/************************************************************************
 **
 **  @file   vtheme.cpp
 **  @author Roman Telezhynskyi <dismine(at)gmail.com>
 **  @date   17 7, 2023
 **
 **  @brief
 **  @copyright
 **  This source code is part of the Valentina project, a pattern making
 **  program, whose allow create and modeling patterns of clothing.
 **  Copyright (C) 2023 Valentina project
 **  <https://gitlab.com/smart-pattern/valentina> All Rights Reserved.
 **
 **  Valentina 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.
 **
 **  Valentina 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 Valentina.  If not, see <http://www.gnu.org/licenses/>.
 **
 *************************************************************************/
#include "vtheme.h"
#include "../vcommonsettings.h"

#include <QIcon>
#include <QPainter>
#include <QPalette>
#include <QPixmap>
#include <QTextStream>
#include <QtDebug>
#include <QtGlobal>

#if QT_VERSION >= QT_VERSION_CHECK(5, 9, 0)
#include <QOperatingSystemVersion>
#else
#if defined(Q_OS_WIN)
#include <Ntddkbd.h> // Required for RtlGetVersion
#include <Windows.h>
#endif // defined(Q_OS_WIN)
#endif // QT_VERSION >= QT_VERSION_CHECK(5, 9, 0)

#if defined(Q_OS_MACX)
#include "macutils.h"
#endif

#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
#include <QStyleHints>
#endif

#if (defined(Q_CC_GNU) && Q_CC_GNU < 409) && !defined(Q_CC_CLANG)
// DO NOT WORK WITH GCC 4.8
#else
#if __cplusplus >= 201402L
using namespace std::chrono_literals;
#else
#include "../bpstd/chrono.hpp"
using namespace bpstd::literals::chrono_literals;
#endif // __cplusplus >= 201402L
#endif //(defined(Q_CC_GNU) && Q_CC_GNU < 409) && !defined(Q_CC_CLANG)

#include "../defglobal.h"
#include "../vabstractapplication.h"
#include "vscenestylesheet.h"

namespace
{
#if QT_VERSION < QT_VERSION_CHECK(5, 9, 0)
#if defined(Q_OS_WIN)
// Define the RtlGetVersion function
typedef NTSTATUS(WINAPI *RtlGetVersionFunc)(PRTL_OSVERSIONINFOW);

// Function to get the OS version using RtlGetVersion if available, otherwise fallback to GetVersionEx
bool GetTrueWindowsVersion(RTL_OSVERSIONINFOW &osVersionInfo)
{
    // Function pointer to driver function
    RtlGetVersionFunc pRtlGetVersion = nullptr;

    // Load the System-DLL
    HINSTANCE hNTdllDll = LoadLibrary(L"ntdll.dll");

    // Successfully loaded?
    if (hNTdllDll != nullptr)
    {
        // Get the function pointer to RtlGetVersion
        pRtlGetVersion = reinterpret_cast<RtlGetVersionFunc>(GetProcAddress(hNTdllDll, "RtlGetVersion"));

        // If successful then read the function
        if (pRtlGetVersion != nullptr)
        {
            ZeroMemory(&osVersionInfo, sizeof(RTL_OSVERSIONINFOW));
            osVersionInfo.dwOSVersionInfoSize = sizeof(RTL_OSVERSIONINFOW);

            if (pRtlGetVersion(&osVersionInfo) == 0)
            {
                // Successfully obtained OS version using RtlGetVersion
                FreeLibrary(hNTdllDll);
                return true;
            }
        }

        // Free the library if RtlGetVersion failed
        FreeLibrary(hNTdllDll);
    }

    // Fallback to GetVersionEx if RtlGetVersion is not available
    OSVERSIONINFOEX osVersionFallback;
    ZeroMemory(&osVersionFallback, sizeof(OSVERSIONINFOEX));
    osVersionFallback.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);

    if (GetVersionEx(reinterpret_cast<OSVERSIONINFO *>(&osVersionFallback)))
    {
        // Successfully obtained OS version using GetVersionEx
        osVersionInfo.dwMajorVersion = osVersionFallback.dwMajorVersion;
        osVersionInfo.dwMinorVersion = osVersionFallback.dwMinorVersion;
        osVersionInfo.dwBuildNumber = osVersionFallback.dwBuildNumber;
        return true;
    }

