/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtWidgets module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qgtkstyle_p_p.h"

// This file is responsible for resolving all GTK functions we use
// dynamically. This is done to avoid link-time dependency on GTK
// as well as crashes occurring due to usage of the GTK_QT engines
//
// Additionally we create a map of common GTK widgets that we can pass
// to the GTK theme engine as many engines resort to querying the
// actual widget pointers for details that are not covered by the
// state flags

#include <QtCore/qglobal.h>

#include <QtCore/QEvent>
#include <QtCore/QFile>
#include <QtCore/QStringList>
#include <QtCore/QTextStream>
#include <QtCore/QHash>
#include <QtCore/QUrl>
#include <QtCore/QDebug>

#include "qgtk2painter_p.h"
#include <private/qapplication_p.h>
#include <private/qiconloader_p.h>
#include <qpa/qplatformfontdatabase.h>

#include <QtWidgets/QMenu>
#include <QtWidgets/QStyle>
#include <QtWidgets/QApplication>
#include <QtGui/QPixmapCache>
#include <QtWidgets/QStatusBar>
#include <QtWidgets/QMenuBar>
#include <QtWidgets/QToolBar>
#include <QtWidgets/QToolButton>

// X11 Includes:

// the following is necessary to work around breakage in many versions
// of XFree86's Xlib.h still in use
// ### which versions?
#if defined(_XLIB_H_) // crude hack, but...
#error "cannot include <X11/Xlib.h> before this file"
#endif
#define XRegisterIMInstantiateCallback qt_XRegisterIMInstantiateCallback
#define XUnregisterIMInstantiateCallback qt_XUnregisterIMInstantiateCallback
#define XSetIMValues qt_XSetIMValues
#include <X11/Xlib.h>
#undef XRegisterIMInstantiateCallback
#undef XUnregisterIMInstantiateCallback
#undef XSetIMValues

QT_BEGIN_NAMESPACE

Q_GLOBAL_STATIC(QGtkStyleUpdateScheduler, styleScheduler)

Ptr_ubuntu_gtk_set_use_overlay_scrollbar QGtkStylePrivate::ubuntu_gtk_set_use_overlay_scrollbar = 0;

typedef int (*x11ErrorHandler)(Display*, XErrorEvent*);

QT_END_NAMESPACE

Q_DECLARE_METATYPE(QGtkStylePrivate*);

QT_BEGIN_NAMESPACE

static void gtkStyleSetCallback(GtkWidget*)
{
    qRegisterMetaType<QGtkStylePrivate *>();

    // We have to let this function return and complete the event
    // loop to ensure that all gtk widgets have been styled before
    // updating
    QMetaObject::invokeMethod(styleScheduler(), "updateTheme", Qt::QueuedConnection);
}

static void update_toolbar_style(GtkWidget *gtkToolBar, GParamSpec *, gpointer)
{
    GtkToolbarStyle toolbar_style = GTK_TOOLBAR_ICONS;
    g_object_get(gtkToolBar, "toolbar-style", &toolbar_style, NULL);
    QWidgetList widgets = QApplication::allWidgets();
    for (int i = 0; i < widgets.size(); ++i) {
        QWidget *widget = widgets.at(i);
        if (qobject_cast<QToolButton*>(widget)) {
            QEvent event(QEvent::StyleChange);
            QApplication::sendEvent(widget, &event);
        }
    }
}

static QHashableLatin1Literal classPath(GtkWidget *widget)
{
    char *class_path;
    gtk_widget_path (widget, NULL, &class_path, NULL);

    char *copy = class_path;
    if (strncmp(copy, "GtkWindow.", 10) == 0)
        copy += 10;
    if (strncmp(copy, "GtkFixed.", 9) == 0)
        copy += 9;

    copy = strdup(copy);

    g_free(class_path);

    return QHashableLatin1Literal::fromData(copy);
}



bool QGtkStyleFilter::eventFilter(QObject *obj, QEvent *e)
{
    if (e->type() == QEvent::ApplicationPaletteChange) {
        // Only do this the first time since this will also
        // generate applicationPaletteChange events
        //if (!qt_app_palettes_hash() ||  qt_app_palettes_hash()->isEmpty()) {
        //    stylePrivate->applyCustomPaletteHash();
        //}
    }
    return QObject::eventFilter(obj, e);
}

