#include <Grid/Hadrons/Modules/MScalar/ChargedProp.hpp>
#include <Grid/Hadrons/Modules/MScalar/ScalarVP.hpp>
#include <Grid/Hadrons/Modules/MScalar/Scalar.hpp>

using namespace Grid;
using namespace Hadrons;
using namespace MScalar;

/******************************************************************************
*                  TScalarVP implementation                             *
******************************************************************************/
// constructor /////////////////////////////////////////////////////////////////
TScalarVP::TScalarVP(const std::string name)
: Module<ScalarVPPar>(name)
{}

// dependencies/products ///////////////////////////////////////////////////////
std::vector<std::string> TScalarVP::getInput(void)
{
    propQName_ = par().scalarProp + "_Q";
    propSunName_ = par().scalarProp + "_Sun";
    propTadName_ = par().scalarProp + "_Tad";

	std::vector<std::string> in = {par().emField, propQName_, propSunName_,
                                   propTadName_};
    
    return in;
}

std::vector<std::string> TScalarVP::getOutput(void)
{
    std::vector<std::string> out;
    
    for (unsigned int mu = 0; mu < env().getNd(); ++mu)
    {
        out.push_back(getName() + "_propQ_" + std::to_string(mu));

        for (unsigned int nu = 0; nu < env().getNd(); ++nu)
        {
            out.push_back(getName() + "_" + std::to_string(mu) + "_" + std::to_string(nu));
            out.push_back(getName() + "_free_" + std::to_string(mu) + "_" + std::to_string(nu));
        }
    }

    return out;
}

// setup ///////////////////////////////////////////////////////////////////////
void TScalarVP::setup(void)
{
	freeMomPropName_ = FREEMOMPROP(static_cast<TChargedProp *>(env().getModule(par().scalarProp))->par().mass);
	GFSrcName_ = "_" + par().scalarProp + "_DinvSrc";
    prop0Name_ = par().scalarProp + "_0";

	phaseName_.clear();
	muPropQName_.clear();
    vpTensorName_.clear();
    freeVpTensorName_.clear();
    
	for (unsigned int mu = 0; mu < env().getNd(); ++mu)
    {
        phaseName_.push_back("_shiftphase_" + std::to_string(mu));
        muPropQName_.push_back(getName() + "_propQ_" + std::to_string(mu));

        std::vector<std::string> vpTensorName_mu;
        std::vector<std::string> freeVpTensorName_mu;
        for (unsigned int nu = 0; nu < env().getNd(); ++nu)
        {
            vpTensorName_mu.push_back(getName() + "_" + std::to_string(mu)
                                      + "_" + std::to_string(nu));
            freeVpTensorName_mu.push_back(getName() + "_free_" + std::to_string(mu)
                                       + "_" + std::to_string(nu));
        }
        vpTensorName_.push_back(vpTensorName_mu);
        freeVpTensorName_.push_back(freeVpTensorName_mu);
    }

    for (unsigned int mu = 0; mu < env().getNd(); ++mu)
	{
	    env().registerLattice<ScalarField>(muPropQName_[mu]);

        for (unsigned int nu = 0; nu < env().getNd(); ++nu)
        {
            env().registerLattice<ScalarField>(vpTensorName_[mu][nu]);
            env().registerLattice<ScalarField>(freeVpTensorName_[mu][nu]);
        }
	}
}

// execution ///////////////////////////////////////////////////////////////////
void TScalarVP::execute(void)
{
	// Get objects cached by ChargedProp module
    Complex     ci(0.0,1.0);
    FFT         fft(env().getGrid());
    Real        q = static_cast<TChargedProp *>(env().getModule(par().scalarProp))->par().charge;

    freeMomProp_ = env().getObject<ScalarField>(freeMomPropName_);
    for (unsigned int mu = 0; mu < env().getNd(); ++mu)
    {
        phase_.push_back(env().getObject<ScalarField>(phaseName_[mu]));
    }
    GFSrc_ = env().getObject<ScalarField>(GFSrcName_);
    prop0_ = env().getObject<ScalarField>(prop0Name_);

