MooseMesh.C

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//* This file is part of the MOOSE framework
//* https://mooseframework.inl.gov
//*
//* All rights reserved, see COPYRIGHT for full restrictions
//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html

#include "MooseError.h"
#include "MooseMesh.h"
#include "Factory.h"
#include "CacheChangedListsThread.h"
#include "MooseUtils.h"
#include "MooseApp.h"
#include "RelationshipManager.h"
#include "PointListAdaptor.h"
#include "Executioner.h"
#include "NonlinearSystemBase.h"
#include "LinearSystem.h"
#include "AuxiliarySystem.h"
#include "Assembly.h"
#include "SubProblem.h"
#include "MooseVariableBase.h"
#include "MooseMeshUtils.h"
#include "MooseAppCoordTransform.h"
#include "FEProblemBase.h"

#include <utility>

// libMesh
#include "libmesh/bounding_box.h"
#include "libmesh/boundary_info.h"
#include "libmesh/mesh_tools.h"
#include "libmesh/parallel.h"
#include "libmesh/mesh_communication.h"
#include "libmesh/periodic_boundary_base.h"
#include "libmesh/fe_base.h"
#include "libmesh/fe_interface.h"
#include "libmesh/mesh_communication.h"
#include "libmesh/mesh_tools.h"
#include "libmesh/parallel.h"
#include "libmesh/parallel_elem.h"
#include "libmesh/parallel_node.h"
#include "libmesh/parallel_ghost_sync.h"
#include "libmesh/utility.h"
#include "libmesh/remote_elem.h"
#include "libmesh/linear_partitioner.h"
#include "libmesh/centroid_partitioner.h"
#include "libmesh/parmetis_partitioner.h"
#include "libmesh/hilbert_sfc_partitioner.h"
#include "libmesh/morton_sfc_partitioner.h"
#include "libmesh/edge_edge2.h"
#include "libmesh/checkpoint_io.h"
#include "libmesh/mesh_refinement.h"
#include "libmesh/quadrature.h"
#include "libmesh/boundary_info.h"
#include "libmesh/periodic_boundaries.h"
#include "libmesh/quadrature_gauss.h"
#include "libmesh/point_locator_base.h"
#include "libmesh/default_coupling.h"
#include "libmesh/ghost_point_neighbors.h"
#include "libmesh/fe_type.h"
#include "libmesh/enum_to_string.h"
#include "libmesh/elem_side_builder.h"

using namespace libMesh;

// Make newer nanoflann API compatible with older nanoflann versions
#if NANOFLANN_VERSION < 0x150
namespace nanoflann
{
typedef SearchParams SearchParameters;

template <typename T, typename U>
using ResultItem = std::pair<T, U>;
}
#endif

const std::array<bool, 3> MooseMesh::periodic_dim_default{false, false, false};

InputParameters
MooseMesh::validParams()
{
  InputParameters params = MooseObject::validParams();

  MooseEnum parallel_type("DEFAULT REPLICATED DISTRIBUTED", "DEFAULT");
  params.addParam<MooseEnum>("parallel_type",
                             parallel_type,
                             "DEFAULT: Use libMesh::ReplicatedMesh unless --distributed-mesh is "
                             "specified on the command line "
                             "REPLICATED: Always use libMesh::ReplicatedMesh "
                             "DISTRIBUTED: Always use libMesh::DistributedMesh");

  params.addParam<bool>(
      "allow_renumbering",
      true,
      "If allow_renumbering=false, node and element numbers are kept fixed until deletion");

  params.addParam<MooseEnum>(
      "partitioner",
      partitioning(),
      "Specifies a mesh partitioner to use when splitting the mesh for a parallel computation.");
  MooseEnum direction("x y z radial");
  params.addParam<MooseEnum>("centroid_partitioner_direction",
                             direction,
                             "Specifies the sort direction if using the centroid partitioner. "
                             "Available options: x, y, z, radial");

  MooseEnum patch_update_strategy("never always auto iteration", "never");
  params.addParam<MooseEnum>(
      "patch_update_strategy",
      patch_update_strategy,
      "How often to update the geometric search 'patch'.  The default is to "
      "never update it (which is the most efficient but could be a problem "
      "with lots of relative motion). 'always' will update the patch for all "
      "secondary nodes at the beginning of every timestep which might be time "
      "consuming. 'auto' will attempt to determine at the start of which "
      "timesteps the patch for all secondary nodes needs to be updated automatically."
      "'iteration' updates the patch at every nonlinear iteration for a "
      "subset of secondary nodes for which penetration is not detected. If there "
      "can be substantial relative motion between the primary and secondary surfaces "
      "during the nonlinear iterations within a timestep, it is advisable to use "
      "'iteration' option to ensure accurate contact detection.");

