/** \file
 * \brief Merges nodes with neighbour to get a Multilevel Graph
 *
 * \author Gereon Bartel
 *
 * \par License:
 * This file is part of the Open Graph Drawing Framework (OGDF).
 *
 * \par
 * Copyright (C)<br>
 * See README.md in the OGDF root directory for details.
 *
 * \par
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * Version 2 or 3 as published by the Free Software Foundation;
 * see the file LICENSE.txt included in the packaging of this file
 * for details.
 *
 * \par
 * 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.
 *
 * \par
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, see
 * http://www.gnu.org/copyleft/gpl.html
 */

#pragma once

#include <ogdf/basic/HashArray.h>
#include <ogdf/energybased/multilevel_mixer/MultilevelBuilder.h>

namespace ogdf {

//! The local biconnected merger for multilevel layout.
/**
 * @ingroup gd-multi
 */
class OGDF_EXPORT LocalBiconnectedMerger : public MultilevelBuilder {
private:
	double m_levelSizeFactor;
	NodeArray<node> m_substituteNodes;
	NodeArray<bool> m_isCut;
	HashArray<int, int> m_realNodeMarks;

	void initCuts(Graph& G);
	int realNodeMark(int index);

	//! Creates the next level in the hierarchy by merging
	//! vertices based on matching, edge cover, and local biconnectivity check.
	bool buildOneLevel(MultilevelGraph& MLG) override;
	bool doMerge(MultilevelGraph& MLG, node parent, node mergePartner, int level);
	bool doMergeIfPossible(Graph& G, MultilevelGraph& MLG, node parent, node mergePartner, int level);
	bool canMerge(Graph& G, node parent, node mergePartner);
	bool canMerge(Graph& G, node parent, node mergePartner, int testStrength);

public:
	//! Constructs a LocalBiconnectedMerger multilevel builder.
	LocalBiconnectedMerger();
	//! Specifies the ratio between two consecutive level sizes up to which
	//! merging is done.
	void setFactor(double factor);
};

}