QList<QGtkStylePrivate *> QGtkStylePrivate::instances;
QGtkStylePrivate::WidgetMap *QGtkStylePrivate::widgetMap = 0;

QGtkStylePrivate::QGtkStylePrivate()
  : QCommonStylePrivate()
  , filter(this)
{
    instances.append(this);
    animationFps = 60;
}

QGtkStylePrivate::~QGtkStylePrivate()
{
    instances.removeOne(this);
}

void QGtkStylePrivate::init()
{
    initGtkWidgets();
}

QGtkPainter* QGtkStylePrivate::gtkPainter(QPainter *painter)
{
    // TODO: choose between gtk2 and gtk3
    static QGtk2Painter instance;
    instance.reset(painter);
    return &instance;
}

GtkWidget* QGtkStylePrivate::gtkWidget(const QHashableLatin1Literal &path)
{
    GtkWidget *widget = gtkWidgetMap()->value(path);
    if (!widget) {
        // Theme might have rearranged widget internals
        widget = gtkWidgetMap()->value(path);
    }
    return widget;
}

GtkStyle* QGtkStylePrivate::gtkStyle(const QHashableLatin1Literal &path)
{
    if (GtkWidget *w = gtkWidgetMap()->value(path))
        return gtk_widget_get_style(w);
    return 0;
}

void QGtkStylePrivate::gtkWidgetSetFocus(GtkWidget *widget, bool focus)
{
    GdkEvent *event = gdk_event_new(GDK_FOCUS_CHANGE);
    event->focus_change.type = GDK_FOCUS_CHANGE;
    event->focus_change.in = focus;
    gtk_widget_send_focus_change(widget, event);
    gdk_event_free(event);
}

/* \internal
 * Initializes a number of gtk menu widgets.
 * The widgets are cached.
 */
void QGtkStylePrivate::initGtkMenu() const
{
    // Create menubar
    GtkWidget *gtkMenuBar = gtk_menu_bar_new();
    setupGtkWidget(gtkMenuBar);

    GtkWidget *gtkMenuBarItem = gtk_menu_item_new_with_label("X");
    gtk_menu_shell_append((GtkMenuShell*)(gtkMenuBar), gtkMenuBarItem);
    gtk_widget_realize(gtkMenuBarItem);

    // Create menu
    GtkWidget *gtkMenu = gtk_menu_new();
    gtk_menu_item_set_submenu((GtkMenuItem*)(gtkMenuBarItem), gtkMenu);
    gtk_widget_realize(gtkMenu);

    GtkWidget *gtkMenuItem = gtk_menu_item_new_with_label("X");
    gtk_menu_shell_append((GtkMenuShell*)gtkMenu, gtkMenuItem);
    gtk_widget_realize(gtkMenuItem);

    GtkWidget *gtkCheckMenuItem = gtk_check_menu_item_new_with_label("X");
    gtk_menu_shell_append((GtkMenuShell*)gtkMenu, gtkCheckMenuItem);
    gtk_widget_realize(gtkCheckMenuItem);

    GtkWidget *gtkMenuSeparator = gtk_separator_menu_item_new();
    gtk_menu_shell_append((GtkMenuShell*)gtkMenu, gtkMenuSeparator);

    addAllSubWidgets(gtkMenuBar);
    addAllSubWidgets(gtkMenu);
}


void QGtkStylePrivate::initGtkTreeview() const
{
    GtkWidget *gtkTreeView = gtk_tree_view_new();
    gtk_tree_view_append_column((GtkTreeView*)gtkTreeView, gtk_tree_view_column_new());
    gtk_tree_view_append_column((GtkTreeView*)gtkTreeView, gtk_tree_view_column_new());
    gtk_tree_view_append_column((GtkTreeView*)gtkTreeView, gtk_tree_view_column_new());
    addWidget(gtkTreeView);
}


