/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
 * Copyright 2016 Pelican Mapping
 * http://osgearth.org
 *
 * osgEarth is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */
#ifndef OSGEARTHFEATURES_FEATURE_CURSOR_OGR
#define OSGEARTHFEATURES_FEATURE_CURSOR_OGR 1

#include <osgEarthFeatures/FeatureCursor>
#include <osgEarthFeatures/FeatureSource>
#include <osgEarthFeatures/Filter>
#include <osgEarthSymbology/Query>
#include <ogr_api.h>
#include <queue>

using namespace osgEarth;
using namespace osgEarth::Features;

class FeatureCursorOGR : public FeatureCursor
{
public:
    /**
     * Creates a new feature cursor that iterates over an OGR layer.
     *
     * @param source
     *      Feature source that created this cursor
     * @param dsHandle
     *      Handle on the OGR data source to which the results layer belongs
     * @param layerHandle
     *      Handle to the OGR layer containing the features
     * @param profile
     *      Profile of the feature layer corresponding to the feature data
     * @param query
     *      The the query from which this cursor was created.
     */
    FeatureCursorOGR(
        OGRLayerH                 dsHandle,
        OGRLayerH                 layerHandle,
        const FeatureSource*      source,
        const FeatureProfile*     profile,
        const Symbology::Query&   query,
        const FeatureFilterChain* filters );

public: // FeatureCursor

    bool hasMore() const;
    Feature* nextFeature();

protected:
    virtual ~FeatureCursorOGR();

private:
    OGRDataSourceH                      _dsHandle;
    OGRLayerH                           _layerHandle;
    OGRLayerH                           _resultSetHandle;
    OGRGeometryH                        _spatialFilter;
    Symbology::Query                    _query;
    unsigned                            _chunkSize;
    OGRFeatureH                         _nextHandleToQueue;
    osg::ref_ptr<const FeatureSource>   _source;
    osg::ref_ptr<const FeatureProfile>  _profile;
    std::queue< osg::ref_ptr<Feature> > _queue;
    osg::ref_ptr<Feature>               _lastFeatureReturned;
    osg::ref_ptr<const FeatureFilterChain> _filters;
    bool                                _resultSetEndReached;

private:
    void readChunk();    
};


#endif // OSGEARTHFEATURES_FEATURE_CURSOR_OGR