  // Note: This parameter is named to match 'construct_side_list_from_node_list' in SetupMeshAction
  params.addParam<bool>(
      "construct_node_list_from_side_list",
      true,
      "Whether or not to generate nodesets from the sidesets (currently often required).");
  params.addParam<bool>(
      "displace_node_list_by_side_list",
      true,
      "Whether to renumber existing nodesets with ids matching sidesets that "
      "lack names matching sidesets, when constructing nodesets from sidesets via the default "
      "'construct_node_list_from_side_list' option, rather than to merge them with the sideset.");
  params.addParam<unsigned int>(
      "patch_size", 40, "The number of nodes to consider in the NearestNode neighborhood.");
  params.addParam<unsigned int>("ghosting_patch_size",
                                "The number of nearest neighbors considered "
                                "for ghosting purposes when 'iteration' "
                                "patch update strategy is used. Default is "
                                "5 * patch_size.");
  params.addParam<unsigned int>("max_leaf_size",
                                10,
                                "The maximum number of points in each leaf of the KDTree used in "
                                "the nearest neighbor search. As the leaf size becomes larger,"
                                "KDTree construction becomes faster but the nearest neighbor search"
                                "becomes slower.");

  params.addParam<bool>("build_all_side_lowerd_mesh",
                        false,
                        "True to build the lower-dimensional mesh for all sides.");

  params.addParam<bool>("skip_refine_when_use_split",
                        true,
                        "True to skip uniform refinements when using a pre-split mesh.");

  params.addParam<std::vector<SubdomainID>>(
      "add_subdomain_ids",
      "The listed subdomain ids will be assumed valid for the mesh. This permits setting up "
      "subdomain restrictions for subdomains initially containing no elements, which can occur, "
      "for example, in additive manufacturing simulations which dynamically add and remove "
      "elements. Names for this subdomains may be provided using add_subdomain_names. In this case "
      "this list and add_subdomain_names must contain the same number of items.");
  params.addParam<std::vector<SubdomainName>>(
      "add_subdomain_names",
      "The listed subdomain names will be assumed valid for the mesh. This permits setting up "
      "subdomain restrictions for subdomains initially containing no elements, which can occur, "
      "for example, in additive manufacturing simulations which dynamically add and remove "
      "elements. IDs for this subdomains may be provided using add_subdomain_ids. Otherwise IDs "
      "are automatically assigned. In case add_subdomain_ids is set too, both lists must contain "
      "the same number of items.");

  params.addParam<std::vector<BoundaryID>>(
      "add_sideset_ids",
      "The listed sideset ids will be assumed valid for the mesh. This permits setting up boundary "
      "restrictions for sidesets initially containing no sides. Names for this sidesets may be "
      "provided using add_sideset_names. In this case this list and add_sideset_names must contain "
      "the same number of items.");
  params.addParam<std::vector<BoundaryName>>(
      "add_sideset_names",
      "The listed sideset names will be assumed valid for the mesh. This permits setting up "
      "boundary restrictions for sidesets initially containing no sides. Ids for this sidesets may "
      "be provided using add_sideset_ids. In this case this list and add_sideset_ids must contain "
      "the same number of items.");

  params.addParam<std::vector<BoundaryID>>(
      "add_nodeset_ids",
      "The listed nodeset ids will be assumed valid for the mesh. This permits setting up boundary "
      "restrictions for node initially containing no sides. Names for this nodesets may be "
      "provided using add_nodeset_names. In this case this list and add_nodeset_names must contain "
      "the same number of items.");
  params.addParam<std::vector<BoundaryName>>(
      "add_nodeset_names",
      "The listed nodeset names will be assumed valid for the mesh. This permits setting up "
      "boundary restrictions for nodesets initially containing no sides. Ids for this nodesets may "
      "be provided using add_nodesets_ids. In this case this list and add_nodesets_ids must "
      "contain the same number of items.");

  params += MooseAppCoordTransform::validParams();

  // This indicates that the derived mesh type accepts a MeshGenerator, and should be set to true in
  // derived types that do so.
  params.addPrivateParam<bool>("_mesh_generator_mesh", false);

  // Whether or not the mesh is pre split
  params.addPrivateParam<bool>("_is_split", false);

  params.registerBase("MooseMesh");

