/* -*-c++-*- */
/* osgEarth - Dynamic map generation toolkit for OpenSceneGraph
 * Copyright 2008-2013 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 OSGEARTHUTIL_GEODETIC_GRATICLE
#define OSGEARTHUTIL_GEODETIC_GRATICLE

#include <osgEarthUtil/Common>
#include <osgEarth/MapNode>
#include <osgEarth/MapNodeObserver>
#include <osgEarthSymbology/Style>
#include <osgEarthFeatures/Feature>
#include <vector>

namespace osgEarth { namespace Util
{
    using namespace osgEarth;
    using namespace osgEarth::Features;
    using namespace osgEarth::Symbology;

    /**
     * Configuration options for the geodetic graticule.
     */
    class OSGEARTHUTIL_EXPORT GeodeticGraticuleOptions : public ConfigOptions
    {
    public:
        GeodeticGraticuleOptions( const Config& conf =Config() );

        /** dtor */
        virtual ~GeodeticGraticuleOptions() { }

    public:
        struct Level 
        {
            float    _minRange, _maxRange;
            unsigned _subdivisionFactor;
            optional<Style> _lineStyle;
            optional<Style> _textStyle;
        };

        /** Default style for grid lines */
        optional<Style>& lineStyle() { return _defaultLineStyle; }
        const optional<Style>& lineStyle() const { return _defaultLineStyle; }

        /** Default style for text labels */
        optional<Style>& textStyle() { return _defaultTextStyle; }
        const optional<Style>& textStyle() const { return _defaultTextStyle; }

        /** Subdivision levels */
        const std::vector<Level>& levels() const { return _levels; }

        /** Clear out all the levels */
        void clearLevels();

        /**
         * Adds a new level of detail. You should only add levels in descending order of 
         * maxRange (farthest to closest).
         *
         * @param maxRange
         *      Maximum camera range for this level.
         * @param minRange
         *      (optional) Minimum camera range for this level. Though you can set this at any level,
         *      it typically only makes sense to set this at the deepest level in order to
         *      disable the graticule when you zoom closer in.
         * @param subdivisionFactor
         *      (optional) Number of times to subdivide each tile
         * @param lineStyle
         *      (optional) Style to apply to the grid lines at this level
         * @param textStyle
         *      (optional) Style to apply to text labels at this level
         */
        void addLevel( 
            float        maxRange, 
            float        minRange          =0.0f, 
            unsigned     subdivisionFactor =2u, 
            const Style& lineStyle         =Style(),
            const Style& textStyle         =Style() );

    public:
        Config getConfig() const;

    protected:
        optional<Style>    _defaultLineStyle;
        optional<Style>    _defaultTextStyle;
        std::vector<Level> _levels;

        void mergeConfig( const Config& conf );
    };


    /**
     * Implements a map graticule. 
     * 
     * NOTE: So far, this only works for geocentric maps.
     * TODO: Add projected support; add text label support
     */
    class OSGEARTHUTIL_EXPORT GeodeticGraticule : public osg::Group, public MapNodeObserver
    {
    public:

        /**
         * Constructs a new graticule for use with the specified map. The graticule
         * is created with several default levels. If you call addLevel(), the 
         * default levels are deleted.
         *
         * @param map
         *      Map with which you will use this graticule
         * @param options
         *      Optional "options" that configure the graticule. Defaults will be used
         *      if you don't specify this.
         */
        GeodeticGraticule( MapNode* mapNode );
        GeodeticGraticule( MapNode* mapNode, const GeodeticGraticuleOptions& options);

        /** dtor */
        virtual ~GeodeticGraticule() { }

        /** 
         * Applies a new set of options. The graticule will be rebuilt if necessary.
         */
        void setOptions( const GeodeticGraticuleOptions& options );

        /**
         * Gets the options with which the graticule was built.
         */
        const GeodeticGraticuleOptions& getOptions() const { return _options.value(); }


    public: // osg::Node

        virtual void traverse(osg::NodeVisitor& nv);

    public: // MapNodeObserver

        virtual void setMapNode( MapNode* mapNode );

        virtual MapNode* getMapNode() { return _mapNode.get(); }


    private:
        osg::ref_ptr<const Profile> _profile;
        osg::ref_ptr<const FeatureProfile> _featureProfile;

        unsigned int               _id;
        osg::observer_ptr<MapNode> _mapNode;
        osg::Group*                _root;

        optional<GeodeticGraticuleOptions> _options;

    private:
        unsigned int getID() const { return _id; }
        void init();
        void rebuild();
        osg::Node* buildTile( const TileKey& key, Map* map ) const;
        osg::Node* buildChildren( unsigned level, unsigned x, unsigned y ) const;

        friend class GeodeticGraticuleFactory;
    };

} } // namespace osgEarth::Util

#endif // OSGEARTHUTIL_GEODETIC_GRATICLE
