// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedLeptons.hh"
#include "Rivet/Projections/LeptonFinder.hh"
#include "Rivet/Projections/IdentifiedFinalState.hh"
#include "Rivet/Projections/PromptFinalState.hh"
#include "Rivet/Projections/MissingMomentum.hh"

namespace Rivet {


  /// Higgs -> WW -> emu + MET in 8 TeV pp collisions
  class CMS_2017_I1467451 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2017_I1467451);


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

      const double lepConeSize = 0.1;
      const double lepMaxEta = 2.5;
      const Cut lepton_cut = (Cuts::abseta < lepMaxEta);

      MSG_WARNING("\033[91;1mLIMITED VALIDITY - check info file for details!\033[m");


      // Initialise and register projections
      FinalState fs((Cuts::etaIn(-2.5,2.5)));
      FinalState fsm((Cuts::etaIn(-5,5)));
      declare(fs, "FS");
      declare(fsm, "FSM");

      ChargedLeptons charged_leptons(fs);
      IdentifiedFinalState photons(fs);
      photons.acceptIdPair(PID::PHOTON);

      PromptFinalState prompt_leptons(charged_leptons);
      prompt_leptons.acceptMuonDecays(true);
      prompt_leptons.acceptTauDecays(false);

      PromptFinalState prompt_photons(photons);
      prompt_photons.acceptMuonDecays(true);
      prompt_photons.acceptTauDecays(false);

      LeptonFinder dressed_leptons(prompt_leptons, prompt_photons, lepConeSize, lepton_cut);
      declare(dressed_leptons, "LeptonFinder");

      MissingMomentum Met(fsm);
      declare(Met, "MET");


      // Book histograms
      book(histoPtH , 1,1,1);
      book(histoXsec, 2,1,1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {

      Particles leptons = apply<LeptonFinder>(event, "LeptonFinder").particlesByPt(10.0*GeV);
      if (leptons.size() < 2) vetoEvent;
      if (leptons[0].pT() < 20*GeV || leptons[1].pT() < 10*GeV) vetoEvent;
      if (leptons[0].charge() == leptons[1].charge()) vetoEvent;
      if (leptons[0].abspid() == leptons[1].abspid()) vetoEvent;

      FourMomentum LL = (leptons[0].momentum() + leptons[1].momentum());
      if (LL.mass() < 12*GeV) vetoEvent;
      if (LL.pT() < 30*GeV) vetoEvent;

      FourMomentum EtMiss = apply<MissingMomentum>(event,"MET").missingMomentum();
      FourMomentum P4H = LL + EtMiss;

      double dphi = deltaPhi(LL, EtMiss);

      double mT = sqrt(2*LL.pT()*EtMiss.pT()*(1-cos(dphi)));
      if (mT < 50*GeV) vetoEvent;

      histoPtH->fill(min(P4H.pT()/GeV, 199.));
      histoXsec->fill(8000); ///< @todo Should probably be a Counter
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(histoPtH, crossSection()/sumOfWeights()/femtobarn);
      scale(histoXsec, (histoXsec->xMax()-histoXsec->xMin())*crossSection()/sumOfWeights()/femtobarn);
    }


  private:

    Histo1DPtr histoPtH, histoXsec;

  };


  RIVET_DECLARE_PLUGIN(CMS_2017_I1467451);

}
