//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
// class G4SafetyHelper
//
// Class description:
//
// This class is a helper for physics processes which require 
// knowledge of the safety, and the step size for the 'mass' geometry

// First version:  J.Apostolakis,  July 5th, 2006
// --------------------------------------------------------------------
#ifndef G4SAFETYHELPER_HH
#define G4SAFETYHELPER_HH 1

#include <vector>

#include "G4Types.hh"
#include "G4ThreeVector.hh"
#include "G4Navigator.hh"

class G4PathFinder;

class G4SafetyHelper
{
  public: // with description

    G4SafetyHelper(); 
   ~G4SafetyHelper();
      // Constructor and destructor

    G4double CheckNextStep( const G4ThreeVector& position, 
                            const G4ThreeVector& direction,
                            const G4double currentMaxStep,
                                  G4double& newSafety );
      // Return linear step for mass geometry

    G4double ComputeSafety( const G4ThreeVector& pGlobalPoint,
                            G4double maxRadius = DBL_MAX );
      // Return safety for all geometries.
      //
      // The 2nd argument is the radius of your interest (e.g. maximum
      // displacement). Giving this you can reduce the average computational
      // cost. If the second argument is not given, this is the real
      // isotropic safety

    void Locate(const G4ThreeVector& pGlobalPoint,
                const G4ThreeVector& direction);
      // Locate the point for all geometries

    void ReLocateWithinVolume(const G4ThreeVector& pGlobalPoint );
      // Relocate the point in the volume of interest

    G4bool RecheckDistanceToCurrentBoundary(const G4ThreeVector& pGlobalPoint,
                                   const G4ThreeVector& pDirection,
                                   const G4double pCurrentProposedStepLength,
                                         G4double* prDistance,
                                         G4double* prNewSafety = nullptr) const;
      // Trial method for checking potential displacement for MS
      // Check new Globalpoint, to see whether it is in current volume
      // (mother) and not in potential entering daughter.
      // If in mother, check distance to boundary along pDirection.
      // If in entering daughter, check distance back to boundary. 
      // NOTE:
      // Can be called only after ComputeStep is called - before ReLocation
      // Deals only with current volume (and potentially entered)

    inline void EnableParallelNavigation(G4bool parallel);
      //  To have parallel worlds considered, must be true.
      //  Alternative is to use single (mass) Navigator directly

    void InitialiseNavigator();
      // Check for new navigator for tracking, and reinitialise pointer

    inline G4int SetVerboseLevel( G4int lev );
    inline G4VPhysicalVolume* GetWorldVolume();
    inline void SetCurrentSafety(G4double val, const G4ThreeVector& pos);

  public: // without description

    void InitialiseHelper();

  private:

    G4PathFinder* fpPathFinder = nullptr;
    G4Navigator* fpMassNavigator = nullptr;
    G4int fMassNavigatorId = -1;

    G4bool fUseParallelGeometries = false; 
      // Flag whether to use PathFinder or single (mass) Navigator directly
      // By default, one geometry only
    G4bool fFirstCall = true;
      // Flag of first call
    G4int fVerbose = 0; 
      // Whether to print warning in case of move outside safety

    // State used during tracking -- for optimisation

    G4ThreeVector fLastSafetyPosition;
    G4double fLastSafety = 0.0;

    // const G4double fRecomputeFactor = 0.0;
       // parameter for further optimisation: 
       // if ( move < fact*safety )  do fast recomputation of safety

    // End State (tracking)
};

// --------------------------------------------------------------------
// Inline definitions
// --------------------------------------------------------------------

inline G4int G4SafetyHelper::SetVerboseLevel( G4int lev )
{
  G4int oldlv = fVerbose;
  fVerbose = lev;
  return oldlv;
} 

inline
void G4SafetyHelper::EnableParallelNavigation(G4bool parallel) 
{
  fUseParallelGeometries = parallel;
} 

inline
G4VPhysicalVolume* G4SafetyHelper::GetWorldVolume()
{
  return fpMassNavigator->GetWorldVolume();
}

inline
void G4SafetyHelper::SetCurrentSafety(G4double val, const G4ThreeVector& pos)
{
  fLastSafety = val;
  fLastSafetyPosition = pos;
}

#endif
