/*
 * Project: RooFit
 * Authors:
 *   PB, Patrick Bos, Netherlands eScience Center, p.bos@esciencecenter.nl
 *
 * Copyright (c) 2021, CERN
 *
 * Redistribution and use in source and binary forms,
 * with or without modification, are permitted according to the terms
 * listed in LICENSE (http://roofit.sourceforge.net/license.txt)
 */

#ifndef ROOT_ROOFIT_TESTSTATISTICS_RooUnbinnedL
#define ROOT_ROOFIT_TESTSTATISTICS_RooUnbinnedL

#include <RooFit/TestStatistics/RooAbsL.h>
#include <RooGlobalFunc.h>

#include "Math/Util.h" // KahanSum

// forward declarations
class RooAbsPdf;
class RooAbsData;
class RooArgSet;
class RooChangeTracker;

namespace RooFit {

class Evaluator;

namespace TestStatistics {

class RooUnbinnedL : public RooAbsL {
public:
   RooUnbinnedL(RooAbsPdf *pdf, RooAbsData *data, RooAbsL::Extended extended = RooAbsL::Extended::Auto,
                RooFit::EvalBackend evalBackend = RooFit::EvalBackend::Legacy());
   RooUnbinnedL(const RooUnbinnedL &other);
   ~RooUnbinnedL() override;
   bool setApplyWeightSquared(bool flag);

   ROOT::Math::KahanSum<double>
   evaluatePartition(Section events, std::size_t components_begin, std::size_t components_end) override;

   std::string GetClassName() const override { return "RooUnbinnedL"; }

private:
   bool apply_weight_squared = false; ///< Apply weights squared?
   mutable bool _first = true;        ///<!
   std::unique_ptr<RooChangeTracker> paramTracker_;
   Section lastSection_ = {0, 0}; // used for cache together with the parameter tracker
   mutable ROOT::Math::KahanSum<double> cachedResult_{0.};
   std::shared_ptr<RooFit::Evaluator> evaluator_;  ///<! For batched evaluation
   std::stack<std::vector<double>> _vectorBuffers; // used for preserving resources in batched evaluation
};

} // namespace TestStatistics
} // namespace RooFit

#endif // ROOT_ROOFIT_TESTSTATISTICS_RooUnbinnedL