/**
 * TODO:
 * 1) Change example to use offscreen rendering (pbuffer) so that it becomes a true commandline tool with now windows
 * 2) Make example work with other threading models than SingleThreaded
 * 3) Add support for autocapture to movies
 *
 */
#include <osg/ArgumentParser>
#include <osg/CoordinateSystemNode>
#include <osg/Matrix>
#include <osg/NodeVisitor>

#include <osgUtil/IntersectionVisitor>
#include <osgUtil/GLObjectsVisitor>

#include <osgDB/ReadFile>
#include <osgDB/WriteFile>

#include <osgGA/DriveManipulator>
#include <osgGA/FlightManipulator>
#include <osgGA/KeySwitchMatrixManipulator>
#include <osgGA/TerrainManipulator>
#include <osgGA/TrackballManipulator>

#include <osgTerrain/Terrain>
#include <osgTerrain/GeometryTechnique>

#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>
#include <osgViewer/Renderer>

#include <iostream>
#include <sstream>

/** Helper class*/
template<class T>
class FindTopMostNodeOfTypeVisitor : public osg::NodeVisitor
{
public:
    FindTopMostNodeOfTypeVisitor():
        osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ALL_CHILDREN),
        _foundNode(0)
    {}

    void apply(osg::Node& node)
    {
        T* result = dynamic_cast<T*>(&node);
        if (result)
             _foundNode = result;
         else
             traverse(node);
     }

    T* _foundNode;
};

/** Convenience function*/
template<class T>
T* findTopMostNodeOfType(osg::Node* node)
{
    if (!node) return 0;

    FindTopMostNodeOfTypeVisitor<T> fnotv;
    node->accept(fnotv);

    return fnotv._foundNode;
}

/** Capture the frame buffer and write image to disk*/
class WindowCaptureCallback : public osg::Camera::DrawCallback
{
public:
    WindowCaptureCallback(GLenum readBuffer, const std::string& name):
        _readBuffer(readBuffer),
        _fileName(name)
        {
            _image = new osg::Image;
        }

    virtual void operator () (osg::RenderInfo& renderInfo) const
        {
            #if !defined(OSG_GLES1_AVAILABLE) && !defined(OSG_GLES2_AVAILABLE)
            glReadBuffer(_readBuffer);
            #else
            osg::notify(osg::NOTICE)<<"Error: GLES unable to do glReadBuffer"<<std::endl;
            #endif

            OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
            osg::GraphicsContext* gc = renderInfo.getState()->getGraphicsContext();
            if (gc->getTraits())
            {
                GLenum pixelFormat;

                if (gc->getTraits()->alpha)
                    pixelFormat = GL_RGBA;
                else
                    pixelFormat = GL_RGB;

#if defined(OSG_GLES1_AVAILABLE) || defined(OSG_GLES2_AVAILABLE)
                 if (pixelFormat == GL_RGB)
                 {
                    GLint value = 0;
                    #ifndef GL_IMPLEMENTATION_COLOR_READ_FORMAT
                        #define GL_IMPLEMENTATION_COLOR_READ_FORMAT 0x8B9B
                    #endif
                    glGetIntegerv(GL_IMPLEMENTATION_COLOR_READ_FORMAT, &value);
                    if ( value != GL_RGB ||
                         value != GL_UNSIGNED_BYTE )
                    {
                        pixelFormat = GL_RGBA;//always supported
                    }
                 }
#endif
                int width = gc->getTraits()->width;
                int height = gc->getTraits()->height;

                std::cout<<"Capture: size="<<width<<"x"<<height<<", format="<<(pixelFormat == GL_RGBA ? "GL_RGBA":"GL_RGB")<<std::endl;

                _image->readPixels(0, 0, width, height, pixelFormat, GL_UNSIGNED_BYTE);
            }

            if (!_fileName.empty())
            {
                std::cout << "Writing to: " << _fileName << std::endl;
                osgDB::writeImageFile(*_image, _fileName);
            }
        }

protected:
    GLenum                      _readBuffer;
    std::string                 _fileName;
    osg::ref_ptr<osg::Image>    _image;
    mutable OpenThreads::Mutex  _mutex;
};


/** Do Culling only while loading PagedLODs*/
class CustomRenderer : public osgViewer::Renderer
{
public:
    CustomRenderer(osg::Camera* camera)
        : osgViewer::Renderer(camera),
          _cullOnly(true)
        {
        }

    /** Set flag to omit drawing in renderingTraversals */
    void setCullOnly(bool on) { _cullOnly = on; }

    virtual void operator () (osg::GraphicsContext* /*context*/)
        {
            if (_graphicsThreadDoesCull)
            {
                if (_cullOnly)
                    cull();
                else
                    cull_draw();
            }
        }

    virtual void cull()
        {
            osgUtil::SceneView* sceneView = _sceneView[0].get();
            if (!sceneView || _done ) return;

            updateSceneView(sceneView);

            osgViewer::View* view = dynamic_cast<osgViewer::View*>(_camera->getView());
            if (view) sceneView->setFusionDistance(view->getFusionDistanceMode(), view->getFusionDistanceValue());

            sceneView->inheritCullSettings(*(sceneView->getCamera()));
            sceneView->cull();
        }

    bool _cullOnly;
};