    // Propagator from unshifted source
	ScalarField &propQ   = *env().getObject<ScalarField>(propQName_);
    ScalarField &propSun   = *env().getObject<ScalarField>(propSunName_);
    ScalarField &propTad   = *env().getObject<ScalarField>(propTadName_);

    // Propagators from shifted sources
    LOG(Message) << "Computing O(q) charged scalar propagators..."
                 << std::endl;
    std::vector<ScalarField> muPropQ;
    for (unsigned int mu = 0; mu < env().getNd(); ++mu)
    {
        muPropQ.push_back(*env().createLattice<ScalarField>(muPropQName_[mu]));

        // -G*momD1*G*F*tau_mu*Src (momD1 = F*D1*Finv)
        muPropQ[mu] = adj(*phase_[mu])*(*GFSrc_);
        momD1(muPropQ[mu], fft);
        muPropQ[mu] = -(*freeMomProp_)*muPropQ[mu];
        fft.FFT_all_dim(muPropQ[mu], muPropQ[mu], FFT::backward);
    }

    // CONTRACTIONS
    ScalarField prop1(env().getGrid()), prop2(env().getGrid());
    EmField     &A = *env().getObject<EmField>(par().emField);
    ScalarField Amu(env().getGrid());
    TComplex    Anu0;
    std::vector<int> coor0 = {0, 0, 0, 0};
    std::vector<std::vector<ScalarField> > vpTensor, freeVpTensor;
    for (unsigned int mu = 0; mu < env().getNd(); ++mu)
    {
        std::vector<ScalarField> vpTensor_mu;
        std::vector<ScalarField> freeVpTensor_mu;
        for (unsigned int nu = 0; nu < env().getNd(); ++nu)
        {
            vpTensor_mu.push_back(*env().createLattice<ScalarField>(vpTensorName_[mu][nu]));
            freeVpTensor_mu.push_back(*env().createLattice<ScalarField>(freeVpTensorName_[mu][nu]));
        }
        vpTensor.push_back(vpTensor_mu);
        freeVpTensor.push_back(freeVpTensor_mu);
    }

    for (unsigned int nu = 0; nu < env().getNd(); ++nu)
    {
        peekSite(Anu0, peekLorentz(A, nu), coor0);

        for (unsigned int mu = 0; mu < env().getNd(); ++mu)
        {
            LOG(Message) << "Computing Pi[" << mu << "][" << nu << "]..."
                         << std::endl;
            Amu = peekLorentz(A, mu);

            // Free VP
            prop1 = *prop0_;
            prop2 = Cshift(*prop0_, nu, -1);
            freeVpTensor[mu][nu] = adj(prop2) * Cshift(prop1, mu, 1);
            freeVpTensor[mu][nu] -= Cshift(adj(prop2), mu, 1) * prop1;

            // "Exchange" terms
            prop1 += q*propQ;
            prop2 += q*muPropQ[nu];
            vpTensor[mu][nu] = adj(prop2) * (1.0 + ci*q*Amu)
                               * Cshift(prop1, mu, 1) * (1.0 + ci*q*Anu0);
            vpTensor[mu][nu] -= Cshift(adj(prop2), mu, 1) * (1.0 - ci*q*Amu)
                                * prop1 * (1.0 + ci*q*Anu0);

            // Subtract O(alpha^2) term
            prop1 = q*propQ;
            prop2 = q*muPropQ[nu];
            vpTensor[mu][nu] -= adj(prop2) * ci*q*Amu
                                * Cshift(prop1, mu, 1) * ci*q*Anu0;
            vpTensor[mu][nu] += Cshift(adj(prop2), mu, 1) * (-ci)*q*Amu
                                * prop1 * ci*q*Anu0;

