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// $Id: G4InelasticInteraction.cc,v 1.12 2009/01/24 11:56:27 vnivanch Exp $
// GEANT4 tag $Name: geant4-09-03-ref-09 $
//
// Hadronic Process: Inelastic Interaction 
// original by H.P. Wellisch
// modified by J.L. Chuma, TRIUMF, 22-Nov-1996
// Last modified: 27-Mar-1997
// J.P. Wellisch: 23-Apr-97: throw G4HadronicException(__FILE__, __LINE__,  removed
// J.P. Wellisch: 24-Apr-97: correction for SetUpPions
// Modified by J.L. Chuma, 30-Apr-97: added originalTarget to CalculateMomenta
//                                    since TwoBody needed to reset the target particle
// J.L. Chuma, 20-Jun-97: Modified CalculateMomenta to correct the decision process
//                        for whether to use GenerateXandPt or TwoCluster
// J.L. Chuma, 06-Aug-97: added original incident particle, before Fermi motion and
//                        evaporation effects are included, needed for calculating
//                        self absorption and corrections for single particle spectra
// HPW removed misunderstanding of LocalEnergyDeposit, 11.04.98.
// 23-Jan-2009 V.Ivanchenko move constructor and destructor to the body
 
#include "G4InelasticInteraction.hh"
#include "Randomize.hh"
#include "G4HadReentrentException.hh"

G4InelasticInteraction::G4InelasticInteraction(const G4String& modelName) 
  : G4HadronicInteraction(modelName)
{ cache = 0.0;}
    
G4InelasticInteraction::~G4InelasticInteraction()
{}
 
G4double
  G4InelasticInteraction::Pmltpc(      // used in Cascade functions
   G4int np, G4int nm, G4int nz, G4int n, G4double b, G4double c )
  {
    const G4double expxu =  82.;           // upper bound for arg. of exp
    const G4double expxl = -expxu;         // lower bound for arg. of exp
    G4double npf = 0.0;
    G4double nmf = 0.0;
    G4double nzf = 0.0;
    G4int i;
    for( i=2; i<=np; i++ )npf += std::log((double)i);
    for( i=2; i<=nm; i++ )nmf += std::log((double)i);
    for( i=2; i<=nz; i++ )nzf += std::log((double)i);
    G4double r;
    r = std::min( expxu, std::max( expxl, -(np-nm+nz+b)*(np-nm+nz+b)/(2*c*c*n*n)-npf-nmf-nzf ) );
    return std::exp(r);
  }

G4bool
  G4InelasticInteraction::MarkLeadingStrangeParticle(
   const G4ReactionProduct &currentParticle,
   const G4ReactionProduct &targetParticle,
   G4ReactionProduct &leadParticle )
  {
    // the following was in GenerateXandPt and TwoCluster
    // add a parameter to the GenerateXandPt function telling it about the strange particle
    //
    // assumes that the original particle was a strange particle
    //
    G4bool lead = false;
    if( (currentParticle.GetMass() >= G4KaonPlus::KaonPlus()->GetPDGMass()) &&
        (currentParticle.GetDefinition() != G4Proton::Proton()) &&
        (currentParticle.GetDefinition() != G4Neutron::Neutron()) )
    {
      lead = true;
      leadParticle = currentParticle;              //  set lead to the incident particle
    }
    else if( (targetParticle.GetMass() >= G4KaonPlus::KaonPlus()->GetPDGMass()) &&
             (targetParticle.GetDefinition() != G4Proton::Proton()) &&
             (targetParticle.GetDefinition() != G4Neutron::Neutron()) )
    {
      lead = true;
      leadParticle = targetParticle;              //   set lead to the target particle
    }
    return lead;
  }
 
void
  G4InelasticInteraction::SetUpPions(
   const G4int np,
   const G4int nm,
   const G4int nz,
   G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
   G4int &vecLen )
  {
    if( np+nm+nz == 0 )return;
    G4int i;
    G4ReactionProduct *p;
    for( i=0; i<np; ++i )
    {
      p = new G4ReactionProduct;
      p->SetDefinition( G4PionPlus::PionPlus() );
      (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
      vec.SetElement( vecLen++, p );
    }
    for( i=np; i<np+nm; ++i )
    {
      p = new G4ReactionProduct;
      p->SetDefinition( G4PionMinus::PionMinus() );
      (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
      vec.SetElement( vecLen++, p );
    }
    for( i=np+nm; i<np+nm+nz; ++i )
    {
      p = new G4ReactionProduct;
      p->SetDefinition( G4PionZero::PionZero() );
      (G4UniformRand() < 0.5) ? p->SetSide( -1 ) : p->SetSide( 1 );
      vec.SetElement( vecLen++, p );
    }
  }
 
