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

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

    Source file: ./lib/lattice/Lattice_reduction.h

    Copyright (C) 2015

Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
Author: Peter Boyle <paboyle@ph.ed.ac.uk>
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_LATTICE_REDUCTION_H
#define GRID_LATTICE_REDUCTION_H

namespace Grid {
#ifdef GRID_WARN_SUBOPTIMAL
#warning "Optimisation alert all these reduction loops are NOT threaded "
#endif     

    ////////////////////////////////////////////////////////////////////////////////////////////////////
    // Deterministic Reduction operations
    ////////////////////////////////////////////////////////////////////////////////////////////////////
template <class vobj>
inline RealD norm2(const Lattice<vobj> &arg) {
  ComplexD nrm = innerProduct(arg, arg);
  return std::real(nrm);
}

template <class vobj>
inline ComplexD innerProduct(const Lattice<vobj> &left,
                             const Lattice<vobj> &right) {
  typedef typename vobj::scalar_type scalar_type;
  typedef typename vobj::vector_type vector_type;
  scalar_type nrm;

  GridBase *grid = left._grid;

  std::vector<vector_type, alignedAllocator<vector_type> > sumarray(
      grid->SumArraySize());
  for (int i = 0; i < grid->SumArraySize(); i++) {
    sumarray[i] = zero;
  }

  PARALLEL_FOR_LOOP
  for (int thr = 0; thr < grid->SumArraySize(); thr++) {
    int nwork, mywork, myoff;
    GridThread::GetWork(left._grid->oSites(), thr, mywork, myoff);

    decltype(innerProduct(left._odata[0], right._odata[0])) vnrm =
        zero;  // private to thread; sub summation
    for (int ss = myoff; ss < mywork + myoff; ss++) {
      vnrm = vnrm + innerProduct(left._odata[ss], right._odata[ss]);
    }
    sumarray[thr] = TensorRemove(vnrm);
  }
   

  vector_type vvnrm;
  vvnrm = zero;  // sum across threads
  for (int i = 0; i < grid->SumArraySize(); i++) {
    vvnrm = vvnrm + sumarray[i];
  }
  nrm = Reduce(vvnrm);  // sum across simd
  right._grid->GlobalSum(nrm);
  return nrm;
}

template <class Op, class T1>
inline auto sum(const LatticeUnaryExpression<Op, T1> &expr) ->
    typename decltype(
        expr.first.func(eval(0, std::get<0>(expr.second))))::scalar_object {
  return sum(closure(expr));
    }

    template<class Op,class T1,class T2>
      inline auto sum(const LatticeBinaryExpression<Op,T1,T2> & expr)
      ->typename decltype(expr.first.func(eval(0,std::get<0>(expr.second)),eval(0,std::get<1>(expr.second))))::scalar_object
    {
      return sum(closure(expr));
    }


    template<class Op,class T1,class T2,class T3>
      inline auto sum(const LatticeTrinaryExpression<Op,T1,T2,T3> & expr)
      ->typename decltype(expr.first.func(eval(0,std::get<0>(expr.second)),
         eval(0,std::get<1>(expr.second)),
         eval(0,std::get<2>(expr.second))
         ))::scalar_object
    {
      return sum(closure(expr));
    }

    template<class vobj>
    inline typename vobj::scalar_object sum(const Lattice<vobj> &arg){

      GridBase *grid=arg._grid;
      int Nsimd = grid->Nsimd();

      std::vector<vobj,alignedAllocator<vobj> > sumarray(grid->SumArraySize());
      for(int i=0;i<grid->SumArraySize();i++){
  sumarray[i]=zero;
      }

PARALLEL_FOR_LOOP
      for(int thr=0;thr<grid->SumArraySize();thr++){
  int nwork, mywork, myoff;
  GridThread::GetWork(grid->oSites(),thr,mywork,myoff);

  vobj vvsum=zero;
        for(int ss=myoff;ss<mywork+myoff; ss++){
    vvsum = vvsum + arg._odata[ss];
  }
  sumarray[thr]=vvsum;
      }

      vobj vsum=zero;  // sum across threads
      for(int i=0;i<grid->SumArraySize();i++){
  vsum = vsum+sumarray[i];
      } 

      typedef typename vobj::scalar_object sobj;
      sobj ssum=zero;

      std::vector<sobj>               buf(Nsimd);
      extract(vsum,buf);

      for(int i=0;i<Nsimd;i++) ssum = ssum + buf[i];
      arg._grid->GlobalSum(ssum);

      return ssum;
    }



template<class vobj> inline void sliceSum(const Lattice<vobj> &Data,std::vector<typename vobj::scalar_object> &result,int orthogdim)
{
  typedef typename vobj::scalar_object sobj;
  GridBase  *grid = Data._grid;
  assert(grid!=NULL);

  // FIXME
  // std::cout<<GridLogMessage<<"WARNING ! SliceSum is unthreaded "<<grid->SumArraySize()<<" threads "<<std::endl;

  const int    Nd = grid->_ndimension;
  const int Nsimd = grid->Nsimd();

  assert(orthogdim >= 0);
  assert(orthogdim < Nd);

  int fd=grid->_fdimensions[orthogdim];
  int ld=grid->_ldimensions[orthogdim];
  int rd=grid->_rdimensions[orthogdim];

  std::vector<vobj,alignedAllocator<vobj> > lvSum(rd); // will locally sum vectors first
  std::vector<sobj> lsSum(ld,zero); // sum across these down to scalars
  std::vector<sobj> extracted(Nsimd);     // splitting the SIMD

  result.resize(fd); // And then global sum to return the same vector to every node for IO to file
  for(int r=0;r<rd;r++){
    lvSum[r]=zero;
  }

  std::vector<int>  coor(Nd);  

  // sum over reduced dimension planes, breaking out orthog dir

  for(int ss=0;ss<grid->oSites();ss++){
    Lexicographic::CoorFromIndex(coor,ss,grid->_rdimensions);
    int r = coor[orthogdim];
    lvSum[r]=lvSum[r]+Data._odata[ss];
  }  

  // Sum across simd lanes in the plane, breaking out orthog dir.
  std::vector<int> icoor(Nd);

  for(int rt=0;rt<rd;rt++){

    extract(lvSum[rt],extracted);

    for(int idx=0;idx<Nsimd;idx++){

      grid->iCoorFromIindex(icoor,idx);

      int ldx =rt+icoor[orthogdim]*rd;

      lsSum[ldx]=lsSum[ldx]+extracted[idx];

    }
  }
  
  // sum over nodes.
  sobj gsum;
  for(int t=0;t<fd;t++){
    int pt = t/ld; // processor plane
    int lt = t%ld;
    if ( pt == grid->_processor_coor[orthogdim] ) {
      gsum=lsSum[lt];
    } else {
      gsum=zero;
    }

    grid->GlobalSum(gsum);

    result[t]=gsum;
  }

}


}
#endif