#ifndef B1PrimaryGeneratorAction_h
#define B1PrimaryGeneratorAction_h 1

#include "G4ParticleGun.hh"
#include "G4VUserPrimaryGeneratorAction.hh"
#include "globals.hh"

class G4ParticleGun;
class G4Event;
class G4Box;

/// The primary generator action class with particle gun.
///
/// The default kinematic is a 6 MeV gamma, randomly distribued
/// in front of the phantom across 80% of the (X,Y) phantom size.

namespace B1 {

// G4ParticleGun 粒子枪，即辐射源
class PrimaryGeneratorAction : public G4VUserPrimaryGeneratorAction {
public:
    PrimaryGeneratorAction();
    ~PrimaryGeneratorAction() override;

    // method from the base class
    void GeneratePrimaries(G4Event*) override;

    // method to access particle gun
    const G4ParticleGun* GetParticleGun() const { return fParticleGun; }

private:
    G4ParticleGun* fParticleGun = nullptr;  // pointer a to G4 gun class
    G4Box* fEnvelopeBox = nullptr;
};

}  // namespace B1

#endif