/*
 * Copyright (C) 2002 Brett Viren
 * Copyright (C) 2006-2015 Paul Davis <paul@linuxaudiosystems.com>
 * Copyright (C) 2006 Hans Fugal <hans@fugal.net>
 * Copyright (C) 2007-2009 David Robillard <d@drobilla.net>
 * Copyright (C) 2013 John Emmas <john@creativepost.co.uk>
 *
 * This program 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.
 *
 * This program 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef __lib_pbd_undo_h__
#define __lib_pbd_undo_h__

#include <list>
#include <map>
#include <string>

#include <sigc++/bind.h>
#include <sigc++/slot.h>

#ifndef COMPILER_MSVC
#include <sys/time.h>
#else
#include <ardourext/misc.h>
#endif

#include "pbd/command.h"
#include "pbd/libpbd_visibility.h"

namespace PBD {

typedef sigc::slot<void> UndoAction;

class LIBPBD_API UndoTransaction : public PBD::Command
{
public:
	UndoTransaction ();
	UndoTransaction (const UndoTransaction&);
	UndoTransaction& operator= (const UndoTransaction&);
	~UndoTransaction ();

	void clear ();
	bool empty () const;
	bool clearing () const {
		return _clearing;
	}

	void add_command (PBD::Command* const);
	void remove_command (PBD::Command* const);

	std::list<PBD::Command*>::size_type size() const { return actions.size(); }

	void operator() ();
	void undo ();
	void redo ();

	XMLNode& get_state () const;

	void set_timestamp (struct timeval& t)
	{
		_timestamp = t;
	}

	const struct timeval& timestamp () const
	{
		return _timestamp;
	}

private:
	std::list<PBD::Command*> actions;
	struct timeval      _timestamp;
	bool                _clearing;

	void about_to_explicitly_delete ();
};

class LIBPBD_API UndoHistory : public PBD::ScopedConnectionList
{
public:
	UndoHistory ();
	~UndoHistory () {}

	void add (UndoTransaction* ut);
	void undo (unsigned int n);
	void redo (unsigned int n);

	unsigned long undo_depth () const
	{
		return UndoList.size ();
	}
	unsigned long redo_depth () const
	{
		return RedoList.size ();
	}

	std::string next_undo () const
	{
		return (UndoList.empty () ? std::string () : UndoList.back ()->name ());
	}
	std::string next_redo () const
	{
		return (RedoList.empty () ? std::string () : RedoList.back ()->name ());
	}

	void clear ();
	void clear_undo ();
	void clear_redo ();

	/* returns all or part of the history.
	 * If depth==0 it returns just the top
	 * node. If depth<0, it returns everything.
	 * If depth>0, it returns state for that
	 * many elements of the history, or
	 * the full history, whichever is smaller.
	 */

	XMLNode& get_state (int32_t depth = 0);
	void     save_state ();

	void set_depth (uint32_t);

	PBD::Signal0<void> Changed;
	PBD::Signal0<void> BeginUndoRedo;
	PBD::Signal0<void> EndUndoRedo;

private:
	bool                        _clearing;
	uint32_t                    _depth;
	std::list<UndoTransaction*> UndoList;
	std::list<UndoTransaction*> RedoList;

	void remove (UndoTransaction*);
};

} /* namespace */

#endif /* __lib_pbd_undo_h__ */
