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//
// -------------------------------------------------------------------
//      GEANT 4 class file 
//
//      CERN, Geneva, Switzerland
//
//      File name:     G4VGammaDeexcitation
//
//      Author:        Maria Grazia Pia (pia@genova.infn.it)
// 
//      Creation date: 23 October 1998
//
//      Modifications: 
//
//        21 Nov 2001, Fan Lei (flei@space.qinetiq.com)
//           Modified GenerateGamma() and UpdateUncleus() for implementation
//           of Internal Conversion processs 
//      
//        15 April 1999, Alessandro Brunengo (Alessandro.Brunengo@ge.infn.it)
//              Added creation time evaluation for products of evaporation
//
//
// -------------------------------------------------------------------

#include "G4VGammaDeexcitation.hh"

#include "globals.hh"
#include "Randomize.hh"
#include "G4Gamma.hh"
#include "G4Electron.hh"
#include "G4LorentzVector.hh"
#include "G4VGammaTransition.hh"
#include "G4Fragment.hh"
#include "G4FragmentVector.hh"

#include "G4ParticleTable.hh"
#include "G4IonTable.hh"

#include "G4DiscreteGammaTransition.hh"

G4VGammaDeexcitation::G4VGammaDeexcitation(): _transition(0), _verbose(0),
					      _electronO (0), _vSN(-1)
{ }


G4VGammaDeexcitation::~G4VGammaDeexcitation()
{ 
  //  if (_transition != 0) delete _transition;
}


G4FragmentVector* G4VGammaDeexcitation::DoTransition()
{
  // Template method

 Initialize();
 G4FragmentVector* products = new G4FragmentVector;
  
  if (CanDoTransition())
    {
     G4Fragment* gamma = GenerateGamma();
     if (gamma != 0)
       {
	 products->push_back(gamma);
	 UpdateNucleus(gamma);
	 Update();
       }
    }

  if (_verbose > 1)
    G4cout << "G4VGammaDeexcitation::DoTransition - Transition deleted " << G4endl;

  if (_transition != 0) delete _transition;

  return products;
}

G4FragmentVector* G4VGammaDeexcitation::DoChain()
{
  Initialize();
  G4FragmentVector* products = new G4FragmentVector;

  while (CanDoTransition())
    {
      if (_verbose > 5) G4cout << "G4VGammaDeexcitation::DoChain -  Looping" << G4endl;

      G4Fragment* gamma = GenerateGamma();
      if (gamma != 0) 
	{
	  products->push_back(gamma);
	  UpdateNucleus(gamma);
	  UpdateElectrons ();
	}
     Update();
    } 

  if (_verbose > 1)
      G4cout << "G4VGammaDeexcitation::DoChain - Transition deleted, end of chain " << G4endl;

  if (_transition != 0) delete _transition;
  
  return products;
}


const G4Fragment& G4VGammaDeexcitation::GetNucleus() const
{
  return _nucleus; 
}


void G4VGammaDeexcitation::SetNucleus(const G4Fragment& nucleus)
{
  _nucleus = G4Fragment(nucleus);
}


G4Fragment* G4VGammaDeexcitation::GenerateGamma()
{
  G4double eGamma = 0.;

  if (_transition != 0) {
    _transition->SelectGamma();  // it can be conversion electron too
    eGamma = _transition->GetGammaEnergy(); 
  }
  if (_verbose > 1 && _transition != 0 ) 
    {
      G4cout << "G4VGammaDeexcitation::GenerateGamma - Gamma energy " << eGamma 
	     << " ** New excitation " << _nucleus.GetExcitationEnergy() - eGamma
	     << G4endl;
    }
  
  // Photon momentum isotropically generated
  // the same for electron 
  
  if (eGamma > 0.) 
    {
      G4double cosTheta = 1. - 2. * G4UniformRand();
      G4double sinTheta = std::sqrt(1. - cosTheta * cosTheta);
      G4double phi = twopi * G4UniformRand();
      G4double pM = eGamma;
      G4DiscreteGammaTransition* dtransition = 0; 
      dtransition = dynamic_cast <G4DiscreteGammaTransition*> (_transition);
      if ( dtransition && !( dtransition->IsAGamma()) ) {
	G4double eMass = G4Electron::ElectronDefinition()->GetPDGMass();
	pM =std::sqrt(eGamma*(eGamma + 2.0*eMass));
	eGamma = eGamma + eMass;
      }
      G4ThreeVector pGamma( pM * sinTheta * std::cos(phi),
			    pM * sinTheta * std::sin(phi),
			    pM * cosTheta );
      G4LorentzVector gamma(pGamma, eGamma);
      //	gamma.boost(_nucleus.GetMomentum().boostVector() );
      G4Fragment* gammaFragment ;
      if ( dtransition && !(dtransition->IsAGamma()) ){
	gammaFragment = new G4Fragment(gamma,G4Electron::ElectronDefinition());
      } else {
	gammaFragment = new G4Fragment(gamma,G4Gamma::GammaDefinition()); 
      }
      G4double gammaTime = _transition->GetGammaCreationTime();
      gammaTime += _nucleus.GetCreationTime();
      gammaFragment->SetCreationTime(gammaTime);
      
