/**
 *  \file DistanceRestraint.h   \brief Distance restraint between two particles.
 *
 *  Copyright 2007-2010 IMP Inventors. All rights reserved.
 *
 */

#ifndef IMPCORE_DISTANCE_RESTRAINT_H
#define IMPCORE_DISTANCE_RESTRAINT_H

#include "core_config.h"
#include "DistancePairScore.h"
#include "XYZ.h"

#include <IMP/Restraint.h>

#include <iostream>

IMPCORE_BEGIN_NAMESPACE

//! Distance restraint between two particles
/**
   \note If the particles are closer than a certain distance, then
   the contributions to the derivatives are set to 0.

   \see PairRestraint
   \see DistancePairScore
   \see SphereDistancePairScore
 */
class IMPCOREEXPORT DistanceRestraint : public Restraint
{
public:
  //! Create the distance restraint.
  /** \param[in] score_func Scoring function for the restraint.
      \param[in] a Pointer to first particle in distance restraint.
      \param[in] b Pointer to second particle in distance restraint.
   */
  DistanceRestraint(UnaryFunction* score_func,
                    Particle *a, Particle *b);

  DistanceRestraint(UnaryFunction *score_func,
                    XYZ a, XYZ b);

  IMP_RESTRAINT(DistanceRestraint);

private:
  IMP::internal::OwnerPointer<DistancePairScore> dp_;
  RefCountingDecorator<XYZ> p_[2];
};

IMPCORE_END_NAMESPACE

#endif  /* IMPCORE_DISTANCE_RESTRAINT_H */