7)

    static QDate fromString(const QString &string, QStringView format, QCalendar cal);

    static QDate fromString(const QString &string, const QString &format, QCalendar cal)

    { return fromString(string, qToStringViewIgnoringNull(format), QLocale::DefaultTwoDigitBaseYear, cal); }

    // Overriding base year is likely more common than overriding calendar (and

    // likely to get more so, as the legacy base drops ever further behind us).

    static QDate fromString(QStringView string, QStringView format,

                            int baseYear = QLocale::DefaultTwoDigitBaseYear)

    { return fromString(string.toString(), format, baseYear); }

    static QDate fromString(QStringView string, QStringView format,

                            int baseYear, QCalendar cal)

    { return fromString(string.toString(), format, baseYear, cal); }

    static QDate fromString(const QString &string, QStringView format,

                            int baseYear = QLocale::DefaultTwoDigitBaseYear);

    static QDate fromString(const QString &string, QStringView format,

                            int baseYear, QCalendar cal);

    static QDate fromString(const QString &string, const QString &format,

                            int baseYear = QLocale::DefaultTwoDigitBaseYear)

    { return fromString(string, qToStringViewIgnoringNull(format), baseYear); }

    static QDate fromString(const QString &string, const QString &format,

                            int baseYear, QCalendar cal)

    { return fromString(string, qToStringViewIgnoringNull(format), baseYear, cal); }

#endif

    static bool isValid(int y, int m, int d);

    static bool isLeapYear(int year);

    static constexpr inline QDate fromJulianDay(qint64 jd_)

    { return jd_ >= minJd() && jd_ <= maxJd() ? QDate(jd_) : QDate() ; }

    constexpr inline qint64 toJulianDay() const { return jd; }

private:

    // using extra parentheses around min to avoid expanding it if it is a macro

    static constexpr inline qint64 nullJd() { return (std::numeric_limits<qint64>::min)(); }

    static constexpr inline qint64 minJd() { return Q_INT64_C(-784350574879); }

    static constexpr inline qint64 maxJd() { return Q_INT64_C( 784354017364); }

    static constexpr inline qint64 unixEpochJd() { return Q_INT64_C(2440588); }

// INTEGRITY incident-85878 (timezone and clock_cast are not supported)

#if __cpp_lib_chrono >= 201907L && !defined(Q_OS_INTEGRITY)

#if !QT_CORE_REMOVED_SINCE(6, 7)

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

#endif

    static constexpr qint64

    stdSysDaysToJulianDay(const std::chrono::sys_days &days) noexcept

    {

        const auto epochDays = days.time_since_epoch().count();

        // minJd() and maxJd() fit into 40 bits.

        if constexpr (sizeof(epochDays) * CHAR_BIT >= 41) {

            constexpr auto top = maxJd() - unixEpochJd();

            constexpr auto bottom = minJd() - unixEpochJd();

            if (epochDays > top || epochDays < bottom)

                return nullJd();

        }

        return unixEpochJd() + epochDays;

    }

#endif // __cpp_lib_chrono >= 201907L

    qint64 jd;

    friend class QDateTime;

    friend class QDateTimeParser;

    friend class QDateTimePrivate;

    friend constexpr bool comparesEqual(const QDate &lhs, const QDate &rhs) noexcept

    { return lhs.jd == rhs.jd; }

    friend constexpr Qt::strong_ordering

    compareThreeWay(const QDate &lhs, const QDate &rhs) noexcept

    { return Qt::compareThreeWay(lhs.jd, rhs.jd); }

    Q_DECLARE_STRONGLY_ORDERED_LITERAL_TYPE(QDate)

#ifndef QT_NO_DATASTREAM

    friend Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, QDate);

    friend Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QDate &);

#endif

};

Q_DECLARE_TYPEINFO(QDate, Q_RELOCATABLE_TYPE);

class Q_CORE_EXPORT QTime

{

    explicit constexpr QTime(int ms) : mds(ms)

