////////////////////////////////////////////////////////////////////////
/// \class RAT::IBDCrossSec
///  \author Nuno Barros <nfbarros@hep.upenn.edu> -- contact person
///  \date 17-Oct-2016
///
///  \brief Standalone, easily expandable class to calculate IBD cross sections.
///
///  REVISION HISTORY:
///  - 17-Oct-2016 : Nuno Barros <nfbarros@hep.upenn.edu>
///                 - Initial revision.
///
///  - 16-Jul-2019 : Charlie Mills
///                 * Changed default definition of Sigma0, see docDB #5805
///                 * Default strategy can be changed in line 39 to use different definition of Sigma0
///
///  - 11-Oct-2019 : Nuno Barros <barros@lip.pt>
///                 * Modified code to maintain consistency with the CrossSectionBase class
///                 * Refactored code to use the cross section manager (maintains backwards compatibility)
///
///  - 14-Oct-2019 : Nuno Barros <barros@lip.pt>
///                 * Introduced pre-computed tables for both strategies
///                 * Refactored and cleaned the code to avoid code duplication.
///
////////////////////////////////////////////////////////////////////////

#ifndef SRC_UTIL_IBDCROSSSEC_HH_
#define SRC_UTIL_IBDCROSSSEC_HH_

#include <map>
#include <string>
#include <RAT/Log.hh>
#include <RAT/CrossSectionBase.hh>

class TFile;
class TH2F;


namespace RAT {
class IBDCrossSecMessenger;

class IBDCrossSec : public CrossSectionBase {
public:

  enum Strategy {Unknown=-1,Vogel=0,VogelTable,VogelNeutron,VogelNeutronTable,NoStrategy};

  IBDCrossSec();

  virtual ~IBDCrossSec();

  void SetStrategy(Strategy strat);

  virtual void SetStrategy(const short int strat);

  double dSigmadTheta(const double Enu, const double cosThetaLab) const ;

  virtual double Sigma(const double E) const;


  static std::string GetStrategyName(Strategy str) {
    return _str_map.find(str)->second;
  }

  static Strategy GetStrategyCode(std::string str) {
    std::map<Strategy,std::string>::const_iterator it;
    Strategy st = Unknown;
    for (it = _str_map.begin(); it != _str_map.end(); ++it) {
      if(it->second == str) {
        st = it->first;
      }
    }
    if (st == Unknown)
    {
      Log::Die("Strategy [" + str + "] does not exist.");
    }
    return st;
  }

protected:
  // Concrete cross section implementations using different strategies
  double dSigmadThetaVogel(const double Enu, const double cosThetaLab) const;
  double dSigmadThetaVogelTable(const double Enu, const double cosThetaLab) const;
  double SigmaVogel(const double Enu) const;
  double Sigma_numericInt(const double Enu) const;

  virtual void LoadTablesDB();

  double Sigma0() const;
  double Sigma0_Neutron() const;
  double Sigma0_Original() const;

private:

  static std::map<Strategy,std::string> init_map() {
    std::map<Strategy,std::string> m;
    m[Vogel] = "Vogel";
    m[VogelNeutron] = "VogelNeutron";
    m[VogelTable] = "VogelTable";
    m[VogelNeutronTable] = "VogelNeutronTable";

    return m;
  }
  static const std::map<Strategy,std::string> _str_map;

  Strategy convert_strategy(const short int strat);

  TFile *fInputFile;
  TH2F* fXsTable;

  /// Define a series of constants that are used througout the code,
  /// these are invariant with respect to the strategy used
  // -- couplings

  static const double fPhase_f;
  static const double fPhase_f2;
  static const double fPhase_g;
  static const double fPhaseFactor;

  // -- neutron lifetime
  static const double fNeutronLifetime;

  // -- delta mass
  static const double fDelta;

  // -- fermi coupling constant
  static const double fGFermi;
  static const double fCosThetaC;

};

} /* namespace RAT */

#endif /* SRC_UTIL_IBDCROSSSEC_HH_ */