/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield 
 * Copyright (C) 2003-2005 3Dlabs Inc. Ltd.
 * Copyright (C) 2004-2005 Nathan Cournia
 * Copyright (C) 2008 Zebra Imaging
 *
 * This application is open source and may be redistributed and/or modified
 * freely and without restriction, both in commericial and non commericial
 * applications, as long as this copyright notice is maintained.
 * 
 * This application 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.
*/

/* file:        include/osg/Program
 * author:      Mike Weiblen 2008-01-02
*/

#ifndef OSG_PROGRAM
#define OSG_PROGRAM 1

#include <string>
#include <vector>
#include <map>

#include <osg/buffered_value>
#include <osg/ref_ptr>
#include <osg/Uniform>
#include <osg/Shader>
#include <osg/StateAttribute>

namespace osg {

class State;

///////////////////////////////////////////////////////////////////////////
/** osg::Program is an application-level abstraction of an OpenGL glProgram.
  * It is an osg::StateAttribute that, when applied, will activate a
  * glProgram for subsequent rendering.
  * osg::Shaders containing the actual shader source code are
  * attached to a Program, which will then manage the compilation,
  * linking, and activation of the GLSL program.
  * osg::Program will automatically manage per-context instancing of the
  * OpenGL glPrograms, if that is necessary for a particular display
  * configuration.
  */

class OSG_EXPORT Program : public osg::StateAttribute
{
    public:
        Program();

        /** Copy constructor using CopyOp to manage deep vs shallow copy.*/
        Program(const Program& rhs, const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY);

        META_StateAttribute(osg, Program, PROGRAM);

        /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
        virtual int compare(const osg::StateAttribute& sa) const;

        /** If enabled, activate our program in the GL pipeline,
          * performing any rebuild operations that might be pending. */
        virtual void apply(osg::State& state) const;

        /** Set whether to use a mutex to ensure ref() and unref() are thread safe.*/
        virtual void setThreadSafeRefUnref(bool threadSafe);

        /** Compile program and associated shaders.*/
        virtual void compileGLObjects(osg::State& state) const;

        /** Resize any per context GLObject buffers to specified size. */
        virtual void resizeGLObjectBuffers(unsigned int maxSize);

        /** release OpenGL objects in specified graphics context if State
            object is passed, otherwise release OpenGL objects for all graphics context if
            State object pointer NULL.*/
        virtual void releaseGLObjects(osg::State* state=0) const;

        /** Mark our PCSOs as needing relink */
        void dirtyProgram();

        /** Attach an osg::Shader to this osg::Program.
          * Mark Program as needing relink.  Return true for success */
        bool addShader( Shader* shader );

        unsigned int getNumShaders() const { return _shaderList.size(); }

        Shader* getShader( unsigned int i ) { return _shaderList[i].get(); }
        const Shader* getShader( unsigned int i ) const { return _shaderList[i].get(); }

        /** Remove osg::Shader from this osg::Program.
          * Mark Program as needing relink.  Return true for success */
        bool removeShader( Shader* shader );

        /** Set/get GL program parameters */
        void setParameter( GLenum pname, GLint value );
        GLint getParameter( GLenum pname ) const;

        /** Add an attribute location binding. */
        void addBindAttribLocation( const std::string& name, GLuint index );
        
        /** Remove an attribute location binding. */
        void removeBindAttribLocation( const std::string& name );

        /** Add an frag data location binding. See EXT_gpu_shader4 for BindFragDataLocationEXT */
        void addBindFragDataLocation( const std::string& name, GLuint index );

        /** Remove an frag data location binding. */
        void removeBindFragDataLocation( const std::string& name );

        typedef std::map<std::string,GLuint> AttribBindingList;
        typedef std::map<std::string,GLuint> FragDataBindingList;

        const AttribBindingList& getAttribBindingList() const { return _attribBindingList; }
        const FragDataBindingList& getFragDataBindingList() const { return _fragDataBindingList; }

        /** Return true if this Program represents "fixed-functionality" rendering */
        bool isFixedFunction() const;

        /** Query InfoLog from a glProgram */
        bool getGlProgramInfoLog(unsigned int contextID, std::string& log) const;

        /** Mark internal glProgram for deletion.
          * Deletion requests are queued until they can be executed
          * in the proper GL context. */
        static void deleteGlProgram(unsigned int contextID, GLuint program);

        /** flush all the cached glPrograms which need to be deleted
          * in the OpenGL context related to contextID.*/
        static void flushDeletedGlPrograms(unsigned int contextID,double currentTime, double& availableTime);

        /** discard all the cached glPrograms which need to be deleted
          * in the OpenGL context related to contextID.
          * Note, unlike flush no OpenGL calls are made, instead the handles are all removed.
          * this call is useful for when an OpenGL context has been destroyed. */
        static void discardDeletedGlPrograms(unsigned int contextID);

        struct ActiveVarInfo {
            ActiveVarInfo() : _location(-1), _type(Uniform::UNDEFINED), _size(-1) {}
            ActiveVarInfo( GLint loc, GLenum type, GLint size ) : _location(loc), _type(type), _size(size) {}
            GLint _location;
            GLenum _type;
            GLint _size;
        };
        typedef std::map< std::string, ActiveVarInfo > ActiveVarInfoMap;
        const ActiveVarInfoMap& getActiveUniforms(unsigned int contextID) const;
        const ActiveVarInfoMap& getActiveAttribs(unsigned int contextID) const;

    public:

