/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the Qt Virtual Keyboard module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:GPL$
** Commercial License Usage
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** accordance with the commercial license agreement provided with the
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3 or (at your option) any later version
** approved by the KDE Free Qt Foundation. The licenses are as published by
** the Free Software Foundation and appearing in the file LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
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** $QT_END_LICENSE$
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****************************************************************************/

#include "desktopinputpanel.h"
#include "inputview.h"
#include "platforminputcontext.h"
#include "inputcontext.h"
#include <QGuiApplication>
#include <QQmlEngine>
#include <QScreen>
#include "virtualkeyboarddebug.h"
#if defined(QT_VIRTUALKEYBOARD_HAVE_XCB)
#include <xcb/xcb.h>
#include <xcb/xfixes.h>
#endif
#include <qpa/qplatformnativeinterface.h>
#include <QtCore/private/qobject_p.h>
#include <QtCore/QLibraryInfo>

namespace QtVirtualKeyboard {

class DesktopInputPanelPrivate : public AppInputPanelPrivate
{
public:
    enum WindowingSystem {
        Windows,
        Xcb,
        Other,
    };

    DesktopInputPanelPrivate() :
        AppInputPanelPrivate(),
        view(),
        keyboardRect(),
        previewRect(),
        previewVisible(false),
        previewBindingActive(false),
        windowingSystem(Other)
    {
        const QString platformName = QGuiApplication::platformName();
        if (platformName == QLatin1String("windows"))
            windowingSystem = Windows;
        else if (platformName == QLatin1String("xcb"))
            windowingSystem = Xcb;
    }

    QScopedPointer<InputView> view;
    QRectF keyboardRect;
    QRectF previewRect;
    bool previewVisible;
    bool previewBindingActive;
    WindowingSystem windowingSystem;
};

/*!
    \class QtVirtualKeyboard::DesktopInputPanel
    \internal
*/

DesktopInputPanel::DesktopInputPanel(QObject *parent) :
    AppInputPanel(*new DesktopInputPanelPrivate(), parent)
{
    /*  Activate the alpha buffer for this application.
    */
    QQuickWindow::setDefaultAlphaBuffer(true);
    QScreen *screen = QGuiApplication::primaryScreen();
    connect(screen, SIGNAL(virtualGeometryChanged(QRect)), SLOT(repositionView(QRect)));
}

DesktopInputPanel::~DesktopInputPanel()
{
}

void DesktopInputPanel::show()
{
    AppInputPanel::show();
    Q_D(DesktopInputPanel);
    if (d->view) {
        repositionView(QGuiApplication::primaryScreen()->availableGeometry());
        d->view->show();
    }
}

void DesktopInputPanel::hide()
{
    AppInputPanel::hide();
    Q_D(DesktopInputPanel);
    if (d->view)
        d->view->hide();
}

bool DesktopInputPanel::isVisible() const
{
    return AppInputPanel::isVisible();
}

void DesktopInputPanel::setInputRect(const QRect &inputRect)
{
    Q_D(DesktopInputPanel);
    d->keyboardRect = inputRect;
    updateInputRegion();
}

void DesktopInputPanel::createView()
{
    Q_D(DesktopInputPanel);
    if (!d->view) {
        if (qGuiApp) {
            connect(qGuiApp, SIGNAL(focusWindowChanged(QWindow*)), SLOT(focusWindowChanged(QWindow*)));
            focusWindowChanged(qGuiApp->focusWindow());
        }
        d->view.reset(new InputView());
        d->view->setFlags(Qt::FramelessWindowHint | Qt::WindowStaysOnTopHint | Qt::WindowDoesNotAcceptFocus);
        /*  Set appropriate WindowType for target environment.
            There seems to be no common type which would
            work in all environments. The purpose of this
            flag is to avoid the window from capturing focus,
            as well as hiding it from the task bar. */
        switch (d->windowingSystem) {
        case DesktopInputPanelPrivate::Xcb:
            d->view->setFlags(d->view->flags() | Qt::Window | Qt::BypassWindowManagerHint);
            break;
        default:
            d->view->setFlags(d->view->flags() | Qt::Tool);
            break;
        }
        d->view->setColor(QColor(Qt::transparent));
        d->view->setSource(QUrl("qrc:///QtQuick/VirtualKeyboard/content/InputPanel.qml"));
        if (QGuiApplication *app = qGuiApp)
            connect(app, SIGNAL(aboutToQuit()), SLOT(destroyView()));
    }
}

void DesktopInputPanel::destroyView()
{
    Q_D(DesktopInputPanel);
    d->view.reset();
    d->previewBindingActive = false;
}

