#ifndef Hadrons_MScalar_ScalarVP_hpp_
#define Hadrons_MScalar_ScalarVP_hpp_

#include <Grid/Hadrons/Global.hpp>
#include <Grid/Hadrons/Module.hpp>
#include <Grid/Hadrons/ModuleFactory.hpp>

BEGIN_HADRONS_NAMESPACE

/******************************************************************************
 *                         Scalar vacuum polarisation                         *
 ******************************************************************************/
BEGIN_MODULE_NAMESPACE(MScalar)

class ScalarVPPar: Serializable
{
public:
    GRID_SERIALIZABLE_CLASS_MEMBERS(ScalarVPPar,
                                    std::string, emField,
                                    std::string, scalarProp,
                                    std::string, output,
                                    std::vector<std::string>, outputMom);
};

class TScalarVP: public Module<ScalarVPPar>
{
public:
    SCALAR_TYPE_ALIASES(SIMPL,);
    typedef PhotonR::GaugeField     EmField;
    typedef PhotonR::GaugeLinkField EmComp;
public:
    // constructor
    TScalarVP(const std::string name);
    // destructor
    virtual ~TScalarVP(void) = default;
    // dependency relation
    virtual std::vector<std::string> getInput(void);
    virtual std::vector<std::string> getOutput(void);
protected:
    // setup
    virtual void setup(void);
    // execution
    virtual void execute(void);
private:
    void makeCaches(void);
    // conserved vector two-point contraction
    void vpContraction(ScalarField &vp,
                       ScalarField &prop_0_x, ScalarField &prop_nu_x,
                       TComplex u_src, ScalarField &u_snk, int mu);
    // conserved vector two-point contraction with unit gauge link at sink
    void vpContraction(ScalarField &vp,
                       ScalarField &prop_0_x, ScalarField &prop_nu_x,
                       TComplex u_src, int mu);
    // write momentum-projected vacuum polarisation to file(s)
    void writeVP(std::vector<ResultWriter *> &writer, const ScalarField &vp,
                 std::string dsetName);
    // momentum-space Delta_1 insertion
    void momD1(ScalarField &s, FFT &fft);
private:
    bool                                        momPhasesDone_;
    std::string                                 freeMomPropName_, GFSrcName_,
                                                prop0Name_, propQName_,
                                                propSunName_, propTadName_,
                                                fftName_;
    std::vector<std::string>                    phaseName_, muPropQName_,
                                                momPhaseName_;
    std::vector<std::vector<std::string> >      vpTensorName_;
    // ScalarField                                 *freeMomProp_, *GFSrc_,
    //                                             *prop0_;
    std::vector<ScalarField *>                  phase_, momPhase_;
    // EmField                                     *A;
};

MODULE_REGISTER_NS(ScalarVP, TScalarVP, MScalar);

END_MODULE_NAMESPACE

END_HADRONS_NAMESPACE

#endif // Hadrons_MScalar_ScalarVP_hpp_