    // Failed to obtain OS version
    return false;
}
#endif // defined(Q_OS_WIN)
#endif // QT_VERSION < QT_VERSION_CHECK(5, 9, 0)

//---------------------------------------------------------------------------------------------------------------------
#ifdef Q_OS_WIN
auto NativeWindowsDarkThemeAvailable() -> bool
{
    // dark mode supported Windows 10 1809 10.0.17763 onward
    // https://stackoverflow.com/questions/53501268/win10-dark-theme-how-to-use-in-winapi
#if QT_VERSION >= QT_VERSION_CHECK(5, 9, 0)
    if (QOperatingSystemVersion::current().majorVersion() > 10)
    {
        return true;
    }

    if (QOperatingSystemVersion::current().majorVersion() == 10)
    {
        return QOperatingSystemVersion::current().microVersion() >= 17763;
    }
#else
    RTL_OSVERSIONINFOW osVersionInfo;
    if (GetTrueWindowsVersion(osVersionInfo))
    {
        if (osVersionInfo.dwMajorVersion > 10)
        {
            return true;
        }

        if (osVersionInfo.dwMajorVersion == 10)
        {
            return osVersionInfo.dwBuildNumber >= 17763;
        }
    }
#endif // QT_VERSION >= QT_VERSION_CHECK(5, 9, 0)

    return false;
}
#endif // Q_OS_WIN

//---------------------------------------------------------------------------------------------------------------------
#if defined(Q_OS_MACX)
auto NativeMacDarkThemeAvailable() -> bool
{
    return NSNativeMacDarkThemeAvailable();
}
#endif

//---------------------------------------------------------------------------------------------------------------------
#if defined(Q_OS_LINUX)
auto NativeLinuxDarkThemeAvailable() -> bool
{
    // There is no way to check native support. Assume always available.
    return true;
}
#endif

//---------------------------------------------------------------------------------------------------------------------
void ActivateCustomLightTheme()
{
    QFile f(QStringLiteral(":/light/stylesheet.qss"));
    if (!f.exists())
    {
        qDebug() << "Unable to set stylesheet, file not found\n";
    }
    else
    {
        f.open(QFile::ReadOnly | QFile::Text);
        QTextStream ts(&f);
        qApp->setStyleSheet(ts.readAll()); // NOLINT(cppcoreguidelines-pro-type-static-cast-downcast)
    }
}

//---------------------------------------------------------------------------------------------------------------------
void ActivateCustomDarkTheme()
{
    QFile f(QStringLiteral(":/dark/stylesheet.qss"));
    if (!f.exists())
    {
        qDebug() << "Unable to set stylesheet, file not found\n";
    }
    else
    {
        f.open(QFile::ReadOnly | QFile::Text);
        QTextStream ts(&f);
        qApp->setStyleSheet(ts.readAll()); // NOLINT(cppcoreguidelines-pro-type-static-cast-downcast)
    }
}

//---------------------------------------------------------------------------------------------------------------------
void ActivateDefaultTheme()
{
    qApp->setStyleSheet(QString()); // NOLINT(cppcoreguidelines-pro-type-static-cast-downcast)

#if defined(Q_OS_MACX)
    NSMacSetToAutoTheme();
#endif
}

//---------------------------------------------------------------------------------------------------------------------
auto GetResourceName(const QString &root, const QString &iconName, bool dark) -> QString
{
    return QStringLiteral(":/%1/%2/%3").arg(root, dark ? "dark" : "light", iconName);
}

//---------------------------------------------------------------------------------------------------------------------
auto GetPixmapResource(const QString &root, const QString &iconName, bool dark) -> QPixmap
{
    QString resourceName = GetResourceName(root, iconName, dark);
    QPixmap pixmap = QPixmap(resourceName);
    Q_ASSERT(!pixmap.isNull());
    return pixmap;
}
} // namespace