    {}

public:

    constexpr QTime(): mds(NullTime)

    {}

    QTime(int h, int m, int s = 0, int ms = 0);

    constexpr bool isNull() const { return mds == NullTime; }

    bool isValid() const;

    int hour() const;

    int minute() const;

    int second() const;

    int msec() const;

#if QT_CONFIG(datestring)

    QString toString(Qt::DateFormat f = Qt::TextDate) const;

    QString toString(const QString &format) const

    { return toString(qToStringViewIgnoringNull(format)); }

    QString toString(QStringView format) const;

#endif

    bool setHMS(int h, int m, int s, int ms = 0);

    [[nodiscard]] QTime addSecs(int secs) const;

    int secsTo(QTime t) const;

    [[nodiscard]] QTime addMSecs(int ms) const;

    int msecsTo(QTime t) const;

    static constexpr inline QTime fromMSecsSinceStartOfDay(int msecs) { return QTime(msecs); }

    constexpr inline int msecsSinceStartOfDay() const { return mds == NullTime ? 0 : mds; }

    static QTime currentTime();

#if QT_CONFIG(datestring)

    static QTime fromString(QStringView string, Qt::DateFormat format = Qt::TextDate);

    static QTime fromString(QStringView string, QStringView format)

    { return fromString(string.toString(), format); }

    static QTime fromString(const QString &string, QStringView format);

    static QTime fromString(const QString &string, Qt::DateFormat format = Qt::TextDate)

    { return fromString(qToStringViewIgnoringNull(string), format); }

    static QTime fromString(const QString &string, const QString &format)

    { return fromString(string, qToStringViewIgnoringNull(format)); }

#endif

    static bool isValid(int h, int m, int s, int ms = 0);

private:

    enum TimeFlag { NullTime = -1 };

    constexpr inline int ds() const { return mds == -1 ? 0 : mds; }

    int mds;

    friend constexpr bool comparesEqual(const QTime &lhs, const QTime &rhs) noexcept

    { return lhs.mds == rhs.mds; }

    friend constexpr Qt::strong_ordering

    compareThreeWay(const QTime &lhs, const QTime &rhs) noexcept

    { return Qt::compareThreeWay(lhs.mds, rhs.mds); }

    Q_DECLARE_STRONGLY_ORDERED_LITERAL_TYPE(QTime)

    friend class QDateTime;

    friend class QDateTimePrivate;

#ifndef QT_NO_DATASTREAM

    friend Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, QTime);

    friend Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QTime &);

#endif

};

Q_DECLARE_TYPEINFO(QTime, Q_RELOCATABLE_TYPE);

class QDateTimePrivate;

class Q_CORE_EXPORT QDateTime

{

    struct ShortData {

#if QT_VERSION >= QT_VERSION_CHECK(7,0,0) || defined(QT_BOOTSTRAPPED)

#  if Q_BYTE_ORDER == Q_LITTLE_ENDIAN

        qint64 status : 8;

#  endif

        qint64 msecs : 56;

#  if Q_BYTE_ORDER == Q_BIG_ENDIAN

        qint64 status : 8;

#  endif

#else

#  if Q_BYTE_ORDER == Q_LITTLE_ENDIAN

        quintptr status : 8;

#  endif

        // note: this is only 24 bits on 32-bit systems...

        qintptr msecs : sizeof(void *) * 8 - 8;

#  if Q_BYTE_ORDER == Q_BIG_ENDIAN

        quintptr status : 8;

#  endif

#endif

        friend constexpr bool operator==(ShortData lhs, ShortData rhs)

        { return lhs.status == rhs.status && lhs.msecs == rhs.msecs; }

    };

    union Data {

        // To be of any use, we need at least 60 years around 1970, which

        // is 1,893,456,000,000 ms. That requires 41 bits to store, plus

        // the sign bit. With the status byte, the minimum size is 50 bits.

        static constexpr bool CanBeSmall = sizeof(ShortData) * 8 > 50;

        Data() noexcept;

