static char help[] = "Test DMStag IS computation\n\n";

#include <petscdm.h>
#include <petscdmstag.h>

int main(int argc, char **argv)
{
  DM        dm;
  PetscInt  dim, dof0, dof1, dof2, dof3;
  PetscBool flg;

  /* Create a DMStag object */
  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-dim", &dim, &flg));
  if (!flg) {
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Supply -dim option\n"));
    return 1;
  }
  if (dim == 1) {
    PetscCall(DMStagCreate1d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, 8, 1, 1, DMSTAG_STENCIL_BOX, 1, NULL, &dm));
  } else if (dim == 2) {
    PetscCall(DMStagCreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, 4, 6, PETSC_DECIDE, PETSC_DECIDE, 0, 1, 1, DMSTAG_STENCIL_BOX, 1, NULL, NULL, &dm));
  } else if (dim == 3) {
    PetscCall(DMStagCreate3d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, 2, 3, 3, PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE, 1, 1, 1, 1, DMSTAG_STENCIL_BOX, 1, NULL, NULL, NULL, &dm));
  } else {
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Supply -dim option with value 1, 2, or 3\n"));
    return 1;
  }
  PetscCall(DMSetFromOptions(dm));
  PetscCall(DMSetUp(dm));
  PetscCall(DMView(dm, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(DMStagGetDOF(dm, &dof0, &dof1, &dof2, &dof3));

  {
    IS            is;
    DMStagStencil s;
    s.c   = 0;
    s.loc = DMSTAG_ELEMENT;
    PetscCall(DMStagCreateISFromStencils(dm, 1, &s, &is));
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test 1\n"));
    PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(ISDestroy(&is));
  }
  {
    IS            is;
    DMStagStencil s;
    s.c   = 0;
    s.loc = DMSTAG_RIGHT;
    PetscCall(DMStagCreateISFromStencils(dm, 1, &s, &is));
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test 2\n"));
    PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(ISDestroy(&is));
  }
  if (dim > 1) {
    IS            is;
    DMStagStencil s[2];
    s[0].c   = 0;
    s[0].loc = DMSTAG_DOWN;
    s[1].c   = 0;
    s[1].loc = DMSTAG_LEFT;
    PetscCall(DMStagCreateISFromStencils(dm, 2, s, &is));
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test 3\n"));
    PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(ISDestroy(&is));
  }
  if (dim == 2 && dof1 > 1) {
    IS            is;
    DMStagStencil s[5];
    s[0].c   = 0;
    s[0].loc = DMSTAG_DOWN;
    s[1].c   = 0;
    s[1].loc = DMSTAG_DOWN; /* redundant, should be ignored */
    s[2].c   = 0;
    s[2].loc = DMSTAG_LEFT;
    s[3].c   = 0;
    s[3].loc = DMSTAG_RIGHT; /* redundant, should be ignored */
    s[4].c   = 1;
    s[4].loc = DMSTAG_RIGHT;
    PetscCall(DMStagCreateISFromStencils(dm, 5, s, &is));
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test 4\n"));
    PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(ISDestroy(&is));
  }
  if (dim == 3 && dof0 > 1) {
    IS            is;
    DMStagStencil s[3];
    s[0].c   = 0;
    s[0].loc = DMSTAG_BACK_DOWN_LEFT;
    s[1].c   = 0;
    s[1].loc = DMSTAG_FRONT_UP_RIGHT; /* redundant, should be ignored */
    s[2].c   = 1;
    s[2].loc = DMSTAG_FRONT_DOWN_RIGHT;
    PetscCall(DMStagCreateISFromStencils(dm, 3, s, &is));
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test 5\n"));
    PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(ISDestroy(&is));
  }
  if (dim == 3) {
    IS            is;
    DMStagStencil s[4];

    s[0].c   = 0;
    s[0].loc = DMSTAG_ELEMENT;
    s[1].c   = 0;
    s[1].loc = DMSTAG_BACK_LEFT;
    s[2].c   = 0;
    s[2].loc = DMSTAG_BACK_DOWN_LEFT;
    s[3].c   = 0;
    s[3].loc = DMSTAG_DOWN;
    PetscCall(DMStagCreateISFromStencils(dm, 4, s, &is));
    PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Test 6\n"));
    PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(ISDestroy(&is));
  }

  PetscCall(DMDestroy(&dm));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:
      suffix: 1
      nsize: 1
      args: -dim 2

   test:
      suffix: 2
      nsize: 1
      args: -dim 2

   test:
      suffix: 3
      nsize: 2
      args: -dim 2 -stag_dof_1 2

   test:
      suffix: 4
      nsize: 1
      args: -dim 3 -stag_dof_0 3

   test:
      suffix: 5
      nsize: 2
      args: -dim 3 -stag_dof_0 2

   test:
      suffix: 6
      nsize: 1
      args: -dim 1

   test:
      suffix: 7
      nsize: 2
      args: -dim 1

TEST*/