/* -*-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.
*/

#ifndef OSGUTIL_INCREMENTALCOMPILEOPERATOR
#define OSGUTIL_INCREMENTALCOMPILEOPERATOR

#include <osgUtil/GLObjectsVisitor>
#include <osg/GraphicsCostEstimator>
#include <osg/Geometry>

namespace osgUtil {


class OSGUTIL_EXPORT StateToCompile : public osg::NodeVisitor
{
    public:

        StateToCompile(GLObjectsVisitor::Mode mode);

        typedef std::set<osg::Drawable*> DrawableSet;
        typedef std::set<osg::StateSet*> StateSetSet;
        typedef std::set<osg::Texture*> TextureSet;
        typedef std::set<osg::Program*> ProgramSet;

        DrawableSet _drawablesHandled;
        StateSetSet _statesetsHandled;

        GLObjectsVisitor::Mode _mode;
        DrawableSet _drawables;
        TextureSet  _textures;
        ProgramSet  _programs;
        bool        _assignPBOToImages;

        bool empty() const { return _textures.empty() &&  _programs.empty() && _drawables.empty(); }

        virtual void apply(osg::Node& node);
        virtual void apply(osg::Geode& node);

        virtual void apply(osg::Drawable& drawable);
        virtual void apply(osg::StateSet& stateset);
        virtual void apply(osg::Texture& texture);
};

class OSGUTIL_EXPORT IncrementalCompileOperation : public osg::GraphicsOperation
{
    public:

        IncrementalCompileOperation();

        /** Return true if the IncrementCompileOperation is active.*/
        bool isActive() const { return !_contexts.empty(); }

        bool requiresCompile(StateToCompile& stateToCompile);

        /** Set the target frame rate that the IncrementalCompileOperation should assume.
          * Typically one would set this to the value refresh rate of your display system i.e. 60Hz.
          * Default value is 100.
          * Usage notes.  The TargetFrameRate and the MinimumTimeAvailableForGLCompileAndDeletePerFrame
          * parameters are not directly used by IncrementalCompileOperation, but are should be used as a guide for how
          * long to set aside per frame for compiling and deleting OpenGL objects. The longer amount of
          * time to set aside  the faster databases will be paged in but with increased chance of frame drops,
          * the lower the amount of time the set aside the slower databases will paged it but with better
          * chance of avoid any frame drops.  The default values are chosen to achieve the later when running
          * on a modern mid to high end  PC. 
          * The way to compute the amount of available time use a scheme such as :
          *    availableTime = maximum(1.0/targetFrameRate - timeTakenDuringUpdateCullAndDraw, minimumTimeAvailableForGLCompileAndDeletePerFrame). 
          */
        void setTargetFrameRate(double tfr) { _targetFrameRate = tfr; }

        /** Get the target frame rate that the IncrementalCompileOperation should assume.*/
        double getTargetFrameRate() const { return _targetFrameRate; }
        
        /** Set the minimum amount of time (in seconds) that should be made available for compiling and delete OpenGL objects per frame.
          * Default value is 0.001 (1 millisecond). 
          * For usage see notes in setTargetFrameRate.*/
        void setMinimumTimeAvailableForGLCompileAndDeletePerFrame(double ta) { _minimumTimeAvailableForGLCompileAndDeletePerFrame = ta; }

        /** Get the minimum amount of time that should be made available for compiling and delete OpenGL objects per frame.
          * For usage see notes in setTargetFrameRate.*/
        double getMinimumTimeAvailableForGLCompileAndDeletePerFrame() const { return _minimumTimeAvailableForGLCompileAndDeletePerFrame; }

        /** Set the maximum number of OpenGL objects that the page should attempt to compile per frame.
          * Note, Lower values reduces chances of a frame drop but lower the rate that database will be paged in at.
          * Default value is 8. */
        void setMaximumNumOfObjectsToCompilePerFrame(unsigned int num) { _maximumNumOfObjectsToCompilePerFrame = num; }

        /** Get the maximum number of OpenGL objects that the page should attempt to compile per frame.*/
        unsigned int getMaximumNumOfObjectsToCompilePerFrame() const { return _maximumNumOfObjectsToCompilePerFrame; }