        // make PerContextProgram a friend to allow it access Program's protected
        // methods and member variables.
        class PerContextProgram;
        friend class PerContextProgram;

        /** PerContextProgram (PCP) is an OSG-internal encapsulation of glPrograms per-GL context.  */
        class OSG_EXPORT PerContextProgram : public osg::Referenced
        {
            public:
                PerContextProgram(const Program* program, unsigned int contextID);

                GLuint getHandle() const {return _glProgramHandle;}

                void requestLink();
                void linkProgram();
                bool validateProgram();
                bool needsLink() const {return _needsLink;}
                bool isLinked() const {return _isLinked;}
                bool getInfoLog( std::string& infoLog ) const;

                void useProgram() const;

                void resetAppliedUniforms() const
                {
                    for(LastAppliedUniformList::iterator itr=_lastAppliedUniformList.begin();
                        itr!=_lastAppliedUniformList.end();
                        ++itr)
                    {
                        (*itr).first = 0;
                        (*itr).second = 0;
                    }
                }
                
                
                inline void apply(const Uniform& uniform) const
                {
                    GLint location = getUniformLocation(uniform.getName());
                    if (location>=0)
                    {
                        if ((unsigned int)location>=_lastAppliedUniformList.size()) _lastAppliedUniformList.resize(location+1);
                        const Uniform* lastAppliedUniform = _lastAppliedUniformList[location].first.get();
                        if (lastAppliedUniform != &uniform)
                        {
                            // new attribute
                            uniform.apply(_extensions.get(),location);
                            _lastAppliedUniformList[location].first = &uniform;
                            _lastAppliedUniformList[location].second = uniform.getModifiedCount();
                        }
                        else if (_lastAppliedUniformList[location].second != uniform.getModifiedCount())
                        {
                            // existing attribute has been modified
                            uniform.apply(_extensions.get(),location);
                            _lastAppliedUniformList[location].first = &uniform;
                            _lastAppliedUniformList[location].second = uniform.getModifiedCount();
                        }
                    }
                }

                const ActiveVarInfoMap& getActiveUniforms() const {return _uniformInfoMap;}
                const ActiveVarInfoMap& getActiveAttribs() const {return _attribInfoMap;}

                inline GLint getUniformLocation( const std::string& name ) const { ActiveVarInfoMap::const_iterator itr = _uniformInfoMap.find(name); return (itr!=_uniformInfoMap.end()) ? itr->second._location : -1; }
                inline GLint getAttribLocation( const std::string& name ) const { ActiveVarInfoMap::const_iterator itr = _attribInfoMap.find(name); return (itr!=_attribInfoMap.end()) ? itr->second._location : -1; }

                inline void addShaderToAttach(Shader *shader)
                {
                    _shadersToAttach.push_back(shader);
                }

                inline void addShaderToDetach(Shader *shader)
                {
                    _shadersToDetach.push_back(shader);
                }
      
            protected:        /*methods*/
                ~PerContextProgram();

            protected:        /*data*/
                /** Pointer to our parent Program */
                const Program* _program;
                /** Pointer to this context's extension functions */
                osg::ref_ptr<GL2Extensions> _extensions;
                /** Handle to the actual OpenGL glProgram */
                GLuint _glProgramHandle;
                /** Does our glProgram need to be linked? */
                bool _needsLink;
                /** Is our glProgram successfully linked? */
                bool _isLinked;
                const unsigned int _contextID;

                ActiveVarInfoMap _uniformInfoMap;
                ActiveVarInfoMap _attribInfoMap;
                
                typedef std::pair<osg::ref_ptr<const osg::Uniform>, unsigned int> UniformModifiedCountPair;
                typedef std::vector<UniformModifiedCountPair> LastAppliedUniformList;
                mutable LastAppliedUniformList _lastAppliedUniformList;
      
                typedef std::vector< ref_ptr<Shader> > ShaderList;
                ShaderList _shadersToDetach;
                ShaderList _shadersToAttach;

            private:
                PerContextProgram();        // disallowed
                PerContextProgram(const PerContextProgram&);        // disallowed
                PerContextProgram& operator=(const PerContextProgram&);        // disallowed
        };

        /** Get the PCP for a particular GL context */
        PerContextProgram* getPCP(unsigned int contextID) const;

    protected:        /*methods*/
        virtual ~Program();

    protected:        /*data*/

        mutable osg::buffered_value< osg::ref_ptr<PerContextProgram> > _pcpList;
        AttribBindingList _attribBindingList;
        FragDataBindingList _fragDataBindingList;

        typedef std::vector< ref_ptr<Shader> > ShaderList;
        ShaderList _shaderList;

        /** Parameters maintained with glProgramParameteriEXT */
        GLint _geometryVerticesOut;
        GLint _geometryInputType;
        GLint _geometryOutputType;

    private:
        Program& operator=(const Program&);        // disallowed
};

}

#endif
