// PropJoinCyl.h

#ifndef PropJoinCyl_H
#define PropJoinCyl_H

// Propagates tracks from a starting surface to a cylinder and
// then to the final surface.  The radius of the intermediate
// cylinder is calculated from two parameters rmin and rfac and
// the starting radius r0:
// if rfac*r0 < rmin, the r = rmin, otherwise r = rfac*r0.
//
// ObjStream example:
//
// [ myprop PropJoinCyl rmin=0.1 rfac=1.0 prop1=@propcz prop2=@propzc ]
//

#include "trfbase/PropDirected.h"
#include "trfbase/PropagatorPtr.h"

namespace trf {

class PropJoinCyl : public PropDirected {

public:  // static methods

  // Return the type name.
  static TypeName get_type_name() { return "PropJoinCyl"; }

  // Return the creator.
  static ObjCreator get_creator();

  // Return the type.
  static Type get_static_type() { return get_creator(); }

private:  // attributes

  // parameters to calculate radius
  double _rmin;
  double _rfac;

  // The propagators.
  PropagatorPtr _pprop1;
  PropagatorPtr _pprop2;

private:

  // output stream
  void ostr(std::ostream& stream) const;

public:

  // constructor from the two constituent propagators
  PropJoinCyl(double rmin, double rfac, const PropagatorPtr& pprop1,
                                        const PropagatorPtr& pprop2);

  // destructor
  ~PropJoinCyl();

  // Clone.
  Propagator* new_propagator( ) const;

  // Return the type.
  Type get_type() const { return get_static_type(); }

  // Write the object data.
  ObjData write_data() const;

  // Return the attributes.
  double get_rmin() const { return _rmin; }
  double get_rfac() const { return _rfac; }
  const PropagatorPtr& get_prop1() const { return _pprop1; }
  const PropagatorPtr& get_prop2() const { return _pprop2; }

  // propagate a track without error in the specified direction
  PropStat vec_dir_prop(VTrack& trv, const Surface& srf,
                        PropDir dir, TrackDerivative* pder =0) const;

  // propagate a track with error in the specified direction
  PropStat err_dir_prop(ETrack& trv, const Surface& srf,
                        PropDir dir, TrackDerivative* pder =0) const;

};

}  // end namespace trf

#endif