/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 *
 * This library is open source and may be redistributed and/or modified under  
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
 * OpenSceneGraph Public License for more details.
*/


#include <osgUtil/IntersectionVisitor>
#include <osgUtil/LineSegmentIntersector>

#include <osg/PagedLOD>
#include <osg/Transform>
#include <osg/Projection>
#include <osg/Camera>
#include <osg/Geode>
#include <osg/Billboard>
#include <osg/Geometry>
#include <osg/Notify>
#include <osg/io_utils>

using namespace osgUtil;


///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
//  IntersectorGroup
//

IntersectorGroup::IntersectorGroup()
{
}

void IntersectorGroup::addIntersector(Intersector* intersector)
{
    _intersectors.push_back(intersector);
}

void IntersectorGroup::clear()
{
    _intersectors.clear();
}

Intersector* IntersectorGroup::clone(osgUtil::IntersectionVisitor& iv)
{
    IntersectorGroup* ig = new IntersectorGroup;
    
    // now copy across all intersectors that arn't disabled.
    for(Intersectors::iterator itr = _intersectors.begin();
        itr != _intersectors.end();
        ++itr)
    {
        if (!(*itr)->disabled())
        {
            ig->addIntersector( (*itr)->clone(iv) );
        }
    }

    return ig;
}

bool IntersectorGroup::enter(const osg::Node& node)
{
    if (disabled()) return false;
    
    bool foundIntersections = false;
    
    for(Intersectors::iterator itr = _intersectors.begin();
        itr != _intersectors.end();
        ++itr)
    {
        if ((*itr)->disabled()) (*itr)->incrementDisabledCount();
        else if ((*itr)->enter(node)) foundIntersections = true;
        else (*itr)->incrementDisabledCount();
    }
    
    if (!foundIntersections) 
    {
        // need to call leave to clean up the DisabledCount's.
        leave();
        return false;
    }
    
    // we have found at least one suitable intersector, so return true
    return true;
}

void IntersectorGroup::leave()
{
    for(Intersectors::iterator itr = _intersectors.begin();
        itr != _intersectors.end();
        ++itr)
    {
        if ((*itr)->disabled()) (*itr)->decrementDisabledCount();
    }
}

void IntersectorGroup::intersect(osgUtil::IntersectionVisitor& iv, osg::Drawable* drawable)
{
    if (disabled()) return;

    unsigned int numTested = 0;
    for(Intersectors::iterator itr = _intersectors.begin();
        itr != _intersectors.end();
        ++itr)
    {
        if (!(*itr)->disabled())
        {
            (*itr)->intersect(iv, drawable);
            
            ++numTested;
        }
    }
    
    // OSG_NOTICE<<"Number testing "<<numTested<<std::endl;

}

void IntersectorGroup::reset()
{
    Intersector::reset();
    
    for(Intersectors::iterator itr = _intersectors.begin();
        itr != _intersectors.end();
        ++itr)
    {
        (*itr)->reset();
    }
}

bool IntersectorGroup::containsIntersections()
{
    for(Intersectors::iterator itr = _intersectors.begin();
        itr != _intersectors.end();
        ++itr)
    {
        if ((*itr)->containsIntersections()) return true;
    }
    return false;
}


///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
//  IntersectionVisitor
//

IntersectionVisitor::IntersectionVisitor(Intersector* intersector, ReadCallback* readCallback)
{
    // override the default node visitor mode.
    setTraversalMode(osg::NodeVisitor::TRAVERSE_ACTIVE_CHILDREN);
    
    _useKdTreesWhenAvailable = true;
    _dummyTraversal = false;
    
    _lodSelectionMode = USE_HIGHEST_LEVEL_OF_DETAIL;
    _eyePointDirty = true;
    
    LineSegmentIntersector* ls = dynamic_cast<LineSegmentIntersector*>(intersector);
    if (ls) 
    {
        setReferenceEyePoint(ls->getStart());
        setReferenceEyePointCoordinateFrame(ls->getCoordinateFrame());
    }
    else
    {
        setReferenceEyePoint(osg::Vec3(0.0f,0.0f,0.0f));
        setReferenceEyePointCoordinateFrame(Intersector::VIEW);
    }

    setIntersector(intersector);
    
    setReadCallback(readCallback);
}

void IntersectionVisitor::setIntersector(Intersector* intersector)
{
    // keep reference around just in case intersector is already in the _intersectorStack, otherwise the clear could delete it.
    osg::ref_ptr<Intersector> temp = intersector;

    _intersectorStack.clear();

    if (intersector) _intersectorStack.push_back(intersector);
}

void IntersectionVisitor::reset()
{
    if (!_intersectorStack.empty())
    {
        osg::ref_ptr<Intersector> intersector = _intersectorStack.front();
        intersector->reset();
        
        _intersectorStack.clear();
        _intersectorStack.push_back(intersector);
    }
}

void IntersectionVisitor::apply(osg::Node& node)
{
    // OSG_NOTICE<<"apply(Node&)"<<std::endl;

    if (!enter(node)) return;

