/** \file
 * \brief Declaration of class numexcept (handling of numeric problems).
 *
 * \author Stefan Hachul
 *
 * \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/basic/geometry.h>

namespace ogdf {
namespace energybased {
namespace fmmm {

//! This class is developed for exceptions that might occure, when nodes are
//! placed at the same position and a new random position has to be found, or
//! when the calculated forces are near the machine accuracy, where no
//! reasonable numeric and logic calculations are possible any more
class numexcept {
public:
	//! Returns a distinct random point within the smallest disque D with center
	//! old_point that is contained in the box defined by xmin,...,ymax; The size of
	//! D is shrunk by multiplying with epsilon = 0.1; Precondition:
	//! old_point is contained in the box and the box is not equal to old_point.
	static DPoint choose_distinct_random_point_in_disque(DPoint old_point, double xmin, double xmax,
			double ymin, double ymax);

	//! If distance has a value near the machine precision the (attractive)force
	//! calculation is not possible (calculated values exceed the machine accuracy) in
	//! this cases true is returned and force is set to a reasonable value that does
	//! not cause problems; Else false is returned and force keeps unchanged.
	static bool f_near_machine_precision(double distance, DPoint& force);

	//! Returns true if a is "nearly" equal to b (needed, when machine accuracy is
	//! insufficient in functions well_seperated and bordering of NMM)
	static bool nearly_equal(double a, double b);

	static DPoint f_rep_u_on_v(DPoint pos_u, DPoint pos_v);

protected:
	//! A random point (distinct from old_pos) on the disque around old_pos with
	//! radius epsilon = 0.1 is computed.
	static DPoint choose_distinct_random_point_in_radius_epsilon(DPoint old_pos);

	//! If distance has a value near the machine precision the repulsive force calculation
	//! is not possible (calculated values exceed the machine accuracy) in this cases
	//! true is returned and force is set to a reasonable value that does
	//! not cause problems; Else false is returned and force keeps unchanged.
	static bool f_rep_near_machine_precision(double distance, DPoint& force);

	//! Returns the repulsing force_function_value of scalar d.
	static double f_rep_scalar(double d) {
		OGDF_ASSERT(d != 0);
		return 1 / d;
	}
};

}
}
}