        /** FlushTimeRatio governs how much of the spare time in each frame is used for flushing deleted OpenGL objects.
          * Default value is 0.5, valid range is 0.1 to 0.9.*/
        void setFlushTimeRatio(double ratio) { _flushTimeRatio = ratio; }
        double getFlushTimeRatio() const { return _flushTimeRatio; }

        /** ConservativeTimeRatio governs how much of the measured spare time in each frame is used for flushing deleted and compile new OpenGL objects.
          * Default value is 0.5, valid range is 0.1 to 1.0.
          * A ratio near 1.0 will lead to paged databases being compiled and merged quicker but increase the chances of frame drop.
          * A ratio near 0.1 will lead to paged databases being compiled and merged closer but reduse the chances of frame drop.*/
        void setConservativeTimeRatio(double ratio) { _conservativeTimeRatio = ratio; }
        double getConservativeTimeRatio() const { return _conservativeTimeRatio; }

        /** Assign a geometry and associated StateSet than is applied after each texture compile to atttempt to force the OpenGL
          * drive to download the texture object to OpenGL graphics card.*/
        void assignForceTextureDownloadGeometry();

        /** Set the osg::Geometry to apply after each texture compile to atttempt to force the OpenGL
          * drive to download the texture object to OpenGL graphics card.*/
        void setForceTextureDownloadGeometry(osg::Geometry* geom) { _forceTextureDownloadGeometry = geom; }
        osg::Geometry* getForceTextureDownloadGeometry() { return _forceTextureDownloadGeometry.get(); }
        const osg::Geometry* getForceTextureDownloadGeometry() const { return _forceTextureDownloadGeometry.get(); }

        osg::GraphicsCostEstimator* getGraphicsCostEstimator() { return _graphicsCostEstimator.get(); }
        const osg::GraphicsCostEstimator* getGraphicsCostEstimator() const { return _graphicsCostEstimator.get(); }


        typedef std::vector<osg::GraphicsContext*> Contexts;
        void assignContexts(Contexts& contexts);
        void removeContexts(Contexts& contexts);

        void addGraphicsContext(osg::GraphicsContext* gc);
        void removeGraphicsContext(osg::GraphicsContext* gc);

        typedef std::set<osg::GraphicsContext*> ContextSet;
        ContextSet& getContextSet() { return _contexts; }
        const ContextSet& getContextSet() const { return _contexts; }


        /** Merge subgraphs that have been compiled.*/
        void mergeCompiledSubgraphs();

        virtual void operator () (osg::GraphicsContext* context);

        struct OSGUTIL_EXPORT CompileInfo : public osg::RenderInfo
        {
            CompileInfo(osg::GraphicsContext* context, IncrementalCompileOperation* ico);

            double availableTime() { return allocatedTime - timer.elapsedTime(); }
            
            IncrementalCompileOperation*        incrementalCompileOperation;
            osg::GraphicsCostEstimator*         graphicsCostEstimator;
            unsigned int                        maxNumObjectsToCompile;
            osg::ElapsedTime                    timer;
            double                              allocatedTime;
        };
        
        struct CompileOp : public osg::Referenced
        {
            /** return an estimate for how many seconds the compile will take.*/
            virtual double estimatedTimeForCompile(CompileInfo& compileInfo) const = 0;
            /** compile associated objects, return true if object as been fully compiled and this CompileOp can be removed from the to compile list.*/
            virtual bool compile(CompileInfo& compileInfo) = 0;
        };

        struct OSGUTIL_EXPORT CompileDrawableOp : public CompileOp
        {
            CompileDrawableOp(osg::Drawable* drawable);
            double estimatedTimeForCompile(CompileInfo& compileInfo) const;
            bool compile(CompileInfo& compileInfo);
            osg::ref_ptr<osg::Drawable> _drawable;
        };

        struct OSGUTIL_EXPORT CompileTextureOp : public CompileOp
        {
            CompileTextureOp(osg::Texture* texture);
            double estimatedTimeForCompile(CompileInfo& compileInfo) const;
            bool compile(CompileInfo& compileInfo);
            osg::ref_ptr<osg::Texture> _texture;
        };