            // Sunset+tadpole from source
            prop1 = q*q*(propSun + propTad);
            prop2 = Cshift(*prop0_, nu, -1);
            vpTensor[mu][nu] += adj(prop2) * Cshift(prop1, mu, 1);
            vpTensor[mu][nu] -= Cshift(adj(prop2), mu, 1) * prop1;

            // Sunset+tadpole from shifted source
            prop1 = Cshift(prop1, nu, -1);
            vpTensor[mu][nu] += Cshift(adj(*prop0_), mu, 1) * prop1;
            vpTensor[mu][nu] -= adj(*prop0_) * Cshift(prop1, mu, 1);

            // Source tadpole
            prop1 = *prop0_;
            vpTensor[mu][nu] += adj(prop2)
                                * Cshift(prop1, mu, 1)
                                * (-0.5)*q*q*Anu0*Anu0;
            vpTensor[mu][nu] -= Cshift(adj(prop2), mu, 1)
                                * prop1
                                * (-0.5)*q*q*Anu0*Anu0;

            // Sink tadpole
            vpTensor[mu][nu] += adj(prop2)
                                * (-0.5)*q*q*Amu*Amu
                                * Cshift(prop1, mu, 1);
            vpTensor[mu][nu] -= Cshift(adj(prop2), mu, 1)
                                * (-0.5)*q*q*Amu*Amu
                                * prop1;

            freeVpTensor[mu][nu] = 2.0*real(freeVpTensor[mu][nu]);
            vpTensor[mu][nu] = 2.0*real(vpTensor[mu][nu]);
        }
    }

    // OUTPUT IF NECESSARY
    if (!par().output.empty())
    {
        std::string           filename = par().output + "." +
                                         std::to_string(env().getTrajectory());
        
        LOG(Message) << "Saving zero-momentum projection to '"
                     << filename << "'..." << std::endl;
        
        CorrWriter              writer(filename);
        std::vector<TComplex>   vecBuf;
        std::vector<Complex>    result;
        
        write(writer, "charge", q);
        write(writer, "mass", static_cast<TChargedProp *>(env().getModule(par().scalarProp))->par().mass);

        for (unsigned int mu = 0; mu < env().getNd(); ++mu)
        {
            for (unsigned int nu = 0; nu < env().getNd(); ++nu)
            {
                sliceSum(vpTensor[mu][nu], vecBuf, Tp);
                result.resize(vecBuf.size());
                for (unsigned int t = 0; t < vecBuf.size(); ++t)
                {
                    result[t] = TensorRemove(vecBuf[t]);
                }
                write(writer, "Pi_"+std::to_string(mu)+"_"+std::to_string(nu),
                      result);

                sliceSum(freeVpTensor[mu][nu], vecBuf, Tp);
                result.resize(vecBuf.size());
                for (unsigned int t = 0; t < vecBuf.size(); ++t)
                {
                    result[t] = TensorRemove(vecBuf[t]);
                }
                write(writer,
                      "Pi_"+std::to_string(mu)+"_"+std::to_string(nu)+"_free",
                      result);
            }
        }
    }
}

void TScalarVP::momD1(ScalarField &s, FFT &fft)
{
    EmField     &A = *env().getObject<EmField>(par().emField);
    ScalarField buf(env().getGrid()), result(env().getGrid()),
                Amu(env().getGrid());
    Complex     ci(0.0,1.0);

    result = zero;

    for (unsigned int mu = 0; mu < env().getNd(); ++mu)
    {
        Amu = peekLorentz(A, mu);
        buf = (*phase_[mu])*s;
        fft.FFT_all_dim(buf, buf, FFT::backward);
        buf = Amu*buf;
        fft.FFT_all_dim(buf, buf, FFT::forward);
        result = result - ci*buf;
    }
    fft.FFT_all_dim(s, s, FFT::backward);
    for (unsigned int mu = 0; mu < env().getNd(); ++mu)
    {
        Amu = peekLorentz(A, mu);
        buf = Amu*s;
        fft.FFT_all_dim(buf, buf, FFT::forward);
        result = result + ci*adj(*phase_[mu])*buf;
    }

    s = result;
}