#include <stdlib.h>

#include <simgear/compiler.h>
#include <simgear/structure/exception.hxx>
#include <simgear/debug/logstream.hxx>

#include <osg/GraphicsContext>
#include <osg/Group>
#include <osg/Matrixd>
#include <osg/Viewport>
#include <osg/Version>
#include <osgViewer/StatsHandler>
#include <osgViewer/Viewer>
#include <osgGA/MatrixManipulator>

#include "fg_os.hxx"
#include "fg_props.hxx"
#include "util.hxx"
#include "globals.hxx"
#include "renderer.hxx"

#if ((1 == OSG_VERSION_MAJOR) && (9 == OSG_VERSION_MINOR) && \
     (8 <= OSG_VERSION_PATCH)) || \
    ((1 == OSG_VERSION_MAJOR) && (9 < OSG_VERSION_MINOR)) ||      \
    (1 < OSG_VERSION_MAJOR)
#define OSG_HAS_MOUSE_CURSOR_PATCH
#endif

// fg_os implementation using OpenSceneGraph's osgViewer::Viewer class
// to create the graphics window and run the event/update/render loop.
//
// fg_os callback registration APIs
//


// Event handling and scene graph update is all handled by a
// manipulator. See FGManipulator.cpp
void fgRegisterIdleHandler(fgIdleHandler func)
{
    globals->get_renderer()->getManipulator()->setIdleHandler(func);
}

void fgRegisterDrawHandler(fgDrawHandler func)
{
    globals->get_renderer()->getManipulator()->setDrawHandler(func);
}

void fgRegisterWindowResizeHandler(fgWindowResizeHandler func)
{
    globals->get_renderer()->getManipulator()->setWindowResizeHandler(func);
}

void fgRegisterKeyHandler(fgKeyHandler func)
{
    globals->get_renderer()->getManipulator()->setKeyHandler(func);
}

void fgRegisterMouseClickHandler(fgMouseClickHandler func)
{
    globals->get_renderer()->getManipulator()->setMouseClickHandler(func);
}

void fgRegisterMouseMotionHandler(fgMouseMotionHandler func)
{
    globals->get_renderer()->getManipulator()->setMouseMotionHandler(func);
}

// Redraw "happens" every frame whether you want it or not.
void fgRequestRedraw()
{
}

//
// fg_os implementation
//

static osg::ref_ptr<osgViewer::Viewer> viewer;
static osg::ref_ptr<osg::Camera> mainCamera;

void fgOSOpenWindow(int w, int h, int bpp,
                    bool alpha, bool stencil, bool fullscreen)
{
    osg::GraphicsContext::WindowingSystemInterface* wsi;
    wsi = osg::GraphicsContext::getWindowingSystemInterface();

    viewer = new osgViewer::Viewer;
    // Avoid complications with fg's custom drawables.
    std::string mode;
    mode = fgGetString("/sim/rendering/multithreading-mode", "SingleThreaded");
    if (mode == "AutomaticSelection")
      viewer->setThreadingModel(osgViewer::Viewer::AutomaticSelection);
    else if (mode == "CullDrawThreadPerContext")
      viewer->setThreadingModel(osgViewer::Viewer::CullDrawThreadPerContext);
    else if (mode == "DrawThreadPerContext")
      viewer->setThreadingModel(osgViewer::Viewer::DrawThreadPerContext);
    else if (mode == "CullThreadPerCameraDrawThreadPerContext")
      viewer->setThreadingModel(osgViewer::Viewer::CullThreadPerCameraDrawThreadPerContext);
    else
      viewer->setThreadingModel(osgViewer::Viewer::SingleThreaded);
    osg::ref_ptr<osg::GraphicsContext::Traits> traits;
    traits = new osg::GraphicsContext::Traits;
    int cbits = (bpp <= 16) ?  5 :  8;
    int zbits = (bpp <= 16) ? 16 : 24;
    traits->red = traits->green = traits->blue = cbits;
    traits->depth = zbits;
    if (alpha)
	traits->alpha = 8;
    if (stencil)
	traits->stencil = 8;
    traits->doubleBuffer = true;
    traits->mipMapGeneration = true;
    traits->windowName = "FlightGear";
    traits->sampleBuffers = fgGetBool("/sim/rendering/multi-sample-buffers", traits->sampleBuffers);
    traits->samples = fgGetBool("/sim/rendering/multi-samples", traits->samples);
    traits->vsync = fgGetBool("/sim/rendering/vsync-enable", traits->vsync);

