// -*- C++ -*-
#include "FinalStateBreit.hh"
#include "Rivet/Cmp.hh"
#include "Rivet/Projections/DISKinematics.hh"
#include "Rivet/Rivet.hh"
#include "Rivet/Math/Constants.hh"
#include "Rivet/Tools/ParticleIdUtils.hh"

 
namespace Rivet {


  int FinalStateBreit::compare(const Projection& p) const {
    return mkNamedPCmp(p, "Kinematics");
  }


  void FinalStateBreit::project(const Event& e) {
    const DISKinematics& diskin = applyProjection<DISKinematics>(e, "Kinematics");
    const LorentzTransform breitboost = diskin.boostBreit();
    const DISLepton& dislep = diskin.applyProjection<DISLepton>(e, "Lepton");
    const GenParticle& dislepGP = dislep.out().genParticle();
    const FinalState& fs = dislep.applyProjection<FinalState>(e, "FS");

    // Fill the particle list with all particles _other_ than the DIS scattered
    // lepton, with momenta boosted into the Breit frame.
     _theParticles.clear();
    _theParticles.reserve(fs.particles().size());
    for (ParticleVector::const_iterator p = fs.particles().begin(); p != fs.particles().end(); ++p) {
      const GenParticle& loopGP = p->genParticle();
      if (&loopGP != &dislepGP) { //< Ensure that we skip the DIS lepton
        Particle temp = *p;
        const FourMomentum breitMom = breitboost.transform(temp.momentum());
        temp.setMomentum(breitMom);
        _theParticles.push_back(temp);
      }
    }
  } 
}