        Data(const QTimeZone &);

        Data(const Data &other) noexcept;

        Data(Data &&other) noexcept;

        Data &operator=(const Data &other) noexcept;

        Data &operator=(Data &&other) noexcept { swap(other); return *this; }

        ~Data();

        void swap(Data &other) noexcept

        { std::swap(data, other.data); }

        bool isShort() const;

        inline void invalidate();

        void detach();

        QTimeZone timeZone() const;

        const QDateTimePrivate *operator->() const;

        QDateTimePrivate *operator->();

        QDateTimePrivate *d;

        ShortData data;

    };

public:

    QDateTime() noexcept;

    enum class TransitionResolution {

        Reject = 0,

        RelativeToBefore,

        RelativeToAfter,

        PreferBefore,

        PreferAfter,

        PreferStandard,

        PreferDaylightSaving,

        // Closest match to behavior prior to introducing TransitionResolution:

        LegacyBehavior = RelativeToBefore

    };

#if QT_DEPRECATED_SINCE(6, 9)

    QT_DEPRECATED_VERSION_X_6_9("Pass QTimeZone instead")

    QDateTime(QDate date, QTime time, Qt::TimeSpec spec, int offsetSeconds = 0);

#endif

#if QT_CORE_REMOVED_SINCE(6, 7)

    QDateTime(QDate date, QTime time, const QTimeZone &timeZone);

    QDateTime(QDate date, QTime time);

#endif

    QDateTime(QDate date, QTime time, const QTimeZone &timeZone,

              TransitionResolution resolve = TransitionResolution::LegacyBehavior);

    QDateTime(QDate date, QTime time,

              TransitionResolution resolve = TransitionResolution::LegacyBehavior);

    QDateTime(const QDateTime &other) noexcept;

    QDateTime(QDateTime &&other) noexcept;

    ~QDateTime();

    QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QDateTime)

    QDateTime &operator=(const QDateTime &other) noexcept;

    void swap(QDateTime &other) noexcept { d.swap(other.d); }

    bool isNull() const;

    bool isValid() const;

    QDate date() const;

    QTime time() const;

    Qt::TimeSpec timeSpec() const;

    int offsetFromUtc() const;

    QTimeZone timeRepresentation() const;

#if QT_CONFIG(timezone)

    QTimeZone timeZone() const;

#endif // timezone

    QString timeZoneAbbreviation() const;

    bool isDaylightTime() const;

    qint64 toMSecsSinceEpoch() const;

    qint64 toSecsSinceEpoch() const;

#if QT_CORE_REMOVED_SINCE(6, 7)

    void setDate(QDate date);

    void setTime(QTime time);

#endif

    void setDate(QDate date, TransitionResolution resolve = TransitionResolution::LegacyBehavior);

    void setTime(QTime time, TransitionResolution resolve = TransitionResolution::LegacyBehavior);

#if QT_DEPRECATED_SINCE(6, 9)

    QT_DEPRECATED_VERSION_X_6_9("Use setTimeZone() instead")

    void setTimeSpec(Qt::TimeSpec spec);

    QT_DEPRECATED_VERSION_X_6_9("Use setTimeZone() instead")

    void setOffsetFromUtc(int offsetSeconds);

#endif

#if QT_CORE_REMOVED_SINCE(6, 7)

    void setTimeZone(const QTimeZone &toZone);

#endif

    void setTimeZone(const QTimeZone &toZone,

                     TransitionResolution resolve = TransitionResolution::LegacyBehavior);

    void setMSecsSinceEpoch(qint64 msecs);

    void setSecsSinceEpoch(qint64 secs);

#if QT_CONFIG(datestring)

    QString toString(Qt::DateFormat format = Qt::TextDate) const;

    QString toString(const QString &format) const;

    QString toString(const QString &format, QCalendar cal) const

    { return toString(qToStringViewIgnoringNull(format), cal); }

    QString toString(QStringView format) const;

    QString toString(QStringView format, QCalendar cal) const;