    if (fullscreen) {
        unsigned width = 0;
        unsigned height = 0;
        wsi->getScreenResolution(*traits, width, height);
	traits->windowDecoration = false;
        traits->width = width;
        traits->height = height;
        traits->supportsResize = false;
    } else {
	traits->windowDecoration = true;
        traits->width = w;
        traits->height = h;
#ifdef WIN32
	// Ugly Hack, why does CW_USEDEFAULT works like phase of the moon?
	traits->x = 100;
	traits->y = 100;
#endif
        traits->supportsResize = true;
    }

    osg::Camera::ProjectionResizePolicy rsp = osg::Camera::VERTICAL;

    // Ok, first the children.
    // that achieves some magic ordering og the slaves so that we end up
    // in the main window more often.
    // This can be sorted out better when we got rid of glut and sdl.
    if (fgHasNode("/sim/rendering/camera")) {
      SGPropertyNode* renderingNode = fgGetNode("/sim/rendering");
      for (int i = 0; i < renderingNode->nChildren(); ++i) {
        SGPropertyNode* cameraNode = renderingNode->getChild(i);
        if (strcmp(cameraNode->getName(), "camera") != 0)
          continue;

        // get a new copy of the traits struct
        osg::ref_ptr<osg::GraphicsContext::Traits> cameraTraits;
        cameraTraits = new osg::GraphicsContext::Traits(*traits);

        double shearx = cameraNode->getDoubleValue("shear-x", 0);
        double sheary = cameraNode->getDoubleValue("shear-y", 0);
        cameraTraits->hostName = cameraNode->getStringValue("host-name", "");
        cameraTraits->displayNum = cameraNode->getIntValue("display", 0);
        cameraTraits->screenNum = cameraNode->getIntValue("screen", 0);
        if (cameraNode->getBoolValue("fullscreen", fullscreen)) {
          unsigned width = 0;
          unsigned height = 0;
          wsi->getScreenResolution(*cameraTraits, width, height);
          cameraTraits->windowDecoration = false;
          cameraTraits->width = width;
          cameraTraits->height = height;
          cameraTraits->supportsResize = false;
        } else {
          cameraTraits->windowDecoration = true;
          cameraTraits->width = cameraNode->getIntValue("width", w);
          cameraTraits->height = cameraNode->getIntValue("height", h);
          cameraTraits->supportsResize = true;
        }
        // FIXME, currently this is too much of a problem to route the resize
        // events. When we do no longer need sdl and such this
        // can be simplified
        cameraTraits->supportsResize = false;

        // ok found a camera configuration, add a new slave ...
        osg::ref_ptr<osg::Camera> camera = new osg::Camera;

        osg::GraphicsContext* gc;
        gc = osg::GraphicsContext::createGraphicsContext(cameraTraits.get());
        gc->realize();
        camera->setGraphicsContext(gc);
        // If a viewport isn't set on the camera, then it's hard to dig it
        // out of the SceneView objects in the viewer, and the coordinates
        // of mouse events are somewhat bizzare.
        camera->setViewport(new osg::Viewport(0, 0, cameraTraits->width, cameraTraits->height));
        camera->setProjectionResizePolicy(rsp);
        viewer->addSlave(camera.get(), osg::Matrix::translate(-shearx, -sheary, 0), osg::Matrix());
      }
    }