//===============================================================
// MAIN
//
int main( int argc, char **argv )
{
    osg::ArgumentParser arguments(&argc, argv);
    osg::ApplicationUsage* usage = arguments.getApplicationUsage();

    usage->setApplicationName(arguments.getApplicationName());
    usage->setDescription(arguments.getApplicationName()+" loads a model, sets a camera position and automatically captures screenshot to disk");
    usage->setCommandLineUsage(arguments.getApplicationName()+" [options] filename ...");
    usage->addCommandLineOption("--camera <lat> <lon> <alt> <heading> <incline> <roll>", "Specify camera position for image capture. Angles are specified in degrees and altitude in meters above sealevel (e.g. --camera 55 10 300000 0 30 0)");
    usage->addCommandLineOption("--filename", "Filename for the captured image", "autocapture.jpg");
    usage->addCommandLineOption("--db-threads", "Number of DatabasePager threads to use", "2");
    usage->addCommandLineOption("--active", "Use active rendering instead of passive / lazy rendering");
    usage->addCommandLineOption("--pbuffer", "Render into a pbuffer, not into a window");

    // Construct the viewer and register options arguments.
    osgViewer::Viewer viewer(arguments);

    if (arguments.argc()<=1)
    {
        arguments.getApplicationUsage()->write(std::cout,osg::ApplicationUsage::COMMAND_LINE_OPTION);
        return 1;
    }

   // Get user specified number of DatabaseThreads
    int dbThreads = 2;
    arguments.read("--db-threads", dbThreads);
    if (dbThreads < 1) dbThreads = 1;

    osg::DisplaySettings::instance()->setNumOfDatabaseThreadsHint(dbThreads);

    // Get user specified file name
    std::string fileName("autocapture.jpg");
    arguments.read("--filename", fileName);

    // Rendering mode is passive by default
    bool activeMode = false;
    if (arguments.read("--active"))
        activeMode = true;

    bool use_pbuffer = false;
    if (arguments.read("--pbuffer")) {
        if (!activeMode) {
            use_pbuffer = true;
        } else {
            osg::notify(osg::NOTICE)<<"ignoring --pbuffer because --active specified on commandline"<<std::endl;
        }
    }
    if (use_pbuffer) {
        osg::DisplaySettings* ds = osg::DisplaySettings::instance().get();
        osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits(ds);

        if (viewer.getCamera()->getGraphicsContext() && viewer.getCamera()->getGraphicsContext()->getTraits()) {
            //use viewer settings for window size
            osg::ref_ptr<const osg::GraphicsContext::Traits> src_traits = viewer.getCamera()->getGraphicsContext()->getTraits();
            traits->screenNum = src_traits->screenNum;
            traits->displayNum = src_traits->displayNum;
            traits->hostName = src_traits->hostName;
            traits->width = src_traits->width;
            traits->height = src_traits->height;
            traits->red = src_traits->red;
            traits->green = src_traits->green;
            traits->blue = src_traits->blue;
            traits->alpha = src_traits->alpha;
            traits->depth = src_traits->depth;
            traits->pbuffer = true;
        } else {
            //viewer would use fullscreen size (unknown here) pbuffer will use 4096 x4096 (or best available)
            traits->width = 1 << 12;
            traits->height = 1 << 12;
            traits->pbuffer = true;
        }
        osg::ref_ptr<osg::GraphicsContext> pbuffer = osg::GraphicsContext::createGraphicsContext(traits.get());
        if (pbuffer.valid())
        {
            osg::notify(osg::NOTICE)<<"Pixel buffer has been created successfully."<<std::endl;
            osg::ref_ptr<osg::Camera> camera = new osg::Camera(*viewer.getCamera());
            camera->setGraphicsContext(pbuffer.get());
            camera->setViewport(new osg::Viewport(0,0,traits->width,traits->height));
            GLenum buffer = pbuffer->getTraits()->doubleBuffer ? GL_BACK : GL_FRONT;
            camera->setDrawBuffer(buffer);
            camera->setReadBuffer(buffer);
            viewer.setCamera(camera.get());
        }
        else
        {
            osg::notify(osg::NOTICE)<<"Pixel buffer has not been created successfully."<<std::endl;
        }
    }

    // Read camera settings for screenshot
    double lat=50;
    double lon=10;
    double alt=2000;
    double heading=0;
    double incline=45;
    double roll=0;
    bool camera_specified=false;
    if (arguments.read("--camera", lat, lon, alt, heading, incline, roll))
    {
        camera_specified=true;
        lat = osg::DegreesToRadians(lat);
        lon = osg::DegreesToRadians(lon);
        heading = osg::DegreesToRadians(heading);
        incline = osg::DegreesToRadians(incline);
        roll = osg::DegreesToRadians(roll);
    }

