include/BTagWeight.h

#ifndef HZZ2L2NU_INCLUDE_BTAGWEIGHT_H_
#define HZZ2L2NU_INCLUDE_BTAGWEIGHT_H_

#include <WeightBase.h>

#include <array>
#include <memory>
#include <string>

#include <TH2F.h>
#include <TTreeReaderArray.h>

#include <BTagger.h>
#include <Dataset.h>
#include <EventCache.h>
#include <JetBuilder.h>
#include <Options.h>
#include <PhysicsObjects.h>


class BTagCalibrationReader;


class BTagWeight : public WeightBase {
 public:
  BTagWeight(Dataset &dataset, Options const &options, BTagger const *bTagger,
             JetBuilder const *jetBuilder);

  ~BTagWeight() noexcept;

  virtual double NominalWeight() const override {
    if (cache_.IsUpdated())
      Update();
    return weights_[0];
  }

  virtual int NumVariations() const override {
    return 4;
  }

  virtual double operator()() const override {
    if (cache_.IsUpdated())
      Update();
    return weights_[int(defaultVariation_)];
  }

  virtual double RelWeight(int variation) const override {
    if (cache_.IsUpdated())
      Update();
    return weights_[variation + 1] / weights_[0];
  }

  virtual std::string_view VariationName(int variation) const override;

 private:
  enum class Variation : int {
    kNominal = 0,
    kTagUp = 1,
    kTagDown = 2,
    kMistagUp = 3,
    kMistagDown = 4
  };

  double ComputeWeight(Variation variation) const;

  void LoadEffTables();

  double GetEfficiency(double pt, double eta, int flavour) const;

  double GetScaleFactor(double pt, double eta, int flavour,
                        Variation variation) const;

  void Update() const;

  BTagger const *bTagger_;

  JetBuilder const *jetBuilder_;

  std::filesystem::path const effTablesPath_;

  std::map<std::string, std::unique_ptr<TH2F>> effTables_;

  std::unique_ptr<BTagCalibrationReader> scaleFactorReader_;

  Variation defaultVariation_;

  EventCache cache_;

  mutable std::array<double, 5> weights_;
};

#endif  // HZZ2L2NU_INCLUDE_BTAGWEIGHT_H_

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