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#ifndef CC_FILE_IO_FILTER_HEADER
#define CC_FILE_IO_FILTER_HEADER

//qCC_db
#include <ccHObject.h>

//local
#include "ccGlobalShiftManager.h"

class QWidget;

//! Typical I/O filter errors
enum CC_FILE_ERROR {CC_FERR_NO_ERROR,
					CC_FERR_BAD_ARGUMENT,
					CC_FERR_UNKNOWN_FILE,
					CC_FERR_WRONG_FILE_TYPE,
					CC_FERR_WRITING,
					CC_FERR_READING,
					CC_FERR_NO_SAVE,
					CC_FERR_NO_LOAD,
					CC_FERR_BAD_ENTITY_TYPE,
					CC_FERR_CANCELED_BY_USER,
					CC_FERR_NOT_ENOUGH_MEMORY,
					CC_FERR_MALFORMED_FILE,
					CC_FERR_CONSOLE_ERROR,
					CC_FERR_BROKEN_DEPENDENCY_ERROR,
					CC_FERR_FILE_WAS_WRITTEN_BY_UNKNOWN_PLUGIN,
					CC_FERR_THIRD_PARTY_LIB_FAILURE,
					CC_FERR_THIRD_PARTY_LIB_EXCEPTION,
					CC_FERR_NOT_IMPLEMENTED,
};

//! Generic file I/O filter
/** Gives static access to file loader.
	Must be implemented by any specific I/O filter.
**/
class FileIOFilter
{	
public:
	virtual ~FileIOFilter() = default;
	
	//! Generic loading parameters
	struct LoadParameters
	{
		//! Default constructor
		LoadParameters()
			: shiftHandlingMode(ccGlobalShiftManager::DIALOG_IF_NECESSARY)
			, alwaysDisplayLoadDialog(true)
			, coordinatesShiftEnabled(nullptr)
			, coordinatesShift(nullptr)
			, preserveShiftOnSave(true)
			, autoComputeNormals(false)
			, parentWidget(nullptr)
			, sessionStart(true)
		{}
		
		//! How to handle big coordinates
		ccGlobalShiftManager::Mode shiftHandlingMode;
		//! Wether to always display a dialog (if any), even if automatic guess is possible
		bool alwaysDisplayLoadDialog;
		//! Whether shift on load has been applied after loading (optional)
		bool* coordinatesShiftEnabled;
		//! If applicable, applied shift on load (optional)
		CCVector3d* coordinatesShift;
		//! If applicable, whether shift should be preserved or not (optional)
		bool preserveShiftOnSave;
		//! Whether normals should be computed at loading time (if possible - e.g. for gridded clouds) or not
		bool autoComputeNormals;
		//! Parent widget (if any)
		QWidget* parentWidget;
		//! Session start (whether the load action is the first of a session)
		bool sessionStart;
	};
	
	//! Generic saving parameters
	struct SaveParameters
	{
		//! Default constructor
		SaveParameters()
			: alwaysDisplaySaveDialog(true)
			, parentWidget(nullptr)
		{}
		
		//! Wether to always display a dialog (if any), even if automatic guess is possible
		bool alwaysDisplaySaveDialog;
		//! Parent widget (if any)
		QWidget* parentWidget;
	};
	
	//! Shared type
	using Shared = QSharedPointer<FileIOFilter>;
	
public: //public interface
	
	//! Returns whether this I/O filter can import files
	QCC_IO_LIB_API bool importSupported() const;
	
	//! Returns whether this I/O filter can export files
	QCC_IO_LIB_API bool exportSupported() const;
	
	//! Returns the file filter(s) for this I/O filter
	/** E.g. 'ASCII file (*.asc)'
		\param onImport whether the requested filters are for import or export
		\return list of filters
	**/
	QCC_IO_LIB_API const QStringList& getFileFilters(bool onImport) const;
	
	//! Returns the default file extension
	QCC_IO_LIB_API QString getDefaultExtension() const;

public: //public interface (to be reimplemented by each I/O filter)
	
