#include "LGPrimaryGeneratorAction.hh"
#include "LGPrimaryGeneratorMessenger.hh"

#include "G4Event.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"

#include <math.h>

LGPrimaryGeneratorAction::LGPrimaryGeneratorAction(G4int randomdir)
{
  generator_Messenger = new LGPrimaryGeneratorMessenger(this);	
  RandomDir = randomdir;
  RandGen.setTheSeed(38470987038941);
  
  //	G4ThreeVector gun_Position(0.1*cm, 0.1*cm, -36.*cm);		// the position of the particle gun
  G4ThreeVector gun_Position(0., 0., -60.*cm);
  G4ThreeVector momentum_Direction(0, 0, 1);			// the momentum direction of incident particles
  G4ThreeVector particle_Polarization(0, 0, 0);			// set the particle polarization
  particle_Energy = 2.76*eV;					// set the particle energy
  G4int n_Incident_Particles = 1; 				// set the number of incident particles
  
  particle_Gun = new G4ParticleGun(n_Incident_Particles);		// generate an object of G4ParticleGun
  G4ParticleTable* particle_Table = G4ParticleTable::GetParticleTable();
  G4ParticleDefinition* particle = particle_Table->FindParticle("opticalphoton");	
  particle_Gun->SetParticleDefinition(particle);  // This command should appear first.
  particle_Gun->SetParticleMomentumDirection(momentum_Direction);
  particle_Gun->SetParticleTime(0.*ns);	
  particle_Gun->SetParticleEnergy(particle_Energy);		
  particle_Gun->SetParticlePosition(gun_Position);
  particle_Gun->SetParticlePolarization(particle_Polarization); 
}

LGPrimaryGeneratorAction::~LGPrimaryGeneratorAction()
{
  delete generator_Messenger;
  delete particle_Gun;
}

void LGPrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent) 
{
  if (RandomDir) {
    G4double x = RandGen.flat()*2.5 - 1.25;
    //G4double y = RandGen.flat()*6.0 - 3.0;
    G4double y = 0.;
    G4ThreeVector gun_Position;
    gun_Position.set(x*cm, y*cm, -60.0*cm);
    
    G4double theta = RandGen.flat()*M_PI/2. ;
    G4double phi   = RandGen.flat()*M_PI*2. ;
    
    G4double dz = cos(theta);
    G4double dr = sin(theta);
    G4double dx = dr*cos(phi);
    G4double dy = dr*sin(phi);
    G4ThreeVector gun_Direction;
    gun_Direction.set(dx, dy, dz);
    
    particle_Gun->SetParticlePosition(gun_Position);
    particle_Gun->SetParticleMomentumDirection(gun_Direction);
  }
  particle_Gun->GeneratePrimaryVertex(anEvent);			// generate the particle

} 

void LGPrimaryGeneratorAction::setParticleEnergy(G4double new_Value)
{
  particle_Energy = new_Value;
  particle_Gun->SetParticleEnergy(particle_Energy);
}

void LGPrimaryGeneratorAction::setGunPosition(G4ThreeVector new_Value)
{
  G4ThreeVector gun_Position = new_Value;
  particle_Gun->SetParticlePosition(gun_Position);
}