/** \file
 * \brief Preprocessor Layout simplifies Graphs for use in other Algorithms
 *
 * \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/LayoutModule.h>
#include <ogdf/basic/basic.h>
#include <ogdf/energybased/multilevel_mixer/MultilevelLayoutModule.h>

#include <memory>
#include <vector>

namespace ogdf {
class Graph;
class GraphAttributes;
class MultilevelGraph;

/** \brief The PreprocessorLayout removes multi-edges and self-loops.
 *
 * @ingroup graph-drawing
 *
 * To draw a graph using the ModularMultilevelMixer or other layouts the
 * graph must be simple, i.e., contain neither multi-edges nor self-loops.
 * Edges that conflict with these rules are deleted in the PreprocessorLayout.
 * A secondary layout is then called that can work on the graph in required form.
 * After the layout has been computed, the edges are inserted back into the
 * graph, as they may have been relevant for the user.
 */
class OGDF_EXPORT PreprocessorLayout : public MultilevelLayoutModule {
private:
	/** \brief Deleted Edges are stored in EdgeData
	 *
	 * EdgeData stores the deleted edges to allow restauration of the original
	 * graph after the layout has been computed.
	 */
	struct EdgeData {
		EdgeData(int edgeInd, int sourceInd, int targetInd, double edgeWeight)
			: edgeIndex(edgeInd), sourceIndex(sourceInd), targetIndex(targetInd), weight(edgeWeight) { }

		int edgeIndex;
		int sourceIndex;
		int targetIndex;
		double weight;
	};

	std::unique_ptr<LayoutModule> m_secondaryLayout;
	std::vector<EdgeData> m_deletedEdges;
	bool m_randomize;

	void call(Graph& G, MultilevelGraph& MLG);

public:
	//! Constructor
	PreprocessorLayout();

	//! Destructor
	~PreprocessorLayout() { }

	using MultilevelLayoutModule::call;

	//! Calculates a drawing for the Graph \p MLG.
	virtual void call(MultilevelGraph& MLG) override;

	//! Calculates a drawing for the Graph \p GA.
	virtual void call(GraphAttributes& GA) override;

	//! Sets the secondary layout.
	void setLayoutModule(LayoutModule* layout) { m_secondaryLayout.reset(layout); }

	//! Defines whether the positions of the node are randomized before the secondary layout call.
	void setRandomizePositions(bool on) { m_randomize = on; }
};

}