        struct OSGUTIL_EXPORT CompileProgramOp : public CompileOp
        {
            CompileProgramOp(osg::Program* program);
            double estimatedTimeForCompile(CompileInfo& compileInfo) const;
            bool compile(CompileInfo& compileInfo);
            osg::ref_ptr<osg::Program> _program;
        };

        class OSGUTIL_EXPORT CompileList
        {
        public:
            CompileList();
            ~CompileList();

            bool empty() const { return _compileOps.empty(); }
            void add(CompileOp* compileOp);
            void add(osg::Drawable* drawable) { add(new CompileDrawableOp(drawable)); }
            void add(osg::Texture* texture) { add(new CompileTextureOp(texture)); }
            void add(osg::Program* program) { add(new CompileProgramOp(program)); }

            double estimatedTimeForCompile(CompileInfo& compileInfo) const;
            bool compile(CompileInfo& compileInfo);


            typedef std::list< osg::ref_ptr<CompileOp> > CompileOps;
            CompileOps _compileOps;
        };


        class CompileSet;
        
        struct CompileCompletedCallback : public virtual osg::Referenced
        {
            /// return true if the callback assumes responsibility for merging any associated subgraphs with the main scene graph
            /// return false if callback doesn't handle the merge, and instead requires the IncrementalCompileOperation to handle this for us
            virtual bool compileCompleted(CompileSet* compileSet) = 0;
        };

        class OSGUTIL_EXPORT CompileSet : public osg::Referenced
        {
        public:
            CompileSet() {}

            CompileSet(osg::Node*subgraphToCompile):
                _subgraphToCompile(subgraphToCompile) {}

            CompileSet(osg::Group* attachmentPoint, osg::Node* subgraphToCompile):
                _attachmentPoint(attachmentPoint),
                _subgraphToCompile(subgraphToCompile) {}

            void buildCompileMap(ContextSet& contexts, StateToCompile& stateToCompile);
            void buildCompileMap(ContextSet& contexts, GLObjectsVisitor::Mode mode=GLObjectsVisitor::COMPILE_DISPLAY_LISTS|GLObjectsVisitor::COMPILE_STATE_ATTRIBUTES);

            bool compile(CompileInfo& compileInfo);

            OpenThreads::Atomic                     _numberCompileListsToCompile;

            osg::observer_ptr<osg::Group>           _attachmentPoint;
            osg::ref_ptr<osg::Node>                 _subgraphToCompile;
            osg::ref_ptr<CompileCompletedCallback>  _compileCompletedCallback;

            typedef std::map<osg::GraphicsContext*, CompileList >  CompileMap;
            CompileMap                              _compileMap;

        protected:

            virtual ~CompileSet() {}
        };

        typedef std::list< osg::ref_ptr<CompileSet> >  CompileSets;

        /** Add a subgraph to be compiled.*/
        void add(osg::Node* subgraphToCompile);

        /** Add a subgraph to be compiled and add automatically to attachPoint on call to mergeCompiledSubgraphs.*/
        void add(osg::Group* attachmentPoint, osg::Node* subgraphToCompile);

        /** Add a CompileSet to be compiled.*/
        void add(CompileSet* compileSet, bool callBuildCompileMap=true);

        /** Remove CompileSet from list.*/
        void remove(CompileSet* compileSet);

        
        OpenThreads::Mutex* getToCompiledMutex() { return &_toCompileMutex; }
        CompileSets& getToCompile() { return _toCompile; }
        
        OpenThreads::Mutex* getCompiledMutex() { return &_compiledMutex; }
        CompileSets& getCompiled() { return _compiled; }

    protected:

        virtual ~IncrementalCompileOperation();
        
    
        double                              _targetFrameRate;
        double                              _minimumTimeAvailableForGLCompileAndDeletePerFrame;
        unsigned int                        _maximumNumOfObjectsToCompilePerFrame;
        double                              _flushTimeRatio;
        double                              _conservativeTimeRatio;

        osg::ref_ptr<osg::Geometry>         _forceTextureDownloadGeometry;
        osg::ref_ptr<osg::GraphicsCostEstimator> _graphicsCostEstimator;

        OpenThreads::Mutex                  _toCompileMutex;
        CompileSets                         _toCompile;
        
        OpenThreads::Mutex                  _compiledMutex;
        CompileSets                         _compiled;
        
        ContextSet                          _contexts;

};

}

#endif