/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2013 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/
#ifndef __GLSLLinkProgramManager_H__
#define __GLSLLinkProgramManager_H__

#include "OgreGLPrerequisites.h"
#include "OgreSingleton.h"

#include "OgreGLSLExtSupport.h"
#include "OgreGLSLLinkProgram.h"

namespace Ogre {

    namespace GLSL {

	/** Ogre assumes that there are separate vertex and fragment programs to deal with but
		GLSL has one program object that represents the active vertex and fragment shader objects
		during a rendering state.  GLSL Vertex and fragment 
		shader objects are compiled separately and then attached to a program object and then the
		program object is linked.  Since Ogre can only handle one vertex program and one fragment
		program being active in a pass, the GLSL Link Program Manager does the same.  The GLSL Link
		program manager acts as a state machine and activates a program object based on the active
		vertex and fragment program.  Previously created program objects are stored along with a unique
		key in a hash_map for quick retrieval the next time the program object is required.

	*/

	class _OgreGLExport GLSLLinkProgramManager : public Singleton<GLSLLinkProgramManager>
	{

	private:
	
		typedef map<uint64, GLSLLinkProgram*>::type LinkProgramMap;
		typedef LinkProgramMap::iterator LinkProgramIterator;

		/// container holding previously created program objects 
		LinkProgramMap mLinkPrograms; 

		/// active objects defining the active rendering gpu state
		GLSLGpuProgram* mActiveVertexGpuProgram;
		GLSLGpuProgram* mActiveGeometryGpuProgram;
		GLSLGpuProgram* mActiveFragmentGpuProgram;
		GLSLLinkProgram* mActiveLinkProgram;

		typedef map<String, GLenum>::type StringToEnumMap;
		StringToEnumMap mTypeEnumMap;

		/// Use type to complete other information
		void completeDefInfo(GLenum gltype, GpuConstantDefinition& defToUpdate);
		/// Find where the data for a specific uniform should come from, populate
		bool completeParamSource(const String& paramName,
			const GpuConstantDefinitionMap* vertexConstantDefs, 
			const GpuConstantDefinitionMap* geometryConstantDefs,
			const GpuConstantDefinitionMap* fragmentConstantDefs,
			GLUniformReference& refToUpdate);

	public:

		GLSLLinkProgramManager(void);

		~GLSLLinkProgramManager(void);

		/**
			Get the program object that links the two active shader objects together
			if a program object was not already created and linked a new one is created and linked
		*/
		GLSLLinkProgram* getActiveLinkProgram(void);

		/** Set the active fragment shader for the next rendering state.
			The active program object will be cleared.
			Normally called from the GLSLGpuProgram::bindProgram and unbindProgram methods
		*/
		void setActiveFragmentShader(GLSLGpuProgram* fragmentGpuProgram);
		/** Set the active geometry shader for the next rendering state.
			The active program object will be cleared.
			Normally called from the GLSLGpuProgram::bindProgram and unbindProgram methods
		*/
		void setActiveGeometryShader(GLSLGpuProgram* geometryGpuProgram);
		/** Set the active vertex shader for the next rendering state.
			The active program object will be cleared.
			Normally called from the GLSLGpuProgram::bindProgram and unbindProgram methods
		*/
		void setActiveVertexShader(GLSLGpuProgram* vertexGpuProgram);

		/** Populate a list of uniforms based on a program object.
		@param programObject Handle to the program object to query
		@param vertexConstantDefs Definition of the constants extracted from the
			vertex program, used to match up physical buffer indexes with program
			uniforms. May be null if there is no vertex program.
		@param geometryConstantDefs Definition of the constants extracted from the
			geometry program, used to match up physical buffer indexes with program
			uniforms. May be null if there is no geometry program.
		@param fragmentConstantDefs Definition of the constants extracted from the
			fragment program, used to match up physical buffer indexes with program
			uniforms. May be null if there is no fragment program.
		@param list The list to populate (will not be cleared before adding, clear
		it yourself before calling this if that's what you want).
		*/
		void extractUniforms(GLhandleARB programObject, 
			const GpuConstantDefinitionMap* vertexConstantDefs, 
			const GpuConstantDefinitionMap* geometryConstantDefs,
			const GpuConstantDefinitionMap* fragmentConstantDefs,
			GLUniformReferenceList& list);
		/** Populate a list of uniforms based on GLSL source.
		@param src Reference to the source code
		@param constantDefs The defs to populate (will not be cleared before adding, clear
		it yourself before calling this if that's what you want).
		@param filename The file name this came from, for logging errors.
		*/
		void extractConstantDefs(const String& src, GpuNamedConstants& constantDefs, 
			const String& filename);

		static GLSLLinkProgramManager& getSingleton(void);
        static GLSLLinkProgramManager* getSingletonPtr(void);

	};

    }
}

#endif // __GLSLLinkProgramManager_H__
