#ifndef REWEIGHTFACTORSMANAGER_HPP
#define REWEIGHTFACTORSMANAGER_HPP

#include "TH1.h"
#include "TH2.h"
#include "TLorentzVector.h"
#include <vector>

class ReweightFactorsManager {
public:

  /// Singleton.  If no instance exists, create one.  Get pointer to instance.
  static ReweightFactorsManager* get_instance();
  
  /// Just check if an instance already exists.
  static bool check_instance() { return _instance !=0 ; }

  /// initialize
  void initialize();  
  
  /// get muon trigger efficiency for data and MC
  void getMuonTrigEff(bool isData, bool useGeV, double pT, double eta, double phi, double& eff, double& err);

  /// get electron trigger efficiency for data and MC
  void getElecTrigEff(bool isData, bool useGeV, double pT, double eta, double phi, double& eff, double& err);

  /// get event trigger effciency for events with various configurations, 
  /// can have several electrons, muons or electrons/muons (such as emumu, eemu etc)
  double getEventTrigSF(bool useGeV, std::vector<TLorentzVector> electrons, std::vector<TLorentzVector> muons);

private:

  /// Pointer to singleton
  static ReweightFactorsManager* _instance;
  
  /// This is a singleton, so hide constructor. It gets invoked by calling
  /// get_instance. Constructor does nothing.  
  ReweightFactorsManager();

  /// Destructor
  ~ReweightFactorsManager();
  
  /// histograms for muon
  TH2D *_MuonTrigEff_EtaPhi_Barrel_Data;
  TH2D *_MuonTrigEff_EtaPhi_Barrel_MC;
  TH1D *_MuonTrigEff_Pt_Endcap_Data;
  TH1D *_MuonTrigEff_Pt_Endcap_MC;

  /// histograms for electron
  TH1D *_ElecTrigEff_Eta_MC;
};

#endif