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// -------------------------------------------------------------------
//
// GEANT4 Class file
//
//
// File name:     G4ionIonisation
//
// Author:        Vladimir Ivanchenko
//
// Creation date: 07.05.2002
//
// Modifications:
//
// 23-12-02 Change interface in order to move to cut per region (V.Ivanchenko)
// 26-12-02 Secondary production moved to derived classes (V.Ivanchenko)
// 13-02-03 SubCutoff regime is assigned to a region (V.Ivanchenko)
// 18-04-03 Use IonFluctuations (V.Ivanchenko)
// 03-08-03 Add effective charge (V.Ivanchenko)
// 12-11-03 G4EnergyLossSTD -> G4EnergyLossProcess (V.Ivanchenko)
// 27-05-04 Set integral to be a default regime (V.Ivanchenko)
// 08-11-04 Migration to new interface of Store/Retrieve tables (V.Ivantchenko)
// 08-04-05 Major optimisation of internal interfaces (V.Ivantchenko)
// 10-01-06 SetStepLimits -> SetStepFunction (V.Ivantchenko)
// 10-05-06 Add a possibility to download user data (V.Ivantchenko)
// 13-05-06 Add data for light ion stopping in water (V.Ivantchenko)
// 14-01-07 use SetEmModel() and SetFluctModel() from G4VEnergyLossProcess (mma)
// 16-05-07 Add data for light ion stopping only for GenericIon (V.Ivantchenko)
// 07-11-07 Fill non-ionizing energy loss (V.Ivantchenko)
// 12-09-08 Removed InitialiseMassCharge and CorrectionsAlongStep (VI)
//
//
// -------------------------------------------------------------------
//
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#include "G4ionIonisation.hh"
#include "G4PhysicalConstants.hh"
#include "G4SystemOfUnits.hh"
#include "G4Electron.hh"
#include "G4GenericIon.hh"
#include "G4BraggModel.hh"
#include "G4BraggIonModel.hh"
#include "G4BetheBlochModel.hh"
#include "G4LossTableManager.hh"
#include "G4EmParameters.hh"
#include "G4EmStandUtil.hh"

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G4ionIonisation::G4ionIonisation(const G4String& name)
  : G4VEnergyLossProcess(name)
{
  SetLinearLossLimit(0.02);
  SetProcessSubType(fIonisation);
  SetSecondaryParticle(G4Electron::Electron());
  eth = 2*CLHEP::MeV;
}

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G4bool G4ionIonisation::IsApplicable(const G4ParticleDefinition&)
{
  return true;
}

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G4double G4ionIonisation::MinPrimaryEnergy(const G4ParticleDefinition* p, 
					   const G4Material*, 
					   G4double cut)
{
  return p->GetPDGMass()*(std::sqrt(1. + 0.5*cut/CLHEP::electron_mass_c2) - 1.0);
}

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void G4ionIonisation::InitialiseEnergyLossProcess(
		      const G4ParticleDefinition* part,
		      const G4ParticleDefinition* bpart)
{
  const G4ParticleDefinition* ion = G4GenericIon::GenericIon();

  if(!isInitialised) {
    theParticle = part;

    // define base particle
    const G4ParticleDefinition* theBaseParticle = nullptr;
    const G4int pdg = part->GetPDGEncoding();

    if(part == bpart) { 
      theBaseParticle = nullptr;
    } else if(nullptr != bpart) { 
      theBaseParticle = bpart;
    } else if(part == ion || pdg == 1000020040) { 
      theBaseParticle = nullptr;
    } else { 
      theBaseParticle = ion; 
    }
    SetBaseParticle(theBaseParticle);

    // model limit defined for protons
    eth = 2*CLHEP::MeV*part->GetPDGMass()/CLHEP::proton_mass_c2;

    G4EmParameters* param = G4EmParameters::Instance();
    G4double emin = param->MinKinEnergy();
    G4double emax = param->MaxKinEnergy();

    // define model of energy loss fluctuations
    if (nullptr == FluctModel()) {
      SetFluctModel(G4EmStandUtil::ModelOfFluctuations(true));
    }

    if (nullptr == EmModel(0)) { SetEmModel(new G4BraggIonModel()); }
    // to compute ranges correctly we have to use low-energy
    // model even if activation limit is high
    EmModel(0)->SetLowEnergyLimit(emin);

    // high energy limit may be eth or DBL_MAX
    G4double emax1 = (EmModel(0)->HighEnergyLimit() < emax) ? eth : emax;
    EmModel(0)->SetHighEnergyLimit(emax1);
    AddEmModel(1, EmModel(0), FluctModel());

    // second model is used if the first does not cover energy range
    if(emax1 < emax) {
      if (nullptr == EmModel(1)) { SetEmModel(new G4BetheBlochModel()); }
      EmModel(1)->SetLowEnergyLimit(emax1);

      // for extremely heavy particles upper limit of the model
      // should be increased
      emax = std::max(emax, eth*10); 
      EmModel(1)->SetHighEnergyLimit(emax);
      AddEmModel(2, EmModel(1), FluctModel());  
    }
    isInitialised = true;
  }
}

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void G4ionIonisation::ProcessDescription(std::ostream& out) const
{
  out << "  Ion ionisation";
  G4VEnergyLossProcess::ProcessDescription(out);
}

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