/* -*-c++-*- */
/* osgEarth - Geospatial SDK for OpenSceneGraph
 * Copyright 2008-2014 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 OSGEARTH_REX_UNLOADER
#define OSGEARTH_REX_UNLOADER 1

#include "Common"
#include "TileNode"
#include <osgEarth/FrameClock>
#include <osgEarth/Threading>
#include <osg/Group>


namespace osgEarth { namespace REX
{
    class TileNodeRegistry; // for UnloaderGroup

    /**
     * Group-based tile unloader.
     */
    class UnloaderGroup : public osg::Group
    {
    public:
        UnloaderGroup(TileNodeRegistry* tiles);

        //! Permit up to this many Tiles to remain in memory even if they are expired
        void setCacheSize(unsigned t) { _cacheSize = t; }
        unsigned getCacheSize() const { return _cacheSize; }

        //! A Tile must be at least this old before it can be removed:
        void setMaxAge(double value) { _maxAge = osg::clampAbove(value, 1.0); }
        double getMaxAge() const { return _maxAge; }

        //! Maximum number of tiles to expire per frame
        void setMaxTilesToUnloadPerFrame(unsigned value) { _maxTilesToUnloadPerFrame = value; }
        unsigned getMaxTilesToUnloadPerFrame() const { return _maxTilesToUnloadPerFrame; }

        //! A Tile must be at least this far from the camera before it can be unloaded:
        void setMinimumRange(float value) { _minRange = osg::clampAbove(value, 0.0f); }
        float getMinimumRange() const { return _minRange; }

        //! Set the frame clock to use
        void setFrameClock(const FrameClock* value) { _clock = value; }

    public: // Unloader

        //void unloadChildren(const std::vector<TileKey>& keys);

    public: // osg::Node
        void traverse(osg::NodeVisitor& nv);

    protected:
        unsigned _cacheSize;
        double _maxAge;
        float _minRange;
        unsigned _maxTilesToUnloadPerFrame;
        TileNodeRegistry* _tiles;
        std::vector<osg::observer_ptr<TileNode> > _deadpool;
        unsigned _frameLastUpdated;
        const FrameClock* _clock;
    };

} } // namespace osgEarth::REX


#endif // OSGEARTH_REX_UNLOADER
