// SurfXYPlane.h

#ifndef SurfXYPlane_H
#define SurfXYPlane_H

// Defines the pure suface correponding to a plane parallel to
// the z-axis.
//
// The corresponding track parameters are:
// u (cm) is fixed 
// 0 - v (cm)
// 1 - z (cm)
// 2 - dv/du 
// 3 - dz/du 
// 4 - q/p   p is momentum of a track, q is its charge
//
// (u,v,z) forms a right-handed orthogonal coordinate system
//
// dist is closest distance between the  z-axis and the plane
// phi is an angle normal to the plane forms with the x-axis
// phi is between 0 and 2*pi 
// phi  is positive counterclockwise from x to u
// This class serves as a base class for bounded cylinders.
//
// The forward direction for the surface is +u.

#include "trfbase/Surface.h"

namespace trf {

class VTrack;
class CrossStat;

class SurfXYPlane : public Surface {

public:  

  // enums identifying surface parameters
  enum {NORMPHI = 0,DISTNORM = 1};

  // track parameter indices
  enum { IV=0, IZ=1, IDVDU=2, IDZDU=3, IQP=4 };

public:

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

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

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

protected:  // attributes

  double _normphi,_distnorm;

protected:

  // Output stream operator.
  // used by operator<<.
  virtual void ostr(std::ostream& stream) const;
  void raw_ostr(std::ostream& stream) const;

  // Return true if two surfaces have the same pure surface.
  // Argument may be safely downcast.
  bool safe_pure_equal(const Surface& srf) const;

  // Return true if this surface and the argument are in order.
  // See Surface::pure_less_than() for more information.
  // Argument may be safely downcast.
  bool safe_pure_less_than(const Surface& srf) const ;

public:

  // constructor
  SurfXYPlane(double dist, double phi);

  // destructor
  virtual ~SurfXYPlane();

  // pure type
  Type get_pure_type() const { return  get_static_type(); };

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

  // Virtual constructor.
  SurfXYPlane* new_pure_surface() const;
  
  // Find crossing status for a track.
  CrossStat pure_status(const VTrack& trv) const;

  // Return the surface parameter.
  double get_parameter(int i) const;

  // Return the difference between two track vectors.
  TrackVector vec_diff(const TrackVector& vec1, 
                       const TrackVector& vec2) const;

  // Return the space point for a track vector.
  SpacePoint space_point(const TrackVector& vec) const;

  // Return the space vector for a track vector.
  SpacePath space_vector(const TrackVector& vec, 
                         TrackSurfaceDirection dir) const;

};

}  // end namespace trf

#endif