static char help[] = "Test DMStag 2d periodic and ghosted boundary conditions\n\n";
#include <petscdm.h>
#include <petscdmstag.h>

int main(int argc, char **argv)
{
  DM             dm;
  Vec            vec, vecLocal1, vecLocal2;
  PetscScalar   *a, ***a1, ***a2, expected;
  PetscInt       startx, starty, nx, ny, i, j, d, is, js, dof0, dof1, dof2, dofTotal, stencilWidth, Nx, Ny;
  DMBoundaryType boundaryTypex, boundaryTypey;
  PetscMPIInt    rank;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  dof0         = 1;
  dof1         = 1;
  dof2         = 1;
  stencilWidth = 2;
  PetscCall(DMStagCreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_PERIODIC, DM_BOUNDARY_PERIODIC, 4, 4, PETSC_DECIDE, PETSC_DECIDE, dof0, dof1, dof2, DMSTAG_STENCIL_BOX, stencilWidth, NULL, NULL, &dm));
  PetscCall(DMSetFromOptions(dm));
  PetscCall(DMSetUp(dm));
  PetscCall(DMStagGetDOF(dm, &dof0, &dof1, &dof2, NULL));
  dofTotal = dof0 + 2 * dof1 + dof2;
  PetscCall(DMStagGetStencilWidth(dm, &stencilWidth));

  PetscCall(DMCreateLocalVector(dm, &vecLocal1));
  PetscCall(VecDuplicate(vecLocal1, &vecLocal2));

  PetscCall(DMCreateGlobalVector(dm, &vec));
  PetscCall(VecSet(vec, 1.0));
  PetscCall(VecSet(vecLocal1, 0.0));
  PetscCall(DMGlobalToLocalBegin(dm, vec, INSERT_VALUES, vecLocal1));
  PetscCall(DMGlobalToLocalEnd(dm, vec, INSERT_VALUES, vecLocal1));

  PetscCall(DMStagGetCorners(dm, &startx, &starty, NULL, &nx, &ny, NULL, NULL, NULL, NULL));
  PetscCall(DMStagVecGetArrayRead(dm, vecLocal1, &a1));
  PetscCall(DMStagVecGetArray(dm, vecLocal2, &a2));
  for (j = starty; j < starty + ny; ++j) {
    for (i = startx; i < startx + nx; ++i) {
      for (d = 0; d < dofTotal; ++d) {
        if (a1[j][i][d] != 1.0) PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] Unexpected value %g (expecting %g)\n", rank, (double)PetscRealPart(a1[j][i][d]), 1.0));
        a2[j][i][d] = 0.0;
        for (js = -stencilWidth; js <= stencilWidth; ++js) {
          for (is = -stencilWidth; is <= stencilWidth; ++is) a2[j][i][d] += a1[j + js][i + is][d];
        }
      }
    }
  }
  PetscCall(DMStagVecRestoreArrayRead(dm, vecLocal1, &a1));
  PetscCall(DMStagVecRestoreArray(dm, vecLocal2, &a2));

  PetscCall(DMLocalToGlobalBegin(dm, vecLocal2, INSERT_VALUES, vec));
  PetscCall(DMLocalToGlobalEnd(dm, vecLocal2, INSERT_VALUES, vec));

