/******************************************************************************
 * Copyright 1998-2019 Lawrence Livermore National Security, LLC and other
 * HYPRE Project Developers. See the top-level COPYRIGHT file for details.
 *
 * SPDX-License-Identifier: (Apache-2.0 OR MIT)
 ******************************************************************************/

#include "_hypre_parcsr_ls.h"
 
/*--------------------------------------------------------------------------
 * hypre_GenerateVarDifConv
 *--------------------------------------------------------------------------*/

HYPRE_ParCSRMatrix 
GenerateVarDifConv( MPI_Comm comm,
                 HYPRE_BigInt   nx,
                 HYPRE_BigInt   ny,
                 HYPRE_BigInt   nz, 
                 HYPRE_Int      P,
                 HYPRE_Int      Q,
                 HYPRE_Int      R,
                 HYPRE_Int      p,
                 HYPRE_Int      q,
                 HYPRE_Int      r,
                 HYPRE_Real eps,
		 HYPRE_ParVector *rhs_ptr)
{
   hypre_ParCSRMatrix *A;
   hypre_CSRMatrix *diag;
   hypre_CSRMatrix *offd;
   hypre_ParVector *par_rhs;
   hypre_Vector *rhs;
   HYPRE_Real *rhs_data;

   HYPRE_Int    *diag_i;
   HYPRE_Int    *diag_j;
   HYPRE_Real *diag_data;

   HYPRE_Int    *offd_i;
   HYPRE_Int    *offd_j;
   HYPRE_BigInt *big_offd_j;
   HYPRE_Real *offd_data;

   HYPRE_BigInt *global_part;
   HYPRE_BigInt ix, iy, iz;
   HYPRE_Int cnt, o_cnt;
   HYPRE_Int local_num_rows; 
   HYPRE_BigInt *col_map_offd;
   HYPRE_Int row_index;
   HYPRE_Int i,j;

   HYPRE_Int nx_local, ny_local, nz_local;
   HYPRE_Int num_cols_offd;
   HYPRE_BigInt grid_size;

   HYPRE_BigInt *nx_part;
   HYPRE_BigInt *ny_part;
   HYPRE_BigInt *nz_part;

   HYPRE_Int num_procs;
   HYPRE_Int P_busy, Q_busy, R_busy;

   HYPRE_Real hhx, hhy, hhz;
   HYPRE_Real xx, yy, zz;
   HYPRE_Real afp, afm, bfp, bfm, cfp, cfm, df, ef, ff, gf;

   hypre_MPI_Comm_size(comm,&num_procs);

   grid_size = nx*ny*nz;

   hypre_GeneratePartitioning(nx,P,&nx_part);
   hypre_GeneratePartitioning(ny,Q,&ny_part);
   hypre_GeneratePartitioning(nz,R,&nz_part);

   nx_local = (HYPRE_Int)(nx_part[p+1] - nx_part[p]);
   ny_local = (HYPRE_Int)(ny_part[q+1] - ny_part[q]);
   nz_local = (HYPRE_Int)(nz_part[r+1] - nz_part[r]);

   local_num_rows = nx_local*ny_local*nz_local;

#ifdef HYPRE_NO_GLOBAL_PARTITION

   global_part = hypre_CTAlloc(HYPRE_BigInt,2,HYPRE_MEMORY_HOST);
   global_part[0] = nz_part[r]*nx*ny+(ny_part[q]*nx+nx_part[p]*ny_local)*nz_local;
   global_part[1] = global_part[0] + (HYPRE_BigInt)local_num_rows;

#else
   HYPRE_Int nx_size, ny_size, nz_size;
   HYPRE_Int jx, jy, jz;

   global_part = hypre_CTAlloc(HYPRE_BigInt, P*Q*R+1, HYPRE_MEMORY_HOST);

   global_part[0] = 0;
   cnt = 1;
   for (jz = 0; jz < R; jz++)
   {
      nz_size = (HYPRE_Int)(nz_part[jz+1]-nz_part[jz]);
      for (jy = 0; jy < Q; jy++)
      {
         ny_size = (HYPRE_Int)(ny_part[jy+1]-ny_part[jy]);
         for (jx = 0; jx < P; jx++)
         {
            nx_size = (HYPRE_Int)(nx_part[jx+1] - nx_part[jx]);
            global_part[cnt] = global_part[cnt-1];
            global_part[cnt++] += (HYPRE_BigInt)(nx_size*ny_size*nz_size);
         }
      }
   }

