#ifndef T_UNDO_INCLUDED
#define T_UNDO_INCLUDED

#include <memory>

// TnzCore includes
#include "tsmartpointer.h"

// Qt includes
#include <QObject>
#include <QString>

#undef DVAPI
#undef DVVAR
#ifdef TNZCORE_EXPORTS
#define DVAPI DV_EXPORT_API
#define DVVAR DV_EXPORT_VAR
#else
#define DVAPI DV_IMPORT_API
#define DVVAR DV_IMPORT_VAR
#endif

//************************************************************************
//    TUndo  class
//************************************************************************

class DVAPI TUndo
{
public:
	bool m_isLastInBlock;

public:
	TUndo() {}
	virtual ~TUndo() {}

	virtual int getSize() const = 0;

	virtual void undo() const = 0;
	virtual void redo() const = 0;

	virtual void onAdd() {}

	// for history viewer panel
	virtual QString getHistoryString() { return QObject::tr("Unidentified Action"); }
	virtual int getHistoryType() { return 0; } //HistoryType::Unidentified

private:
	// Noncopyable
	TUndo(const TUndo &undo);
	TUndo &operator=(const TUndo &undo);
};

//************************************************************************
//    TUndoManager  class
//************************************************************************

class DVAPI TUndoManager : public QObject
{
	Q_OBJECT

public:
	TUndoManager();
	~TUndoManager();

	static TUndoManager *manager();

	void beginBlock();
	void endBlock();

	void add(TUndo *undo);

	bool undo();
	bool redo();

	void reset();

	/*!If forward = false remove n elements in the stack before m_imp->m_current;
    else if forward = true remove n elements in the stack after m_imp->m_current.
    If n = -1 remove all elements before or after m_imp->m_current.*/

	void popUndo(int n = -1, bool forward = false);

	//! undo() and redo() methods call TUndoManager::manager()->skip() if
	//! they want another undo/redo performed

	void skip();

	//! Set the size of memory used for undo redo.
	//! \b memorySyze is expressed in MB
	void setUndoMemorySize(int memorySyze);

	// for history viewer pane
	int getHistoryCount();
	int getCurrentHistoryIndex();
	TUndo *getUndoItem(int index);

	Q_SIGNALS :

		void
		historyChanged();

	void somethingChanged();

private:
	struct TUndoManagerImp;
	std::unique_ptr<TUndoManagerImp> m_imp;

private:
	// Noncopyable
	TUndoManager(const TUndoManager &);
	TUndoManager &operator=(const TUndoManager &);
};

//************************************************************************
//    TUndoScopedBlock  class
//************************************************************************

struct TUndoScopedBlock {
	TUndoScopedBlock() { TUndoManager::manager()->beginBlock(); }
	~TUndoScopedBlock() { TUndoManager::manager()->endBlock(); }

private:
	// Noncopyable
	TUndoScopedBlock(const TUndoScopedBlock &);
	TUndoScopedBlock &operator=(const TUndoScopedBlock &);
};

#endif // T_UNDO_INCLUDED