/* -*-c++-*- */
/* osgEarth - Geospatial SDK for OpenSceneGraph
 * Copyright 2020 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/>
 */
#pragma once

#include <osgEarth/Common>
#include <osgEarth/LatLongFormatter>
#include <osgEarth/GeodeticLabelingEngine>
#include <osgEarth/VisibleLayer>
#include <osgEarth/MapNode>
#include <osgEarth/Style>
#include <osgEarth/LabelNode>
#include <osg/ClipPlane>

namespace osgEarth { namespace Util
{
    using namespace osgEarth;
    using namespace osgEarth::Util;

    /**
     * Graticule that shows lat/long lines and automatically places labels.
     */
    class OSGEARTH_EXPORT GeodeticGraticule : public VisibleLayer
    {
    public: // serialization        
        class OSGEARTH_EXPORT Options : public VisibleLayer::Options {
        public:
            META_LayerOptions(osgEarth, Options, VisibleLayer::Options);
            OE_OPTION(Color, color, Color(Color::Yellow, 0.5f));
            OE_OPTION(Style, gridLabelStyle);
            OE_OPTION(Style, edgeLabelStyle);
            OE_OPTION(float, lineWidth, 2.0f);
            OE_OPTION(int, gridLines, 10);
            OE_OPTION(std::string, resolutions, { "10 5 2.5 1.0 0.5 0.25 0.125 0.0625 0.03125" });
            OE_OPTION(bool, gridLinesVisible, true);
            OE_OPTION(bool, gridLabelsVisible, true);
            OE_OPTION(bool, edgeLabelsVisible, true);
            virtual Config getConfig() const;
        private:
            void fromConfig( const Config& conf );
        };

    public:
        META_Layer(osgEarth, GeodeticGraticule, Options, VisibleLayer, GeodeticGraticule);

        //! Rebuild the graticule after changing options.
        void dirty();

        //! Grid line color
        void setColor(const Color& value);
        const Color& getColor() const;

        //! Grid line width in pixels
        void setLineWidth(const float& value);
        const float& getLineWidth() const;

        //! A target number of grid lines to view on screen at once.
        void setNumGridLines(const int& value);
        const int& getNumGridLines() const;

        //! Get whether to show the grid lines
        bool getGridLinesVisible() const;

        //! Set whether to show the grid lines
        void setGridLinesVisible(bool gridLinesVisible);

        //! Get whether to show the grid labels
        bool getGridLabelsVisible() const;

        //! Set whether to show the grid labels
        void setGridLabelsVisible(bool gridLabelsVisible);

        //! Get whether to show the edge labels
        bool getEdgeLabelsVisible() const;

        //! Set whether to show the edge labels
        void setEdgeLabelsVisible(bool edgeLabelsVisible);

        //! Set the styling to use for grid labels
        void setGridLabelStyle(const Style& style);
        const Style& getGridLabelStyle() const { return options().gridLabelStyle().get(); }

        //! Set ths styling to use for edge labels
        void setEdgeLabelStyle(const Style& style);
        const Style& getEdgeLabelStyle() const { return options().edgeLabelStyle().get(); }

    public: // Layer

        void addedToMap(const Map* map) override;
        void removedFromMap(const Map* map) override;
        osg::Node* getNode() const override;
        void init() override;

    public: // osg::Object

        void resizeGLObjectBuffers(unsigned maxSize) override;
        void releaseGLObjects(osg::State* state) const override;

    protected:

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

    private:

        void rebuild();

        void updateGridLineVisibility();

        UID _uid;
        osg::ref_ptr<const Profile> _profile;
        osg::ref_ptr<osg::Group> _root;
        osg::ref_ptr<const SpatialReference> _mapSRS;
        osg::ref_ptr<osg::NodeCallback > _callback;
        osg::ref_ptr<LatLongFormatter> _formatter;
        float _defaultResolution;
        osg::Vec2f _centerOffset;
        std::vector< double > _resolutions;

        struct OSGEARTH_EXPORT CameraData
        {
            osg::ref_ptr<osg::StateSet> _stateset;
            osg::ref_ptr<osg::Uniform> _resolutionUniform;
            osg::ref_ptr<osg::StateSet> _labelStateset;
            std::vector< osg::ref_ptr<LabelNode> > _labelPool;
            float _resolution;
            osg::Matrixd _lastViewMatrix;
            GeoExtent _viewExtent;
            double _lon;
            double _lat;
            double _metersPerPixel;
            void releaseGLObjects(osg::State*) const;
            ~CameraData();
        };
        typedef std::unordered_map<osg::Camera*, CameraData> CameraDataMap;
        mutable CameraDataMap _cameraDataMap;
        mutable std::mutex _cameraDataMapMutex;

        CameraData& getCameraData(osg::Camera*) const;

        void initLabelPool(CameraData&);

        std::string getText(const GeoPoint& location, bool lat);

        GeodeticLabelingEngine* _labelingEngine;

        GeoExtent getViewExtent(osgUtil::CullVisitor*) const;


    public:

        void updateLabels();
        void cull(osgUtil::CullVisitor*);
        osg::StateSet* getStateSet(osgUtil::CullVisitor* cv);

    private:
        osg::observer_ptr<MapNode> _mapNode;
        void setMapNode(MapNode*);

        struct MyGroup : public osg::Group {
            MyGroup(GeodeticGraticule*);
            GeodeticGraticule* _graticule;
            void traverse(osg::NodeVisitor& nv); 
        };
        friend struct MyGroup;
    };
} }