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

    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>

#include <Grid/algorithms/iterative/PrecGeneralisedConjugateResidual.h>
#include <Grid/algorithms/iterative/PrecGeneralisedConjugateResidualNonHermitian.h>
#include <Grid/algorithms/iterative/BiCGSTAB.h>

using namespace std;
using namespace Grid;

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);
  }
  
};

template<class Matrix,class Field>
class PVdagMLinearOperator : public LinearOperatorBase<Field> {
  Matrix &_Mat;
  Matrix &_PV;
public:
  PVdagMLinearOperator(Matrix &Mat,Matrix &PV): _Mat(Mat),_PV(PV){};

  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){
    Field tmp(in.Grid());
    _Mat.M(in,tmp);
    _PV.Mdag(tmp,out);
  }
  void AdjOp     (const Field &in, Field &out){
    Field tmp(in.Grid());
    _PV.M(tmp,out);
    _Mat.Mdag(in,tmp);
  }
  void HermOpAndNorm(const Field &in, Field &out,RealD &n1,RealD &n2){    assert(0);  }
  void HermOp(const Field &in, Field &out){
    Field tmp(in.Grid());
    _Mat.M(in,tmp);
    _PV.Mdag(tmp,out);
    _PV.M(out,tmp);
    _Mat.Mdag(tmp,out);
  }
};

template<class Field> class DumbOperator  : public LinearOperatorBase<Field> {
public:
  LatticeComplex scale;
  DumbOperator(GridBase *grid) : scale(grid)
  {
    scale = 0.0;
    LatticeComplex scalesft(grid);
    LatticeComplex scaletmp(grid);
    for(int d=0;d<4;d++){
      Lattice<iScalar<vInteger> > x(grid); LatticeCoordinate(x,d+1);
      LatticeCoordinate(scaletmp,d+1);
      scalesft = Cshift(scaletmp,d+1,1);
      scale = 100.0*scale + where( mod(x    ,2)==(Integer)0, scalesft,scaletmp);
    }
    //    std::cout << " scale\n" << scale << std::endl;
  }
  // Support for coarsening to a multigrid
  void OpDiag (const Field &in, Field &out) {};
  void OpDir  (const Field &in, Field &out,int dir,int disp){};
  void OpDirAll  (const Field &in, std::vector<Field> &out) {};

  void Op     (const Field &in, Field &out){
    out = scale * in;
  }
  void AdjOp  (const Field &in, Field &out){
    out = scale * in;
  }
  void HermOp(const Field &in, Field &out){
    double n1, n2;
    HermOpAndNorm(in,out,n1,n2);
  }
  void HermOpAndNorm(const Field &in, Field &out,double &n1,double &n2){
    ComplexD dot;

    out = scale * in;

    dot= innerProduct(in,out);
    n1=real(dot);

    dot = innerProduct(out,out);
    n2=real(dot);
  }
};


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

  const int Ls=4;

  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
  Coordinate clatt = GridDefaultLatt();
  for(int d=0;d<clatt.size();d++){
    clatt[d] = clatt[d]/2;
  }
  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);

  LatticeFermion    src(FGrid); random(RNG5,src);
  LatticeFermion result(FGrid); result=Zero();
  LatticeFermion    ref(FGrid); ref=Zero();
  LatticeFermion    tmp(FGrid);
  LatticeFermion    err(FGrid);
  LatticeGaugeField Umu(UGrid);
  //SU<Nc>::HotConfiguration(RNG4,Umu);
  SU<Nc>::ColdConfiguration(Umu);
  //  auto U = peekLorentz(Umu,0);
  //  Umu=Zero(); // Make operator local for now
  //  pokeLorentz(Umu,U,0);
  
  RealD mass=0.5;
  RealD M5=1.8;

  DomainWallFermionD Ddwf(Umu,*FGrid,*FrbGrid,*UGrid,*UrbGrid,mass,M5);
  DomainWallFermionD Dpv(Umu,*FGrid,*FrbGrid,*UGrid,*UrbGrid,1.0,M5);

  const int nbasis = 20;
  const int cb = 0 ;
  LatticeFermion prom(FGrid);

  std::vector<LatticeFermion> subspace(nbasis,FGrid);

  std::cout<<GridLogMessage<<"Calling Aggregation class" <<std::endl;

  // Possible tactics -- with zero gauge field, verify block locality of dirac op
  // Possible tactics -- with zero gauge field, take inner products
  
  // Squared operator
  MdagMLinearOperator<DomainWallFermionD,LatticeFermion> HermDefOp(Ddwf);
  DumbOperator<LatticeFermion> Diagonal(FGrid);
  typedef Aggregation<vSpinColourVector,vTComplex,nbasis> Subspace;