    // OSG_NOTICE<<"inside apply(Node&)"<<std::endl;

    traverse(node);

    leave();
}

void IntersectionVisitor::apply(osg::Group& group)
{
    if (!enter(group)) return;

    traverse(group);

    leave();
}

void IntersectionVisitor::apply(osg::Geode& geode)
{
    // OSG_NOTICE<<"apply(Geode&)"<<std::endl;

    if (!enter(geode)) return;

    // OSG_NOTICE<<"inside apply(Geode&)"<<std::endl;

    for(unsigned int i=0; i<geode.getNumDrawables(); ++i)
    {
        intersect( geode.getDrawable(i) );
    }

    leave();
}

void IntersectionVisitor::apply(osg::Billboard& billboard)
{
    if (!enter(billboard)) return;

#if 1
    // IntersectVisitor doesn't have getEyeLocal(), can we use NodeVisitor::getEyePoint()?
    osg::Vec3 eye_local = getEyePoint();

    for(unsigned int i = 0; i < billboard.getNumDrawables(); i++ )
    {
        const osg::Vec3& pos = billboard.getPosition(i);
        osg::ref_ptr<osg::RefMatrix> billboard_matrix = new osg::RefMatrix;
        if (getViewMatrix())
        {
            if (getModelMatrix()) billboard_matrix->mult( *getModelMatrix(), *getViewMatrix() );
            else billboard_matrix->set( *getViewMatrix() );
        }
        else if (getModelMatrix()) billboard_matrix->set( *getModelMatrix() );

        billboard.computeMatrix(*billboard_matrix,eye_local,pos);

        if (getViewMatrix()) billboard_matrix->postMult( osg::Matrix::inverse(*getViewMatrix()) );
        pushModelMatrix(billboard_matrix.get());

        // now push an new intersector clone transform to the new local coordinates
        push_clone();

        intersect( billboard.getDrawable(i) );

        // now push an new intersector clone transform to the new local coordinates
        pop_clone();

        popModelMatrix();

    }
#else

    for(unsigned int i=0; i<billboard.getNumDrawables(); ++i)
    {
        intersect( billboard.getDrawable(i) );
    }
#endif

    leave();
}

void IntersectionVisitor::apply(osg::LOD& lod)
{
    if (!enter(lod)) return;

    traverse(lod);

    leave();
}


void IntersectionVisitor::apply(osg::PagedLOD& plod)
{
    if (!enter(plod)) return;

    if (plod.getNumFileNames()>0)
    {
#if 1
        // Identify the range value for the highest res child
        float targetRangeValue;
        if( plod.getRangeMode() == osg::LOD::DISTANCE_FROM_EYE_POINT )
            targetRangeValue = 1e6; // Init high to find min value
        else
            targetRangeValue = 0; // Init low to find max value
            
        const osg::LOD::RangeList rl = plod.getRangeList();
        osg::LOD::RangeList::const_iterator rit;
        for( rit = rl.begin();
             rit != rl.end();
             rit++ )
        {
            if( plod.getRangeMode() == osg::LOD::DISTANCE_FROM_EYE_POINT )
            {
                if( rit->first < targetRangeValue )
                    targetRangeValue = rit->first;
            }
            else
            {
                if( rit->first > targetRangeValue )
                    targetRangeValue = rit->first;
            }
        }

        // Perform an intersection test only on children that display
        // at the maximum resolution.
        unsigned int childIndex;
        for( rit = rl.begin(), childIndex = 0;
             rit != rl.end();
             rit++, childIndex++ )
        {
            if( rit->first != targetRangeValue )
                // This is not one of the highest res children
                continue;

            osg::ref_ptr<osg::Node> child( NULL );
            if( plod.getNumChildren() > childIndex )
                child = plod.getChild( childIndex );

            if( (!child.valid()) && (_readCallback.valid()) )
            {
                // Child is NULL; attempt to load it, if we have a readCallback...
                unsigned int validIndex( childIndex );
                if (plod.getNumFileNames() <= childIndex)
                    validIndex = plod.getNumFileNames()-1;

                child = _readCallback->readNodeFile( plod.getDatabasePath() + plod.getFileName( validIndex ) );
            }

            if ( !child.valid() && plod.getNumChildren()>0)
            {
                // Child is still NULL, so just use the one at the end of the list.
                child = plod.getChild( plod.getNumChildren()-1 );
            }

            if (child.valid())
            {
                child->accept(*this);
            }
        }
#else    
        // older code than above block, that assumes that the PagedLOD is ordered correctly
        // i.e. low res children first, no duplicate ranges.
        
