/* Copyright (C) 2011 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * 0 A.D. 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_SHADERMANAGER
#define INCLUDED_SHADERMANAGER

#define USE_SHADER_XML_VALIDATION 1

#include <boost/unordered_map.hpp>
#include <boost/weak_ptr.hpp>

#include "graphics/ShaderProgram.h"

#if USE_SHADER_XML_VALIDATION
# include "ps/XML/RelaxNG.h"
#endif

#include <set>

/**
 * Shader manager: loads and caches shader programs.
 */
class CShaderManager
{
public:
	CShaderManager();
	~CShaderManager();

	/**
	 * Load a shader program.
	 * @param name name of shader XML specification (file is loaded from shaders/${name}.xml)
	 * @param defines key/value set of preprocessor definitions
	 * @return loaded program, or null pointer on error
	 */
	CShaderProgramPtr LoadProgram(const char* name, const std::map<CStr, CStr>& defines);

private:
	bool NewProgram(const char* name, const std::map<CStr, CStr>& defines, CShaderProgramPtr& program);

	static Status ReloadChangedFileCB(void* param, const VfsPath& path);
	Status ReloadChangedFile(const VfsPath& path);

	struct CacheKey
	{
		std::string name;
		std::map<CStr, CStr> defines;

		bool operator<(const CacheKey& k) const
		{
			if (name < k.name) return true;
			if (k.name < name) return false;
			return defines < k.defines;
		}
	};

	std::map<CacheKey, CShaderProgramPtr> m_Cache;

	// Store the set of shaders that need to be reloaded when the given file is modified
	typedef boost::unordered_map<VfsPath, std::set<boost::weak_ptr<CShaderProgram> > > HotloadFilesMap;
	HotloadFilesMap m_HotloadFiles;

#if USE_SHADER_XML_VALIDATION
	RelaxNGValidator m_Validator;
#endif
};

#endif // INCLUDED_SHADERMANAGER