// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/RivetAIDA.hh"
#include "Rivet/Tools/Logging.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "HepMC/GenEvent.h"
#include "Rivet/Particle.hh"

/// @todo Include more projections as required, e.g. ChargedFinalState, FastJets, ZFinder...

namespace Rivet {


  class TEST_GENPARTICLE : public Analysis {
  public:

    /// @name Constructors etc.
    //@{

    /// Constructor
    TEST_GENPARTICLE()
      : Analysis("TEST_GENPARTICLE")
    {    }

    //@}


  public:

    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      /// @todo Initialise and register projections here
      const FinalState fs(-4.5, 4.5);
      addProjection(fs, "ALL_FS");

      // Get the jets
      FastJets jets(fs, FastJets::ANTIKT, 0.4);
      addProjection(jets, "JETS");

    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const double weight = event.weight();

      /// @todo Do the event by event analysis here
      const Jets& jets = applyProjection<FastJets>(event, "JETS").jetsByPt(25.0*GeV, MAXDOUBLE, -2.5, 2.5);

      if(jets.size() < 1) return;

      vector<Particle> constituents = jets.at(0).particles();
      
      HepMC::GenParticle constituent_g = constituents.at(0).genParticle();
      int constituent_g_barcode = constituent_g.barcode();
      MSG_INFO("GenParticle from Jet::particles() :");
      constituent_g.print();

      HepMC::GenEvent evt = event.genEvent();

      for (HepMC::GenEvent::particle_const_iterator p = evt.particles_begin(); p != evt.particles_end(); ++p) {
        int p_bcode = (*p)->barcode();
        if(p_bcode != constituent_g_barcode) continue;
        MSG_INFO("GenParticle directly from GenEvent:");
        (*p)->print();
      }


    }


    /// Normalise histograms etc., after the run
    void finalize() {

      /// @todo Normalise, scale and otherwise manipulate histograms here

      // scale(_h_YYYY, crossSection()/sumOfWeights()); # norm to cross section
      // normalize(_h_YYYY); # normalize to unity

    }

    //@}


  private:

    // Data members like post-cuts event weight counters go here

  };



  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(TEST_GENPARTICLE);

}