//
// ********************************************************************
// * 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.          *
// ********************************************************************
//
//
// $Id: G4ParallelNavigator.hh,v 1.10 2006/06/29 18:16:23 gunter Exp $
// GEANT4 tag $Name: geant4-08-01 $
//
// ----------------------------------------------------------------------
// Class G4ParallelNavigator
//
// Class description:
//
// Used internaly for importance sampling and scoring in a "parallel"
// geometry. 
// It implements the interface G4VPGeoDriver (see G4VPGeoDriver.hh).
// It uses a G4Navigator.

// Author: Michael Dressel (Michael.Dressel@cern.ch)
// ----------------------------------------------------------------------
#ifndef G4ParallelNavigator_hh
#define G4ParallelNavigator_hh G4ParallelNavigator_hh

#include "G4VPGeoDriver.hh"
#include "geomdefs.hh"

#include "G4TouchableHandle.hh"
#include "G4Navigator.hh"

class G4GeometryCell ;
class G4VPhysicalVolume;

class G4ParallelNavigator : public G4VPGeoDriver
{

public:  // with description

  explicit G4ParallelNavigator(G4VPhysicalVolume &aWorldVolume);
    // initialise and create G4Navigator and a TouchableHistory

  virtual ~G4ParallelNavigator();
    // delete Touchable and Navigator

   virtual G4GeometryCell 
   LocateOnBoundary(const G4ThreeVector &aPosition, 
		    const G4ThreeVector &aDirection);
    // The location of a track according to it's position
    // and direction in case the track crosses a boundary
    // of a "parallel" geometry.
    // Must be called in the PostDOIT of the ParallelTransportation.
    // (The track crosses the boundary if PostDOIT gets called.)
  

  virtual G4GeometryCell GetCurrentGeometryCell() const;
    // get the current G4GeometryCell of the "parallel" geometry

   virtual G4double 
   ComputeStepLengthInit(const G4ThreeVector &aPosition, 
			 const G4ThreeVector &aDirection);
    // compute step length for a starting track. 
  
  virtual  G4double 
  ComputeStepLengthCrossBoundary(const G4ThreeVector &aPosition, 
				 const G4ThreeVector &aDirection);
    // compute the step length after a track crossed a boundary
    // in a "parallel" geometry
  
   virtual G4double 
   ComputeStepLengthInVolume(const G4ThreeVector &aPosition, 
			     const G4ThreeVector &aDirection);
    // compute step length when track moves inside a volume.  
  
  void SetVerboseity(G4int v);

private:

  G4ParallelNavigator(const G4ParallelNavigator &);
  G4ParallelNavigator &operator=(const G4ParallelNavigator &);

  G4double ComputeStepLengthShifted(const G4String &m,
				    const G4ThreeVector &aPosition, 
				    const G4ThreeVector &aDirection);

  G4double GetStepLength(const G4String &methodname,
			 const G4ThreeVector &aPosition, 
			 const G4ThreeVector &aDirection);
  
  G4double GetStepLengthUseLocate(const G4String &methodname,
				  const G4ThreeVector &aPosition, 
				  const G4ThreeVector &aDirection);
  
  void Locate(const G4ThreeVector &aPosition, 
	      const G4ThreeVector &aDirection,
	      G4bool historysearch,
	      G4bool useDirection); 
			
  void Error(const G4String &m,
             const G4ThreeVector &pos,
             const G4ThreeVector &dir);

  G4double Shift(G4double d);

private:
  
  G4Navigator fNavigator;
  G4int fNlocated;
  G4int fMaxShiftedTrys;  
  G4TouchableHandle fCurrentTouchableH;
  G4int fVerbose;
};

#endif