/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 Robert Osfield 
 * Copyright (C) 2003-2005 3Dlabs Inc. Ltd.
 * Copyright (C) 2004-2005 Nathan Cournia
 *
 * 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/Shader
 * author:	Mike Weiblen 2005-04-06
*/

#ifndef OSG_SHADER
#define OSG_SHADER 1

#include <set>
#include <string>

#include <osg/Program>

namespace osg {

///////////////////////////////////////////////////////////////////////////
/** osg::Shader is an application-level abstraction of an OpenGL glShader.
  * It is a container to load the shader source code text and manage its
  * compilation.
  * An osg::Shader may be attached to more than one osg::Program.
  * Shader will automatically manage per-context instancing of the
  * internal objects, if that is necessary for a particular display
  * configuration.
  */

class OSG_EXPORT Shader : public osg::Object
{
    public:

	enum Type {
	    VERTEX = GL_VERTEX_SHADER,
	    FRAGMENT = GL_FRAGMENT_SHADER,
	    UNDEFINED = -1
	};

        Shader();
        Shader( Type type, const char* sourceText = 0 );

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

	META_Object(osg, Shader);

        int compare(const Shader& rhs) const;

	bool setType( Type t );

	/** Load the Shader's source code text from a string. */
	void setShaderSource( const char* sourceText );

	/** Load the Shader's source code text from a file. */
	bool loadShaderSourceFromFile( const char* fileName );

	/** Query the shader's source code text */
	inline const std::string& getShaderSource() const { return _shaderSource; }

	/** Get the Shader type as an enum. */
	inline Type getType() const { return _type; }

	/** Get the Shader type as a descriptive string. */
	const char* getTypename() const;

        /** Mark our PCSs as needing recompilation.
	  * Also mark Programs that depend on us as needing relink */
        void dirtyShader();        

	/** If needed, compile the PCS's glShader */
	void compileShader(unsigned int contextID) const;

	/** For a given GL context, attach a glShader to a glProgram */
	void attachShader(unsigned int contextID, GLuint program) const;

	/** Query InfoLog from a glShader */
	void getGlShaderInfoLog(unsigned int contextID, std::string& log) const;

	/** A name for use by the application */
	void setName( const std::string& name ) { _name = name; }
	void setName( const char* name ) { _name = name; }
	const std::string& getName() const { return _name; };

	/** Mark internal glShader for deletion.
	  * Deletion requests are queued tuntil they can be executed
	  * in the proper GL context. */
	static void deleteGlShader(unsigned int contextID, GLuint shader);

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

	static Shader::Type getTypeId( const std::string& tname );

    protected:
	/** PerContextShader (PCS) is an OSG-internal encapsulation of glShader per-GL context. */
	class PerContextShader : public osg::Referenced
	{
	    public:
		PerContextShader(const Shader* shader, unsigned int contextID);

		GLuint getHandle() const {return _glShaderHandle;}

		void requestCompile();
		void compileShader();
		void getInfoLog( std::string& infoLog ) const;

		/** Attach our glShader to a glProgram */
		void attachShader(GLuint program) const;

		/** Detach our glShader from a glProgram */
		void detachShader(GLuint program) const;

	    protected:	/*methods*/
		~PerContextShader();

	    protected:	/*data*/
		/** Pointer to our parent osg::Shader */
		const Shader* _shader;
		/** Pointer to this context's extension functions. */
		osg::ref_ptr<osg::GL2Extensions> _extensions;
		/** Handle to the actual glShader. */
		GLuint _glShaderHandle;
		/** Does our glShader need to be recompiled? */
		bool _needsCompile;
		/** Is our glShader successfully compiled? */
		bool _isCompiled;
		const unsigned int _contextID;

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

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

        PerContextShader* getPCS(unsigned int contextID) const;

	friend class Program;
	bool addProgramRef( Program* program );
	bool removeProgramRef( Program* program );

    protected:	/*data*/
	Type _type;
	std::string _name;
	std::string _shaderSource;
	/** osg::Programs that this osg::Shader is attached to */
	typedef std::set< Program* > ProgramSet;
	ProgramSet _programSet;
        mutable osg::buffered_value< osg::ref_ptr<PerContextShader> > _pcsList;

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

}

#endif

/*EOF*/