/* \internal
 * Initializes a number of gtk widgets that we can later on use to determine some of our styles.
 * The widgets are cached.
 */
void QGtkStylePrivate::initGtkWidgets() const
{
    // From gtkmain.c
    uid_t ruid = getuid ();
    uid_t rgid = getgid ();
    uid_t euid = geteuid ();
    uid_t egid = getegid ();
    if (ruid != euid || rgid != egid) {
        qWarning("\nThis process is currently running setuid or setgid.\nGTK+ does not allow this "
                 "therefore Qt cannot use the GTK+ integration.\nTry launching your app using \'gksudo\', "
                 "\'kdesudo\' or a similar tool.\n\n"
                 "See http://www.gtk.org/setuid.html for more information.\n");
        return;
    }

    // Gtk will set the Qt error handler so we have to reset it afterwards
    x11ErrorHandler qt_x_errhandler = XSetErrorHandler(0);
    gtk_init (NULL, NULL);
    XSetErrorHandler(qt_x_errhandler);

    ubuntu_gtk_set_use_overlay_scrollbar = (Ptr_ubuntu_gtk_set_use_overlay_scrollbar)QLibrary::resolve(QLS("gtk-x11-2.0"), "ubuntu_gtk_set_use_overlay_scrollbar");
    if (ubuntu_gtk_set_use_overlay_scrollbar)
        ubuntu_gtk_set_use_overlay_scrollbar(false);

    // make a window
    GtkWidget* gtkWindow = gtk_window_new(GTK_WINDOW_POPUP);
    gtk_widget_realize(gtkWindow);
    QHashableLatin1Literal widgetPath = QHashableLatin1Literal::fromData(strdup("GtkWindow"));
    removeWidgetFromMap(widgetPath);
    gtkWidgetMap()->insert(widgetPath, gtkWindow);


    // Make all other widgets. respect the text direction
    if (qApp->layoutDirection() == Qt::RightToLeft)
        gtk_widget_set_default_direction(GTK_TEXT_DIR_RTL);

    if (!gtkWidgetMap()->contains("GtkButton")) {
        GtkWidget *gtkButton = gtk_button_new();
        addWidget(gtkButton);
        g_signal_connect(gtkButton, "style-set", G_CALLBACK(gtkStyleSetCallback), 0);
        addWidget(GTK_WIDGET(gtk_tool_button_new(NULL, "Qt")));
        addWidget(GTK_WIDGET(gtk_arrow_new(GTK_ARROW_DOWN, GTK_SHADOW_NONE)));
        addWidget(GTK_WIDGET(gtk_hbutton_box_new()));
        addWidget(GTK_WIDGET(gtk_check_button_new()));
        addWidget(GTK_WIDGET(gtk_radio_button_new(NULL)));
        addWidget(GTK_WIDGET(gtk_combo_box_new()));
        addWidget(GTK_WIDGET(gtk_combo_box_entry_new()));
        GtkWidget *entry = gtk_entry_new();
        // gtk-im-context-none is supported in gtk+ since 2.19.5
        // and also exists in gtk3
        // http://git.gnome.org/browse/gtk+/tree/gtk/gtkimmulticontext.c?id=2.19.5#n33
        // reason that we don't use gtk-im-context-simple here is,
        // gtk-im-context-none has less overhead, and 2.19.5 is
        // relatively old. and even for older gtk+, it will fallback
        // to gtk-im-context-simple if gtk-im-context-none doesn't
        // exists.
        g_object_set(entry, "im-module", "gtk-im-context-none", NULL);
        addWidget(entry);
        addWidget(gtk_frame_new(NULL));
        addWidget(gtk_expander_new(""));
        addWidget(gtk_statusbar_new());
        addWidget(gtk_hscale_new(GTK_ADJUSTMENT(gtk_adjustment_new(1, 0, 1, 0, 0, 0))));
        addWidget(gtk_hscrollbar_new(NULL));
        addWidget(gtk_scrolled_window_new(NULL, NULL));

