/* Portions copyright (c) 2006-2016 Stanford University and Simbios.
 * Contributors: Pande Group
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject
 * to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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 */

#ifndef __ReferenceProperDihedralBond_H__
#define __ReferenceProperDihedralBond_H__

#include "ReferenceBondIxn.h"

namespace OpenMM {

class OPENMM_EXPORT ReferenceProperDihedralBond : public ReferenceBondIxn {

   private:

        bool usePeriodic;
        Vec3 boxVectors[3];
       
   public:

      /**---------------------------------------------------------------------------------------
      
         Constructor
      
         --------------------------------------------------------------------------------------- */

       ReferenceProperDihedralBond();

      /**---------------------------------------------------------------------------------------
      
         Destructor
      
         --------------------------------------------------------------------------------------- */

       ~ReferenceProperDihedralBond();

       /**---------------------------------------------------------------------------------------
      
         Set the force to use periodic boundary conditions.
      
         @param vectors    the vectors defining the periodic box
      
         --------------------------------------------------------------------------------------- */
      
       void setPeriodic(OpenMM::Vec3* vectors);

      /**---------------------------------------------------------------------------------------
      
        Calculate proper dihedral bond ixn
      
         @param atomIndices      atom indices of 4 atoms in bond
         @param atomCoordinates  atom coordinates
         @param parameters       3 parameters: parameters[0] = k
                                               parameters[1] = ideal bond angle in radians
                                               parameters[2] = multiplicity
         @param forces           force array (forces added to current values)
         @param totalEnergy      if not null, the energy will be added to this
      
         --------------------------------------------------------------------------------------- */
      
      void calculateBondIxn(std::vector<int>& atomIndices, std::vector<OpenMM::Vec3>& atomCoordinates,
                            std::vector<double>& parameters, std::vector<OpenMM::Vec3>& forces,
                            double* totalEnergy, double* energyParamDerivs);

};

} // namespace OpenMM

#endif // __ReferenceProperDihedralBond_H__