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/// \file SteppingAction.cc
/// \brief Implementation of the SteppingAction class

#include "SteppingAction.hh"

#include "DetectorConstruction.hh"
#include "HistoManager.hh"
#include "RunAction.hh"

#include "G4ParticleTypes.hh"
#include "G4RunManager.hh"

#include <G4RotationMatrix.hh>
#include <G4ThreeVector.hh>

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SteppingAction::SteppingAction(DetectorConstruction* det, RunAction* RuAct)
  : G4UserSteppingAction(), fDetector(det), fRunAction(RuAct)
{}

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SteppingAction::~SteppingAction() {}

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void SteppingAction::UserSteppingAction(const G4Step* aStep)
{
  G4StepPoint* prePoint = aStep->GetPreStepPoint();

  // if World --> return
  if (prePoint->GetTouchableHandle()->GetVolume() == fDetector->GetWorld()) return;

  // here we enter in the absorber Box
  // tag the event to be killed anyway after this step
  //
  G4RunManager::GetRunManager()->AbortEvent();

  // count processes and keep only Multiple Scattering or gamma converion
  //
  G4StepPoint* endPoint = aStep->GetPostStepPoint();
  G4String procName = endPoint->GetProcessDefinedStep()->GetProcessName();
  fRunAction->CountProcesses(procName);

  if (procName == "msc" || procName == "muMsc" || procName == "stepMax") {
    // below, only multiple Scattering happens
    //
    G4ThreeVector position = endPoint->GetPosition();
    G4ThreeVector direction = endPoint->GetMomentumDirection();

    G4double truePathLength = aStep->GetStepLength();
    G4double geomPathLength = position.x() + 0.5 * fDetector->GetBoxSize();
    G4double ratio = geomPathLength / truePathLength;
    fRunAction->SumPathLength(truePathLength, geomPathLength);
    G4AnalysisManager* analysisManager = G4AnalysisManager::Instance();
    analysisManager->FillH1(1, truePathLength);
    analysisManager->FillH1(2, geomPathLength);
    analysisManager->FillH1(3, ratio);

    G4double yend = position.y(), zend = position.z();
    G4double lateralDisplacement = std::sqrt(yend * yend + zend * zend);
    fRunAction->SumLateralDisplacement(lateralDisplacement);
    analysisManager->FillH1(4, lateralDisplacement);

    G4double psi = std::atan(lateralDisplacement / geomPathLength);
    fRunAction->SumPsi(psi);
    analysisManager->FillH1(5, psi);

    G4double xdir = direction.x(), ydir = direction.y(), zdir = direction.z();
    G4double tetaPlane = std::atan2(ydir, xdir);
    fRunAction->SumTetaPlane(tetaPlane);
    analysisManager->FillH1(6, tetaPlane);
    tetaPlane = std::atan2(zdir, xdir);
    fRunAction->SumTetaPlane(tetaPlane);
    analysisManager->FillH1(6, tetaPlane);

    G4double phiPos = std::atan2(zend, yend);
    analysisManager->FillH1(7, phiPos);
    G4double phiDir = std::atan2(zdir, ydir);
    analysisManager->FillH1(8, phiDir);

    G4double phiCorrel = 0.;
    if (lateralDisplacement > 0.) phiCorrel = (yend * ydir + zend * zdir) / lateralDisplacement;
    fRunAction->SumPhiCorrel(phiCorrel);
    analysisManager->FillH1(9, phiCorrel);
  }
  else if (procName == "conv" || procName == "GammaToMuPair") {
    // gamma conversion

    G4StepPoint* PrePoint = aStep->GetPreStepPoint();
    G4double EGamma = PrePoint->GetTotalEnergy();
    G4ThreeVector PGamma = PrePoint->GetMomentum();
    G4ThreeVector PolaGamma = PrePoint->GetPolarization();

    G4double Eplus = -1;
    G4ThreeVector Pplus, Pminus, Precoil;

    const G4TrackVector* secondary = fpSteppingManager->GetSecondary();

    const size_t Nsecondaries = (*secondary).size();

    // No conversion , E < threshold
    if (Nsecondaries == 0) return;

    for (size_t lp = 0; lp < std::min(Nsecondaries, size_t(2)); lp++) {
      if (((*secondary)[lp]->GetDefinition() == G4Electron::Definition())
          || ((*secondary)[lp]->GetDefinition() == G4MuonMinus::Definition()))
      {
        Pminus = (*secondary)[lp]->GetMomentum();
      }
      if (((*secondary)[lp]->GetDefinition() == G4Positron::Definition())
          || ((*secondary)[lp]->GetDefinition() == G4MuonPlus::Definition()))
      {
        Eplus = (*secondary)[lp]->GetTotalEnergy();
        Pplus = (*secondary)[lp]->GetMomentum();
      }
    }

    if (Nsecondaries >= 3) {
      Precoil = (*secondary)[2]->GetMomentum();
    }

    G4AnalysisManager* analysisManager = G4AnalysisManager::Instance();

    // Fill Histograms

    G4ThreeVector z = PGamma.unit();  // gamma direction
    G4ThreeVector x(1., 0., 0.);

    // pola perpendicular to direction

    if (PolaGamma.mag() != 0.0) {
      x = PolaGamma.unit();
    }
    else {  // Pola = 0 case
      x = z.orthogonal().unit();
    }

    G4ThreeVector y = z;
    y = y.cross(x);

    G4RotationMatrix GtoW(x, y, z);  // from  gamma ref. sys. to World
    G4RotationMatrix WtoG = inverseOf(GtoW);  // from World to gamma ref. sys.

    G4double angleE = Pplus.angle(Pminus) * EGamma;
    analysisManager->FillH1(10, angleE);

    if (Nsecondaries >= 3) {
      // recoil returned
      analysisManager->FillH1(11, std::log10(Precoil.mag()));
      analysisManager->FillH1(12, Precoil.transform(WtoG).phi());
    }
    G4double phiPlus = Pplus.transform(WtoG).phi();
    G4double phiMinus = Pminus.transform(WtoG).phi();
    analysisManager->FillH1(13, phiPlus);
    analysisManager->FillH1(14, std::cos(phiPlus + phiMinus) * -2.0);
    analysisManager->FillH1(15, Eplus / EGamma);

    G4double phiPola = PolaGamma.transform(WtoG).phi();
    analysisManager->FillH1(16, phiPola);
  }
}

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