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/// \file errProp.cc
/// \brief Main program of the errorpropagation/errProp example

// ------------------------------------------------------------
//      GEANT 4 example main
// ------------------------------------------------------------
//
// History:
// - Created:   P. Arce   May 2007
//

#include "ExErrorDetectorConstruction.hh"

#include "G4ErrorCylSurfaceTarget.hh"
#include "G4ErrorFreeTrajState.hh"
#include "G4ErrorGeomVolumeTarget.hh"
#include "G4ErrorPlaneSurfaceTarget.hh"
#include "G4ErrorPropagator.hh"
#include "G4ErrorPropagatorData.hh"
#include "G4ErrorPropagatorManager.hh"
#include "G4ErrorTrackLengthTarget.hh"
#include "G4SteppingVerbose.hh"
#include "G4SystemOfUnits.hh"
#include "G4UImanager.hh"

void Initialize();
G4ErrorTarget* BuildTarget(G4int iTarget);
void ProcessEvent(G4int iProp, size_t nEv);
void Finalize();

G4ErrorTarget* theTarget;
G4ErrorMode theG4ErrorMode;

//-------------------------------------------------------------
int main()
{
  Initialize();

  //----- Choose propagation mode
  // 0: propagate until target, all steps in one go
  // 1: propagate until target, returning control to the user at each step
  G4int iProp = 0;
  char* prop = std::getenv("G4ERROR_PROP");
  if (prop) {
    if (G4String(prop) == G4String("UNTIL_TARGET")) {
      iProp = 0;
    }
    else if (G4String(prop) == G4String("STEP_BY_STEP")) {
      iProp = 1;
    }
    else {
      G4Exception("exG4eReco", "Fatal error in Argument", FatalErrorInArgument,
                  G4String("Variable G4ERROR_PROP = " + G4String(prop)
                           + "   It must be: UNTIL_TARGET or STEP_BY_STEP")
                    .c_str());
    }
  }
  else {
    G4Exception("exG4eReco", "Fatal error in Argument", JustWarning,
                "Variable G4ERROR_PROP not defined, taking it = UNTIL_TARGET");
  }

  size_t nEvents = 3;
  for (size_t ii = 0; ii < nEvents; ii++) {
    ProcessEvent(iProp, ii);
  }

  Finalize();
}

//-------------------------------------------------------------
void Initialize()
{
  G4VSteppingVerbose::SetInstance(new G4SteppingVerbose);

  // Initialize the GEANT4e manager
  G4ErrorPropagatorManager* g4emgr = G4ErrorPropagatorManager::GetErrorPropagatorManager();
  G4ErrorPropagatorData* g4edata = G4ErrorPropagatorData::GetErrorPropagatorData();

  g4emgr->SetUserInitialization(new ExErrorDetectorConstruction);

  G4UImanager::GetUIpointer()->ApplyCommand("/exerror/setField -10. kilogauss");

  g4emgr->InitGeant4e();

  G4UImanager::GetUIpointer()->ApplyCommand("/control/verbose 1");
  G4UImanager::GetUIpointer()->ApplyCommand("/tracking/verbose 1");
  G4UImanager::GetUIpointer()->ApplyCommand("/geant4e/limits/stepLength 100 mm");

  //----- Choose target type:
  // 1: PlaneSurfaceTarget
  // 2: CylSurfaceTarget
  // 3: GeomVolumeTarget
  // 4: TrackLengthTarget
  G4int iTarget = 1;
  char* target = std::getenv("G4ERROR_TARGET");
  if (target) {
    if (G4String(target) == G4String("PLANE_SURFACE")) {
      iTarget = 1;
    }
    else if (G4String(target) == G4String("CYL_SURFACE")) {
      iTarget = 2;
    }
    else if (G4String(target) == G4String("VOLUME")) {
      iTarget = 3;
    }
    else if (G4String(target) == G4String("TRKLEN")) {
      iTarget = 4;
    }
    else {
      G4Exception("exG4eReco", "Fatal error in Argument", FatalErrorInArgument,
                  G4String("Variable G4ERROR_TARGET = " + G4String(target)
                           + "   It must be:  PLANE_SURFACE, CYL_SURFACE, VOLUME, TRKLEN")
                    .c_str());
    }
  }
  else {
    G4Exception("exG4eReco", "Fatal error in Argument", JustWarning,
                "Variable G4ERROR_TARGET not defined, taking it = PLANE_SURFACE");
  }