#endif

   diag_i = hypre_CTAlloc(HYPRE_Int,  local_num_rows+1, HYPRE_MEMORY_SHARED);
   offd_i = hypre_CTAlloc(HYPRE_Int,  local_num_rows+1, HYPRE_MEMORY_SHARED);
   rhs_data = hypre_CTAlloc(HYPRE_Real,  local_num_rows, HYPRE_MEMORY_SHARED);

   P_busy = hypre_min(nx,P);
   Q_busy = hypre_min(ny,Q);
   R_busy = hypre_min(nz,R);

   num_cols_offd = 0;
   if (p) num_cols_offd += ny_local*nz_local;
   if (p < P_busy-1) num_cols_offd += ny_local*nz_local;
   if (q) num_cols_offd += nx_local*nz_local;
   if (q < Q_busy-1) num_cols_offd += nx_local*nz_local;
   if (r) num_cols_offd += nx_local*ny_local;
   if (r < R_busy-1) num_cols_offd += nx_local*ny_local;

   if (!local_num_rows) num_cols_offd = 0;

   col_map_offd = hypre_CTAlloc(HYPRE_BigInt,  num_cols_offd, HYPRE_MEMORY_HOST);

   hhx = 1.0/(HYPRE_Real)(nx+1);
   hhy = 1.0/(HYPRE_Real)(ny+1);
   hhz = 1.0/(HYPRE_Real)(nz+1);

   cnt = 1;
   o_cnt = 1;
   diag_i[0] = 0;
   offd_i[0] = 0;
   for (iz = nz_part[r]; iz < nz_part[r+1]; iz++)
   {
      for (iy = ny_part[q];  iy < ny_part[q+1]; iy++)
      {
         for (ix = nx_part[p]; ix < nx_part[p+1]; ix++)
         {
            diag_i[cnt] = diag_i[cnt-1];
            offd_i[o_cnt] = offd_i[o_cnt-1];
            diag_i[cnt]++;
            if (iz > nz_part[r]) 
               diag_i[cnt]++;
            else
            {
               if (iz) 
               {
                  offd_i[o_cnt]++;
               }
            }
            if (iy > ny_part[q]) 
               diag_i[cnt]++;
            else
            {
               if (iy) 
               {
                  offd_i[o_cnt]++;
               }
            }
            if (ix > nx_part[p]) 
               diag_i[cnt]++;
            else
            {
               if (ix) 
               {
                  offd_i[o_cnt]++; 
               }
            }
            if (ix+1 < nx_part[p+1]) 
               diag_i[cnt]++;
            else
            {
               if (ix+1 < nx) 
               {
                  offd_i[o_cnt]++; 
               }
            }
            if (iy+1 < ny_part[q+1]) 
               diag_i[cnt]++;
            else
            {
               if (iy+1 < ny) 
               {
                  offd_i[o_cnt]++;
               }
            }
            if (iz+1 < nz_part[r+1]) 
               diag_i[cnt]++;
            else
            {
               if (iz+1 < nz) 
               {
                  offd_i[o_cnt]++;
               }
            }
            cnt++;
            o_cnt++;
         }
      }
   }

   diag_j = hypre_CTAlloc(HYPRE_Int,  diag_i[local_num_rows], HYPRE_MEMORY_SHARED);
   diag_data = hypre_CTAlloc(HYPRE_Real,  diag_i[local_num_rows], HYPRE_MEMORY_SHARED);

   if (num_procs > 1)
   {
      big_offd_j = hypre_CTAlloc(HYPRE_BigInt,  offd_i[local_num_rows], HYPRE_MEMORY_HOST);
      offd_j = hypre_CTAlloc(HYPRE_Int,  offd_i[local_num_rows], HYPRE_MEMORY_SHARED);
      offd_data = hypre_CTAlloc(HYPRE_Real,  offd_i[local_num_rows], HYPRE_MEMORY_SHARED);
   }

