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//
// G4FieldTrack
//
// Class description:
//
// Data structure bringing together a magnetic track's state.
// (position, momentum direction & modulus, energy, spin, ... )
// Uses/abilities:
//  - does not maintain any relationship between its data (eg energy/momentum).
//  - for use in Runge-Kutta solver (in passing it the values right now).

// Author: John Apostolakis, CERN - First version, 14.10.1996
// -------------------------------------------------------------------
#ifndef G4FIELDTRACK_HH
#define G4FIELDTRACK_HH

#include "G4ThreeVector.hh"
#include "G4ChargeState.hh"

class G4FieldTrack
{
   public:  // with description

     G4FieldTrack( const G4ThreeVector& pPosition, 
                         G4double       LaboratoryTimeOfFlight,
                   const G4ThreeVector& pMomentumDirection,
                         G4double       kineticEnergy,
                         G4double       restMass_c2,
                         G4double       charge, 
                   const G4ThreeVector& polarization,
                         G4double       magnetic_dipole_moment = 0.0,
                         G4double       curve_length = 0.0,
                         G4double       PDGspin = -1.0 );

     G4FieldTrack( char );
       // Almost default constructor

     G4FieldTrack( const G4ThreeVector& pPosition, 
                   const G4ThreeVector& pMomentumDirection,
                         G4double       curve_length,
                         G4double       kineticEnergy,
                   const G4double       restMass_c2,
                         G4double       velocity,
                         G4double       LaboratoryTimeOfFlight = 0.0,
                         G4double       ProperTimeOfFlight = 0.0, 
                   const G4ThreeVector* pPolarization = nullptr,
                         G4double       PDGspin = -1.0 );
        // Older constructor
        // ---> Misses charge !!!

     ~G4FieldTrack();
       // Destructor 

     inline G4FieldTrack( const G4FieldTrack& pFieldTrack ); 
     inline G4FieldTrack& operator= ( const G4FieldTrack& rStVec );
       // Copy constructor & Assignment operator

     inline void UpdateState( const G4ThreeVector& pPosition, 
                                    G4double       LaboratoryTimeOfFlight,
                              const G4ThreeVector& pMomentumDirection,
                                    G4double       kineticEnergy); 
        // Update four-vectors for space/time and momentum/energy
        // Also resets curve length.

     inline void UpdateFourMomentum( G4double kineticEnergy, 
                                     const G4ThreeVector& momentumDirection ); 
        // Update momentum (and direction), and kinetic energy 

     void SetChargeAndMoments(G4double charge, 
                              G4double magnetic_dipole_moment = DBL_MAX,
                              G4double electric_dipole_moment = DBL_MAX,
                              G4double magnetic_charge = DBL_MAX );
        // Set the charges and moments that are not given as DBL_MAX

     inline void SetPDGSpin(G4double pdgSpin);
     inline G4double GetPDGSpin();

     inline G4ThreeVector GetMomentum() const;   
     inline G4ThreeVector GetPosition() const; 
     inline const G4ThreeVector& GetMomentumDir() const;
     inline G4ThreeVector GetMomentumDirection() const;
     inline G4double      GetCurveLength() const;
       // Distance along curve of point.

     inline G4ThreeVector GetPolarization() const; 
     inline void          SetPolarization( const G4ThreeVector& vecPol );

     inline const G4ChargeState* GetChargeState() const;
     inline G4double      GetLabTimeOfFlight() const;
     inline G4double      GetProperTimeOfFlight() const;
     inline G4double      GetKineticEnergy() const;
     inline G4double      GetCharge() const;
     inline G4double      GetRestMass() const;
       // Accessors.

     inline void SetPosition(G4ThreeVector nPos); 
     inline void SetMomentum(G4ThreeVector nMomDir);
       // Does change mom-dir too.

     inline void SetMomentumDir(G4ThreeVector nMomDir);
       // Does NOT change Momentum or Velocity Vector.

     inline void SetRestMass(G4double Mass_c2);
   
     inline void SetCurveLength(G4double nCurve_s);
       // Distance along curve.
     inline void SetKineticEnergy(G4double nEnergy);
       // Does not modify momentum.

     inline void SetLabTimeOfFlight(G4double tofLab); 
     inline void SetProperTimeOfFlight(G4double tofProper);
       //  Modifiers

   public: // without description

     enum { ncompSVEC = 12 };
       // Needed and should be used only for RK integration driver

     inline void DumpToArray(G4double valArr[ncompSVEC]) const; 
     void LoadFromArray(const G4double valArr[ncompSVEC],
                              G4int noVarsIntegrated);
     friend  std::ostream&
             operator<<( std::ostream& os, const G4FieldTrack& SixVec);

   public:  // Obsolete methods -- due to potential confusion with PDG spin

     inline void InitialiseSpin( const G4ThreeVector& vecPolarization );
     inline G4ThreeVector GetSpin() const;
     inline void SetSpin(G4ThreeVector vSpin);

   private: // Implementation method -- Obsolete

     inline G4FieldTrack& SetCurvePnt(const G4ThreeVector& pPosition, 
                                      const G4ThreeVector& pMomentum,
                                            G4double       s_curve );
   private:

     G4double SixVector[6];
     G4double fDistanceAlongCurve;  // distance along curve of point
     G4double fKineticEnergy;
     G4double fRestMass_c2;
     G4double fLabTimeOfFlight;
     G4double fProperTimeOfFlight;
     G4ThreeVector fPolarization;
     G4ThreeVector fMomentumDir;
     // G4double  fInitialMomentumMag;  // At 'track' creation.
     // G4double  fLastMomentumMag;     // From last Update (for checking.)

     G4ChargeState fChargeState;
}; 

#include "G4FieldTrack.icc"

#endif
