/** \file
 * \brief Declaration of MultilevelBuilder
 *
 * \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/basic.h>
#include <ogdf/energybased/multilevel_mixer/MultilevelGraph.h>

namespace ogdf {

//! Base class for merger modules.
/**
 * @ingroup gd-multi
 */
class OGDF_EXPORT MultilevelBuilder {
private:
	/**
	 * \brief This method constructs one more level on top of an existing MultilevelGraph.
	 * It must be implemented in any MultilevelBuilder. A level is built by
	 *  adding node-merges to the MultilevelGraph and updating the graph accordingly.
	 * This is achieved by calling MLG.
	 *
	 * @param MLG is the MultilevelGraph for which a new gevel will be built.
	 *
	 * @return true if the Graph was changed or false if no level can be built.
	 */
	virtual bool buildOneLevel(MultilevelGraph& MLG) = 0;

protected:
	// if set to true the length of the edge between two merged nodes will be added to
	//  all edges that are moved to the other node in this merge.
	int m_adjustEdgeLengths;
	int m_numLevels; //!< stores number of levels for statistics purposes

public:
	virtual ~MultilevelBuilder() { }

	MultilevelBuilder() : m_adjustEdgeLengths(0), m_numLevels(1) { }

	virtual void buildAllLevels(MultilevelGraph& MLG) {
		m_numLevels = 1;
		MLG.updateReverseIndizes();
		MLG.updateMergeWeights();
		while (buildOneLevel(MLG)) {
			m_numLevels++;
		}
		MLG.updateReverseIndizes();
	}

	void setEdgeLengthAdjustment(int factor) { m_adjustEdgeLengths = factor; }

	int getNumLevels() { return m_numLevels; }
};

}