   row_index = 0;
   cnt = 0;
   o_cnt = 0;
   for (iz = nz_part[r]; iz < nz_part[r+1]; iz++)
   {
      zz = (HYPRE_Real)(iz+1)*hhz;
      for (iy = ny_part[q];  iy < ny_part[q+1]; iy++)
      {
         yy = (HYPRE_Real)(iy+1)*hhy;
         for (ix = nx_part[p]; ix < nx_part[p+1]; ix++)
         {
            xx = (HYPRE_Real)(ix+1)*hhx;
	    afp = eps*afun(xx+0.5*hhx,yy,zz)/hhx/hhx;
	    afm = eps*afun(xx-0.5*hhx,yy,zz)/hhx/hhx;
	    bfp = eps*bfun(xx,yy+0.5*hhy,zz)/hhy/hhy;
	    bfm = eps*bfun(xx,yy-0.5*hhy,zz)/hhy/hhy;
	    cfp = eps*cfun(xx,yy,zz+0.5*hhz)/hhz/hhz;
	    cfm = eps*cfun(xx,yy,zz-0.5*hhz)/hhz/hhz;
	    df = dfun(xx,yy,zz)/hhx;
	    ef = efun(xx,yy,zz)/hhy;
	    ff = ffun(xx,yy,zz)/hhz;
	    gf = gfun(xx,yy,zz);
            diag_j[cnt] = row_index;
            diag_data[cnt++] = afp+afm+bfp+bfm+cfp+cfm+gf-df-ef-ff;
	    rhs_data[row_index] = rfun(xx,yy,zz);
	    if (ix == 0) rhs_data[row_index] += afm*bndfun(0,yy,zz);
	    if (iy == 0) rhs_data[row_index] += bfm*bndfun(xx,0,zz);
	    if (iz == 0) rhs_data[row_index] += cfm*bndfun(xx,yy,0);
	    if (ix+1 == nx) rhs_data[row_index] += (afp-df)*bndfun(1.0,yy,zz);
	    if (iy+1 == ny) rhs_data[row_index] += (bfp-ef)*bndfun(xx,1.0,zz);
	    if (iz+1 == nz) rhs_data[row_index] += (cfp-ff)*bndfun(xx,yy,1.0);
            if (iz > nz_part[r]) 
            {
               diag_j[cnt] = row_index-nx_local*ny_local;
               diag_data[cnt++] = -cfm;
            }
            else
            {
               if (iz) 
               {
                  big_offd_j[o_cnt] = hypre_map(ix,iy,iz-1,p,q,r-1,nx,ny,
                                      nx_part,ny_part,nz_part);
                  offd_data[o_cnt++] = -cfm;
               }
            }
            if (iy > ny_part[q]) 
            {
               diag_j[cnt] = row_index-nx_local;
               diag_data[cnt++] = -bfm;
            }
            else
            {
               if (iy) 
               {
                  big_offd_j[o_cnt] = hypre_map(ix,iy-1,iz,p,q-1,r,nx,ny,
                                      nx_part,ny_part,nz_part);
                  offd_data[o_cnt++] = -bfm;
               }
            }
            if (ix > nx_part[p]) 
            {
               diag_j[cnt] = row_index-1;
               diag_data[cnt++] = -afm;
            }
            else
            {
               if (ix) 
               {
                  big_offd_j[o_cnt] = hypre_map(ix-1,iy,iz,p-1,q,r,nx,ny,
                                      nx_part,ny_part,nz_part);
                  offd_data[o_cnt++] = -afm;
               }
            }
            if (ix+1 < nx_part[p+1]) 
            {
               diag_j[cnt] = row_index+1;
               diag_data[cnt++] = -afp+df;
            }
            else
            {
               if (ix+1 < nx) 
               {
                  big_offd_j[o_cnt] = hypre_map(ix+1,iy,iz,p+1,q,r,nx,ny,
                                      nx_part,ny_part,nz_part);
                  offd_data[o_cnt++] = -afp+df;
               }
            }
            if (iy+1 < ny_part[q+1]) 
            {
               diag_j[cnt] = row_index+nx_local;
               diag_data[cnt++] = -bfp +ef;
            }
            else
            {
               if (iy+1 < ny) 
               {
                  big_offd_j[o_cnt] = hypre_map(ix,iy+1,iz,p,q+1,r,nx,ny,
                                      nx_part,ny_part,nz_part);
                  offd_data[o_cnt++] = -bfp+ef;
               }
            }
            if (iz+1 < nz_part[r+1]) 
            {
               diag_j[cnt] = row_index+nx_local*ny_local;
               diag_data[cnt++] = -cfp+ff;
            }
            else
            {
               if (iz+1 < nz) 
               {
                  big_offd_j[o_cnt] = hypre_map(ix,iy,iz+1,p,q,r+1,nx,ny,
                                      nx_part,ny_part,nz_part);
                  offd_data[o_cnt++] = -cfp+ff;
               }
            }
            row_index++;
         }
      }
   }

