#include <QTimer>
#include <QApplication>
#include <QGridLayout>

#include <osgViewer/CompositeViewer>
#include <osgViewer/ViewerEventHandlers>

#include <osgGA/MultiTouchTrackballManipulator>

#include <osgDB/ReadFile>

#include <osgQt/GraphicsWindowQt>

#include <iostream>

class ViewerWidget : public QWidget, public osgViewer::CompositeViewer
{
public:
    ViewerWidget(QWidget* parent = 0, Qt::WindowFlags f = 0, osgViewer::ViewerBase::ThreadingModel threadingModel=osgViewer::CompositeViewer::SingleThreaded) : QWidget(parent, f)
    {
        setThreadingModel(threadingModel);

        // disable the default setting of viewer.done() by pressing Escape.
        setKeyEventSetsDone(0);

        QWidget* widget1 = addViewWidget( createGraphicsWindow(0,0,100,100), osgDB::readRefNodeFile("cow.osgt") );
        QWidget* widget2 = addViewWidget( createGraphicsWindow(0,0,100,100), osgDB::readRefNodeFile("glider.osgt") );
        QWidget* widget3 = addViewWidget( createGraphicsWindow(0,0,100,100), osgDB::readRefNodeFile("axes.osgt") );
        QWidget* widget4 = addViewWidget( createGraphicsWindow(0,0,100,100), osgDB::readRefNodeFile("fountain.osgt") );
        QWidget* popupWidget = addViewWidget( createGraphicsWindow(900,100,320,240,"Popup window",true), osgDB::readRefNodeFile("dumptruck.osgt") );
        popupWidget->show();

        QGridLayout* grid = new QGridLayout;
        grid->addWidget( widget1, 0, 0 );
        grid->addWidget( widget2, 0, 1 );
        grid->addWidget( widget3, 1, 0 );
        grid->addWidget( widget4, 1, 1 );
        setLayout( grid );

        connect( &_timer, SIGNAL(timeout()), this, SLOT(update()) );
        _timer.start( 10 );
    }

    QWidget* addViewWidget( osgQt::GraphicsWindowQt* gw, osg::ref_ptr<osg::Node> scene )
    {
        osgViewer::View* view = new osgViewer::View;
        addView( view );

        osg::Camera* camera = view->getCamera();
        camera->setGraphicsContext( gw );

        const osg::GraphicsContext::Traits* traits = gw->getTraits();

        camera->setClearColor( osg::Vec4(0.2, 0.2, 0.6, 1.0) );
        camera->setViewport( new osg::Viewport(0, 0, traits->width, traits->height) );

        // set the draw and read buffers up for a double buffered window with rendering going to back buffer
        camera->setDrawBuffer(GL_BACK);
        camera->setReadBuffer(GL_BACK);

        camera->setProjectionMatrixAsPerspective(30.0f, static_cast<double>(traits->width)/static_cast<double>(traits->height), 1.0f, 10000.0f );

        view->setSceneData( scene );
        view->addEventHandler( new osgViewer::StatsHandler );
        view->setCameraManipulator( new osgGA::MultiTouchTrackballManipulator );
        gw->setTouchEventsEnabled( true );
        return gw->getGLWidget();
    }

    osgQt::GraphicsWindowQt* createGraphicsWindow( int x, int y, int w, int h, const std::string& name="", bool windowDecoration=false )
    {
        osg::DisplaySettings* ds = osg::DisplaySettings::instance().get();
        osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
        traits->windowName = name;
        traits->windowDecoration = windowDecoration;
        traits->x = x;
        traits->y = y;
        traits->width = w;
        traits->height = h;
        traits->doubleBuffer = true;
        traits->alpha = ds->getMinimumNumAlphaBits();
        traits->stencil = ds->getMinimumNumStencilBits();
        traits->sampleBuffers = ds->getMultiSamples();
        traits->samples = ds->getNumMultiSamples();

        return new osgQt::GraphicsWindowQt(traits.get());
    }

    virtual void paintEvent( QPaintEvent* event )
    { frame(); }

protected:

    QTimer _timer;
};

int main( int argc, char** argv )
{
    osg::ArgumentParser arguments(&argc, argv);

#if QT_VERSION >= 0x050000
    // Qt5 is currently crashing and reporting "Cannot make QOpenGLContext current in a different thread" when the viewer is run multi-threaded, this is regression from Qt4
    osgViewer::ViewerBase::ThreadingModel threadingModel = osgViewer::ViewerBase::SingleThreaded;
#else
    osgViewer::ViewerBase::ThreadingModel threadingModel = osgViewer::ViewerBase::CullDrawThreadPerContext;
#endif

    while (arguments.read("--SingleThreaded")) threadingModel = osgViewer::ViewerBase::SingleThreaded;
    while (arguments.read("--CullDrawThreadPerContext")) threadingModel = osgViewer::ViewerBase::CullDrawThreadPerContext;
    while (arguments.read("--DrawThreadPerContext")) threadingModel = osgViewer::ViewerBase::DrawThreadPerContext;
    while (arguments.read("--CullThreadPerCameraDrawThreadPerContext")) threadingModel = osgViewer::ViewerBase::CullThreadPerCameraDrawThreadPerContext;

#if QT_VERSION >= 0x040800
    // Required for multithreaded QGLWidget on Linux/X11, see http://blog.qt.io/blog/2011/06/03/threaded-opengl-in-4-8/
    if (threadingModel != osgViewer::ViewerBase::SingleThreaded)
        QApplication::setAttribute(Qt::AA_X11InitThreads);
#endif

    QApplication app(argc, argv);
    ViewerWidget* viewWidget = new ViewerWidget(0, Qt::Widget, threadingModel);
    viewWidget->setGeometry( 100, 100, 800, 600 );
    viewWidget->show();
    return app.exec();
}