#endif

    [[nodiscard]] QDateTime addDays(qint64 days) const;

    [[nodiscard]] QDateTime addMonths(int months) const;

    [[nodiscard]] QDateTime addYears(int years) const;

    [[nodiscard]] QDateTime addSecs(qint64 secs) const;

    [[nodiscard]] QDateTime addMSecs(qint64 msecs) const;

    [[nodiscard]] QDateTime addDuration(std::chrono::milliseconds msecs) const

    {

        return addMSecs(msecs.count());

    }

#if QT_DEPRECATED_SINCE(6, 9)

    QT_DEPRECATED_VERSION_X_6_9("Use toTimeZone instead")

    QDateTime toTimeSpec(Qt::TimeSpec spec) const;

#endif

    QDateTime toLocalTime() const;

    QDateTime toUTC() const;

    QDateTime toOffsetFromUtc(int offsetSeconds) const;

    QDateTime toTimeZone(const QTimeZone &toZone) const;

    qint64 daysTo(const QDateTime &) const;

    qint64 secsTo(const QDateTime &) const;

    qint64 msecsTo(const QDateTime &) const;

    static QDateTime currentDateTime(const QTimeZone &zone);

    static QDateTime currentDateTime();

    static QDateTime currentDateTimeUtc();

#if QT_CONFIG(datestring)

    // No DateFormat accepts a two-digit year, so no need for baseYear:

    static QDateTime fromString(QStringView string, Qt::DateFormat format = Qt::TextDate);

    static QDateTime fromString(const QString &string, Qt::DateFormat format = Qt::TextDate)

    { return fromString(qToStringViewIgnoringNull(string), format); }

    // Accept calendar without over-ride of base year:

    static QDateTime fromString(QStringView string, QStringView format, QCalendar cal)

    { return fromString(string.toString(), format, QLocale::DefaultTwoDigitBaseYear, cal); }

    QT_CORE_INLINE_SINCE(6, 7)

    static QDateTime fromString(const QString &string, QStringView format, QCalendar cal);

    static QDateTime fromString(const QString &string, const QString &format, QCalendar cal)

    { return fromString(string, qToStringViewIgnoringNull(format), QLocale::DefaultTwoDigitBaseYear, cal); }

    // Overriding base year is likely more common than overriding calendar (and

    // likely to get more so, as the legacy base drops ever further behind us).

    static QDateTime fromString(QStringView string, QStringView format,

                                int baseYear = QLocale::DefaultTwoDigitBaseYear)

    { return fromString(string.toString(), format, baseYear); }

    static QDateTime fromString(QStringView string, QStringView format,

                                int baseYear, QCalendar cal)

    { return fromString(string.toString(), format, baseYear, cal); }

    static QDateTime fromString(const QString &string, QStringView format,

                                int baseYear = QLocale::DefaultTwoDigitBaseYear);

    static QDateTime fromString(const QString &string, QStringView format,

                                int baseYear, QCalendar cal);

    static QDateTime fromString(const QString &string, const QString &format,

                                int baseYear = QLocale::DefaultTwoDigitBaseYear)

    { return fromString(string, qToStringViewIgnoringNull(format), baseYear); }

    static QDateTime fromString(const QString &string, const QString &format,

                                int baseYear, QCalendar cal)

    { return fromString(string, qToStringViewIgnoringNull(format), baseYear, cal); }

#endif

#if QT_DEPRECATED_SINCE(6, 9)

    QT_DEPRECATED_VERSION_X_6_9("Pass QTimeZone instead of time-spec, offset")

    static QDateTime fromMSecsSinceEpoch(qint64 msecs, Qt::TimeSpec spec, int offsetFromUtc = 0);

    QT_DEPRECATED_VERSION_X_6_9("Pass QTimeZone instead of time-spec, offset")

    static QDateTime fromSecsSinceEpoch(qint64 secs, Qt::TimeSpec spec, int offsetFromUtc = 0);

