#ifndef HELICALSURFACE_HH
#define HELICALSURFACE_HH
//
// $Id: HelicalSurface.hpp,v 1.4 2001/03/31 16:43:13 hobbs Exp $
//
// File: HelicalSurface.hpp
// Purpose: 
// Created: 14-JUL-1999   Andrei Mayorov
//
// $Revision: 1.4 $
//
//

// Include files
#include <geometry_system/components/GeometryElement.hpp>
#include <geometry_system/components/CylindricalSurface.hpp>
#include <geometry_system/components/HelicalCoordinate.hpp>
#include <exception>

namespace dgs {

/**  A helical surface.
       
       A helical surface specified by its radius, z half-length and half-width
       in phi.   The surface is oriented with its axis along the z-axis. 
       Center of the surface is  positioned at z=0 phi=0
       
*/
class HelicalSurface: public CylindricalSurface

{
public:
  
  ///  Default constructor.
  HelicalSurface():  CylindricalSurface(0,0),_dphi(0),_dphidz(0), _cvers("Revision:$") {};
  
  ///  Construct helical surface with specified radius,  z half-length, width in phi and dphi/dz.
  HelicalSurface(const double radius, const double zhalf,const double dphi,const double dphidz):
      CylindricalSurface(radius,zhalf),_dphi(dphi),_dphidz(dphidz), _cvers("Revision:$") {};
  ///  helical width
    double get_dphi() const {return _dphi;};
  /// 
  double get_dphidz() const {return _dphidz;};
  ///  Convert local point to global one.
  SpacePoint local_to_global( const HelicalCoordinate& lpt) const;
  
  ///  Convert global point to local one.
  HelicalCoordinate global_to_local(const SpacePoint &gpt) const;
  // assuming point is on surface, so we do not need r.
  HelicalCoordinate global_to_local(double phi,double z) const;
  
  ///  Resize cylinder by specied change in radius and z half-length.
  bool resize(const double dr, const double dzhalf, const double dphi,const double ddphidz=0.0);
  
  ///  Position child surface at specified local point.
  bool position_child_at(const HelicalCoordinate& lpt, GeometryElement& kid);
  
  /// check if global point is on surface
  bool  onSurface(const SpacePoint &gpt) const;
  
  // comparisons
  friend bool operator ==(const HelicalSurface& lhs, const HelicalSurface& rhs);
  friend bool operator !=(const HelicalSurface& lhs, const HelicalSurface& rhs);
  friend bool operator <(const HelicalSurface& lhs, const HelicalSurface &rhs);
  
  /// Get source code version. Kept to allow following code changes
  const std::string& code_version() const { return _cvers; };
  
  ///  Stream insertion operator.
  friend std::ostream& operator<<(std::ostream &os, const HelicalSurface &me);
  
private:
    /// halp width in phi
  double _dphi;
  /// direction - dphi/dz
  double _dphidz;
  /// Support for positioning child on surface.
  HelicalCoordinate xform_to_local(const GeometryXform &xf) const;
  
  /// Support for positioning child on surface.
  GeometryXform local_to_xform(const HelicalCoordinate &lpt) const;
  
  /// RCS version
  std::string _cvers;  // Replaced at checkout
protected:
  bool onSurface(const HelicalCoordinate& lpt) const;
public:
  std::exception OutOfSurface;
  D0_OBJECT_SETUP(HelicalSurface);
};
}
#endif // HELICALSURFACE_HH