  Subspace Aggregates(Coarse5d,FGrid,cb);
  Aggregates.CreateSubspaceRandom(RNG5);

  std::cout<<GridLogMessage << "Called aggregation class"<< std::endl;

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

  NextToNearestStencilGeometry5D geom;
  LittleDiracOperator LittleDiracOp(geom,FGrid,Coarse5d);
  LittleDiracOp.CoarsenOperator(HermDefOp,Aggregates);
  //  LittleDiracOp.CoarsenOperator(Diagonal,Aggregates);

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

  subspace=Aggregates.subspace;

  Complex one(1.0);
  c_src = one;  // 1 in every element for vector 1.
  Coordinate coor(5,0);
  
  //  std::cout << "c_src"<< c_src<< std::endl;
  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;

  //  blockPick(Coarse5d,c_src,c_src,coor);
  //  blockPromote(c_src,prom,subspace);

  //  Diagonal.HermOp(prom,tmp);
  HermDefOp.Op(prom,tmp);
  //  HermDefOp.Op(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<<" Little "<< c_res<<std::endl;
  std::cout<<GridLogMessage<<"Big dop in subspace : "<<norm2(c_proj)<<std::endl;
  //  std::cout<<GridLogMessage<<" Big "<< c_proj<<std::endl;
  c_proj = c_proj - c_res;
  std::cout<<GridLogMessage<<" ldop error: "<<norm2(c_proj)<<std::endl;
  //  std::cout<<GridLogMessage<<" error "<< c_proj<<std::endl;

  std::cout<<GridLogMessage << "Testing Hermiticity stochastically "<< std::endl;
  CoarseVector phi(Coarse5d);
  CoarseVector chi(Coarse5d);
  CoarseVector Aphi(Coarse5d);
  CoarseVector Achi(Coarse5d);

  random(CRNG,phi);
  random(CRNG,chi);

  std::cout<<GridLogMessage<<"Made randoms "<<norm2(phi)<<" " << norm2(chi)<<std::endl;

  LittleDiracOp.M(phi,Aphi);
  LittleDiracOp.Mdag(chi,Achi);
  std::cout<<GridLogMessage<<"Aphi "<<norm2(Aphi)<<" Adag chi" << norm2(Achi)<<std::endl;

  ComplexD pAc = innerProduct(chi,Aphi);
  ComplexD cAp = innerProduct(phi,Achi);
  ComplexD cAc = innerProduct(chi,Achi);
  ComplexD pAp = innerProduct(phi,Aphi);

  std::cout<<GridLogMessage<< "pAc "<<pAc<<" cAp "<< cAp<< " diff "<<pAc-adj(cAp)<<std::endl;

  std::cout<<GridLogMessage<< "pAp "<<pAp<<" cAc "<< cAc<<"Should be real"<< std::endl;

  std::cout<<GridLogMessage<<"Testing linearity"<<std::endl;
  CoarseVector PhiPlusChi(Coarse5d);
  CoarseVector APhiPlusChi(Coarse5d);
  CoarseVector linerr(Coarse5d);
  PhiPlusChi = phi+chi;
  LittleDiracOp.M(PhiPlusChi,APhiPlusChi);

  linerr= APhiPlusChi-Aphi;
  linerr= linerr-Achi;
  std::cout<<GridLogMessage<<"**Diff "<<norm2(linerr)<<std::endl;

  std::cout<<GridLogMessage<<std::endl;
  std::cout<<GridLogMessage<<std::endl;
  std::cout<<GridLogMessage<<"*******************************************"<<std::endl;
  std::cout<<GridLogMessage<<"*******************************************"<<std::endl;
  std::cout<<GridLogMessage<<"*******************************************"<<std::endl;
  std::cout<<GridLogMessage<<std::endl;
  std::cout<<GridLogMessage<<std::endl;
  
  PVdagMLinearOperator<DomainWallFermionD,LatticeFermionD> PVdagM(Ddwf,Dpv);
  HermOpAdaptor<LatticeFermionD> HOA(PVdagM);

  // Run power method on HOA??
  PowerMethod<LatticeFermion>       PM;   PM(HOA,src);
 
  // Warning: This routine calls PVdagM.Op, not PVdagM.HermOp
  Subspace AggregatesPD(Coarse5d,FGrid,cb);
  AggregatesPD.CreateSubspaceChebyshev(RNG5,
				     HOA,
				     nbasis,
				     5000.0,
				     0.02,
				     100,
				     50,
				     50,
				     0.0);
  
  LittleDiracOperator LittleDiracOpPV(geom,FGrid,Coarse5d);
  LittleDiracOpPV.CoarsenOperator(PVdagM,AggregatesPD);

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

  Grid_finalize();
  return 0;
}