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//
// class G4MultiNavigator
//
// Class description:
//
// Utility class for polling the navigators of several geometries to
// identify the next boundary. 

// History:
// - Created. John Apostolakis, November 2006
// --------------------------------------------------------------------
#ifndef G4MULTINAVIGATOR_HH
#define G4MULTINAVIGATOR_HH

#include <iostream>

#include "geomdefs.hh"
#include "G4ThreeVector.hh"
#include "G4Navigator.hh"

#include "G4TouchableHandle.hh"

#include "G4NavigationHistory.hh"

enum  ELimited { kDoNot,kUnique,kSharedTransport,kSharedOther,kUndefLimited };

class G4TransportationManager;
class G4VPhysicalVolume;

class G4MultiNavigator : public G4Navigator
{
  public:  // with description

  friend std::ostream& operator << (std::ostream& os, const G4Navigator& n);

  G4MultiNavigator();
    // Constructor - initialisers and setup.

  ~G4MultiNavigator() override;
    // Destructor. No actions.

  G4double ComputeStep( const G4ThreeVector& pGlobalPoint,
                        const G4ThreeVector& pDirection,
                        const G4double       pCurrentProposedStepLength,
                              G4double&      pNewSafety ) override;
    // Return the distance to the next boundary of any geometry

  G4double ObtainFinalStep( G4int        navigatorId, 
                            G4double&    pNewSafety,     // for this geom 
                            G4double&    minStepLast,
                            ELimited&    limitedStep ); 
    // Get values for a single geometry

  void PrepareNavigators(); 
    // Find which geometries are registered for this particles, and keep info
  void PrepareNewTrack( const G4ThreeVector& position, 
                        const G4ThreeVector direction ); 
    // Prepare Navigators and locate 

  G4VPhysicalVolume* ResetHierarchyAndLocate( const G4ThreeVector& point,
                                   const G4ThreeVector& direction,
                                   const G4TouchableHistory& h ) override;
    // Reset the geometrical hierarchy for all geometries.
    // Use the touchable history for the first (mass) geometry.
    // Return the volume in the first (mass) geometry.
    // 
    // Important Note: In order to call this the geometries MUST be closed.

  G4VPhysicalVolume* LocateGlobalPointAndSetup( const G4ThreeVector& point,
                                   const G4ThreeVector* direction = nullptr,
                                   const G4bool pRelativeSearch = true,
                                   const G4bool ignoreDirection = true) override;
    // Locate in all geometries.
    // Return the volume in the first (mass) geometry
    //  Maintain vector of other volumes,  to be returned separately
    // 
    // Important Note: In order to call this the geometry MUST be closed.

  void LocateGlobalPointWithinVolume( const G4ThreeVector& position ) override; 
    // Relocate in all geometries for point that has not changed volume
    // (ie is within safety  in all geometries or is distance less that 
    // along the direction of a computed step.

  G4double ComputeSafety( const G4ThreeVector& globalpoint,
                          const G4double pProposedMaxLength = DBL_MAX,
                          const G4bool keepState = false ) override;
    // Calculate the isotropic distance to the nearest boundary 
    // in any geometry from the specified point in the global coordinate
    // system. The geometry must be closed.

  G4TouchableHandle CreateTouchableHistoryHandle() const override;
    // Returns a reference counted handle to a touchable history.

  G4ThreeVector GetLocalExitNormal( G4bool* obtained ) override; // const
  G4ThreeVector GetLocalExitNormalAndCheck( const G4ThreeVector &E_Pt,
                                            G4bool* obtained ) override; // const
  G4ThreeVector GetGlobalExitNormal( const G4ThreeVector &E_Pt,
                                           G4bool* obtained ) override; // const
    // Return Exit Surface Normal and validity too.
    // Can only be called if the Navigator's last Step either
    //  - has just crossed a volume geometrical boundary and relocated, or
    //  - has arrived at a boundary in a ComputeStep
    // It returns the Normal to the surface pointing out of the volume that
    //   was left behind and/or into the volume that was entered.
    // Convention:x
    //   The *local* normal is in the coordinate system of the *final* volume.
    // Restriction:
    //   Normals are not available for replica volumes (returns obtained= false)

 public:  // without description

  inline G4Navigator* GetNavigator( G4int n ) const
  { 
    if( (n>fNoActiveNavigators) || (n<0) ) { n=0; }
    return fpNavigator[n]; 
  }

 protected:  // with description

  void ResetState() override;
    // Utility method to reset the navigator state machine.

  void SetupHierarchy() override;
    // Renavigate & reset hierarchy described by current history
    // o Reset volumes
    // o Recompute transforms and/or solids of replicated/parameterised
    //   volumes.

  void WhichLimited(); // Flag which processes limited the step
  void PrintLimited(); // Auxiliary, debugging printing 
  void CheckMassWorld(); 

 private:

   // STATE Information 

   G4int fNoActiveNavigators = 0; 
   static const G4int fMaxNav = 16;
   G4VPhysicalVolume* fLastMassWorld = nullptr; 

   G4Navigator*  fpNavigator[fMaxNav];
     // Global state (retained during stepping for one track

   // State after a step computation 
   //
   ELimited      fLimitedStep[fMaxNav];
   G4bool        fLimitTruth[fMaxNav];
   G4double      fCurrentStepSize[fMaxNav]; 
   G4double      fNewSafety[ fMaxNav ]; // Safety for starting point
   G4int         fNoLimitingStep = -1;  // How many geometries limited the step
   G4int         fIdNavLimiting = -1;   // Id of Navigator limiting step

   // Lowest values - determine step length, and safety
   //
   G4double      fMinStep = -kInfinity; // As reported by Navigators
   G4double      fMinSafety = -kInfinity;
   G4double      fTrueMinStep = -kInfinity; // Corrected if fMinStep>=proposed

   // State after calling 'locate'
   //
   G4VPhysicalVolume* fLocatedVolume[fMaxNav];
   G4ThreeVector      fLastLocatedPosition; 

   // Cache of safety information
   //
   G4ThreeVector fSafetyLocation;
     // point where ComputeSafety is called
   G4double      fMinSafety_atSafLocation = -1.0;
     // - corresponding value of safety
   G4ThreeVector fPreStepLocation;
     // point where last ComputeStep called
   G4double      fMinSafety_PreStepPt = -1.0;
     // - corresponding value of safety

   G4TransportationManager* pTransportManager; // Cache for frequent use
};

#endif