// PropDirected.h

#ifndef PropDirected_H
#define PropDirected_H

// Derive from propagator and add a modifable default direction.
// We implement the methods that do not specify a direction using
// those that do.

#include "Propagator.h"

class ObjData;

namespace trf {

class PropDirected : public Propagator {

private:

  PropDir _dir;

public:

  // constructor with default direction = NEAREST
  PropDirected();

  // constructor from direction
  PropDirected(PropDir dir);

  // destructor
  virtual ~PropDirected();

  // set the default direction
  void set_direction(PropDir dir);

  // Use OBS data to define the direction.
  // The string dir is used if present.
  // Otherwise no action is taken.
  // Returns true if the string is found and is valid.
  // Allowed values are nearest, forward, backward, nearest_move,
  // forward_move and backward_move.
  // Here is how it might be called from the creator for PropXXX:
  //   Ptr<PropDirected,LocalSharedDeletePolicy> pobj(new PropXXX);
  //   pobj->set_direction(data);
  //   return ObjPtr(pobj);

  bool set_direction(const ObjData& data);


  // set the default direction
  PropDir get_direction() const;

  // Propagate a track without error in the default direction.
  PropStat vec_prop(VTrack& trv, const Surface& srf,
                    TrackDerivative* pder =0) const;

  // Propagate a track with error in the default direction.
  PropStat err_prop( ETrack& trv, const Surface& srf,
                     TrackDerivative* pder =0) const;

};

}  // end namespace trf

#endif