  // groups
  params.addParamNamesToGroup("patch_update_strategy patch_size max_leaf_size", "Geometric search");
  params.addParamNamesToGroup("add_subdomain_ids add_subdomain_names add_sideset_ids "
                              "add_sideset_names add_nodeset_ids add_nodeset_names",
                              "Pre-declaration of future mesh sub-entities");
  params.addParamNamesToGroup("construct_node_list_from_side_list build_all_side_lowerd_mesh "
                              "displace_node_list_by_side_list",
                              "Automatic definition of mesh element sides entities");
  params.addParamNamesToGroup("partitioner centroid_partitioner_direction", "Partitioning");

  return params;
}

MooseMesh::MooseMesh(const InputParameters & parameters)
  : MooseObject(parameters),
    Restartable(this, "Mesh"),
    PerfGraphInterface(this),
    _parallel_type(getParam<MooseEnum>("parallel_type").getEnum<MooseMesh::ParallelType>()),
    _use_distributed_mesh(false),
    _distribution_overridden(false),
    _parallel_type_overridden(false),
    _mesh(nullptr),
    _partitioner_name(getParam<MooseEnum>("partitioner")),
    _partitioner_overridden(false),
    _custom_partitioner_requested(false),
    _uniform_refine_level(0),
    _skip_refine_when_use_split(getParam<bool>("skip_refine_when_use_split")),
    _skip_deletion_repartition_after_refine(false),
    _is_nemesis(false),
    _patch_size(getParam<unsigned int>("patch_size")),
    _ghosting_patch_size(isParamValid("ghosting_patch_size")
                             ? getParam<unsigned int>("ghosting_patch_size")
                             : 5 * _patch_size),
    _max_leaf_size(getParam<unsigned int>("max_leaf_size")),
    _patch_update_strategy(
        getParam<MooseEnum>("patch_update_strategy").getEnum<Moose::PatchUpdateType>()),
    _regular_orthogonal_mesh(false),
    _is_split(getParam<bool>("_is_split")),
    _allow_recovery(true),
    _construct_node_list_from_side_list(getParam<bool>("construct_node_list_from_side_list")),
    _displace_node_list_by_side_list(getParam<bool>("displace_node_list_by_side_list")),
    _need_delete(false),
    _allow_remote_element_removal(true),
    _need_ghost_ghosted_boundaries(true),
    _is_displaced(false),
    _coord_sys(
        declareRestartableData<std::map<SubdomainID, Moose::CoordinateSystemType>>("coord_sys")),
    _rz_coord_axis(getParam<MooseEnum>("rz_coord_axis")),
    _coord_system_set(false),
    _doing_p_refinement(false)
{
  if (isParamValid("ghosting_patch_size") && (_patch_update_strategy != Moose::Iteration))
    mooseError("Ghosting patch size parameter has to be set in the mesh block "
               "only when 'iteration' patch update strategy is used.");

  if (isParamValid("coord_block"))
  {
    if (isParamValid("block"))
      paramWarning("block",
                   "You set both 'Mesh/block' and 'Mesh/coord_block'. The value of "
                   "'Mesh/coord_block' will be used.");

    _provided_coord_blocks = getParam<std::vector<SubdomainName>>("coord_block");
  }
  else if (isParamValid("block"))
    _provided_coord_blocks = getParam<std::vector<SubdomainName>>("block");

  if (getParam<bool>("build_all_side_lowerd_mesh"))
    // Do not initially allow removal of remote elements
    allowRemoteElementRemoval(false);

  determineUseDistributedMesh();

#ifdef MOOSE_KOKKOS_ENABLED
  if (_app.isKokkosAvailable())
    _kokkos_mesh = std::make_unique<Moose::Kokkos::Mesh>(*this);
#endif
}