void
  G4InelasticInteraction::GetNormalizationConstant(
   const G4double energy,  // MeV,  <0 means annihilation channels
   G4double &n,
   G4double &anpn )
  {
    const G4double expxu =  82.;          // upper bound for arg. of exp
    const G4double expxl = -expxu;        // lower bound for arg. of exp
    const G4int numSec = 60;
    //
    // the only difference between the calculation for annihilation channels
    // and normal is the starting value, iBegin, for the loop below
    //
    G4int iBegin = 1;
    G4double en = energy;
    if( energy < 0.0 )
    {
      iBegin = 2;
      en *= -1.0;
    }
    //
    // number of total particles vs. centre of mass Energy - 2*proton mass
    //
    G4double aleab = std::log(en/GeV);
    n = 3.62567 + aleab*(0.665843 + aleab*(0.336514 + aleab*(0.117712 + 0.0136912*aleab)));
    n -= 2.0;
    //
    // normalization constant for kno-distribution
    //
    anpn = 0.0;
    G4double test, temp;
    for( G4int i=iBegin; i<=numSec; ++i )
    {
      temp = pi*i/(2.0*n*n);
      test = std::exp( std::min( expxu, std::max( expxl, -(pi/4.0)*(i*i)/(n*n) ) ) );
      if( temp < 1.0 )
      {
        if( test >= 1.0e-10 )anpn += temp*test;
      }
      else
        anpn += temp*test;
    }
  }
 
void
  G4InelasticInteraction::CalculateMomenta(
   G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
   G4int &vecLen,
   const G4HadProjectile *originalIncident,   // the original incident particle
   const G4DynamicParticle *originalTarget,
   G4ReactionProduct &modifiedOriginal,   // Fermi motion and evap. effects included
   G4Nucleus &targetNucleus,
   G4ReactionProduct &currentParticle,
   G4ReactionProduct &targetParticle,
   G4bool &incidentHasChanged,
   G4bool &targetHasChanged,
   G4bool quasiElastic )
  {
    cache = 0;
    what = originalIncident->Get4Momentum().vect();


    theReactionDynamics.ProduceStrangeParticlePairs( vec, vecLen,
                                                     modifiedOriginal, originalTarget,
                                                     currentParticle, targetParticle,
                                                     incidentHasChanged, targetHasChanged );

    if( quasiElastic )
    {
      theReactionDynamics.TwoBody( vec, vecLen,
                                   modifiedOriginal, originalTarget,
                                   currentParticle, targetParticle,
                                   targetNucleus, targetHasChanged );
      return;
    }
    G4ReactionProduct leadingStrangeParticle;
    G4bool leadFlag = MarkLeadingStrangeParticle( currentParticle,
                                                  targetParticle,
                                                  leadingStrangeParticle );
    //
    // Note: the number of secondaries can be reduced in GenerateXandPt and TwoCluster
    //
    G4bool finishedGenXPt = false;
    G4bool annihilation = false;
    if( originalIncident->GetDefinition()->GetPDGEncoding() < 0 &&
        currentParticle.GetMass() == 0.0 && targetParticle.GetMass() == 0.0 )
    {
      // original was an anti-particle and annihilation has taken place
      annihilation = true;
      G4double ekcor = 1.0;
      G4double ek = originalIncident->GetKineticEnergy();
      G4double ekOrg = ek;
      
