BansheeEngine/BansheeCore/Include/BsGpuProgramManager.h

#pragma once

#include "BsCorePrerequisites.h"
#include "BsModule.h"
#include "BsException.h"
#include "BsGpuProgram.h"

namespace BansheeEngine 
{
	/**
	 * @brief	Factory responsible for creating GPU programs of a certain type.
	 */
	class BS_CORE_EXPORT GpuProgramFactory
	{
	public:
        GpuProgramFactory() {}
        virtual ~GpuProgramFactory();

		/**
		 * @brief	Returns GPU program language this factory is capable creating GPU programs from.
		 */
		virtual const String& getLanguage() const = 0;

		/**
		 * @brief	Creates a new GPU program using the provided source code. If compilation fails or program is not supported
		 *			"isCompiled" method on the returned program will return false, and you will be able to retrieve the error message 
		 *			via "getCompileErrorMessage".
		 *
		 * @param	source		Source code to compile the shader from.
		 * @param	entryPoint	Name of the entry point function, e.g. "main".
		 * @param	gptype		Type of the program, e.g. vertex or fragment.
		 * @param	profile		Program profile specifying supported feature-set. Must match the type.
		 * @param	includes	Optional includes to append to the source before compiling.
		 * @param	requiresAdjacency	If true then adjacency information will be provided when rendering using this program.
		 */
		virtual GpuProgramPtr create(const String& source, const String& entryPoint, GpuProgramType gptype, 
			GpuProgramProfile profile, const Vector<HGpuProgInclude>* includes, bool requiresAdjacencyInformation) = 0;

		/**
		 * @copydoc	GpuProgramManager::createEmpty
		 */
		virtual GpuProgramPtr create(GpuProgramType type) = 0;
	};

	/**
	 * @brief	Manager responsible for creating GPU programs. It will automatically
	 *			try to find the approriate handler for a specific GPU program language
	 *			and create the program if possible.
	 *
	 * @note	Sim thread only.
	 */
	class BS_CORE_EXPORT GpuProgramManager : public Module<GpuProgramManager>
	{
	public:
		
	public:
		GpuProgramManager();
		~GpuProgramManager();

		/**
		 * @brief	Registers a new factory that is able to create GPU programs for a certain language.
		 *			If any other factory for the same language exists, it will overwrite it.
		 */
		void addFactory(GpuProgramFactory* factory);

		/**
		 * @brief	Unregisters a GPU program factory, essentially making it not possible to create GPU programs
		 *			using the language the factory supported.
		 */
		void removeFactory(GpuProgramFactory* factory);

		/**
		 * @brief	Query if a GPU program language is supported. (.e.g. "hlsl", "glsl").
		 */
		bool isLanguageSupported(const String& lang);

		/**
		 * @brief	Creates a new GPU program using the provided source code. If compilation fails or program is not supported
		 *			"isCompiled" method on the returned program will return false, and you will be able to retrieve the error message 
		 *			via "getCompileErrorMessage".
		 *
		 * @param	source		Source code to compile the shader from.
		 * @param	entryPoint	Name of the entry point function, e.g. "main".
		 * @param	language	Language the source is written in, e.g. "hlsl" or "glsl".
		 * @param	gptype		Type of the program, e.g. vertex or fragment.
		 * @param	profile		Program profile specifying supported feature-set. Must match the type.
		 * @param	includes	Optional includes to append to the source before compiling.
		 * @param	requiresAdjacency	If true then adjacency information will be provided when rendering using this program.
		 */
		GpuProgramPtr create(const String& source, const String& entryPoint, const String& language, 
			GpuProgramType gptype, GpuProgramProfile profile, const Vector<HGpuProgInclude>* includes,
			bool requiresAdjacency = false);

		/**
		 * @brief	Creates a completely empty and uninitialized GpuProgram.
		 * 			Should only be used for specific purposes, like deserialization,
		 * 			as it requires additional manual initialization that is not required normally.
		 */
		GpuProgramPtr createEmpty(const String& language, GpuProgramType type);

	protected:
		/**
		 * @brief	Attempts to find a factory for the specified language. Returns null if it cannot find one.
		 */
		GpuProgramFactory* getFactory(const String& language);

	protected:
		typedef Map<String, GpuProgramFactory*> FactoryMap;

		FactoryMap mFactories;
		GpuProgramFactory* mNullFactory; /**< Factory for dealing with GPU programs that can't be created. */
	};
}