  theTarget = BuildTarget(iTarget);
  g4edata->SetTarget(theTarget);

  theG4ErrorMode = G4ErrorMode_PropBackwards;
  char* mode = std::getenv("G4ERROR_MODE");
  if (mode) {
    if (G4String(mode) == G4String("FORWARDS")) {
      theG4ErrorMode = G4ErrorMode_PropForwards;
    }
    else if (G4String(mode) == G4String("BACKWARDS")) {
      theG4ErrorMode = G4ErrorMode_PropBackwards;
    }
    else {
      G4Exception("exG4eReco", "Fatal error in Argument", FatalErrorInArgument,
                  G4String("Variable G4ERROR_MODE = " + G4String(mode)
                           + "   It must be:  FORWARDS or BACKWARDS")
                    .c_str());
    }
  }
  else {
    G4Exception("exG4eReco", "Fatal error in Argument", JustWarning,
                "Variable G4ERROR_MODE not defined, taking it = BACKWARDS");
  }
}

void ProcessEvent(G4int iProp, size_t)
{
  // Set the starting trajectory.
  G4ThreeVector xv3(0, 0, 0);
  G4ThreeVector pv3(20.0 * GeV, 0.0, 0.0);
  G4ErrorTrajErr error(5, 0);
  G4ErrorFreeTrajState* g4ErrorTrajState = new G4ErrorFreeTrajState("mu-", xv3, pv3, error);

  G4ErrorPropagatorManager* g4emgr = G4ErrorPropagatorManager::GetErrorPropagatorManager();

  // int ierr = 0;

  G4Point3D surfPos(224. * cm, 0., 0.);
  G4Normal3D surfNorm(1., 0., 0.);
  //-  G4ErrorTarget* theG4ErrorTarget
  //     = new G4ErrorPlaneSurfaceTarget(surfNorm, surfPos );

  if (iProp == 0) {
    // Propagate until G4ErrorTarget is found all in one go
    // ierr =
    g4emgr->Propagate(g4ErrorTrajState, theTarget, theG4ErrorMode);
  }
  else if (iProp == 1) {
    // Propagate until G4ErrorTarget is reached step by step

    g4emgr->InitTrackPropagation();

    //    G4Track* aTrack
    //      = G4EventManager::GetEventManager()->GetTrackingManager()->GetTrack();
    bool moreEvt = TRUE;
    while (moreEvt) {
      // ierr =
      g4emgr->PropagateOneStep(g4ErrorTrajState, theG4ErrorMode);

      //---- Check if target is reached
      if (g4emgr->GetPropagator()->CheckIfLastStep(g4ErrorTrajState->GetG4Track())) {
        g4emgr->GetPropagator()->InvokePostUserTrackingAction(g4ErrorTrajState->GetG4Track());
        moreEvt = 0;
        G4cout << "STEP_BY_STEP propagation: Last Step " << G4endl;
      }
    }
  }

  G4cout << " $$$ PROPAGATION ENDED " << G4endl;
  // extract current state info
  G4Point3D posEnd = g4ErrorTrajState->GetPosition();
  G4Normal3D momEnd = g4ErrorTrajState->GetMomentum();
  G4ErrorTrajErr errorEnd = g4ErrorTrajState->GetError();

  G4cout << " Position: " << posEnd << G4endl << " Momentum: " << momEnd << G4endl
         << " Error: " << errorEnd << G4endl;
}

//-------------------------------------------------------------
G4ErrorTarget* BuildTarget(G4int iTarget)
{
  G4ErrorTarget* target = 0;
  if (iTarget == 1) {
    G4Point3D surfPos(221. * cm, 0., 0.);
    G4Normal3D surfNorm(1., 0., 0.);
    target = new G4ErrorPlaneSurfaceTarget(surfNorm, surfPos);
  }
  else if (iTarget == 2) {
    G4double radius = 222 * cm;
    target = new G4ErrorCylSurfaceTarget(radius);
  }
  else if (iTarget == 3) {
    target = new G4ErrorGeomVolumeTarget("MUON");
  }
  else if (iTarget == 4) {
    target = new G4ErrorTrackLengthTarget(223. * cm);
  }
  else {
    G4Exception("exG4eReco", "Fatal error in Argument", FatalErrorInArgument,
                "Target type has to be between 1 and 4");
  }
  return target;
}

//-------------------------------------------------------------
void Finalize()
{
  G4ErrorPropagatorManager::GetErrorPropagatorManager()->CloseGeometry();
}