	//! Loads one or more entities from a file
	/** This method must be implemented by children classes.
		\param filename file to load
		\param container container to store loaded entities
		\param parameters generic loading parameters
		\return error
	**/
	virtual CC_FILE_ERROR loadFile(	const QString& filename,
									ccHObject& container,
									LoadParameters& parameters)
	{
		Q_UNUSED( filename );
		Q_UNUSED( container );
		Q_UNUSED( parameters );
		
		return CC_FERR_NOT_IMPLEMENTED;
	}
	
	//! Saves an entity (or a group of) to a file
	/** This method must be implemented by children classes.
		\param entity entity (or group of) to save
		\param filename filename
		\param parameters generic saving parameters
		\return error
	**/
	virtual CC_FILE_ERROR saveToFile(	ccHObject* entity,
										const QString& filename,
										const SaveParameters& parameters)
	{
		Q_UNUSED( entity );
		Q_UNUSED( filename );
		Q_UNUSED( parameters );
		
		return CC_FERR_NOT_IMPLEMENTED;
	}
	
	//! Returns whether this I/O filter can save the specified type of entity
	/** \param type entity type
		\param multiple whether the filter can save multiple instances of this entity at once
		\param exclusive whether the filter can only save this type of entity if selected or if it can be mixed with other types
		\return whether the entity type can be saved
	**/
	virtual bool canSave(CC_CLASS_ENUM type, bool& multiple, bool& exclusive) const
	{
		Q_UNUSED( type );
		Q_UNUSED( multiple );
		Q_UNUSED( exclusive );
		
		return false;
	}
	
public: //static methods
	//! Get a list of all the available importer filter strings for use in a drop down menu.
	//! Includes "All (*.)" as the first item in the list.
	QCC_IO_LIB_API static QStringList ImportFilterList();
	
	//! Loads one or more entities from a file with a known filter
	/** Shortcut to FileIOFilter::loadFile
		\param filename filename
		\param parameters generic loading parameters
		\param filter input filter
		\param[out] result file error code
		\return loaded entities (or 0 if an error occurred)
	**/
	QCC_IO_LIB_API static ccHObject* LoadFromFile(	const QString& filename,
													LoadParameters& parameters,
													Shared filter,
													CC_FILE_ERROR& result);
	
	//! Loads one or more entities from a file with known type
	/** Shortcut to the other version of FileIOFilter::LoadFromFile
		\param filename filename
		\param parameters generic loading parameters
		\param[out] result file error code
		\param fileFilter input filter 'file filter' (if empty, the best I/O filter will be guessed from the file extension)
		\return loaded entities (or 0 if an error occurred)
	**/
	QCC_IO_LIB_API static ccHObject* LoadFromFile(	const QString& filename,
													LoadParameters& parameters,
													CC_FILE_ERROR& result,
													const QString& fileFilter = QString());
	
	//! Saves an entity (or a group of) to a specific file thanks to a given filter
	/** Shortcut to FileIOFilter::saveFile
		\param entities entity to save (can be a group of other entities)
		\param filename filename
		\param parameters saving parameters
		\param filter output filter
		\return error type (if any)
	**/
	QCC_IO_LIB_API static CC_FILE_ERROR SaveToFile(	ccHObject* entities,
													const QString& filename,
													const SaveParameters& parameters,
													Shared filter);
	
	//! Saves an entity (or a group of) to a specific file thanks to a given filter
	/** Shortcut to the other version of FileIOFilter::SaveToFile
		\param entities entity to save (can be a group of other entities)
		\param filename filename
		\param parameters saving parameters
		\param fileFilter output filter 'file filter'
		\return error type (if any)
	**/
	QCC_IO_LIB_API static CC_FILE_ERROR SaveToFile(	ccHObject* entities,
													const QString& filename,
													const SaveParameters& parameters,
													const QString& fileFilter);
	
	//! Shortcut to the ccGlobalShiftManager mechanism specific for files
	/** \param[in] P sample point (typically the first loaded)
		\param[out] Pshift global shift
		\param[out] preserveCoordinateShift whether shift sould be preserved on save
		\param[in] loadParameters loading parameters
		\param[in] useInputCoordinatesShiftIfPossible whether to use the input 'PShift' vector if possible
		\return whether global shift has been defined/enabled
	**/
	QCC_IO_LIB_API static bool HandleGlobalShift(	const CCVector3d& P,
													CCVector3d& Pshift,
													bool& preserveCoordinateShift,
													LoadParameters& loadParameters,
													bool useInputCoordinatesShiftIfPossible = false);
	
