//
// ********************************************************************
// * 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.          *
// ********************************************************************
//
// -------------------------------------------------------------------
//
// Geant4 Class file
//
// File name:     G4PolarizedPhotoElectricModel
//
// Author:        Andreas Schaelicke & Karim Laihem
//
// Class Description:
//   Implementation of Photo electric effect
//   including polarization transfer from circularly polarised gammas

#include "G4PolarizedPhotoElectricModel.hh"

#include "G4DataVector.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4PolarizationHelper.hh"
#include "G4PolarizedPhotoElectricXS.hh"

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
G4PolarizedPhotoElectricModel::G4PolarizedPhotoElectricModel(
  const G4ParticleDefinition*, const G4String& nam)
  : G4PEEffectFluoModel(nam)
  , fCrossSectionCalculator(nullptr)
  , fVerboseLevel(0)
{}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
G4PolarizedPhotoElectricModel::~G4PolarizedPhotoElectricModel()
{
  if(fCrossSectionCalculator)
    delete fCrossSectionCalculator;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo....
void G4PolarizedPhotoElectricModel::Initialise(const G4ParticleDefinition* pd,
                                               const G4DataVector& dv)
{
  G4PEEffectFluoModel::Initialise(pd, dv);
  if(!fCrossSectionCalculator)
    fCrossSectionCalculator = new G4PolarizedPhotoElectricXS();
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
void G4PolarizedPhotoElectricModel::SampleSecondaries(
  std::vector<G4DynamicParticle*>* vdp, const G4MaterialCutsCouple* couple,
  const G4DynamicParticle* dp, G4double tmin, G4double maxEnergy)
{
  G4PEEffectFluoModel::SampleSecondaries(vdp, couple, dp, tmin, maxEnergy);

  if(fVerboseLevel >= 1)
  {
    G4cout << "G4PolarizedPhotoElectricModel::SampleSecondaries" << G4endl;
  }

  if(vdp && !vdp->empty())
  {
    G4double gamEnergy0 = dp->GetKineticEnergy();
    G4double lepEnergy1 = (*vdp)[0]->GetKineticEnergy();
    G4double sintheta =
      dp->GetMomentumDirection().cross((*vdp)[0]->GetMomentumDirection()).mag();
    if(sintheta > 1.)
      sintheta = 1.;

    G4StokesVector beamPol = G4StokesVector(dp->GetPolarization());
    beamPol.SetPhoton();

    // determine interaction plane
    G4ThreeVector nInteractionFrame = G4PolarizationHelper::GetFrame(
      dp->GetMomentumDirection(), (*vdp)[0]->GetMomentumDirection());
    if(dp->GetMomentumDirection()
         .cross((*vdp)[0]->GetMomentumDirection())
         .mag() < 1.e-10)
    {
      nInteractionFrame =
        G4PolarizationHelper::GetRandomFrame(dp->GetMomentumDirection());
    }

    // transform polarization into interaction frame
    beamPol.InvRotateAz(nInteractionFrame, dp->GetMomentumDirection());

    // calulcate polarization transfer
    fCrossSectionCalculator->SetMaterial(
      GetCurrentElement()->GetN(),  // number of nucleons
      GetCurrentElement()->GetZ(), GetCurrentElement()->GetfCoulomb());
    fCrossSectionCalculator->Initialize(gamEnergy0, lepEnergy1, sintheta,
                                        beamPol, G4StokesVector::ZERO);

    // determine final state polarization
    G4StokesVector lep1Pol = fCrossSectionCalculator->GetPol2();
    lep1Pol.RotateAz(nInteractionFrame, (*vdp)[0]->GetMomentumDirection());
    (*vdp)[0]->SetPolarization(lep1Pol.p1(), lep1Pol.p2(), lep1Pol.p3());

    if(vdp->size() != 1)
    {
      G4ExceptionDescription ed;
      ed << " WARNING " << vdp->size()
         << " secondaries in polarized photo electric effect not supported!\n";
      G4Exception("G4PolarizedPhotoElectricModel::SampleSecondaries", "pol024",
                  JustWarning, ed);
    }
  }
}