        initGtkMenu();
        addWidget(gtk_notebook_new());
        addWidget(gtk_progress_bar_new());
        addWidget(gtk_spin_button_new(GTK_ADJUSTMENT(gtk_adjustment_new(1, 0, 1, 0, 0, 0)), 0.1, 3));
        GtkWidget *toolbar = gtk_toolbar_new();
        g_signal_connect (toolbar, "notify::toolbar-style", G_CALLBACK (update_toolbar_style), toolbar);
        gtk_toolbar_insert((GtkToolbar*)toolbar, gtk_separator_tool_item_new(), -1);
        addWidget(toolbar);
        initGtkTreeview();
        addWidget(gtk_vscale_new(GTK_ADJUSTMENT(gtk_adjustment_new(1, 0, 1, 0, 0, 0))));
        addWidget(gtk_vscrollbar_new(NULL));
    }
    else // Rebuild map
    {
        // When styles change subwidgets can get rearranged
        // as with the combo box. We need to update the widget map
        // to reflect this;
        QHash<QHashableLatin1Literal, GtkWidget*> oldMap = *gtkWidgetMap();
        gtkWidgetMap()->clear();
        QHashIterator<QHashableLatin1Literal, GtkWidget*> it(oldMap);
        while (it.hasNext()) {
            it.next();
            if (!strchr(it.key().data(), '.')) {
                addAllSubWidgets(it.value());
            }
            free(const_cast<char *>(it.key().data()));
        }
    }
}

/*! \internal
 * destroys all previously buffered widgets.
 */
void QGtkStylePrivate::cleanupGtkWidgets()
{
    if (!widgetMap)
        return;
    if (widgetMap->contains("GtkWindow")) // Gtk will destroy all children
        gtk_widget_destroy(widgetMap->value("GtkWindow"));
    for (QHash<QHashableLatin1Literal, GtkWidget *>::const_iterator it = widgetMap->constBegin();
         it != widgetMap->constEnd(); ++it)
        free(const_cast<char *>(it.key().data()));
}

QString QGtkStylePrivate::getThemeName()
{
    QString themeName;
    // Read the theme name from GtkSettings
    GtkSettings *settings = gtk_settings_get_default();
    gchararray value;
    g_object_get(settings, "gtk-theme-name", &value, NULL);
    themeName = QString::fromUtf8(value);
    g_free(value);
    return themeName;
}

// Get size of the arrow controls in a GtkSpinButton
int QGtkStylePrivate::getSpinboxArrowSize() const
{
    const int MIN_ARROW_WIDTH = 6;
    GtkWidget *spinButton = gtkWidget("GtkSpinButton");
    GtkStyle *style = gtk_widget_get_style(spinButton);
    gint size = pango_font_description_get_size (style->font_desc);
    gint arrow_size;
    arrow_size = qMax(PANGO_PIXELS (size), MIN_ARROW_WIDTH) + style->xthickness;
    arrow_size += arrow_size%2 + 1;
    return arrow_size;
}


bool QGtkStylePrivate::isKDE4Session()
{
    static int version = -1;
    if (version == -1)
        version = qgetenv("KDE_SESSION_VERSION").toInt();
    return (version == 4);
}

void QGtkStylePrivate::applyCustomPaletteHash()
{
    QPalette menuPal = gtkWidgetPalette("GtkMenu");
    GdkColor gdkBg = gtk_widget_get_style(gtkWidget("GtkMenu"))->bg[GTK_STATE_NORMAL];
    QColor bgColor(gdkBg.red>>8, gdkBg.green>>8, gdkBg.blue>>8);
    menuPal.setBrush(QPalette::Base, bgColor);
    menuPal.setBrush(QPalette::Window, bgColor);
    qApp->setPalette(menuPal, "QMenu");