  /* For the all-periodic case, all values are the same . Otherwise, just check the local version */
  PetscCall(DMStagGetBoundaryTypes(dm, &boundaryTypex, &boundaryTypey, NULL));
  if (boundaryTypex == DM_BOUNDARY_PERIODIC && boundaryTypey == DM_BOUNDARY_PERIODIC) {
    PetscCall(VecGetArray(vec, &a));
    expected = 1.0;
    for (d = 0; d < 2; ++d) expected *= (2 * stencilWidth + 1);
    for (i = 0; i < ny * nx * dofTotal; ++i) {
      if (a[i] != expected) PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] Unexpected value %g (expecting %g)\n", rank, (double)PetscRealPart(a[i]), (double)PetscRealPart(expected)));
    }
    PetscCall(VecRestoreArray(vec, &a));
  } else {
    PetscCall(DMStagVecGetArrayRead(dm, vecLocal2, &a2));
    PetscCall(DMStagGetGlobalSizes(dm, &Nx, &Ny, NULL));
    PetscCheck(stencilWidth <= 1, PETSC_COMM_WORLD, PETSC_ERR_SUP, "Non-periodic check implemented assuming stencilWidth = 1");
    for (j = starty; j < starty + ny; ++j) {
      for (i = startx; i < startx + nx; ++i) {
        PetscInt  dd, extra[2];
        PetscBool bnd[2];
        bnd[0]   = (PetscBool)((i == 0 || i == Nx - 1) && boundaryTypex != DM_BOUNDARY_PERIODIC);
        bnd[1]   = (PetscBool)((j == 0 || j == Ny - 1) && boundaryTypey != DM_BOUNDARY_PERIODIC);
        extra[0] = i == Nx - 1 && boundaryTypex != DM_BOUNDARY_PERIODIC ? 1 : 0;
        extra[1] = j == Ny - 1 && boundaryTypey != DM_BOUNDARY_PERIODIC ? 1 : 0;
        { /* vertices */
          PetscScalar expected = 1.0;
          for (dd = 0; dd < 2; ++dd) expected *= (bnd[dd] ? stencilWidth + 1 + extra[dd] : 2 * stencilWidth + 1);
          for (d = 0; d < dof0; ++d) {
            if (a2[j][i][d] != expected) {
              PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] Element (%" PetscInt_FMT ",%" PetscInt_FMT ")[%" PetscInt_FMT "] Unexpected value %g (expecting %g)\n", rank, i, j, d, (double)PetscRealPart(a2[j][i][d]), (double)PetscRealPart(expected)));
            }
          }
        }
        { /* down edges */
          PetscScalar expected = (bnd[1] ? stencilWidth + 1 + extra[1] : 2 * stencilWidth + 1);
          expected *= ((bnd[0] ? 1 : 2) * stencilWidth + 1);
          for (d = dof0; d < dof0 + dof1; ++d) {
            if (a2[j][i][d] != expected) {
              PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] Element (%" PetscInt_FMT ",%" PetscInt_FMT ")[%" PetscInt_FMT "] Unexpected value %g (expecting %g)\n", rank, i, j, d, (double)PetscRealPart(a2[j][i][d]), (double)PetscRealPart(expected)));
            }
          }
        }
        { /* left edges */
          PetscScalar expected = (bnd[0] ? stencilWidth + 1 + extra[0] : 2 * stencilWidth + 1);
          expected *= ((bnd[1] ? 1 : 2) * stencilWidth + 1);
          for (d = dof0 + dof1; d < dof0 + 2 * dof1; ++d) {
            if (a2[j][i][d] != expected) {
              PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] Element (%" PetscInt_FMT ",%" PetscInt_FMT ")[%" PetscInt_FMT "] Unexpected value %g (expecting %g)\n", rank, i, j, d, (double)PetscRealPart(a2[j][i][d]), (double)PetscRealPart(expected)));
            }
          }
        }
        { /* elements */
          PetscScalar expected = 1.0;
          for (dd = 0; dd < 2; ++dd) expected *= ((bnd[dd] ? 1 : 2) * stencilWidth + 1);
          for (d = dofTotal - dof2; d < dofTotal; ++d) {
            if (a2[j][i][d] != expected) {
              PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] Element (%" PetscInt_FMT ",%" PetscInt_FMT ")[%" PetscInt_FMT "] Unexpected value %g (expecting %g)\n", rank, i, j, d, (double)PetscRealPart(a2[j][i][d]), (double)PetscRealPart(expected)));
            }
          }
        }
      }
    }
    PetscCall(DMStagVecRestoreArrayRead(dm, vecLocal2, &a2));
  }

  PetscCall(VecDestroy(&vec));
  PetscCall(VecDestroy(&vecLocal1));
  PetscCall(VecDestroy(&vecLocal2));
  PetscCall(DMDestroy(&dm));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:
      suffix: 1
      nsize: 4
      args: -stag_ranks_x 2 -stag_ranks_y 2 -stag_stencil_width 1 -stag_dof_2 2
      output_file: output/empty.out

   test:
      suffix: 2
      nsize: 4
      args: -stag_ranks_x 2 -stag_ranks_y 2 -stag_dof_1 2 -stag_grid_y 5
      output_file: output/empty.out

   test:
      suffix: 3
      nsize: 6
      args: -stag_ranks_x 3 -stag_ranks_y 2 -stag_dof_0 2 -stag_grid_x 6
      output_file: output/empty.out

   test:
      suffix: 4
      nsize: 6
      args: -stag_ranks_x 3 -stag_ranks_y 2 -stag_dof_0 0 -stag_dof_1 0 -stag_dof_2 0 -stag_grid_x 4 -stag_boundary_type_x ghosted -stag_boundary_type_y ghosted -stag_stencil_width 1
      output_file: output/empty.out

   test:
      suffix: 5
      nsize: 6
      args: -stag_ranks_x 3 -stag_ranks_y 2 -stag_dof_0 0 -stag_dof_1 0 -stag_dof_2 0 -stag_grid_x 4 -stag_boundary_type_x ghosted -stag_stencil_width 1
      output_file: output/empty.out

   test:
      suffix: 6
      nsize: 9
      args: -stag_dof_0 2 -stag_dof_1 2 -stag_dof_2 1 -stag_dof_2 1 -stag_boundary_type_y ghosted -stag_grid_x 9 -stag_grid_y 13 -stag_ranks_x 3 -stag_ranks_y 3 -stag_stencil_width 1
      output_file: output/empty.out

   test:
      suffix: 7
      nsize: 1
      args: -stag_dof_0 2 -stag_dof_1 2 -stag_dof_2 1 -stag_dof_2 1 stag_grid_x 9 -stag_grid_y 13 -stag_stencil_width 1
      output_file: output/empty.out

TEST*/