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::Instance() -> VTheme *
{
    static VTheme *instance = nullptr; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
    if (instance == nullptr)
    {
        instance = new VTheme();
    }

    return instance;
}

//---------------------------------------------------------------------------------------------------------------------
void VTheme::StoreDefaultThemeName(const QString &themeName)
{
    m_defaultThemeName = themeName;
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::NativeDarkThemeAvailable() -> bool
{
#if defined(Q_OS_MACX)
    return NSNativeMacDarkThemeAvailable();
#elif defined(Q_OS_WIN)
    return NativeWindowsDarkThemeAvailable();
#elif defined(Q_OS_LINUX)
    return NativeLinuxDarkThemeAvailable();
#else
    return false;
#endif
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::IsInDarkTheme() -> bool
{
    if (NativeDarkThemeAvailable())
    {
#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
        QStyleHints *hints = QGuiApplication::styleHints();
        return hints->colorScheme() == Qt::ColorScheme::Dark;
#else
#if defined(Q_OS_MACX)
        return NSMacIsInDarkTheme();
#elif defined(Q_OS_WIN)
        QSettings settings("HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize",
                           QSettings::NativeFormat);
        return settings.value("AppsUseLightTheme", 1).toInt() == 0;
#elif defined(Q_OS_LINUX)
        return ShouldApplyDarkTheme();
#endif
#endif // QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
    }

    return false;
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::ShouldApplyDarkTheme() -> bool
{
    QPalette palette = qApp->palette(); // NOLINT(cppcoreguidelines-pro-type-static-cast-downcast)
    return palette.color(QPalette::WindowText).lightness() > palette.color(QPalette::Window).lightness();
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::ColorSheme() -> VColorSheme
{
    VThemeMode themeMode = VAbstractApplication::VApp()->Settings()->GetThemeMode();

    if (themeMode == VThemeMode::Light)
    {
        return VColorSheme::Light;
    }

    if (themeMode == VThemeMode::Dark)
    {
        return VColorSheme::Dark;
    }

    if (NativeDarkThemeAvailable())
    {
        if (IsInDarkTheme())
        {
            return VColorSheme::Dark;
        }

        return VColorSheme::Light;
    }

    if (ShouldApplyDarkTheme())
    {
        return VColorSheme::Dark;
    }

    return VColorSheme::Light;
}

//---------------------------------------------------------------------------------------------------------------------
void VTheme::SetIconTheme()
{
    VColorSheme colorScheme = ColorSheme();
    QString themePrefix = (colorScheme == VColorSheme::Light ? QStringLiteral("Light") : QStringLiteral("Dark"));

    static const char *GENERIC_ICON_TO_CHECK = "document-open";
    if (not QIcon::hasThemeIcon(GENERIC_ICON_TO_CHECK))
    {
        // If there is no default working icon theme then we should
        // use an icon theme that we provide via a .qrc file
        // This case happens under Windows and Mac OS X
        // This does not happen under GNOME or KDE

#if defined(Q_OS_MACX)
        QIcon::setThemeName(QStringLiteral("La-Sierra-%1").arg(themePrefix));
#else
        QIcon::setThemeName(QStringLiteral("Eleven-%1").arg(themePrefix));
#endif
    }
    else
    {
        VThemeMode themeMode = VAbstractApplication::VApp()->Settings()->GetThemeMode();

        if ((themeMode == VThemeMode::Dark && !ShouldApplyDarkTheme()) ||
            (themeMode == VThemeMode::Light && ShouldApplyDarkTheme()))
        {
            QIcon::setThemeName(QStringLiteral("Eleven-%1").arg(themePrefix));
        }
    }
}

//---------------------------------------------------------------------------------------------------------------------
void VTheme::SetToAutoTheme() const
{
    qApp->setStyleSheet(QString()); // NOLINT(cppcoreguidelines-pro-type-static-cast-downcast)
    QIcon::setThemeName(m_defaultThemeName);
}