      if (_verbose > 1 && dtransition )
	G4cout << "G4VGammaDeexcitation::GenerateGamma -  Gamma fragment generated:  " 
	       << (dtransition->IsAGamma() ? " Gamma" : " Electron" ) << G4endl;
      return gammaFragment;
    }
  else
    {
      return 0;
    }
}

void G4VGammaDeexcitation::UpdateNucleus(const G4Fragment*  gamma)
{
  G4LorentzVector p4Gamma = gamma->GetMomentum();
  G4ThreeVector pGamma(p4Gamma.vect());
  
  G4double eGamma = 0.;
  if (_transition != 0)
    eGamma = _transition->GetGammaEnergy();
  G4DiscreteGammaTransition* dtransition = 0; 
  dtransition = dynamic_cast <G4DiscreteGammaTransition*> (_transition);
  if (dtransition && !(dtransition->IsAGamma()) )      
    eGamma += dtransition->GetBondEnergy(); 

  G4LorentzVector p4Nucleus(_nucleus.GetMomentum() );

// New tetravector calculation:

//  G4double Mass = G4ParticleTable::GetParticleTable()->GetIonTable()->GetIonMass(_nucleus.GetZ(),_nucleus.GetA());
  G4double m1 = G4ParticleTable::GetParticleTable()->GetIonTable()->GetIonMass(static_cast<G4int>(_nucleus.GetZ()),
									       static_cast<G4int>(_nucleus.GetA()));
  G4double m2 = _nucleus.GetZ() *  G4Proton::Proton()->GetPDGMass() + 
    (_nucleus.GetA()- _nucleus.GetZ())*G4Neutron::Neutron()->GetPDGMass();

  G4double Mass = std::min(m1,m2);


  G4double newExcitation = p4Nucleus.mag() - Mass - eGamma;
  if(newExcitation < 0)
    newExcitation = 0;
  
  G4ThreeVector p3Residual(p4Nucleus.vect() - pGamma);
  G4double newEnergy = std::sqrt(p3Residual * p3Residual +
			    (Mass + newExcitation) * (Mass + newExcitation));
  G4LorentzVector p4Residual(p3Residual, newEnergy);
  
  //  G4LorentzVector p4Residual(-pGamma, p4Nucleus.e() - eGamma);
  //  p4Residual.boost( _nucleus.GetMomentum().boostVector() );
  
  // Update excited nucleus parameters

  _nucleus.SetMomentum(p4Residual);
  _nucleus.SetCreationTime(gamma->GetCreationTime());

//  if (_transition != 0) 
//  {
//    G4double excitation =_transition->GetEnergyTo();
//    if (excitation < 0.) excitation = 0.0;
//    _nucleus.SetExcitationEnergy(excitation);
//  }

  return;
}

void G4VGammaDeexcitation::UpdateElectrons( )
{
  G4DiscreteGammaTransition* dtransition = 0; 
  dtransition = dynamic_cast <G4DiscreteGammaTransition*> (_transition);
  if (dtransition && !(dtransition->IsAGamma()) ) {    
    
    _vSN = dtransition->GetOrbitNumber();   
    _electronO.RemoveElectron(_vSN);
  }
  return;
}

void G4VGammaDeexcitation::Update()
{
  if (_transition !=  0) 
    { 
      delete _transition;
      _transition = 0;
      if (_verbose > 1)
	G4cout << "G4VGammaDeexcitation::Update - Transition deleted " << G4endl;
    }

  _transition = CreateTransition();
  if (_transition != 0) 
    {
      _transition->SetEnergyFrom(_nucleus.GetExcitationEnergy());
      //      if ( _vSN != -1) (dynamic_cast <G4DiscreteGammaTransition*> (_transition))->SetICM(false);
      // the above line is commented out for bug fix #952. It was intruduced for reason that
      // the k-shell electron is most likely one to be kicked out and there is no time for 
      // the atom to deexcite before the next IC. But this limitation is causing other problems as 
      // reported in #952
    }

  return;
}


void G4VGammaDeexcitation::Initialize()
{
  _transition = CreateTransition();
  if (_transition != 0) {
    _transition->SetEnergyFrom(_nucleus.GetExcitationEnergy());
  }
  return;
}


void G4VGammaDeexcitation::SetVerboseLevel(G4int verbose)
{
  _verbose = verbose;
  return;
}