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// Copyright (C) 2020 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

// Qt-Security score:significant reason:default

#ifndef QUUID_P_H

#define QUUID_P_H

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists for the convenience

// of the QLibrary class.  This header file may change from

// version to version without notice, or even be removed.

//

// We mean it.

//

#include "quuid.h"

#include <QtCore/qrandom.h>

#include <chrono>

QT_BEGIN_NAMESPACE

#ifndef QT_BOOTSTRAPPED

static inline QUuid createUuidV7_internal(

    std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds> tp)

    QUuid result;

    using namespace std::chrono;

    const nanoseconds nsecSinceEpoch = tp.time_since_epoch();

    const auto msecSinceEpoch = floor<milliseconds>(nsecSinceEpoch);

    const quint64 frac = (nsecSinceEpoch - msecSinceEpoch).count();

    // Lower 48 bits of the timestamp

    const quint64 msecs = quint64(msecSinceEpoch.count()) & 0xffffffffffff;

    result.data1 = uint(msecs >> 16);

    result.data2 = ushort(msecs);

    // rand_a: use a 12-bit sub-millisecond timestamp for additional monotonicity

    // https://datatracker.ietf.org/doc/html/rfc9562#monotonicity_counters (Method 3)

    // "frac" is a number between 0 and 999,999, so the lowest 20 bits

    // should be roughly random. Use the high 12 of those for additional

    // monotonicity.

    result.data3 = frac >> 8;

    result.data3 &= 0x0FFF;

    result.data3 |= ushort(7) << 12;

    // rand_b: 62 bits of random data (64 - 2 bits for the variant)

    const quint64 random = QRandomGenerator::system()->generate64();

    memcpy(result.data4, &random, sizeof(quint64));

    result.data4[0] = (result.data4[0] & 0x3F) | 0x80; // UV_DCE

    return result;

#endif

QT_END_NAMESPACE

#endif // QUUID_P_H