//---------------------------------------------------------------------------------------------------------------------
void VTheme::InitThemeMode()
{
    VThemeMode themeMode = VAbstractApplication::VApp()->Settings()->GetThemeMode();

    if (themeMode == VThemeMode::Light)
    {
        if (NativeDarkThemeAvailable())
        {
            if (IsInDarkTheme())
            {
#if defined(Q_OS_MACX)
                NSMacSetToLightTheme();
#else
                ActivateCustomLightTheme();
#endif
            }
        }
        else if (ShouldApplyDarkTheme())
        {
            ActivateCustomLightTheme();
        }
    }
    else if (themeMode == VThemeMode::Dark)
    {
        if (NativeDarkThemeAvailable())
        {
            if (!IsInDarkTheme())
            {
#if defined(Q_OS_MACX)
                NSMacSetToDarkTheme();
#else
                ActivateCustomDarkTheme();
#endif
            }
        }
        else
        {
            ActivateCustomDarkTheme();
        }
    }
    else
    {
        if (NativeDarkThemeAvailable())
        {
            ActivateDefaultTheme();
        }
        else
        {
            if (ShouldApplyDarkTheme())
            {
                ActivateCustomDarkTheme();
            }
            else
            {
                ActivateCustomLightTheme();
            }
        }
    }
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::ThemeStylesheet() -> QString
{
    VThemeMode themeMode = VAbstractApplication::VApp()->Settings()->GetThemeMode();

    if (themeMode == VThemeMode::Light)
    {
        if (NativeDarkThemeAvailable())
        {
            if (IsInDarkTheme())
            {
#if defined(Q_OS_MACX)
                return QStringLiteral("native");
#else
                return QStringLiteral("light");
#endif
            }
        }
        else if (ShouldApplyDarkTheme())
        {
            return QStringLiteral("light");
        }

        return QStringLiteral("native");
    }

    if (themeMode == VThemeMode::Dark)
    {
        if (NativeDarkThemeAvailable())
        {
            if (!IsInDarkTheme())
            {
#if defined(Q_OS_MACX)
                return QStringLiteral("native");
#else
                return QStringLiteral("dark");
#endif
            }
        }
        else
        {
            return QStringLiteral("dark");
        }

        return QStringLiteral("native");
    }

    if (!NativeDarkThemeAvailable())
    {
        if (ShouldApplyDarkTheme())
        {
            return QStringLiteral("dark");
        }

        return QStringLiteral("light");
    }

    return QStringLiteral("native");
}

//---------------------------------------------------------------------------------------------------------------------
void VTheme::ResetThemeSettings() const
{
    SetToAutoTheme();
    SetIconTheme();
    InitThemeMode();
    VSceneStylesheet::ResetStyles();

    emit Instance()->ThemeSettingsChanged();
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::GetIconResource(const QString &root, const QString &iconName) -> QIcon
{
    QIcon icon;
    bool dark = (ColorSheme() == VColorSheme::Dark);
    QPixmap pixmap = ::GetPixmapResource(root, iconName, dark);
    icon.addPixmap(pixmap);
    if (dark)
    {
        // automatic disabled icon is no good for dark
        // paint transparent black to get disabled look
        QPainter p(&pixmap);
        p.fillRect(pixmap.rect(), QColor(48, 47, 47, 128));
        icon.addPixmap(pixmap, QIcon::Disabled);
    }
    return icon;
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::GetPixmapResource(const QString &root, const QString &iconName) -> QPixmap
{
    bool dark = (ColorSheme() == VColorSheme::Dark);
    return ::GetPixmapResource(root, iconName, dark);
}

//---------------------------------------------------------------------------------------------------------------------
auto VTheme::GetResourceName(const QString &root, const QString &iconName) -> QString
{
    return ::GetResourceName(root, iconName, ColorSheme() == VColorSheme::Dark);
}

//---------------------------------------------------------------------------------------------------------------------
VTheme::VTheme(QObject *parent)
  : QObject(parent)
{
#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
    QStyleHints *hints = QGuiApplication::styleHints();
    connect(hints, &QStyleHints::colorSchemeChanged, this, []() { VTheme::Instance()->ResetThemeSettings(); });
#else
    if (VTheme::NativeDarkThemeAvailable())
    {
        m_darkTheme = IsInDarkTheme();
        m_themeTimer = new QTimer(this);
        m_themeTimer->setTimerType(Qt::VeryCoarseTimer);
        connect(m_themeTimer, &QTimer::timeout, this,
                [this]()
                {
                    bool darkTheme = IsInDarkTheme();
                    if (m_darkTheme != darkTheme)
                    {
                        m_darkTheme = darkTheme;
                        VTheme::Instance()->ResetThemeSettings();
                    }
                });
        m_themeTimer->start(V_SECONDS(5));
    }
#endif
}