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// $Id: Sc01PrimaryGeneratorAction.cc,v 1.4 2006/12/13 15:43:44 gunter Exp $
// ------------------------------------------------------------
//	GEANT 4 class header file 
//
//      This is a version for maximum particle set
//	History
//        first version              09  Sept. 1998 by S.Magni
// ------------------------------------------------------------

#include "Sc01PrimaryGeneratorAction.hh"
#include "Sc01DetectorConstruction.hh"

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

#include <iostream>
#include <fstream>

Sc01PrimaryGeneratorAction::
Sc01PrimaryGeneratorAction(Sc01DetectorConstruction*det)
  :
  fDetector(det)
{
  particleGun = new G4ParticleGun();
}

Sc01PrimaryGeneratorAction::~Sc01PrimaryGeneratorAction()
{
  delete particleGun;
}

void Sc01PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{

  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
  G4String particleName;
  G4ParticleDefinition* aParticleDefinition 
    = particleTable->FindParticle(particleName="opticalphoton");

  // create a new vertex in a random position 

  //  G4ThreeVector VertexPosition (GetRandomPosition());
  G4ThreeVector VertexPosition (G4ThreeVector(0,0,0));
  G4PrimaryVertex* aVertex = 
    new G4PrimaryVertex( VertexPosition, 0);

  //  G4int NumberOfParticlesToBeGenerated = 10000;
  G4int NumberOfParticlesToBeGenerated = 1;
  // G4cout << "  A " << NumberOfParticlesToBeGenerated 
  //          << " optical photons vertex has been generated at " 
  //          << VertexPosition << G4endl;
  // create new primaries and set them to the vertex
  for( int i=0; i<NumberOfParticlesToBeGenerated; i++ )
  {
    //	G4ThreeVector m = GetRandomDirection();
		G4ThreeVector m(0.,1.,0.);
    G4PrimaryParticle* aPrimaryParticle =
      new G4PrimaryParticle(aParticleDefinition, m.x(), m.y(), m.z());
    aPrimaryParticle->SetMass (0);
    G4ThreeVector p = GetRandomPolarization ( m );
    aPrimaryParticle->SetPolarization(p.x(),p.y(),p.z());
    aVertex->SetPrimary( aPrimaryParticle );
  }
  anEvent->AddPrimaryVertex( aVertex );
}

G4ThreeVector Sc01PrimaryGeneratorAction::GetRandomDirection() {

  G4ThreeVector retval;

  G4double CosTheta;
  G4double SinTheta;

  G4double Phi;
  G4double SinPhi;
  G4double CosPhi;

  G4double rand;

  rand = G4UniformRand();

  CosTheta = 2.0*rand -1.0;
  SinTheta = std::sqrt (1.-CosTheta*CosTheta);
  rand = G4UniformRand();
  Phi = twopi*rand;
  SinPhi = std::sin (Phi);
  CosPhi = std::cos (Phi);
  retval.setX(SinTheta*CosPhi);
  retval.setY(SinTheta*SinPhi);
  retval.setZ(CosTheta);

  return retval;
}

G4ThreeVector Sc01PrimaryGeneratorAction::GetRandomPosition() 
{
  G4double a = fDetector->GetHallSize();

  G4double x = ( G4UniformRand()*2 - 1 )*a;
  G4double y = ( G4UniformRand()*2 - 1 )*a;
  G4double z = ( G4UniformRand()*2 - 1 )*a;

  G4ThreeVector retval (x, y, z);

  return retval;
}

G4ThreeVector Sc01PrimaryGeneratorAction::GetRandomPolarization(G4ThreeVector Direction) {
  G4ThreeVector Polarization = Direction.orthogonal();
  G4ThreeVector retval = Polarization.unit();
  return retval;
}