      const G4double tarmas = originalTarget->GetDefinition()->GetPDGMass();
      if( ek > 1.0*GeV )ekcor = 1./(ek/GeV);
      const G4double atomicWeight = targetNucleus.GetN();
      ek = 2*tarmas + ek*(1.+ekcor/atomicWeight);
      G4double tkin = targetNucleus.Cinema(ek);
      ek += tkin;
      ekOrg += tkin;
      //      modifiedOriginal.SetKineticEnergy( ekOrg );
      //
      // evaporation --  re-calculate black track energies
      //                 this was Done already just before the cascade
      //
      tkin = targetNucleus.AnnihilationEvaporationEffects(ek, ekOrg);
      ekOrg -= tkin;
      ekOrg = std::max( 0.0001*GeV, ekOrg );
      modifiedOriginal.SetKineticEnergy( ekOrg );
      G4double amas = originalIncident->GetDefinition()->GetPDGMass();
      G4double et = ekOrg + amas;
      G4double p = std::sqrt( std::abs(et*et-amas*amas) );
      G4double pp = modifiedOriginal.GetMomentum().mag();
      if( pp > 0.0 )
      {
        G4ThreeVector momentum = modifiedOriginal.GetMomentum();
        modifiedOriginal.SetMomentum( momentum * (p/pp) );
      }
      if( ekOrg <= 0.0001 )
      {
        modifiedOriginal.SetKineticEnergy( 0.0 );
        modifiedOriginal.SetMomentum( 0.0, 0.0, 0.0 );
      }
    }
    const G4double twsup[] = { 1.0, 0.7, 0.5, 0.3, 0.2, 0.1 };
    G4double rand1 = G4UniformRand();
    G4double rand2 = G4UniformRand();

    // Cache current, target, and secondaries
    G4ReactionProduct saveCurrent = currentParticle;
    G4ReactionProduct saveTarget = targetParticle;
    std::vector<G4ReactionProduct> savevec;
    for (G4int i = 0; i < vecLen; i++) savevec.push_back(*vec[i]);

    if (annihilation || 
        vecLen >= 6 ||
        ( modifiedOriginal.GetKineticEnergy()/GeV >= 1.0 &&
          ( ( (originalIncident->GetDefinition() == G4KaonPlus::KaonPlus() ||
               originalIncident->GetDefinition() == G4KaonMinus::KaonMinus() ||
               originalIncident->GetDefinition() == G4KaonZeroLong::KaonZeroLong() ||
               originalIncident->GetDefinition() == G4KaonZeroShort::KaonZeroShort() ) 
               &&
	       rand1 < 0.5 ) 
	    || rand2 > twsup[vecLen] )  )  )

      finishedGenXPt =
        theReactionDynamics.GenerateXandPt( vec, vecLen,
                                            modifiedOriginal, originalIncident,
                                            currentParticle, targetParticle,
                                            originalTarget,
                                            targetNucleus, incidentHasChanged,
                                            targetHasChanged, leadFlag,
                                            leadingStrangeParticle );
    if( finishedGenXPt )
    {
      Rotate(vec, vecLen);
      return;
    }

    G4bool finishedTwoClu = false;
    if( modifiedOriginal.GetTotalMomentum()/MeV < 1.0 )
    {
      for(G4int i=0; i<vecLen; i++) delete vec[i];
      vecLen = 0;
    }
    else
    {
      // Occaisionally, GenerateXandPt will fail in the annihilation channel.
      // Restore current, target and secondaries to pre-GenerateXandPt state
      // before trying annihilation in TwoCluster

      if (!finishedGenXPt && annihilation) {
        currentParticle = saveCurrent;
        targetParticle = saveTarget;
        for (G4int i = 0; i < vecLen; i++) delete vec[i];
        vecLen = 0;
        vec.Initialize( 0 );
        for (G4int i = 0; i < G4int(savevec.size()); i++) {
          G4ReactionProduct* p = new G4ReactionProduct;
          *p = savevec[i];
          vec.SetElement( vecLen++, p );
        }
      }

      theReactionDynamics.SuppressChargedPions( vec, vecLen,
                                      modifiedOriginal, currentParticle,
                                      targetParticle, targetNucleus,
                                      incidentHasChanged, targetHasChanged );
      try
      {
      finishedTwoClu = theReactionDynamics.TwoCluster( vec, vecLen,
                                      modifiedOriginal, originalIncident,
                                      currentParticle, targetParticle,
                                      originalTarget,
                                      targetNucleus, incidentHasChanged,
                                      targetHasChanged, leadFlag,
                                      leadingStrangeParticle );
       }
       catch(G4HadReentrentException aC)
       {
         aC.Report(G4cout);
	 throw G4HadReentrentException(__FILE__, __LINE__, "Failing to calculate momenta");
       }
    }

