#include "YourPrimaryGeneratorAction.hh"

#include "YourDetectorConstruction.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleTable.hh"

YourPrimaryGeneratorAction::YourPrimaryGeneratorAction(YourDetectorConstruction* det)
:  G4VUserPrimaryGeneratorAction(),
   fDetector(det),
   fGun(nullptr) {
   G4int numParticles = 1;
   fGun = new G4ParticleGun(numParticles);
   SetDefault(); 
}

YourPrimaryGeneratorAction::~YourPrimaryGeneratorAction() {
   delete fGun;
}


void YourPrimaryGeneratorAction::GeneratePrimaries(G4Event* evt) {
   fGun->GeneratePrimaryVertex(evt);
}


void YourPrimaryGeneratorAction::SetDefault() {
   // e-  // G4Electron::Definition()
   G4ParticleDefinition* part = G4ParticleTable::GetParticleTable()->FindParticle("e-");
   // you might chek if ( part == nullptr) !!!
   fGun->SetParticleDefinition(part);
   fGun->SetParticleEnergy(30.0*CLHEP::MeV);
   fGun->SetParticleMomentumDirection( G4ThreeVector(1.0, 0.0, 0.0) );
   UpdatePosition();
}


void YourPrimaryGeneratorAction::UpdatePosition() {
   fGun->SetParticlePosition( G4ThreeVector( fDetector->GetGunXPosition(), 0.0, 0.0  ) );
}