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

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

    Source file: ./lib/qcd/action/gauge/GaugeImpl.h

    Copyright (C) 2015

Author: paboyle <paboyle@ph.ed.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  GRID_QCD_GAUGE_IMPL_H
#define  GRID_QCD_GAUGE_IMPL_H

namespace Grid {

  namespace QCD {

    
    ////////////////////////////////////////////////////////////////////////
    // Implementation dependent gauge types
    ////////////////////////////////////////////////////////////////////////

template<class Gimpl> class WilsonLoops;

#define INHERIT_GIMPL_TYPES(GImpl) \
    typedef typename GImpl::Simd                           Simd;\
    typedef typename GImpl::GaugeLinkField       GaugeLinkField;\
    typedef typename GImpl::GaugeField               GaugeField;	

    // 
    template<class S,int Nrepresentation=Nc>
    class GaugeImplTypes { 
    public:
    
      typedef S Simd;
    
      template<typename vtype> using iImplGaugeLink          = iScalar<iScalar<iMatrix<vtype, Nrepresentation> > >;
      template<typename vtype> using iImplGaugeField         = iVector<iScalar<iMatrix<vtype, Nrepresentation> >, Nd  >;
    
      typedef iImplGaugeLink    <Simd>           SiteGaugeLink;
      typedef iImplGaugeField   <Simd>           SiteGaugeField;
    
      typedef Lattice<SiteGaugeLink>                GaugeLinkField; // bit ugly naming; polarised gauge field, lorentz... all ugly
      typedef Lattice<SiteGaugeField>                   GaugeField;

    // Move this elsewhere?
    static inline void AddGaugeLink(GaugeField& U, GaugeLinkField& W, int mu){  // U[mu] += W 
PARALLEL_FOR_LOOP
      for(auto ss=0;ss<U._grid->oSites();ss++){
	U._odata[ss]._internal[mu] = U._odata[ss]._internal[mu] + W._odata[ss]._internal;
        }  
    }
    
      
    };

    // Composition with smeared link, bc's etc.. probably need multiple inheritance
    // Variable precision "S" and variable Nc
    template<class GimplTypes>
    class PeriodicGaugeImpl : public GimplTypes  { 
    public:

    INHERIT_GIMPL_TYPES(GimplTypes);

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////
    // Support needed for the assembly of loops including all boundary condition effects such as conjugate bcs
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////
    
      template<class covariant>  static inline
      Lattice<covariant> CovShiftForward (const GaugeLinkField &Link, int mu, const Lattice<covariant> &field) {
	return PeriodicBC::CovShiftForward(Link,mu,field);
      }

      template<class covariant> static inline
      Lattice<covariant> CovShiftBackward(const GaugeLinkField &Link, int mu,const Lattice<covariant> &field) {
	return PeriodicBC::CovShiftBackward(Link,mu,field);
      }
      static inline
      GaugeLinkField CovShiftIdentityBackward(const GaugeLinkField &Link, int mu) {
	return Cshift(adj(Link),mu,-1);
      }
      static inline
      GaugeLinkField CovShiftIdentityForward(const GaugeLinkField &Link, int mu) {
	return Link;
      }
      static inline
      GaugeLinkField ShiftStaple(const GaugeLinkField &Link, int mu) {
	return Cshift(Link,mu,1);
      }

      static inline bool isPeriodicGaugeField(void) {
	return true;
      }

    };

    
    // Composition with smeared link, bc's etc.. probably need multiple inheritance
    // Variable precision "S" and variable Nc
    template<class GimplTypes>
    class ConjugateGaugeImpl : public GimplTypes { 
    public:

      INHERIT_GIMPL_TYPES(GimplTypes);

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////
    // Support needed for the assembly of loops including all boundary condition effects such as Gparity.
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////
    template<class covariant>  static
    Lattice<covariant> CovShiftForward (const GaugeLinkField &Link, int mu, const Lattice<covariant> &field) {
      return ConjugateBC::CovShiftForward(Link,mu,field);
    }

    template<class covariant> static
    Lattice<covariant> CovShiftBackward(const GaugeLinkField &Link, int mu,const Lattice<covariant> &field) {
      return ConjugateBC::CovShiftBackward(Link,mu,field);
    }

    static inline
    GaugeLinkField CovShiftIdentityBackward(const GaugeLinkField &Link, int mu) {
      GridBase *grid = Link._grid;
      int Lmu = grid->GlobalDimensions()[mu]-1;
      
      Lattice<iScalar<vInteger> > coor(grid);    LatticeCoordinate(coor,mu);

      GaugeLinkField tmp (grid);
      tmp=adj(Link);
      tmp = where(coor==Lmu,conjugate(tmp),tmp);
      return Cshift(tmp,mu,-1);// moves towards positive mu
    }
    static inline
    GaugeLinkField CovShiftIdentityForward(const GaugeLinkField &Link, int mu) {
      return Link;
    }

    static inline
    GaugeLinkField ShiftStaple(const GaugeLinkField &Link, int mu) {
      GridBase *grid = Link._grid;
      int Lmu = grid->GlobalDimensions()[mu]-1;
      
      Lattice<iScalar<vInteger> > coor(grid);    LatticeCoordinate(coor,mu);

      GaugeLinkField tmp (grid);
      tmp=Cshift(Link,mu,1);
      tmp=where(coor==Lmu,conjugate(tmp),tmp);
      return tmp;
    }

    static inline bool isPeriodicGaugeField(void) {
      return false;
    }
    
    };

    typedef GaugeImplTypes<vComplex,Nc>     GimplTypesR;
    typedef GaugeImplTypes<vComplexF,Nc>    GimplTypesF;
    typedef GaugeImplTypes<vComplexD,Nc>    GimplTypesD;

    typedef PeriodicGaugeImpl<GimplTypesR> PeriodicGimplR; // Real.. whichever prec
    typedef PeriodicGaugeImpl<GimplTypesF> PeriodicGimplF; // Float
    typedef PeriodicGaugeImpl<GimplTypesD> PeriodicGimplD; // Double

    typedef ConjugateGaugeImpl<GimplTypesR> ConjugateGimplR; // Real.. whichever prec
    typedef ConjugateGaugeImpl<GimplTypesF> ConjugateGimplF; // Float
    typedef ConjugateGaugeImpl<GimplTypesD> ConjugateGimplD; // Double

  }
}

#endif