///////////////////////////////////////////////////////////////////////////////
//
// Simulates optical Rayleigh scattering. This class simulates
// Rayleigh scattering. It should be used in preference to the Geant4
// G4OpRayleigh class as it will calculate mean free paths for all
// materials not just water.
//
// Author: P G Jones <p.g.jones@qmul.ac.uk>
//
// REVISION HISTORY:
//     2014-01-08 : P G Jones - New file.
//     12-05-2015 : I Coulter - Remove use of the "SNOMAN style" RS_SCALE_FACTOR
//                              This already exists in SNOMANOpRayleigh, isn't
//                              used in general use and causes confusion.
//
//////////////////////////////////////////////////////////////////////////////
#ifndef __RAT_OpRayleigh_hh__
#define __RAT_OpRayleigh_hh__

#include <G4VDiscreteProcess.hh>
#include <G4OpticalPhoton.hh>

class G4PhysicsTable;
class G4MaterialPropertiesTable;

namespace RAT
{

class OpRayleigh : public G4VDiscreteProcess
{
public:
  // Construct the class
  //
  // processName: optional, defaults to OpRayleigh
  // type: optional, defaults to fOptical
  OpRayleigh( const G4String& processName = "OpRayleigh",
              G4ProcessType type = fOptical );

  // Deletes the physics table
  ~OpRayleigh();

  // Returns true if this code is applicable to the particle type
  //
  // particleType: definition of the particle type
  // returns true if the particle type is an optical photon
  G4bool IsApplicable( const G4ParticleDefinition& particleType ) { return ( &particleType == G4OpticalPhoton::OpticalPhoton() ); }

  // Returns the mean free path for the track in mm.
  //
  // previousStepSize and condition are unused
  G4double GetMeanFreePath( const G4Track& track,
                            G4double previousStepSize,
                            G4ForceCondition* condition );

  // Invoke scattering to the track
  //
  // returns a particle change description
  G4VParticleChange* PostStepDoIt( const G4Track& track,
                                   const G4Step& step );
private:
  // Builds the physics table, i.e. a table of mean free paths
  void BuildThePhysicsTable();

  G4PhysicsTable* fPhysicsTable; // The physics table used
};

} //::RAT

#endif