/*************************************************************************************

Grid physics library, www.github.com/paboyle/Grid 

Source file: Hadrons/Modules/MContraction/Meson.hpp

Copyright (C) 2015-2019

Author: Antonin Portelli <antonin.portelli@me.com>
Author: Lanny91 <andrew.lawson@gmail.com>
Author: Vera Guelpers <vmg1n14@soton.ac.uk>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

See the full license in the file "LICENSE" in the top level distribution directory
*************************************************************************************/
/*  END LEGAL */

#ifndef Hadrons_MContraction_Meson_hpp_
#define Hadrons_MContraction_Meson_hpp_

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

BEGIN_HADRONS_NAMESPACE

/*
 
 Meson contractions
 -----------------------------
 
 * options:
 - q1: input propagator 1 (string)
 - q2: input propagator 2 (string)
 - gammas: gamma products to insert at sink & source, pairs of gamma matrices 
           (space-separated strings) in round brackets (i.e. (g_sink g_src)),
           in a sequence (e.g. "(Gamma5 Gamma5)(Gamma5 GammaT)").

           Special values: "all" - perform all possible contractions.
 - sink: module to compute the sink to use in contraction (string).
*/

/******************************************************************************
 *                                TMeson                                       *
 ******************************************************************************/
BEGIN_MODULE_NAMESPACE(MContraction)

typedef std::pair<Gamma::Algebra, Gamma::Algebra> GammaPair;

class MesonPar: Serializable
{
public:
    GRID_SERIALIZABLE_CLASS_MEMBERS(MesonPar,
                                    std::string, q1,
                                    std::string, q2,
                                    std::string, gammas,
                                    std::string, sink,
                                    std::string, output);
};

template <typename FImpl1, typename FImpl2>
class TMeson: public Module<MesonPar>
{
public:
    FERM_TYPE_ALIASES(FImpl1, 1);
    FERM_TYPE_ALIASES(FImpl2, 2);
    BASIC_TYPE_ALIASES(ScalarImplCR, Scalar);
    SINK_TYPE_ALIASES(Scalar);
    class Result: Serializable
    {
    public:
        GRID_SERIALIZABLE_CLASS_MEMBERS(Result,
                                        Gamma::Algebra, gamma_snk,
                                        Gamma::Algebra, gamma_src,
                                        std::vector<Complex>, corr);
    };
public:
    // constructor
    TMeson(const std::string name);
    // destructor
    virtual ~TMeson(void) {};
    // dependencies/products
    virtual std::vector<std::string> getInput(void);
    virtual std::vector<std::string> getOutput(void);
    virtual void parseGammaString(std::vector<GammaPair> &gammaList);
protected:
    // execution
    virtual void setup(void);
    // execution
    virtual void execute(void);
};

MODULE_REGISTER_TMP(Meson, ARG(TMeson<FIMPL, FIMPL>), MContraction);

/******************************************************************************
 *                           TMeson implementation                            *
 ******************************************************************************/
// constructor /////////////////////////////////////////////////////////////////
template <typename FImpl1, typename FImpl2>
TMeson<FImpl1, FImpl2>::TMeson(const std::string name)
: Module<MesonPar>(name)
{}

// dependencies/products ///////////////////////////////////////////////////////
template <typename FImpl1, typename FImpl2>
std::vector<std::string> TMeson<FImpl1, FImpl2>::getInput(void)
{
    std::vector<std::string> input = {par().q1, par().q2, par().sink};
    
    return input;
}

template <typename FImpl1, typename FImpl2>
std::vector<std::string> TMeson<FImpl1, FImpl2>::getOutput(void)
{
    std::vector<std::string> output = {};
    
    return output;
}

template <typename FImpl1, typename FImpl2>
void TMeson<FImpl1, FImpl2>::parseGammaString(std::vector<GammaPair> &gammaList)
{
    gammaList.clear();
    // Determine gamma matrices to insert at source/sink.
    if (par().gammas.compare("all") == 0)
    {
        // Do all contractions.
        for (unsigned int i = 1; i < Gamma::nGamma; i += 2)
        {
            for (unsigned int j = 1; j < Gamma::nGamma; j += 2)
            {
                gammaList.push_back(std::make_pair((Gamma::Algebra)i, 
                                                   (Gamma::Algebra)j));
            }
        }
    }
    else
    {
        // Parse individual contractions from input string.
        gammaList = strToVec<GammaPair>(par().gammas);
    } 
}