	//! Displays (to console) the message corresponding to a given error code
	/** \param err error code
		\param action "saving", "reading", etc.
		\param filename corresponding file
	**/
	QCC_IO_LIB_API static void DisplayErrorMessage(CC_FILE_ERROR err,
												   const QString& action,
												   const QString& filename);
	
	//! Returns whether special characters are present in the input string
	QCC_IO_LIB_API static bool CheckForSpecialChars(const QString& filename);
	
public: //loading "sessions" management
	
	//! Indicates to the I/O filters that a new loading/saving session has started (for "Apply all" buttons for instance)
	QCC_IO_LIB_API static void ResetSesionCounter();
	
	//! Indicates to the I/O filters that a new loading/saving action has started
	/** \return the updated session counter
	**/
	QCC_IO_LIB_API static unsigned IncreaseSesionCounter();
	
public: //global filters registration mechanism
	
	//! Init internal filters (should be called once)
	QCC_IO_LIB_API static void InitInternalFilters();
	
	//! Registers a new filter
	QCC_IO_LIB_API static void Register(Shared filter);
	
	//! Returns the filter corresponding to the given 'file filter'
	QCC_IO_LIB_API static Shared GetFilter(const QString& fileFilter, bool onImport);
	
	//! Returns the best filter (presumably) to open a given file extension
	QCC_IO_LIB_API static Shared FindBestFilterForExtension(const QString& ext);
	
	//! Type of a I/O filters container
	using FilterContainer = std::vector<FileIOFilter::Shared>;
	
	//! Returns the set of all registered filters
	QCC_IO_LIB_API static const FilterContainer& GetFilters();
	
	//! Unregisters all filters
	/** Should be called at the end of the application
	**/
	QCC_IO_LIB_API static void UnregisterAll();
	
	//! Called when the filter is unregistered
	/** Does nothing by default **/
	virtual void unregister() {}
	
public:
	enum FilterFeature
	{
		NoFeatures = 0x0000,
		
		Import = 0x00001,	//< Imports data
		Export = 0x0002,	//< Exports data
		
		BuiltIn = 0x0004,	//< Implemented in the core
		
		DynamicInfo = 0x0008,	//< FilterInfo cannot be set statically (this is used for internal consistency checking)
	};
	Q_DECLARE_FLAGS( FilterFeatures, FilterFeature )
	
protected:
	static constexpr float DEFAULT_PRIORITY = 25.0f;

	struct FilterInfo
	{
		//! ID used to uniquely identify the filter (not user-visible)
		QString id;
		
		//! Priority used to determine sort order and which one is the default in the
		//! case of multiple FileIOFilters registering the same extension.
		//! Default is 25.0 /see DEFAULT_PRIORITY.
		float priority;
		
		//! List of extensions this filter can read (lowercase)
		//! e.g. "txt", "foo", "bin"
		//! This is used in FindBestFilterForExtension()
		QStringList importExtensions;
		
		//! The default file extension (for export)
		QString defaultExtension;
		
		//! List of file filters for import (e.g. "Test (*.txt)", "Foo (*.foo))
		QStringList	importFileFilterStrings;
		
		//! List of file filters for export (e.g. "Test (*.txt)", "Foo (*.foo))
		QStringList	exportFileFilterStrings;
		
		//! Supported features \see FilterFeature
		FilterFeatures features;
	};
	
	QCC_IO_LIB_API explicit FileIOFilter( const FilterInfo &info );
	
	//! Allow import extensions to be set after construction
	//! (e.g. for ImageFileFilter & QImageReader::supportedImageFormats())
	void setImportExtensions( const QStringList &extensions );
	
	//! Allow import filter strings to be set after construction
	//! (e.g. for ImageFileFilter & QImageReader::supportedImageFormats())
	void setImportFileFilterStrings( const QStringList &filterStrings );

	//! Allow export filter strings to be set after construction
	//! (e.g. for ImageFileFilter & QImageReader::supportedImageFormats())
	void setExportFileFilterStrings( const QStringList &filterStrings );
	
private:
	void checkFilterInfo() const;
	
	FilterInfo m_filterInfo;
};

Q_DECLARE_OPERATORS_FOR_FLAGS( FileIOFilter::FilterFeatures )

#endif