include/GenWeight.h

#ifndef HZZ2L2NU_INCLUDE_GENWEIGHT_H_
#define HZZ2L2NU_INCLUDE_GENWEIGHT_H_

#include <array>
#include <map>
#include <optional>
#include <tuple>
#include <utility>

#include <TTreeReaderArray.h>

#include <Dataset.h>
#include <Options.h>
#include <WeightBase.h>


class GenWeight : public WeightBase {
public:
  enum class Var {
    Nominal,
    Up,
    Down
  };

  GenWeight(Dataset &dataset, Options const &options);

  double EnvelopeMEScale(Var direction) const;

  double NominalWeight() const override;

  int NumVariations() const override {
    return availableVariations_.size();
  }

  double operator()() const override {
    if (defaultVariationIndex_ == -1)
      return NominalWeight();
    else
      return NominalWeight() * RelWeight(defaultVariationIndex_);
  }

  double RelWeight(int variation) const override;

  double RelWeightAlphaS(Var direction) const;

  double RelWeightMEScale(Var renorm, Var factor) const;

  double RelWeightPdf(Var direction) const;

  std::string_view VariationName(int variation) const override {
    return availableVariations_.at(variation);
  }

private:
  enum class PdfVarType {
    Hessian,  
    MC  
  };

  void InitializeLheScale(Dataset &dataset);
  void InitializePdf(Dataset &dataset);

  static std::tuple<PdfVarType, std::optional<std::array<int, 2>>, double>
  LookUpPdfSet(int lhapdf);

  double datasetWeight_;

  bool lheScaleWeightsPresent_;

  std::map<std::pair<Var, Var>, int> meScaleIndices_;

  bool pdfWeightsPresent_;

  std::pair<int, int> pdfWeightsIndices_;

  PdfVarType pdfVarType_;

  bool alphaSWeightsPresent_;

  std::array<int, 2> alphaSWeightsIndices_;

  double alphaSVarScaleFactor_;

  std::vector<std::string> availableVariations_;

  int defaultVariationIndex_;

  mutable TTreeReaderValue<float> srcLheNominalWeight_;
  mutable TTreeReaderValue<float> srcGenNominalWeight_;
  mutable TTreeReaderArray<float> srcScaleWeights_;
  mutable TTreeReaderArray<float> srcPdfWeights_;
};

#endif  // HZZ2L2NU_INCLUDE_GENWEIGHT_H_

---