    // load the data
    osg::ref_ptr<osg::Node> loadedModel = osgDB::readRefNodeFiles(arguments);
    if (!loadedModel)
    {
        std::cout << arguments.getApplicationName() <<": No data loaded" << std::endl;
        return 1;
    }

     // any option left unread are converted into errors to write out later.
     arguments.reportRemainingOptionsAsUnrecognized();

    // report any errors if they have occurred when parsing the program arguments.
    if (arguments.errors())
    {
        arguments.writeErrorMessages(std::cout);
        return 1;
    }

    // Setup specified camera
    if (camera_specified)
    {
        osg::CoordinateSystemNode* csn = findTopMostNodeOfType<osg::CoordinateSystemNode>(loadedModel.get());
        if(!csn) return 1;

        // Compute eye point in world coordiantes
        osg::Vec3d eye;
        csn->getEllipsoidModel()->convertLatLongHeightToXYZ(lat, lon, alt, eye.x(), eye.y(), eye.z());

        // Build matrix for computing target vector
        osg::Matrixd target_matrix = osg::Matrixd::rotate(-heading, osg::Vec3d(1,0,0),
                                                          -lat,     osg::Vec3d(0,1,0),
                                                          lon,      osg::Vec3d(0,0,1));

        // Compute tangent vector ...
        osg::Vec3d tangent = target_matrix.preMult(osg::Vec3d(0, 0, 1));

        // Compute non-inclined, non-rolled up vector ...
        osg::Vec3d up(eye);
        up.normalize();

        // Incline by rotating the target- and up vector around the tangent/up-vector
        // cross-product ...
        osg::Vec3d up_cross_tangent = up ^ tangent;
        osg::Matrixd incline_matrix = osg::Matrixd::rotate(incline, up_cross_tangent);
        osg::Vec3d target = incline_matrix.preMult(tangent);

        // Roll by rotating the up vector around the target vector ...
        osg::Matrixd roll_matrix = incline_matrix * osg::Matrixd::rotate(roll, target);
        up = roll_matrix.preMult(up);

        viewer.getCamera()->setViewMatrixAsLookAt(eye, eye+target, up);
    }
    else
    {
        // Only add camera manipulators if camera is not specified
        camera_specified=false;
        osg::ref_ptr<osgGA::KeySwitchMatrixManipulator> keyswitchManipulator = new osgGA::KeySwitchMatrixManipulator;

        keyswitchManipulator->addMatrixManipulator( '1', "Trackball", new osgGA::TrackballManipulator() );
        keyswitchManipulator->addMatrixManipulator( '2', "Flight", new osgGA::FlightManipulator() );
        keyswitchManipulator->addMatrixManipulator( '3', "Drive", new osgGA::DriveManipulator() );
        keyswitchManipulator->addMatrixManipulator( '4', "Terrain", new osgGA::TerrainManipulator() );

        viewer.setCameraManipulator( keyswitchManipulator.get() );
    }


    // Optimize DatabasePager for auto-capture
    osgDB::DatabasePager* pager = viewer.getDatabasePager();
    pager->setDoPreCompile(false);

    // Install custom renderer
    osg::ref_ptr<CustomRenderer> customRenderer = new CustomRenderer(viewer.getCamera());
    viewer.getCamera()->setRenderer(customRenderer.get());

    // Override threading model
    viewer.setThreadingModel(osgViewer::Viewer::SingleThreaded);

    // Set the final SceneData to show
    viewer.setSceneData(loadedModel.get());

    // Realize GUI
    viewer.realize();

    //--- Load PageLOD tiles ---

    // Initiate the first PagedLOD request
    viewer.frame();

    osg::Timer_t beforeLoadTick = osg::Timer::instance()->tick();

    // Keep updating and culling until full level of detail is reached
    while(!viewer.done() && pager->getRequestsInProgress())
    {
//        std::cout <<pager->getRequestsInProgress()<<" ";
        viewer.updateTraversal();
        viewer.renderingTraversals();
    }
//    std::cout<<std::endl;

    osg::Timer_t afterLoadTick = osg::Timer::instance()->tick();
    std::cout<<"Load and Compile time = "<<osg::Timer::instance()->delta_s(beforeLoadTick, afterLoadTick)<<" seconds"<<std::endl;

    // Do cull and draw to render the scene correctly
    customRenderer->setCullOnly(false);


    //--- Capture the image!!! ---
    if (!activeMode)
    {
        // Add the WindowCaptureCallback now that we have full resolution
        GLenum buffer = viewer.getCamera()->getGraphicsContext()->getTraits()->doubleBuffer ? GL_BACK : GL_FRONT;
        viewer.getCamera()->setFinalDrawCallback(new WindowCaptureCallback(buffer, fileName));

        osg::Timer_t beforeRenderTick = osg::Timer::instance()->tick();

        // Do rendering with capture callback
         viewer.renderingTraversals();

        osg::Timer_t afterRenderTick = osg::Timer::instance()->tick();
        std::cout<<"Rendering time = "<<osg::Timer::instance()->delta_s(beforeRenderTick, afterRenderTick) <<" seconds"<<std::endl;

        return 0;
    }
    else
    {
        return viewer.run();
    }
}