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

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

    Source file: ./tests/Test_padded_cell.cc

    Copyright (C) 2023

Author: Peter Boyle <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 */
#include <Grid/Grid.h>
#include <Grid/lattice/PaddedCell.h>
#include <Grid/stencil/GeneralLocalStencil.h>
#include <Grid/algorithms/GeneralCoarsenedMatrix.h>

using namespace std;
using namespace Grid;

// Want Op in CoarsenOp to call MatPcDagMatPc
template<class Field>
class HermOpAdaptor : public LinearOperatorBase<Field>
{
  LinearOperatorBase<Field> & wrapped;
public:
  HermOpAdaptor(LinearOperatorBase<Field> &wrapme) : wrapped(wrapme)  {};
  void OpDiag (const Field &in, Field &out) {    assert(0);  }
  void OpDir  (const Field &in, Field &out,int dir,int disp) {    assert(0);  }
  void OpDirAll  (const Field &in, std::vector<Field> &out){    assert(0);  };
  void Op     (const Field &in, Field &out){
    wrapped.HermOp(in,out);
  }
  void AdjOp     (const Field &in, Field &out){
    wrapped.HermOp(in,out);
  }
  void HermOpAndNorm(const Field &in, Field &out,RealD &n1,RealD &n2){    assert(0);  }
  void HermOp(const Field &in, Field &out){
    wrapped.HermOp(in,out);
  }
  
};

int main (int argc, char ** argv)
{
  Grid_init(&argc,&argv);

  const int Ls=16;

  GridCartesian         * UGrid   = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(), GridDefaultSimd(Nd,vComplex::Nsimd()),GridDefaultMpi());
  GridRedBlackCartesian * UrbGrid = SpaceTimeGrid::makeFourDimRedBlackGrid(UGrid);

  GridCartesian         * FGrid   = SpaceTimeGrid::makeFiveDimGrid(Ls,UGrid);
  GridRedBlackCartesian * FrbGrid = SpaceTimeGrid::makeFiveDimRedBlackGrid(Ls,UGrid);

  // Construct a coarsened grid
  // 4^4 cell
  Coordinate clatt = GridDefaultLatt();
  for(int d=0;d<clatt.size();d++){
    clatt[d] = clatt[d]/4;
  }
  GridCartesian *Coarse4d =  SpaceTimeGrid::makeFourDimGrid(clatt, GridDefaultSimd(Nd,vComplex::Nsimd()),GridDefaultMpi());;
  GridCartesian *Coarse5d =  SpaceTimeGrid::makeFiveDimGrid(1,Coarse4d);

  std::vector<int> seeds4({1,2,3,4});
  std::vector<int> seeds5({5,6,7,8});
  std::vector<int> cseeds({5,6,7,8});
  GridParallelRNG          RNG5(FGrid);   RNG5.SeedFixedIntegers(seeds5);
  GridParallelRNG          RNG4(UGrid);   RNG4.SeedFixedIntegers(seeds4);
  GridParallelRNG          CRNG(Coarse5d);CRNG.SeedFixedIntegers(cseeds);

  LatticeGaugeField Umu(UGrid);

  FieldMetaData header;
  std::string file("ckpoint_lat.4000");
  NerscIO::readConfiguration(Umu,header,file);
  
  RealD mass=0.01;
  RealD M5=1.8;

  RealD b=1.5;
  RealD c=0.5;
  MobiusFermionD Ddwf(Umu,*FGrid,*FrbGrid,*UGrid,*UrbGrid,mass,M5,b,c);
  MobiusFermionD Dpv(Umu,*FGrid,*FrbGrid,*UGrid,*UrbGrid,1.0,M5,b,c);

  const int nbasis = 4;
  const int cb = 0 ;
  LatticeFermion prom(FrbGrid);

  typedef GeneralCoarsenedMatrix<vSpinColourVector,vTComplex,nbasis> LittleDiracOperator;
  typedef LittleDiracOperator::CoarseVector CoarseVector;

  NextToNextToNextToNearestStencilGeometry5D geom;

  std::cout<<GridLogMessage<<std::endl;
  std::cout<<GridLogMessage<<"*******************************************"<<std::endl;
  std::cout<<GridLogMessage<<std::endl;
  