void DesktopInputPanel::repositionView(const QRect &rect)
{
    Q_D(DesktopInputPanel);
    VIRTUALKEYBOARD_DEBUG() << "DesktopInputPanel::repositionView():" << rect;
    if (d->view && d->view->geometry() != rect) {
        InputContext *inputContext = qobject_cast<PlatformInputContext *>(parent())->inputContext();
        if (inputContext) {
            inputContext->setAnimating(true);
            if (!d->previewBindingActive) {
                connect(inputContext, SIGNAL(previewRectangleChanged()), SLOT(previewRectangleChanged()));
                connect(inputContext, SIGNAL(previewVisibleChanged()), SLOT(previewVisibleChanged()));
                d->previewBindingActive = true;
            }
        }
        d->view->setResizeMode(QQuickView::SizeViewToRootObject);
        setInputRect(QRect());
        d->view->setGeometry(rect);
        d->view->setResizeMode(QQuickView::SizeRootObjectToView);
        if (inputContext)
            inputContext->setAnimating(false);
    }
}

void DesktopInputPanel::focusWindowChanged(QWindow *focusWindow)
{
    disconnect(this, SLOT(focusWindowVisibleChanged(bool)));
    if (focusWindow)
        connect(focusWindow, &QWindow::visibleChanged, this, &DesktopInputPanel::focusWindowVisibleChanged);
}

void DesktopInputPanel::focusWindowVisibleChanged(bool visible)
{
    if (!visible) {
        InputContext *inputContext = qobject_cast<PlatformInputContext *>(parent())->inputContext();
        if (inputContext)
            inputContext->hideInputPanel();
    }
}

void DesktopInputPanel::previewRectangleChanged()
{
    Q_D(DesktopInputPanel);
    InputContext *inputContext = qobject_cast<PlatformInputContext *>(parent())->inputContext();
    d->previewRect = inputContext->previewRectangle();
    if (d->previewVisible)
        updateInputRegion();
}

void DesktopInputPanel::previewVisibleChanged()
{
    Q_D(DesktopInputPanel);
    InputContext *inputContext = qobject_cast<PlatformInputContext *>(parent())->inputContext();
    d->previewVisible = inputContext->previewVisible();
    if (d->view->isVisible())
        updateInputRegion();
}

#if defined(QT_VIRTUALKEYBOARD_HAVE_XCB)
static inline xcb_rectangle_t qRectToXCBRectangle(const QRect &r)
{
    xcb_rectangle_t result;
    result.x = qMax(SHRT_MIN, r.x());
    result.y = qMax(SHRT_MIN, r.y());
    result.width = qMin((int)USHRT_MAX, r.width());
    result.height = qMin((int)USHRT_MAX, r.height());
    return result;
}
#endif

void DesktopInputPanel::updateInputRegion()
{
    Q_D(DesktopInputPanel);

    if (d->view.isNull() || d->keyboardRect.isEmpty())
        return;

    // Make sure the native window is created
    if (!d->view->handle())
        d->view->create();

    switch (d->windowingSystem) {
    case DesktopInputPanelPrivate::Xcb:
#if defined(QT_VIRTUALKEYBOARD_HAVE_XCB)
        {
            QVector<xcb_rectangle_t> rects;
            rects.push_back(qRectToXCBRectangle(d->keyboardRect.toRect()));
            if (d->previewVisible && !d->previewRect.isEmpty())
                rects.push_back(qRectToXCBRectangle(d->previewRect.toRect()));

            QWindow *window = d->view.data();
            QPlatformNativeInterface *platformNativeInterface = QGuiApplication::platformNativeInterface();
            xcb_connection_t *xbcConnection = static_cast<xcb_connection_t *>(platformNativeInterface->nativeResourceForWindow("connection", window));
            xcb_xfixes_region_t xbcRegion = xcb_generate_id(xbcConnection);
            xcb_xfixes_create_region(xbcConnection, xbcRegion, rects.size(), rects.constData());
            xcb_xfixes_set_window_shape_region(xbcConnection, window->winId(), XCB_SHAPE_SK_INPUT, 0, 0, xbcRegion);
            xcb_xfixes_destroy_region(xbcConnection, xbcRegion);
        }
#endif
        break;

    default:
        {
            QRegion inputRegion(d->keyboardRect.toRect());
            if (d->previewVisible && !d->previewRect.isEmpty())
                inputRegion += d->previewRect.toRect();

            d->view->setMask(inputRegion);
            break;
        }
    }
}

} // namespace QtVirtualKeyboard