#ifndef EWSudakov__EWGoupConstants_H
#define EWSudakov__EWGoupConstants_H

#include "AddOns/EWSud/EWSud.H"

#include "MODEL/Main/Model_Base.H"

namespace EWSud {

  class EWGroupConstants {
  private:
    double dcw2cw2(const double t2)     const;
    double dsw2sw2(const double t2)     const;
    double dalphaalpha(const double t2) const;
    double deltaZem()                   const;
    double dmw2mw2(const double t2)     const;
    double dmz2mz2(const double t2)     const;
    double dmtmt(const double t2)       const;
    double dmh02mh02(const double t2)   const;
    double dvevvev(const double t2)     const;
    mutable MODEL::EWParameters m_ewpar;

  public:

    EWGroupConstants();

    /// Returns a diagonal value of the effective electroweak Casimir operator.
    ///
    /// Cf. eq. (B.10).
    ///
    /// \param flav The particle specification $i_k$ in $C^{ew}_{i_k i_k}(k)$.
    /// Note that longitudinal gauge bosons are not allowed. Use the Goldstone
    /// equivalence theorem eq. (3.4) instead and pass the corresponding
    /// Goldstone boson.
    /// \param pol The chirality/polarisation of the particle:
    /// 0: + (right-handed transverse polarisation)
    /// 1: - (left-handed transverse polarisation)
    /// 2: 0 (longitudinal polarisation)
    /// Note that the polarisation will be ignored in the case of Goldstone
    /// bosons. Hence the user does not need to use the correct polarisation
    /// when the Goldstone equivalence theorem is used.
    double DiagonalCew(const ATOOLS::Flavour& flav, int pol) const;

    /// Returns the value of the non-diagonal (neutral gauge-boson mixing)
    /// effective electroweak Casimir operator, cf. eq. (B.25).
    double NondiagonalCew() const noexcept;

    /// Returns the value of the operator IZ2(), which is always diagonal
    Complex IZ2(const ATOOLS::Flavour&, int pol) const;

    /// Returns the couplings with the Z boson, cf. eq. (B.7).
    ///
    /// The parameter descriptions of DiagonalCew() apply here, too.
    Couplings IZ(const ATOOLS::Flavour&, int pol) const;

    /// Returns the couplings with the W boson.
    ///
    /// The parameter descriptions of DiagonalCew() apply here, too.
    ///
    /// \param isplus Whether the W boson (outgoing) carries away a positive
    /// change.
    Couplings Ipm(const ATOOLS::Flavour& flav, int pol, bool isplus) const;

    /// Returns a diagonal beta function coefficient, cf. eqs. (B.38-42)
    ///
    /// \param flav The particle specification $i_k$ in $b^{ew}_{i_k i_k}(k)$.
    /// For now, only transverse vector bosons are supported.
    /// \param pol Cf. the description of \p pol of DiagonalCew(), and note
    /// that so far only transverse polarisations are allowed.
    double DiagonalBew(const ATOOLS::Flavour& flav, int pol) const;

    /// Returns a non-diagonal beta function coefficient, cf. eqs. (B.42)
    double NondiagonalBew() const noexcept;


    /// Evolve EW parameters according to section 5 of denner-pozzorini.
    /// Note in particular that only e (alphaEW), cw, sw, ht, hh have to
    /// be modified.
    /// The idea is to take eq.(5.6,5.7,5.8) and eq.(5.11) for dcoupling
    /// and write coupling(t2) = coupling(t02)*(1+dcoupling/coupling)
    MODEL::EWParameters EvolveEWparameters(const double t2) const;


    /// relevant EW-couplings needed and their run version
    const double m_sw2, m_cw2, m_sw, m_sw_denner_pozzorini, m_cw, m_aew,
      m_mw2, m_mw, m_mz, m_mt, m_mh0, m_cvev;

    /// prefactor for all coefficients
    const double delta_prefactor {m_aew/4./M_PI};
  };

}

#endif