#ifndef _VIRTUAL_PROGRAM__
#define _VIRTUAL_PROGRAM__ 1

#include<string>
#include<map>
#include<osg/Shader>
#include<osg/Program>

////////////////////////////////////////////////////////////////////////////////
namespace osgCandidate {
////////////////////////////////////////////////////////////////////////////////
class VirtualProgram: public osg::Program
{
public: 
    VirtualProgram( unsigned int mask = 0xFFFFFFFFUL );

    virtual ~VirtualProgram( void );

    VirtualProgram( const VirtualProgram& VirtualProgram, 
                    const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY );

    META_StateAttribute( osgCandidate, VirtualProgram, Type( PROGRAM ) )

    /** return -1 if *this < *rhs, 0 if *this==*rhs, 1 if *this>*rhs.*/
    virtual int compare(const StateAttribute& sa) const
    {
       // check the types are equal and then create the rhs variable
       // used by the COMPARE_StateAttribute_Paramter macro's below.
       COMPARE_StateAttribute_Types(VirtualProgram,sa)

       // compare each paramter in turn against the rhs.
       COMPARE_StateAttribute_Parameter(_mask)
       COMPARE_StateAttribute_Parameter(_shaderMap)
       return 0; // passed all the above comparison macro's, must be equal.
    }

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

    osg::Shader* getShader            ( const std::string & shaderSemantic,
                                        osg::Shader::Type type );
    
    osg::Shader* setShader            ( const std::string & shaderSemantic,
                                        osg::Shader * shader );

protected:
    typedef std::vector< osg::ref_ptr< osg::Shader > >            ShaderList;
    typedef std::pair< std::string, osg::Shader::Type >           ShaderSemantic;
    typedef std::map< ShaderSemantic, osg::ref_ptr<osg::Shader> > ShaderMap;
    typedef std::map< ShaderList, osg::ref_ptr<osg::Program> >    ProgramMap;

    mutable ProgramMap                   _programMap;
    ShaderMap                            _shaderMap;
    unsigned int                         _mask;
}; // class VirtualProgram
////////////////////////////////////////////////////////////////////////////////

} // namespace osgCandidate
////////////////////////////////////////////////////////////////////////////////
#endif