// -*- C++ -*-
#ifndef RIVET_InvMassFinalState_HH
#define RIVET_InvMassFinalState_HH

#include "Rivet/Projections/FinalState.hh"

namespace Rivet {


  class InvMassFinalState : public FinalState {
  public:

    InvMassFinalState(const FinalState& fsp,
                      const std::pair<PdgId, PdgId>& idpair, // pair of decay products
                      double minmass, // min inv mass
                      double maxmass, // max inv mass
                      double masstarget=-1.0);


    InvMassFinalState(const FinalState& fsp,
                      const std::vector<std::pair<PdgId, PdgId> >& idpairs,  // vector of pairs of decay products
                      double minmass, // min inv mass
                      double maxmass, // max inv mass
                      double masstarget=-1.0);


    InvMassFinalState(const std::pair<PdgId, PdgId>& idpair, // pair of decay products
                      double minmass, // min inv mass
                      double maxmass, // max inv mass
                      double masstarget=-1.0);
    InvMassFinalState(const std::vector<std::pair<PdgId, PdgId> >& idpairs,  // vector of pairs of decay products
                      double minmass, // min inv mass
                      double maxmass, // max inv mass
                      double masstarget=-1.0);


    DEFAULT_RIVET_PROJ_CLONE(InvMassFinalState);


    const std::vector<std::pair<Particle, Particle> >& particlePairs() const;


    void useTransverseMass(bool usetrans=true) {
      _useTransverseMass = usetrans;
    }

    void calc(const Particles& inparticles);


    void project(const Event& e);

    CmpState compare(const Projection& p) const;


  private:

    vector<PdgIdPair> _decayids;

    vector<pair<Particle, Particle> > _particlePairs;

    double _minmass;

    double _maxmass;

    double _masstarget;

    bool _useTransverseMass;

  };


}


#endif