  SchurDiagMooeeOperator<MobiusFermionD, LatticeFermion> HermOpEO(Ddwf);
  HermOpAdaptor<LatticeFermionD> HOA(HermOpEO);
  
  // Run power method on HOA??
  LatticeFermion result(FrbGrid); result=Zero();
  LatticeFermion    ref(FrbGrid); ref=Zero();
  LatticeFermion    tmp(FrbGrid);
  LatticeFermion    err(FrbGrid);

  {
    LatticeFermion    src(FrbGrid); random(RNG5,src);
    PowerMethod<LatticeFermion>       PM;   PM(HermOpEO,src);
  }
  //  exit(0);
  
  // Warning: This routine calls PVdagM.Op, not PVdagM.HermOp
  typedef Aggregation<vSpinColourVector,vTComplex,nbasis> Subspace;
  Subspace Aggregates(Coarse5d,FrbGrid,cb);
  Aggregates.CreateSubspaceChebyshev(RNG5,
				     HermOpEO,
				     nbasis,
				     90.0,
				     0.1,
				     500,
				     500,
				     100,
				     0.0);
  ////////////////////////////////////////////////////////////
  // Need to check about red-black grid coarsening
  ////////////////////////////////////////////////////////////
  LittleDiracOperator LittleDiracOp(geom,FrbGrid,Coarse5d);
  LittleDiracOp.CoarsenOperator(HOA,Aggregates);

  std::cout<<GridLogMessage<<std::endl;
  std::cout<<GridLogMessage<<"*******************************************"<<std::endl;

  std::cout<<GridLogMessage<<std::endl;
  std::cout<<GridLogMessage<<"Testing coarsened operator "<<std::endl;
  std::cout<<GridLogMessage<<"*******************************************"<<std::endl;
  
  CoarseVector c_src (Coarse5d);
  CoarseVector c_res (Coarse5d);
  CoarseVector c_proj(Coarse5d);

  std::vector<LatticeFermion> subspace(nbasis,FrbGrid);
  subspace=Aggregates.subspace;

  Complex one(1.0);
  c_src = one;  // 1 in every element for vector 1.
  blockPromote(c_src,err,subspace);

  prom=Zero();
  for(int b=0;b<nbasis;b++){
    prom=prom+subspace[b];
  }
  err=err-prom; 
  std::cout<<GridLogMessage<<"Promoted back from subspace: err "<<norm2(err)<<std::endl;
  std::cout<<GridLogMessage<<"c_src "<<norm2(c_src)<<std::endl;
  std::cout<<GridLogMessage<<"prom  "<<norm2(prom)<<std::endl;

  HermOpEO.HermOp(prom,tmp);
  blockProject(c_proj,tmp,subspace);
  std::cout<<GridLogMessage<<" Called Big Dirac Op "<<norm2(tmp)<<std::endl;

  LittleDiracOp.M(c_src,c_res);
  std::cout<<GridLogMessage<<" Called Little Dirac Op c_src "<< norm2(c_src) << "  c_res "<< norm2(c_res) <<std::endl;

  std::cout<<GridLogMessage<<"Little dop : "<<norm2(c_res)<<std::endl;

  std::cout<<GridLogMessage<<"Big dop in subspace : "<<norm2(c_proj)<<std::endl;

  c_proj = c_proj - c_res;
  std::cout<<GridLogMessage<<" ldop error: "<<norm2(c_proj)<<std::endl;
  
  std::cout<<GridLogMessage<<std::endl;
  std::cout<<GridLogMessage<<"*******************************************"<<std::endl;
  std::cout<<GridLogMessage << "Done "<< std::endl;

  // Build a coarse space solver
  random(CRNG,c_src);
  c_res=Zero();
  //  ZeroGuesser<CoarseVector> Guess;
  RealD tol = 1.0e-8;
  int maxit=2000;
  ConjugateGradient<CoarseVector>  CG(tol,maxit,false);
  HermitianLinearOperator<LittleDiracOperator,CoarseVector> Hop (LittleDiracOp);
  CG(Hop, c_src, c_res);
  Grid_finalize();
  return 0;
}