#endif

    static QDateTime fromMSecsSinceEpoch(qint64 msecs, const QTimeZone &timeZone);

    static QDateTime fromSecsSinceEpoch(qint64 secs, const QTimeZone &timeZone);

    static QDateTime fromMSecsSinceEpoch(qint64 msecs);

    static QDateTime fromSecsSinceEpoch(qint64 secs);

    static qint64 currentMSecsSinceEpoch() noexcept;

    static qint64 currentSecsSinceEpoch() noexcept;

#if defined(Q_OS_DARWIN) || defined(Q_QDOC)

    static QDateTime fromCFDate(CFDateRef date);

    CFDateRef toCFDate() const Q_DECL_CF_RETURNS_RETAINED;

    static QDateTime fromNSDate(const NSDate *date);

    NSDate *toNSDate() const Q_DECL_NS_RETURNS_AUTORELEASED;

#endif

    static QDateTime fromStdTimePoint(

        std::chrono::time_point<

            std::chrono::system_clock,

            std::chrono::milliseconds

        > time

    );

// INTEGRITY incident-85878 (timezone and clock_cast are not supported)

#if (__cpp_lib_chrono >= 201907L && !defined(Q_OS_INTEGRITY)) || defined(Q_QDOC)

#if __cpp_concepts >= 201907L || defined(Q_QDOC)

private:

    // The duration type of the result of a clock_cast<system_clock>.

    // This duration may differ from the duration of the input.

    template <typename Clock, typename Duration>

    using system_clock_cast_duration = decltype(

        std::chrono::clock_cast<std::chrono::system_clock>(

            std::declval<const std::chrono::time_point<Clock, Duration> &>()

        ).time_since_epoch()

    );

public:

    // Generic clock, as long as it's compatible with us (= system_clock)

    template <typename Clock, typename Duration>

    static QDateTime fromStdTimePoint(const std::chrono::time_point<Clock, Duration> &time)

        requires

            requires(const std::chrono::time_point<Clock, Duration> &t) {

                // the clock can be converted to system_clock

                std::chrono::clock_cast<std::chrono::system_clock>(t);

                // after the conversion to system_clock, the duration type

                // we get is convertible to milliseconds

                requires std::is_convertible_v<

                    system_clock_cast_duration<Clock, Duration>,

                    std::chrono::milliseconds

                >;

            }

    {

        using namespace std::chrono;

        const sys_time<milliseconds> sysTime = clock_cast<system_clock>(time);

        return fromStdTimePoint(sysTime);

    }

#endif // __cpp_concepts

    // local_time

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    static QDateTime fromStdTimePoint(const std::chrono::local_time<std::chrono::milliseconds> &time)

    {

        return fromStdLocalTime(time);

    }

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    static QDateTime fromStdLocalTime(const std::chrono::local_time<std::chrono::milliseconds> &time)

    {

        QDateTime result(QDate(1970, 1, 1), QTime(0, 0, 0), TransitionResolution::LegacyBehavior);

        return result.addMSecs(time.time_since_epoch().count());

    }

#if QT_CONFIG(timezone) && (__cpp_lib_chrono >= 201907L || defined(Q_QDOC))

    // zoned_time. defined in qtimezone.h

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    static QDateTime fromStdZonedTime(const std::chrono::zoned_time<

                                          std::chrono::milliseconds,

                                          const std::chrono::time_zone *

                                      > &time);

#endif // QT_CONFIG(timezone)

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    std::chrono::sys_time<std::chrono::milliseconds> toStdSysMilliseconds() const

    {

        const std::chrono::milliseconds duration(toMSecsSinceEpoch());

        return std::chrono::sys_time<std::chrono::milliseconds>(duration);

    }

    QT_POST_CXX17_API_IN_EXPORTED_CLASS

    std::chrono::sys_seconds toStdSysSeconds() const

    {

        const std::chrono::seconds duration(toSecsSinceEpoch());

        return std::chrono::sys_seconds(duration);

