///////////////////////////////////////////////////////////////////
/// \class RAT::DinucleonDecayGen
///
/// \brief  Generator for invisible dinucleon decay events
///
/// \author Ian Coulter <icoulter@hep.upenn.edu> -- contact person
///
/// REVISION HISTORY:
///                  10/08/18 -- Initial commit, I Coulter
///
/// \details Allows user to choose pp, pn or nn
///         and generates the emitted decay products from
///         invisible dinucleon decay in 16O based on
///         spectrum drawn from a ratdb file
///
///////////////////////////////////////////////////////////////////


#ifndef __RAT_VERTEXGEN_DINUCLEONDECAY__
#define __RAT_VERTEXGEN_DINUCLEONDECAY__

#include <CLHEP/Random/Randomize.h>

#include <G4ParticleDefinition.hh>
#include <G4ThreeVector.hh>
#include <G4LorentzVector.hh>
#include <RAT/GLG4VertexGen.hh>
#include <RAT/DB.hh>
#include <vector>

class G4Event;

namespace RAT
{

  class VertexGen_DinucleonDecay : public GLG4VertexGen
  {
  public:
    VertexGen_DinucleonDecay();
    virtual ~VertexGen_DinucleonDecay();
    virtual void GeneratePrimaryVertex(G4Event *event, G4ThreeVector &dx, G4double dt);
    virtual bool IsRepeatable() const { return true; };

    virtual void SetState(G4String state);
    virtual G4String GetState();

    virtual void BeginOfRun();

    // Returns index of the decay mode from a table of possibilities in the ratdb
    int SelectDecayMode(G4String nucleonType);

    // Create a vertex based on particle type and energy
    void CreateVertex(G4String type, G4double energy, G4Event* event, G4ThreeVector& dx, G4double dt);

  protected:
    G4String fStateStr;     // generator initialisation, specified by user:
    G4String fNucleonType;  // Type of nucleon decay: proton (default) or neutron
    DBLinkPtr fDNDecay;      // Links to the NUCLEON_DECAY.ratdb
    /// Vectors recording the energies of the gammas, protons and neutrons for each decay mode.
    /// The final N or P distinguishes weather there are for neutrons or protons
    std::vector<double> fEnergyGammaNN, fEnergyGammaPN, fEnergyGammaPP, fEnergyProtonNN, fEnergyProtonPN, fEnergyProtonPP, fEnergyNeutronNN, fEnergyNeutronPN,  fEnergyNeutronPP;
    /// Vectors recording the branching fractions of each decay mode.
    std::vector<double> fFractionNN, fFractionPN, fFractionPP;

  private:
    G4ParticleDefinition *fGamma, *fProton, *fNeutron;
  };

} // namespace RAT

#endif // __RAT_VERTEXGEN_DinucleonDecay__