const char help[] = "Test MatCreateLocalRef()\n\n";

#include <petscmat.h>

static PetscErrorCode GetLocalRef(Mat A, IS isrow, IS iscol, Mat *B)
{
  IS istmp;

  PetscFunctionBegin;
  PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Extracting LocalRef with isrow:\n"));
  PetscCall(ISOnComm(isrow, PETSC_COMM_WORLD, PETSC_COPY_VALUES, &istmp));
  PetscCall(ISView(istmp, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(ISDestroy(&istmp));
  PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Extracting LocalRef with iscol (only rank=0 shown):\n"));
  PetscCall(ISOnComm(iscol, PETSC_COMM_WORLD, PETSC_COPY_VALUES, &istmp));
  PetscCall(ISView(istmp, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(ISDestroy(&istmp));

  PetscCall(MatCreateLocalRef(A, isrow, iscol, B));
  PetscFunctionReturn(PETSC_SUCCESS);
}

int main(int argc, char *argv[])
{
  MPI_Comm               comm;
  Mat                    J, B;
  PetscInt               i, j, k, l, rstart, rend, m, n, top_bs, row_bs, col_bs, nlocblocks, *idx, nrowblocks, ncolblocks, *ridx, *cidx, *icol, *irow;
  PetscScalar           *vals;
  ISLocalToGlobalMapping brmap;
  IS                     is0, is1;
  PetscBool              diag, blocked;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, 0, help));
  comm = PETSC_COMM_WORLD;

  PetscOptionsBegin(comm, NULL, "LocalRef Test Options", NULL);
  {
    top_bs  = 2;
    row_bs  = 2;
    col_bs  = 2;
    diag    = PETSC_FALSE;
    blocked = PETSC_FALSE;
    PetscCall(PetscOptionsInt("-top_bs", "Block size of top-level matrix", 0, top_bs, &top_bs, NULL));
    PetscCall(PetscOptionsInt("-row_bs", "Block size of row map", 0, row_bs, &row_bs, NULL));
    PetscCall(PetscOptionsInt("-col_bs", "Block size of col map", 0, col_bs, &col_bs, NULL));
    PetscCall(PetscOptionsBool("-diag", "Extract a diagonal black", 0, diag, &diag, NULL));
    PetscCall(PetscOptionsBool("-blocked", "Use block insertion", 0, blocked, &blocked, NULL));
  }
  PetscOptionsEnd();

  PetscCall(MatCreate(comm, &J));
  PetscCall(MatSetSizes(J, 6, 6, PETSC_DETERMINE, PETSC_DETERMINE));
  PetscCall(MatSetBlockSize(J, top_bs));
  PetscCall(MatSetFromOptions(J));
  PetscCall(MatSeqBAIJSetPreallocation(J, top_bs, PETSC_DECIDE, 0));
  PetscCall(MatMPIBAIJSetPreallocation(J, top_bs, PETSC_DECIDE, 0, PETSC_DECIDE, 0));
  PetscCall(MatSetUp(J));
  PetscCall(MatGetSize(J, &m, &n));
  PetscCall(MatGetOwnershipRange(J, &rstart, &rend));

  nlocblocks = (rend - rstart) / top_bs + 2;
  PetscCall(PetscMalloc1(nlocblocks, &idx));
  for (i = 0; i < nlocblocks; i++) idx[i] = (rstart / top_bs + i - 1 + m / top_bs) % (m / top_bs);
  PetscCall(ISLocalToGlobalMappingCreate(comm, top_bs, nlocblocks, idx, PETSC_OWN_POINTER, &brmap));
  PetscCall(PetscPrintf(comm, "Block ISLocalToGlobalMapping:\n"));
  PetscCall(ISLocalToGlobalMappingView(brmap, PETSC_VIEWER_STDOUT_WORLD));

  PetscCall(MatSetLocalToGlobalMapping(J, brmap, brmap));
  PetscCall(ISLocalToGlobalMappingDestroy(&brmap));

  /* Create index sets for local submatrix */
  nrowblocks = (rend - rstart) / row_bs;
  ncolblocks = (rend - rstart) / col_bs;
  PetscCall(PetscMalloc2(nrowblocks, &ridx, ncolblocks, &cidx));
  for (i = 0; i < nrowblocks; i++) ridx[i] = i + ((i > nrowblocks / 2) ^ !rstart);
  for (i = 0; i < ncolblocks; i++) cidx[i] = i + ((i < ncolblocks / 2) ^ !!rstart);
  PetscCall(ISCreateBlock(PETSC_COMM_SELF, row_bs, nrowblocks, ridx, PETSC_COPY_VALUES, &is0));
  PetscCall(ISCreateBlock(PETSC_COMM_SELF, col_bs, ncolblocks, cidx, PETSC_COPY_VALUES, &is1));
  PetscCall(PetscFree2(ridx, cidx));

  if (diag) {
    PetscCall(ISDestroy(&is1));
    PetscCall(PetscObjectReference((PetscObject)is0));
    is1        = is0;
    ncolblocks = nrowblocks;
  }

  PetscCall(GetLocalRef(J, is0, is1, &B));

  PetscCall(MatZeroEntries(J));

  PetscCall(PetscMalloc3(row_bs, &irow, col_bs, &icol, row_bs * col_bs, &vals));
  for (i = 0; i < nrowblocks; i++) {
    for (j = 0; j < ncolblocks; j++) {
      for (k = 0; k < row_bs; k++) {
        for (l = 0; l < col_bs; l++) vals[k * col_bs + l] = i * 100000 + j * 1000 + k * 10 + l;
        irow[k] = i * row_bs + k;
      }
      for (l = 0; l < col_bs; l++) icol[l] = j * col_bs + l;
      if (blocked) {
        PetscCall(MatSetValuesBlockedLocal(B, 1, &i, 1, &j, vals, ADD_VALUES));
      } else {
        PetscCall(MatSetValuesLocal(B, row_bs, irow, col_bs, icol, vals, ADD_VALUES));
      }
    }
  }
  PetscCall(PetscFree3(irow, icol, vals));

  PetscCall(MatAssemblyBegin(J, MAT_FINAL_ASSEMBLY));
  PetscCall(MatAssemblyEnd(J, MAT_FINAL_ASSEMBLY));

  PetscCall(MatView(J, PETSC_VIEWER_STDOUT_WORLD));

  PetscCall(ISDestroy(&is0));
  PetscCall(ISDestroy(&is1));
  PetscCall(MatDestroy(&B));
  PetscCall(MatDestroy(&J));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:
      nsize: 2
      filter: grep -v "type: mpi"
      args: -blocked {{0 1}} -mat_type {{aij baij}}

TEST*/