    QPalette toolbarPal = gtkWidgetPalette("GtkToolbar");
    qApp->setPalette(toolbarPal, "QToolBar");

    QPalette menuBarPal = gtkWidgetPalette("GtkMenuBar");
    qApp->setPalette(menuBarPal, "QMenuBar");
}

/*! \internal
 *  Returns the gtk Widget that should be used to determine text foreground and background colors.
*/
GtkWidget* QGtkStylePrivate::getTextColorWidget() const
{
    return  gtkWidget("GtkEntry");
}

void QGtkStylePrivate::setupGtkWidget(GtkWidget* widget)
{
    if (GTK_IS_WIDGET(widget)) {
        GtkWidget *protoLayout = gtkWidgetMap()->value("GtkContainer");
        if (!protoLayout) {
            protoLayout = gtk_fixed_new();
            gtk_container_add((GtkContainer*)(gtkWidgetMap()->value("GtkWindow")), protoLayout);
            QHashableLatin1Literal widgetPath = QHashableLatin1Literal::fromData(strdup("GtkContainer"));
            gtkWidgetMap()->insert(widgetPath, protoLayout);
        }
        Q_ASSERT(protoLayout);

        if (!gtk_widget_get_parent(widget) && !gtk_widget_is_toplevel(widget))
            gtk_container_add((GtkContainer*)(protoLayout), widget);
        gtk_widget_realize(widget);
    }
}

void QGtkStylePrivate::removeWidgetFromMap(const QHashableLatin1Literal &path)
{
    WidgetMap *map = gtkWidgetMap();
    WidgetMap::iterator it = map->find(path);
    if (it != map->end()) {
        char* keyData = const_cast<char *>(it.key().data());
        map->erase(it);
        free(keyData);
    }
}

void QGtkStylePrivate::addWidgetToMap(GtkWidget *widget)
{
    if (GTK_IS_WIDGET(widget)) {
        gtk_widget_realize(widget);
        QHashableLatin1Literal widgetPath = classPath(widget);

        removeWidgetFromMap(widgetPath);
        gtkWidgetMap()->insert(widgetPath, widget);
#ifdef DUMP_GTK_WIDGET_TREE
        qWarning("Inserted Gtk Widget: %s", widgetPath.data());
#endif
    }
 }

void QGtkStylePrivate::addAllSubWidgets(GtkWidget *widget, gpointer v)
{
    Q_UNUSED(v);
    addWidgetToMap(widget);
    if (G_TYPE_CHECK_INSTANCE_TYPE ((widget), gtk_container_get_type()))
        gtk_container_forall((GtkContainer*)widget, addAllSubWidgets, NULL);
}

// Updates window/windowtext palette based on the indicated gtk widget
QPalette QGtkStylePrivate::gtkWidgetPalette(const QHashableLatin1Literal &gtkWidgetName) const
{
    GtkWidget *gtkWidget = QGtkStylePrivate::gtkWidget(gtkWidgetName);
    Q_ASSERT(gtkWidget);
    QPalette pal = QApplication::palette();
    GdkColor gdkBg = gtk_widget_get_style(gtkWidget)->bg[GTK_STATE_NORMAL];
    GdkColor gdkText = gtk_widget_get_style(gtkWidget)->fg[GTK_STATE_NORMAL];
    GdkColor gdkDisabledText = gtk_widget_get_style(gtkWidget)->fg[GTK_STATE_INSENSITIVE];
    QColor bgColor(gdkBg.red>>8, gdkBg.green>>8, gdkBg.blue>>8);
    QColor textColor(gdkText.red>>8, gdkText.green>>8, gdkText.blue>>8);
    QColor disabledTextColor(gdkDisabledText.red>>8, gdkDisabledText.green>>8, gdkDisabledText.blue>>8);
    pal.setBrush(QPalette::Window, bgColor);
    pal.setBrush(QPalette::Button, bgColor);
    pal.setBrush(QPalette::All, QPalette::WindowText, textColor);
    pal.setBrush(QPalette::Disabled, QPalette::WindowText, disabledTextColor);
    pal.setBrush(QPalette::All, QPalette::ButtonText, textColor);
    pal.setBrush(QPalette::Disabled, QPalette::ButtonText, disabledTextColor);
    return pal;
}


void QGtkStyleUpdateScheduler::updateTheme()
{
    static QString oldTheme(QLS("qt_not_set"));
    QPixmapCache::clear();