    if( finishedTwoClu )
    {
      Rotate(vec, vecLen);
      return;
    }

    theReactionDynamics.TwoBody( vec, vecLen,
                                 modifiedOriginal, originalTarget,
                                 currentParticle, targetParticle,
                                 targetNucleus, targetHasChanged );
  }

 
void G4InelasticInteraction::
 Rotate(G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec, G4int &vecLen)
 {
   G4double rotation = 2.*pi*G4UniformRand();
   cache = rotation;
   G4int i;
   for( i=0; i<vecLen; ++i )
   {
     G4ThreeVector momentum = vec[i]->GetMomentum();
     momentum = momentum.rotate(rotation, what);
     vec[i]->SetMomentum(momentum);
   }
 }      

void
  G4InelasticInteraction::SetUpChange(
   G4FastVector<G4ReactionProduct,GHADLISTSIZE> &vec,
   G4int &vecLen,
   G4ReactionProduct &currentParticle,
   G4ReactionProduct &targetParticle,
   G4bool &incidentHasChanged )
  {
    theParticleChange.Clear();
    G4ParticleDefinition *aKaonZL = G4KaonZeroLong::KaonZeroLong();
    G4ParticleDefinition *aKaonZS = G4KaonZeroShort::KaonZeroShort();
    G4int i;
    if( currentParticle.GetDefinition() == aKaonZL )
    {
      if( G4UniformRand() <= 0.5 )
      {
        currentParticle.SetDefinition( aKaonZS );
        incidentHasChanged = true;
      }
    }
    else if( currentParticle.GetDefinition() == aKaonZS )
    {
      if( G4UniformRand() > 0.5 )
      {
        currentParticle.SetDefinition( aKaonZL );
        incidentHasChanged = true;
      }
    }
    if( targetParticle.GetDefinition() == aKaonZL )
    {
      if( G4UniformRand() <= 0.5 )targetParticle.SetDefinition( aKaonZS );
    }
    else if( targetParticle.GetDefinition() == aKaonZS )
    {
      if( G4UniformRand() > 0.5 )targetParticle.SetDefinition( aKaonZL );
    }
    for( i=0; i<vecLen; ++i )
    {
      if( vec[i]->GetDefinition() == aKaonZL )
      {
        if( G4UniformRand() <= 0.5 )vec[i]->SetDefinition( aKaonZS );
      }
      else if( vec[i]->GetDefinition() == aKaonZS )
      {
        if( G4UniformRand() > 0.5 )vec[i]->SetDefinition( aKaonZL );
      }
    }      
    if( incidentHasChanged )
    {
      G4DynamicParticle* p0 = new G4DynamicParticle;
      p0->SetDefinition( currentParticle.GetDefinition() );
      p0->SetMomentum( currentParticle.GetMomentum() );
      theParticleChange.AddSecondary( p0 );
      theParticleChange.SetStatusChange( stopAndKill );
      theParticleChange.SetEnergyChange( 0.0 );
    }
    else
    {
      G4double p = currentParticle.GetMomentum().mag()/MeV;
      G4ThreeVector m = currentParticle.GetMomentum();
      if( p > DBL_MIN )
        theParticleChange.SetMomentumChange( m.x()/p, m.y()/p, m.z()/p );
      else
        theParticleChange.SetMomentumChange( 1.0, 0.0, 0.0 );

      G4double aE = currentParticle.GetKineticEnergy();
      if (std::fabs(aE)<.1*eV) aE=.1*eV;
      theParticleChange.SetEnergyChange( aE );
    }

    if( targetParticle.GetMass() > 0.0 )  // targetParticle can be eliminated in TwoBody
    {
      G4DynamicParticle *p1 = new G4DynamicParticle;
      p1->SetDefinition( targetParticle.GetDefinition() );
      G4ThreeVector momentum = targetParticle.GetMomentum();
      momentum = momentum.rotate(cache, what);
      p1->SetMomentum( momentum );
      theParticleChange.AddSecondary( p1 );
    }

    G4DynamicParticle *p;
    for( i=0; i<vecLen; ++i )
    {
      p = new G4DynamicParticle();
      p->SetDefinition( vec[i]->GetDefinition() );
      p->SetMomentum( vec[i]->GetMomentum() );
      theParticleChange.AddSecondary( p );
      delete vec[i];
    }
  }
 
  /* end of file */