   if (num_procs > 1)
   {
      for (i=0; i < num_cols_offd; i++)
         col_map_offd[i] = big_offd_j[i];
   	
      hypre_BigQsort0(col_map_offd, 0, num_cols_offd-1);

      for (i=0; i < num_cols_offd; i++)
         for (j=0; j < num_cols_offd; j++)
            if (big_offd_j[i] == col_map_offd[j])
            {
               offd_j[i] = j;
               break;
            }
      hypre_TFree(big_offd_j, HYPRE_MEMORY_HOST);
   }

   par_rhs = hypre_ParVectorCreate(comm, grid_size, global_part);
   hypre_ParVectorOwnsPartitioning(par_rhs) = 0;
   rhs = hypre_ParVectorLocalVector(par_rhs);
   hypre_VectorData(rhs) = rhs_data;

   A = hypre_ParCSRMatrixCreate(comm, grid_size, grid_size,
                                global_part, global_part, num_cols_offd,
                                diag_i[local_num_rows],
                                offd_i[local_num_rows]);

   hypre_ParCSRMatrixColMapOffd(A) = col_map_offd;

   diag = hypre_ParCSRMatrixDiag(A);
   hypre_CSRMatrixI(diag) = diag_i;
   hypre_CSRMatrixJ(diag) = diag_j;
   hypre_CSRMatrixData(diag) = diag_data;

   offd = hypre_ParCSRMatrixOffd(A);
   hypre_CSRMatrixI(offd) = offd_i;
   if (num_cols_offd)
   {
      hypre_CSRMatrixJ(offd) = offd_j;
      hypre_CSRMatrixData(offd) = offd_data;
   }

   hypre_TFree(nx_part, HYPRE_MEMORY_HOST);
   hypre_TFree(ny_part, HYPRE_MEMORY_HOST);
   hypre_TFree(nz_part, HYPRE_MEMORY_HOST);

   *rhs_ptr = (HYPRE_ParVector) par_rhs;

   return (HYPRE_ParCSRMatrix) A;
}

HYPRE_Real afun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   /* value = 1.0 + 1000.0*fabs(xx-yy); */
   if ((xx < 0.1 && yy < 0.1 && zz < 0.1)
      || (xx < 0.1 && yy < 0.1 && zz > 0.9)
      || (xx < 0.1 && yy > 0.9 && zz < 0.1)
      || (xx > 0.9 && yy < 0.1 && zz < 0.1)
      || (xx > 0.9 && yy > 0.9 && zz < 0.1)
      || (xx > 0.9 && yy < 0.1 && zz > 0.9)
      || (xx < 0.1 && yy > 0.9 && zz > 0.9)
      || (xx > 0.9 && yy > 0.9 && zz > 0.9))
      value = 0.01;
   else if (xx >= 0.1 && xx <= 0.9 
	 && yy >= 0.1 && yy <= 0.9
	 && zz >= 0.1 && zz <= 0.9)
      value = 1000.0;
   else   
      value = 1.0 ;
   /* HYPRE_Real value, pi;
   pi = 4.0 * atan(1.0);
   value = cos(pi*xx)*cos(pi*yy); */
   return value;
}

