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/// \file field/field01/include/F01FieldSetup.hh
/// \brief Definition of the F01FieldSetup class
//
//
//
//
//  A class for control of the Magnetic Field of the detector.
//  The field is assumed to be uniform.
//
// Should this be a:
//    i) a messenger class
//   ii) user class that creates the field           ( Current choice )
//  iii) a field manager that creates/updates field
//
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

#ifndef F01FieldSetup_h
#define F01FieldSetup_h 1

#include "G4MagneticField.hh"
#include "G4UniformMagField.hh"

class G4FieldManager;
class G4ChordFinder;
class G4Mag_UsualEqRhs;
class G4MagIntegratorStepper;
class G4VIntegrationDriver;
class F01FieldMessenger;

class F01FieldSetup
{
public:
  F01FieldSetup(G4ThreeVector,                //  The value of the field
                G4int  stepperNum = -1000,    //  -ive = fsal, +ive = old.
                                              // default (-1000) uses next flag
                G4bool useFSALstepper= false );

  F01FieldSetup();               //  A zero field
  F01FieldSetup( F01FieldSetup & ) = delete; 

  virtual ~F01FieldSetup();

  void SetStepperType( G4int i ) 
     { fStepperType = i; CreateStepperAndChordFinder(); }

  void SetStepper();

  void SetMinStep(G4double s) { fMinStep = s; }

  void InitialiseAll();    //  Set parameters and call method below

   // Original method - 
  void CreateStepperAndChordFinder();

   // New method - create FSAL stepper and driver
  void CreateFSALStepperAndChordFinder(); 

  void SetFieldValue(G4ThreeVector fieldVector);
  void SetFieldZValue(G4double      fieldValue);
  G4ThreeVector GetConstantFieldValue();

  void   SetUseFSALstepper(G4bool val= true) { fUseFSALstepper = val; }
  G4bool GetUseFSALstepper()                 { return fUseFSALstepper; }
   
protected:
   // Implementation methods
  G4VIntegrationDriver* CreateFSALStepperAndDriver();

   // Find the global Field Manager
  G4FieldManager*          GetGlobalFieldManager();
   
protected:

  G4FieldManager*          fFieldManager = nullptr;
  G4ChordFinder*           fChordFinder = nullptr;
  G4Mag_UsualEqRhs*        fEquation = nullptr;
  G4MagneticField*         fMagneticField = nullptr;

  G4MagIntegratorStepper*  fStepper = nullptr;
  G4bool                   fUseFSALstepper = false;
  G4VIntegrationDriver*    fDriver =  nullptr;  // If non-null, its new type (FSAL)
  G4int                    fStepperType = -1;

  G4double                 fMinStep = -1.0;
   
  F01FieldMessenger*       fFieldMessenger = nullptr;

};

#endif