    // now the main camera ...
    osg::ref_ptr<osg::Camera> camera = new osg::Camera;
    mainCamera = camera;
    osg::GraphicsContext* gc;
    gc = osg::GraphicsContext::createGraphicsContext(traits.get());
    gc->realize();
    gc->makeCurrent();
    camera->setGraphicsContext(gc);
    // If a viewport isn't set on the camera, then it's hard to dig it
    // out of the SceneView objects in the viewer, and the coordinates
    // of mouse events are somewhat bizzare.
    camera->setViewport(new osg::Viewport(0, 0, traits->width, traits->height));
    camera->setProjectionResizePolicy(rsp);
    viewer->addSlave(camera.get());

    viewer->setCameraManipulator(globals->get_renderer()->getManipulator());
    // Let FG handle the escape key with a confirmation
    viewer->setKeyEventSetsDone(0);
    osgViewer::StatsHandler* statsHandler = new osgViewer::StatsHandler;
    statsHandler->setKeyEventTogglesOnScreenStats('*');
    statsHandler->setKeyEventPrintsOutStats(0);
    viewer->addEventHandler(statsHandler);
    // The viewer won't start without some root.
    viewer->setSceneData(new osg::Group);
    globals->get_renderer()->setViewer(viewer.get());
}

static int status = 0;

void fgOSExit(int code)
{
    viewer->setDone(true);
    status = code;
}

void fgOSMainLoop()
{
    viewer->run();
    fgExit(status);
}

int fgGetKeyModifiers()
{
    return globals->get_renderer()->getManipulator()->getCurrentModifiers();
}

void fgWarpMouse(int x, int y)
{
  // Hack, currently the pointer is just recentered. So, we know the relative coordinates ...
    viewer->requestWarpPointer(0, 0);
}

// Noop
void fgOSInit(int* argc, char** argv)
{
}

// Noop
void fgOSFullScreen()
{
}

#ifdef OSG_HAS_MOUSE_CURSOR_PATCH
static void setMouseCursor(osg::Camera* camera, int cursor)
{
    if (!camera)
        return;
    osg::GraphicsContext* gc = camera->getGraphicsContext();
    if (!gc)
        return;
    osgViewer::GraphicsWindow* gw;
    gw = dynamic_cast<osgViewer::GraphicsWindow*>(gc);
    if (!gw)
        return;
    
    osgViewer::GraphicsWindow::MouseCursor mouseCursor;
    mouseCursor = osgViewer::GraphicsWindow::InheritCursor;
    if     (cursor == MOUSE_CURSOR_NONE)
        mouseCursor = osgViewer::GraphicsWindow::NoCursor;
    else if(cursor == MOUSE_CURSOR_POINTER)
        mouseCursor = osgViewer::GraphicsWindow::RightArrowCursor;
    else if(cursor == MOUSE_CURSOR_WAIT)
        mouseCursor = osgViewer::GraphicsWindow::WaitCursor;
    else if(cursor == MOUSE_CURSOR_CROSSHAIR)
        mouseCursor = osgViewer::GraphicsWindow::CrosshairCursor;
    else if(cursor == MOUSE_CURSOR_LEFTRIGHT)
        mouseCursor = osgViewer::GraphicsWindow::LeftRightCursor;

    gw->setCursor(mouseCursor);
}
#endif

static int _cursor = -1;

void fgSetMouseCursor(int cursor)
{
    _cursor = cursor;
#ifdef OSG_HAS_MOUSE_CURSOR_PATCH
    setMouseCursor(viewer->getCamera(), cursor);
    for (unsigned i = 0; i < viewer->getNumSlaves(); ++i)
        setMouseCursor(viewer->getSlave(i)._camera.get(), cursor);
#endif
}

int fgGetMouseCursor()
{
    return _cursor;
}

void fgMakeCurrent()
{
    if (!mainCamera.valid())
        return;
    osg::GraphicsContext* gc = mainCamera->getGraphicsContext();
    if (!gc)
        return;
    gc->makeCurrent();
}

bool fgOSIsMainContext(const osg::GraphicsContext* context)
{
    if (!mainCamera.valid())
        return false;
    return context == mainCamera->getGraphicsContext();
}

bool fgOSIsMainCamera(const osg::Camera* camera)
{
  if (!camera)
    return false;
  if (camera == mainCamera.get())
    return true;
  if (!viewer.valid())
    return false;
  if (camera == viewer->getCamera())
    return true;
  return false;
}