    QFont font = QGtkStylePrivate::getThemeFont();
    if (QApplication::font() != font)
        qApp->setFont(font);

      if (oldTheme != QGtkStylePrivate::getThemeName()) {
          oldTheme = QGtkStylePrivate::getThemeName();
          QPalette newPalette = qApp->style()->standardPalette();
          QApplicationPrivate::setSystemPalette(newPalette);
          QApplication::setPalette(newPalette);
          if (!QGtkStylePrivate::instances.isEmpty()) {
              QGtkStylePrivate::instances.last()->initGtkWidgets();
              QGtkStylePrivate::instances.last()->applyCustomPaletteHash();
          }
          QList<QWidget*> widgets = QApplication::allWidgets();
          // Notify all widgets that size metrics might have changed
          foreach (QWidget *widget, widgets) {
              QEvent e(QEvent::StyleChange);
              QApplication::sendEvent(widget, &e);
          }
      }
    QIconLoader::instance()->updateSystemTheme();
}

void QGtkStylePrivate::addWidget(GtkWidget *widget)
{
    if (widget) {
        setupGtkWidget(widget);
        addAllSubWidgets(widget);
    }
}


// Fetch the application font from the pango font description
// contained in the theme.
QFont QGtkStylePrivate::getThemeFont()
{
    QFont font;
    GtkStyle *style = gtkStyle();
    if (style && qApp->desktopSettingsAware())
    {
        PangoFontDescription *gtk_font = style->font_desc;
        font.setPointSizeF((float)(pango_font_description_get_size(gtk_font))/PANGO_SCALE);

        QString family = QString::fromLatin1(pango_font_description_get_family(gtk_font));
        if (!family.isEmpty())
            font.setFamily(family);

#if QT_VERSION >= QT_VERSION_CHECK(5, 5, 0)
        const int weight = pango_font_description_get_weight(gtk_font);
        font.setWeight(QPlatformFontDatabase::weightFromInteger(weight));
#else
        int weight = pango_font_description_get_weight(gtk_font);
        if (weight >= PANGO_WEIGHT_HEAVY)
            font.setWeight(QFont::Black);
        else if (weight >= PANGO_WEIGHT_BOLD)
            font.setWeight(QFont::Bold);
        else if (weight >= PANGO_WEIGHT_SEMIBOLD)
            font.setWeight(QFont::DemiBold);
        else if (weight >= PANGO_WEIGHT_NORMAL)
            font.setWeight(QFont::Normal);
        else
            font.setWeight(QFont::Light);
#endif

        PangoStyle fontstyle = pango_font_description_get_style(gtk_font);
        if (fontstyle == PANGO_STYLE_ITALIC)
            font.setStyle(QFont::StyleItalic);
        else if (fontstyle == PANGO_STYLE_OBLIQUE)
            font.setStyle(QFont::StyleOblique);
        else
            font.setStyle(QFont::StyleNormal);
    }
    return font;
}

bool operator==(const QHashableLatin1Literal &l1, const QHashableLatin1Literal &l2)
{
    return l1.size() == l2.size() || qstrcmp(l1.data(), l2.data()) == 0;
}

// copied from qHash.cpp
uint qHash(const QHashableLatin1Literal &key)
{
    int n = key.size();
    const uchar *p = reinterpret_cast<const uchar *>(key.data());
    uint h = 0;
    uint g;

    while (n--) {
        h = (h << 4) + *p++;
        if ((g = (h & 0xf0000000)) != 0)
            h ^= g >> 23;
        h &= ~g;
    }
    return h;
}

QT_END_NAMESPACE
