// AddFitCyl_PhiZ_PhiZ.h

#ifndef AddFitCyl_PhiZ_PhiZ_H
#define AddFitCyl_PhiZ_PhiZ_H

// An add fitter to add a cylinder phiz-measurement to a track
// with one phi-measurement and any number of phi-measurements.
//
// If the propagator is not defined, then the parameters are set at
// directly at the new surface and the fit is performed.
//
// If the optional propagator is defined, then the track is propagated
// back to the first hit, has parameters set, and is then propagated
// to the new hit surface where a fit is performed.
//
// Note that the fitter and propagator are not managed here.
//
// ObjStream example:
//
// [ myfit AddFitCyl_PhiZ_PhiZ
//   bfield=2.0
//   fitter=*myfit
//   propagator=*myprop
//   surface=@mysurf
//   error_matrix=double(
//     0.01
//     0.0   0.02
//     0.0   0.0   0.03
//     0.0   0.0   0.0   0.04
//     0.0   0.0   0.0   0.0   0.05
//   )
//   fit_order="UNCHANGED"
//   flag="DR_ALPHA"
//   z0min=-50
//   z0max=50
// ]
//
// To use the global bfield:
//
// [ myfit AddFitCyl_PhiZ_PhiZ bfield=@bfield ... ]
//
//

#include "ptr/Ptr.h"
#include "trffit/AddFitter.h"
#include "trfcyl/SurfCylinder.h"
#include "trfbase/TrackVector.h"
#include "trfbase/SurfacePtr.h"
#include "trfbase/ObjDoublePtr.h"

namespace trf {

class Propagator;

class AddFitCyl_PhiZ_PhiZ : public AddFitter {

public:  // static methods

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

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

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

public:  // enums

  // Possible states for flag specifying how to calculate tan(lambda)
  enum FlagState { DR_ONLY,            // assumes alpha =0 and C = 0
                   DR_ALPHA,           // assumes C = 0; alpha well known
                   DR_ALPHA_CURV       // alpha and C are well known
                 };

  enum FitOrder {
      INWARD = 0,
      OUTWARD = 1,
      UNCHANGED = 2
  };

private:  // attributes

  // Magnetic field (Tesla)
  ObjDoublePtr _bfield;

  // fitter (used to update error matrix)
  const AddFitter& _fit;

  // propagator
  const Propagator& _prop;

  // surface at which to start track
  SurfacePtr _psrf;

  // Starting error matrix.
  const TrackError _err;

  // flag indicating to use the current track curvature to
  // estimate lambda
  FlagState _flag;

  int _fit_order;
  
  // z0 limits
  double _z0min;
  double _z0max;

private:  // methods

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

public:  // methods

  // constructor
  AddFitCyl_PhiZ_PhiZ(ObjDoublePtr bfield, const AddFitter& fit,
                      const Propagator& prop, const SurfacePtr& psrf,
                      const TrackError& err, double z0min, double z0max,
                      FlagState flag =DR_ALPHA );

  AddFitCyl_PhiZ_PhiZ(ObjDoublePtr bfield, const AddFitter& fit,
                      const Propagator& prop, const SurfacePtr& psrf,
                      const TrackError& err, double z0min, double z0max,
                      FlagState flag, int fit_order );

  // destructor
  ~AddFitCyl_PhiZ_PhiZ();

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

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

  // Return the B-fiield.
  double get_bfield() const { return (*_bfield)(); }

  // Return the fitter.
  const AddFitter& get_fitter() const { return _fit; }

  // Return the propagator.
  const Propagator& get_propagator() const { return _prop; }

  // Return the starting surface.
  const SurfacePtr& get_surface() const { return _psrf; }

  // Return the starting error.
  const TrackError& get_error() const { return _err; }

  // Return the min z0.
  double get_z0min() const { return _z0min; }

  // Return the max z0.
  double get_z0max() const { return _z0max; }

  // Return the flag.
  FlagState get_flag() const { return _flag; }

  // add the hit
  int add_hit(HTrack& trh, const HitPtr& phit) const;

  // Return fit order flag

  int get_fit_order() const { return _fit_order;}

};

}  // end namespace trf

#endif