HYPRE_Real bfun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   /* value = 1.0 + 1000.0*fabs(xx-yy); */
   if ((xx < 0.1 && yy < 0.1 && zz < 0.1)
      || (xx < 0.1 && yy < 0.1 && zz > 0.9)
      || (xx < 0.1 && yy > 0.9 && zz < 0.1)
      || (xx > 0.9 && yy < 0.1 && zz < 0.1)
      || (xx > 0.9 && yy > 0.9 && zz < 0.1)
      || (xx > 0.9 && yy < 0.1 && zz > 0.9)
      || (xx < 0.1 && yy > 0.9 && zz > 0.9)
      || (xx > 0.9 && yy > 0.9 && zz > 0.9))
      value = 0.01;
   else if (xx >= 0.1 && xx <= 0.9 
	 && yy >= 0.1 && yy <= 0.9
	 && zz >= 0.1 && zz <= 0.9)
      value = 1000.0;
   else   
      value = 1.0 ;
   /* HYPRE_Real value, pi;
   pi = 4.0 * atan(1.0);
   value = 1.0 - 2.0*xx; 
   value = cos(pi*xx)*cos(pi*yy); */
   /* HYPRE_Real value;
   value = 1.0 + 1000.0 * fabs(xx-yy); 
   HYPRE_Real value, x0, y0;
   x0 = fabs(xx - 0.5);
   y0 = fabs(yy - 0.5);
   if (y0 > x0) x0 = y0;
   if (x0 >= 0.125 && x0 <= 0.25)
      value = 1.0;
   else
      value = 1000.0;*/
   return value;
}

HYPRE_Real cfun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   if ((xx < 0.1 && yy < 0.1 && zz < 0.1)
      || (xx < 0.1 && yy < 0.1 && zz > 0.9)
      || (xx < 0.1 && yy > 0.9 && zz < 0.1)
      || (xx > 0.9 && yy < 0.1 && zz < 0.1)
      || (xx > 0.9 && yy > 0.9 && zz < 0.1)
      || (xx > 0.9 && yy < 0.1 && zz > 0.9)
      || (xx < 0.1 && yy > 0.9 && zz > 0.9)
      || (xx > 0.9 && yy > 0.9 && zz > 0.9))
      value = 0.01;
   else if (xx >= 0.1 && xx <= 0.9 
	 && yy >= 0.1 && yy <= 0.9
	 && zz >= 0.1 && zz <= 0.9)
      value = 1000.0;
   else   
      value = 1.0 ;
   /*if (xx <= 0.75 && yy <= 0.75 && zz <= 0.75)
      value = 0.1;
   else if (xx > 0.75 && yy > 0.75 && zz > 0.75)
      value = 100000;
   else   
      value = 1.0 ;*/
   return value;
}

HYPRE_Real dfun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   /*HYPRE_Real pi;
   pi = 4.0 * atan(1.0);
   value = -sin(pi*xx)*cos(pi*yy);*/
   value = 0;
   return value;
}

HYPRE_Real efun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   /*HYPRE_Real pi;
   pi = 4.0 * atan(1.0);
   value = sin(pi*yy)*cos(pi*xx);*/
   value = 0;
   return value;
}

HYPRE_Real ffun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   value = 0.0;
   return value;
}

HYPRE_Real gfun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   value = 0.0;
   return value;
}

HYPRE_Real rfun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   /* HYPRE_Real value, pi;
   pi = 4.0 * atan(1.0);
   value = -4.0*pi*pi*sin(pi*xx)*sin(pi*yy)*cos(pi*xx)*cos(pi*yy); */
   HYPRE_Real value;
   /* value = xx*(1.0-xx)*yy*(1.0-yy); */
   value = 1.0;
   return value;
}

HYPRE_Real bndfun(HYPRE_Real xx, HYPRE_Real yy, HYPRE_Real zz)
{
   HYPRE_Real value;
   /*HYPRE_Real pi;
   pi = 4.0 * atan(1.0);
   value = sin(pi*xx)+sin(13*pi*xx)+sin(pi*yy)+sin(13*pi*yy);*/
   value = 0.0;
   return value;
}
