/*
    This file is part of Mitsuba, a physically based rendering system.

    Copyright (c) 2007-2012 by Wenzel Jakob and others.

    Mitsuba is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License Version 3
    as published by the Free Software Foundation.

    Mitsuba 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/

#pragma once
#if !defined(__MITSUBA_RENDER_SCENEHANDLER_H_)
#define __MITSUBA_RENDER_SCENEHANDLER_H_

#include <xercesc/sax/HandlerBase.hpp>
#include <xercesc/sax/AttributeList.hpp>
#include <mitsuba/core/plugin.h>
#include <mitsuba/core/properties.h>
#include <mitsuba/core/version.h>
#include <boost/unordered_map.hpp>
#include <stack>
#include <map>

XERCES_CPP_NAMESPACE_BEGIN
class SAXParser;
class XMLTranscoder;
XERCES_CPP_NAMESPACE_END

MTS_NAMESPACE_BEGIN
namespace xercesc = XERCES_CPP_NAMESPACE;

#ifdef _MSC_VER
// Disable warning 4275: non dll-interface used as base for dll-interface class
// Can be safely ignored when deriving from a type in the Standard C++ Library
# pragma warning( push )
# pragma warning( disable : 4275 )
#endif

/**
 * \brief This exception is thrown when attempting to load an outdated file
 * \ingroup librender
 */
class MTS_EXPORT_RENDER VersionException : public std::runtime_error {
public:
	VersionException(const std::string &str, const Version &version) :
		std::runtime_error(str), m_version(version) { }

	/* For stupid and subtle reasons when compiling with GCC, it is important
	   that this class has a virtual member. This will ensure that its typeid
	   structure is in librender, which is important for throwing exceptions
	   across DLL boundaries */
	virtual ~VersionException() throw ();

	inline const Version &getVersion() const { return m_version; }
private:
	Version m_version;
};

#ifdef _MSC_VER
# pragma warning( pop )
#endif

/**
 * \brief XML parser for Mitsuba scene files. To be used with the
 * SAX interface of Xerces-C++.
 *
 * \remark In the Python bindings, only the static function
 *         \ref loadScene() is exposed.
 * \ingroup librender
 * \ingroup libpython
 */
class MTS_EXPORT_RENDER SceneHandler : public xercesc::HandlerBase {
public:
	typedef std::map<std::string, ConfigurableObject *> NamedObjectMap;
	typedef std::map<std::string, std::string, SimpleStringOrdering> ParameterMap;

	SceneHandler(const xercesc::SAXParser *parser,
			const ParameterMap &params, NamedObjectMap *objects = NULL,
			bool isIncludedFile = false);
	virtual ~SceneHandler();

	/// Convenience method -- load a scene from a given filename
	static ref<Scene> loadScene(const fs::path &filename,
		const ParameterMap &params= ParameterMap());

	/// Convenience method -- load a scene from a given string
	static ref<Scene> loadSceneFromString(const std::string &string,
		const ParameterMap &params= ParameterMap());

	/// Initialize Xerces-C++ (needs to be called once at program startup)
	static void staticInitialization();

	/// Free the memory taken up by staticInitialization()
	static void staticShutdown();

	/// Push a cleanup handler to be executed after loading the scene is done
	static void pushCleanupHandler(void (*cleanup)());

	// -----------------------------------------------------------------------
	//  Implementation of the SAX DocumentHandler interface
	// -----------------------------------------------------------------------
	virtual void startDocument();
	virtual void endDocument();
	virtual void startElement(
		const XMLCh* const name,
		xercesc::AttributeList& attributes
	);
	virtual void endElement(const XMLCh* const name);
	virtual void characters(const XMLCh* const chars, const XMLSize_t length);

	inline const Scene *getScene() const { return m_scene.get(); }
	inline Scene *getScene() { return m_scene; }

	// -----------------------------------------------------------------------
	//  Implementation of the SAX ErrorHandler interface
	// -----------------------------------------------------------------------
	void warning(const xercesc::SAXParseException& exc);
	void error(const xercesc::SAXParseException& exc);
	void fatalError(const xercesc::SAXParseException& exc);
protected:
	std::string transcode(const XMLCh * input) const;

	Float parseFloat(const std::string &name, const std::string &str,
			Float defVal = -1) const;

	void clear();

private:
	struct ParseContext {
		inline ParseContext(ParseContext *_parent)
		 : parent(_parent) {
		}

		ParseContext *parent;
		Properties properties;
		std::map<std::string, std::string> attributes;
		std::vector<std::pair<std::string, ConfigurableObject *> > children;
	};

	/**
	 * Enumeration of all possible tags that can be encountered in a
	 * Mitsuba scene file
	 */
	enum ETag {
		EScene, EShape, ESampler, EFilm,
		EIntegrator, ETexture, ESensor,
		EEmitter, ESubsurface, EMedium,
		EVolume, EPhase, EBSDF, ERFilter,
		ENull, EReference, EInteger, EFloat,
		EBoolean, EString, ETranslate, ERotate,
		ELookAt, EScale, EMatrix, EPoint,
		EVector, ERGB, ESRGB, EBlackBody,
		ESpectrum, ETransform, EAnimation,
		EInclude, EAlias
	};

	typedef std::pair<ETag, const Class *> TagEntry;
	typedef boost::unordered_map<std::string, TagEntry> TagMap;

	const xercesc::SAXParser *m_parser;
	xercesc::XMLTranscoder* m_transcoder;
	ref<Scene> m_scene;
	ParameterMap m_params;
	NamedObjectMap *m_namedObjects;
	PluginManager *m_pluginManager;
	std::stack<ParseContext> m_context;
	TagMap m_tags;
	Transform m_transform;
	ref<AnimatedTransform> m_animatedTransform;
	bool m_isIncludedFile;
};

MTS_NAMESPACE_END

#endif /* __MITSUBA_RENDER_SCENEHANDLER_H_ */