// execution ///////////////////////////////////////////////////////////////////
template <typename FImpl1, typename FImpl2>
void TMeson<FImpl1, FImpl2>::setup(void)
{
    envTmpLat(LatticeComplex, "c");
}

// execution ///////////////////////////////////////////////////////////////////
#define mesonConnected(q1, q2, gSnk, gSrc) \
(g5*(gSnk))*(q1)*(adj(gSrc)*g5)*adj(q2)

template <typename FImpl1, typename FImpl2>
void TMeson<FImpl1, FImpl2>::execute(void)
{
    LOG(Message) << "Computing meson contractions '" << getName() << "' using"
                 << " quarks '" << par().q1 << "' and '" << par().q2 << "'"
                 << std::endl;
    
    std::vector<TComplex>  buf;
    std::vector<Result>    result;
    Gamma                  g5(Gamma::Algebra::Gamma5);
    std::vector<GammaPair> gammaList;
    int                    nt = env().getDim(Tp);
    
    parseGammaString(gammaList);
    result.resize(gammaList.size());
    for (unsigned int i = 0; i < result.size(); ++i)
    {
        result[i].gamma_snk = gammaList[i].first;
        result[i].gamma_src = gammaList[i].second;
        result[i].corr.resize(nt);
    }
    if (envHasType(SlicedPropagator1, par().q1) and
        envHasType(SlicedPropagator2, par().q2))
    {
        auto &q1 = envGet(SlicedPropagator1, par().q1);
        auto &q2 = envGet(SlicedPropagator2, par().q2);
        
        LOG(Message) << "(propagator already sinked)" << std::endl;
        for (unsigned int i = 0; i < result.size(); ++i)
        {
            Gamma gSnk(gammaList[i].first);
            Gamma gSrc(gammaList[i].second);
            
            for (unsigned int t = 0; t < nt; ++t)
            {
                result[i].corr[t] = TensorRemove(trace(mesonConnected(q1[t], q2[t], gSnk, gSrc)));
            }
        }
    }
    else
    {
        auto &q1 = envGet(PropagatorField1, par().q1);
        auto &q2 = envGet(PropagatorField2, par().q2);
        
        envGetTmp(LatticeComplex, c);
        LOG(Message) << "(using sink '" << par().sink << "')" << std::endl;
        for (unsigned int i = 0; i < result.size(); ++i)
        {
            Gamma       gSnk(gammaList[i].first);
            Gamma       gSrc(gammaList[i].second);
            std::string ns;
                
            ns = vm().getModuleNamespace(env().getObjectModule(par().sink));
            if (ns == "MSource")
            {
                PropagatorField1 &sink = envGet(PropagatorField1, par().sink);
                
                c = trace(mesonConnected(q1, q2, gSnk, gSrc)*sink);
                sliceSum(c, buf, Tp);
            }
            else if (ns == "MSink")
            {
                SinkFnScalar &sink = envGet(SinkFnScalar, par().sink);
                
                c   = trace(mesonConnected(q1, q2, gSnk, gSrc));
                buf = sink(c);
            }
            for (unsigned int t = 0; t < buf.size(); ++t)
            {
                result[i].corr[t] = TensorRemove(buf[t]);
            }
        }
    }
    saveResult(par().output, "meson", result);
}

END_MODULE_NAMESPACE

END_HADRONS_NAMESPACE

#endif // Hadrons_MContraction_Meson_hpp_