    }

#endif // __cpp_lib_chrono >= 201907L && !Q_OS_INTEGRITY

    friend std::chrono::milliseconds operator-(const QDateTime &lhs, const QDateTime &rhs)

    {

        return std::chrono::milliseconds(rhs.msecsTo(lhs));

    }

    friend QDateTime operator+(const QDateTime &dateTime, std::chrono::milliseconds duration)

    {

        return dateTime.addMSecs(duration.count());

    }

    friend QDateTime operator+(std::chrono::milliseconds duration, const QDateTime &dateTime)

    {

        return dateTime + duration;

    }

    QDateTime &operator+=(std::chrono::milliseconds duration)

    {

        *this = addMSecs(duration.count());

        return *this;

    }

    friend QDateTime operator-(const QDateTime &dateTime, std::chrono::milliseconds duration)

    {

        return dateTime.addMSecs(-duration.count());

    }

    QDateTime &operator-=(std::chrono::milliseconds duration)

    {

        *this = addMSecs(-duration.count());

        return *this;

    }

    // (1<<63) ms is 292277024.6 (average Gregorian) years, counted from the start of 1970, so

    // Last is floor(1970 + 292277024.6); no year 0, so First is floor(1970 - 1 - 292277024.6)

    enum class YearRange : qint32 { First = -292275056,  Last = +292278994 };

private:

    bool equals(const QDateTime &other) const;

#if QT_CORE_REMOVED_SINCE(6, 7)

    bool precedes(const QDateTime &other) const;

#endif

    friend class QDateTimePrivate;

    Data d;

    friend bool comparesEqual(const QDateTime &lhs, const QDateTime &rhs)

    { return lhs.equals(rhs); }

    friend Q_CORE_EXPORT Qt::weak_ordering

    compareThreeWay(const QDateTime &lhs, const QDateTime &rhs);

    Q_DECLARE_WEAKLY_ORDERED_NON_NOEXCEPT(QDateTime)

#ifndef QT_NO_DATASTREAM

    friend Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, const QDateTime &);

    friend Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QDateTime &);

#endif

#if !defined(QT_NO_DEBUG_STREAM) && QT_CONFIG(datestring)

    friend Q_CORE_EXPORT QDebug operator<<(QDebug, const QDateTime &);

#endif

};

Q_DECLARE_SHARED(QDateTime)

#ifndef QT_NO_DATASTREAM

Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, QDate);

Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QDate &);

Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, QTime);

Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QTime &);

Q_CORE_EXPORT QDataStream &operator<<(QDataStream &, const QDateTime &);

Q_CORE_EXPORT QDataStream &operator>>(QDataStream &, QDateTime &);

#endif // QT_NO_DATASTREAM

#if !defined(QT_NO_DEBUG_STREAM) && QT_CONFIG(datestring)

Q_CORE_EXPORT QDebug operator<<(QDebug, QDate);

Q_CORE_EXPORT QDebug operator<<(QDebug, QTime);

Q_CORE_EXPORT QDebug operator<<(QDebug, const QDateTime &);

#endif

// QDateTime is not noexcept for now -- to be revised once

// timezone and calendaring support is added

Q_CORE_EXPORT size_t qHash(const QDateTime &key, size_t seed = 0);

Q_CORE_EXPORT size_t qHash(QDate key, size_t seed = 0) noexcept;

Q_CORE_EXPORT size_t qHash(QTime key, size_t seed = 0) noexcept;

#if QT_CONFIG(datestring) && QT_CORE_INLINE_IMPL_SINCE(6, 7)

QDate QDate::fromString(const QString &string, QStringView format, QCalendar cal)

{

    return fromString(string, format, QLocale::DefaultTwoDigitBaseYear, cal);

}

QDateTime QDateTime::fromString(const QString &string, QStringView format, QCalendar cal)

{

    return fromString(string, format, QLocale::DefaultTwoDigitBaseYear, cal);

}

#endif

QT_END_NAMESPACE

#endif // QDATETIME_H