        osg::ref_ptr<osg::Node> highestResChild;

        if (plod.getNumFileNames() != plod.getNumChildren() && _readCallback.valid())
        {
            highestResChild = _readCallback->readNodeFile( plod.getDatabasePath() + plod.getFileName(plod.getNumFileNames()-1) );
        }
        
        if ( !highestResChild.valid() && plod.getNumChildren()>0)
        {
            highestResChild = plod.getChild( plod.getNumChildren()-1 );
        }

        if (highestResChild.valid())
        {
            highestResChild->accept(*this);
        }
#endif
    }

    leave();
}


void IntersectionVisitor::apply(osg::Transform& transform)
{
    if (!enter(transform)) return;

    osg::ref_ptr<osg::RefMatrix> matrix = _modelStack.empty() ? new osg::RefMatrix() : new osg::RefMatrix(*_modelStack.back());
    transform.computeLocalToWorldMatrix(*matrix,this);

    pushModelMatrix(matrix.get());

    // now push an new intersector clone transform to the new local coordinates
    push_clone();

    traverse(transform);
    
    // pop the clone.
    pop_clone();
    
    popModelMatrix();

    // tidy up an cached cull variables in the current intersector.
    leave();
}


void IntersectionVisitor::apply(osg::Projection& projection)
{
    if (!enter(projection)) return;

    pushProjectionMatrix(new osg::RefMatrix(projection.getMatrix()) );

    // now push an new intersector clone transform to the new local coordinates
    push_clone();

    traverse(projection);
    
    // pop the clone.
    pop_clone();
    
    popProjectionMatrix();

    leave();
}


void IntersectionVisitor::apply(osg::Camera& camera)
{
    // OSG_NOTICE<<"apply(Camera&)"<<std::endl;

    // note, commenting out right now because default Camera setup is with the culling active.  Should this be changed?
    // if (!enter(camera)) return;
    
    // OSG_NOTICE<<"inside apply(Camera&)"<<std::endl;

    osg::RefMatrix* projection = NULL;
    osg::RefMatrix* view = NULL;
    osg::RefMatrix* model = NULL;

    if (camera.getReferenceFrame()==osg::Transform::RELATIVE_RF && getProjectionMatrix() && getViewMatrix())
    {
        if (camera.getTransformOrder()==osg::Camera::POST_MULTIPLY)
        {
            projection = new osg::RefMatrix(*getProjectionMatrix()*camera.getProjectionMatrix());
            view = new osg::RefMatrix(*getViewMatrix()*camera.getViewMatrix());
            model = new osg::RefMatrix(*getModelMatrix());
        }
        else // pre multiply 
        {
            projection = new osg::RefMatrix(camera.getProjectionMatrix()*(*getProjectionMatrix()));
            view = new osg::RefMatrix(*getViewMatrix());
            model = new osg::RefMatrix(camera.getViewMatrix()*(*getModelMatrix()));
        }       
    } 
    else
    {
        // an absolute reference frame
        projection = new osg::RefMatrix(camera.getProjectionMatrix());
        view = new osg::RefMatrix(camera.getViewMatrix());
        model =  new osg::RefMatrix();
    }
 
    if (camera.getViewport()) pushWindowMatrix( camera.getViewport() );
    pushProjectionMatrix(projection);
    pushViewMatrix(view);
    pushModelMatrix(model);

    // now push an new intersector clone transform to the new local coordinates
    push_clone();

    traverse(camera);
    
    // pop the clone.
    pop_clone();
    
    popModelMatrix();
    popViewMatrix();
    popProjectionMatrix();
    if (camera.getViewport()) popWindowMatrix();

    // leave();
}

osg::Vec3 IntersectionVisitor::getEyePoint() const
{
    if (!_eyePointDirty) return _eyePoint;

    osg::Matrix matrix;
    switch (_referenceEyePointCoordinateFrame)
    {
        case(Intersector::WINDOW): 
            if (getWindowMatrix()) matrix.preMult( *getWindowMatrix() );
            if (getProjectionMatrix()) matrix.preMult( *getProjectionMatrix() );
            if (getViewMatrix()) matrix.preMult( *getViewMatrix() );
            if (getModelMatrix()) matrix.preMult( *getModelMatrix() );
            break;
        case(Intersector::PROJECTION): 
            if (getProjectionMatrix()) matrix.preMult( *getProjectionMatrix() );
            if (getViewMatrix()) matrix.preMult( *getViewMatrix() );
            if (getModelMatrix()) matrix.preMult( *getModelMatrix() );
            break;
        case(Intersector::VIEW): 
            if (getViewMatrix()) matrix.preMult( *getViewMatrix() );
            if (getModelMatrix()) matrix.preMult( *getModelMatrix() );
            break;
        case(Intersector::MODEL):
            if (getModelMatrix()) matrix = *getModelMatrix();
            break;
    }

    osg::Matrix inverse;
    inverse.invert(matrix);

    _eyePoint = _referenceEyePoint * inverse;
    _eyePointDirty = false;
    
    return _eyePoint;
}

float IntersectionVisitor::getDistanceToEyePoint(const osg::Vec3& pos, bool /*withLODScale*/) const
{
    if (_lodSelectionMode==USE_EYE_POINT_FOR_LOD_LEVEL_SELECTION)
    {
        return (pos-getEyePoint()).length();
    }
    else
    {
        return 0.0f;
    }
}