//
//  Copyright (C) 2013 Paolo Tosco
//
//  Copyright (C) 2004-2006 Rational Discovery LLC
//
//   @@ All Rights Reserved @@
//  This file is part of the RDKit.
//  The contents are covered by the terms of the BSD license
//  which is included in the file license.txt, found at the root
//  of the RDKit source tree.
//
#ifndef __RD_MMFFPOSITIONCONSTRAINT_H__
#define __RD_MMFFPOSITIONCONSTRAINT_H__
#include <iostream>
#include <ForceField/Contrib.h>
#include <Geometry/point.h>

namespace ForceFields {
  namespace MMFF {

    //! A position constraint of the type 0.5k * deltaX^2
    class PositionConstraintContrib : public ForceFieldContrib {
    public:
      PositionConstraintContrib() : d_atIdx(-1) {};
      //! Constructor
      /*!
	\param owner       pointer to the owning ForceField
	\param idx         index of the atom in the ForceField's positions
	\param minDispl    minimum displacement
	\param maxDispl    maximum displacement
	\param forceConst  force constant
	
      */
      PositionConstraintContrib(ForceField *owner,
        unsigned int idx, double maxDispl, double forceConst);

      ~PositionConstraintContrib() {
      }
      double getEnergy(double *pos) const;

      void getGrad(double *pos, double *grad) const;
      virtual PositionConstraintContrib *copy() const { return new PositionConstraintContrib(*this); };
    private:
      int d_atIdx; //!< index of the restrained atom
      double d_maxDispl;  //!< maximum allowed displacement
      RDGeom::Point3D d_pos0;  //!< reference position
      double d_forceConstant;  //!< force constant of the bond

    };
  }
}
#endif