MooseMesh::MooseMesh(const MooseMesh & other_mesh)
  : MooseObject(other_mesh._pars),
    Restartable(this, "Mesh"),
    PerfGraphInterface(this, "CopiedMesh"),
    _built_from_other_mesh(true),
    _parallel_type(other_mesh._parallel_type),
    _use_distributed_mesh(other_mesh._use_distributed_mesh),
    _distribution_overridden(other_mesh._distribution_overridden),
    _parallel_type_overridden(other_mesh._parallel_type_overridden),
    _mesh(other_mesh.getMesh().clone()),
    _partitioner_name(other_mesh._partitioner_name),
    _partitioner_overridden(other_mesh._partitioner_overridden),
    _custom_partitioner_requested(other_mesh._custom_partitioner_requested),
    _uniform_refine_level(other_mesh.uniformRefineLevel()),
    _skip_refine_when_use_split(other_mesh._skip_refine_when_use_split),
    _skip_deletion_repartition_after_refine(other_mesh._skip_deletion_repartition_after_refine),
    _is_nemesis(other_mesh._is_nemesis),
    _patch_size(other_mesh._patch_size),
    _ghosting_patch_size(other_mesh._ghosting_patch_size),
    _max_leaf_size(other_mesh._max_leaf_size),
    _patch_update_strategy(other_mesh._patch_update_strategy),
    _regular_orthogonal_mesh(false),
    _is_split(other_mesh._is_split),
    _lower_d_interior_blocks(other_mesh._lower_d_interior_blocks),
    _lower_d_boundary_blocks(other_mesh._lower_d_boundary_blocks),
    _allow_recovery(other_mesh._allow_recovery),
    _construct_node_list_from_side_list(other_mesh._construct_node_list_from_side_list),
    _displace_node_list_by_side_list(other_mesh._displace_node_list_by_side_list),
    _need_delete(other_mesh._need_delete),
    _allow_remote_element_removal(other_mesh._allow_remote_element_removal),
    _need_ghost_ghosted_boundaries(other_mesh._need_ghost_ghosted_boundaries),
    _coord_sys(other_mesh._coord_sys),
    _rz_coord_axis(other_mesh._rz_coord_axis),
    _subdomain_id_to_rz_coord_axis(other_mesh._subdomain_id_to_rz_coord_axis),
    _coord_system_set(other_mesh._coord_system_set),
    _provided_coord_blocks(other_mesh._provided_coord_blocks),
    _doing_p_refinement(other_mesh._doing_p_refinement)
{
  _bounds.resize(other_mesh._bounds.size());
  for (std::size_t i = 0; i < _bounds.size(); ++i)
  {
    _bounds[i].resize(other_mesh._bounds[i].size());
    for (std::size_t j = 0; j < _bounds[i].size(); ++j)
      _bounds[i][j] = other_mesh._bounds[i][j];
  }

  updateCoordTransform();

#ifdef MOOSE_KOKKOS_ENABLED
  if (_app.isKokkosAvailable())
    _kokkos_mesh = std::make_unique<Moose::Kokkos::Mesh>(*this);
#endif
}

MooseMesh::~MooseMesh()
{
  freeBndNodes();
  freeBndElems();
  clearQuadratureNodes();
}

void
MooseMesh::freeBndNodes()
{
  // free memory
  for (auto & bnode : _bnd_nodes)
    delete bnode;

  for (auto & it : _node_set_nodes)
    it.second.clear();

  _node_set_nodes.clear();

  for (auto & it : _bnd_node_ids)
    it.second.clear();

  _bnd_node_ids.clear();
  _bnd_node_range.reset();
}

void
MooseMesh::freeBndElems()
{
  // free memory
  for (auto & belem : _bnd_elems)
    delete belem;

  for (auto & it : _bnd_elem_ids)
    it.second.clear();

  _bnd_elem_ids.clear();
  _bnd_elem_range.reset();
}

bool
MooseMesh::prepare(const MeshBase * const mesh_to_clone)
{
  TIME_SECTION("prepare", 2, "Preparing Mesh", true);

  parallel_object_only();

  bool libmesh_mesh_prepared = false;

  mooseAssert(_mesh, "The MeshBase has not been constructed");

  if (!dynamic_cast<DistributedMesh *>(&getMesh()) || _is_nemesis)
    // For whatever reason we do not want to allow renumbering here nor ever in the future?
    getMesh().allow_renumbering(false);

  if (mesh_to_clone)
  {
    mooseAssert(mesh_to_clone->is_prepared(),
                "The mesh we wish to clone from must already be prepared");
    _mesh = mesh_to_clone->clone();
    _moose_mesh_prepared = false;
  }
  else if (!_mesh->is_prepared())
  {
    _mesh->complete_preparation();
    _moose_mesh_prepared = false;
    libmesh_mesh_prepared = true;
  }

  if (_moose_mesh_prepared)
    return libmesh_mesh_prepared;

  // Collect (local) subdomain IDs
  _mesh_subdomains.clear();
  for (const auto & elem : getMesh().element_ptr_range())
    _mesh_subdomains.insert(elem->subdomain_id());

  bool need_subdomain_name_map_sync = false;
  // add explicitly requested subdomains
  if (isParamValid("add_subdomain_ids") && !isParamValid("add_subdomain_names"))
  {
    // only subdomain ids are explicitly given
    const auto & add_subdomain_id = getParam<std::vector<SubdomainID>>("add_subdomain_ids");
    _mesh_subdomains.insert(add_subdomain_id.begin(), add_subdomain_id.end());
  }
  else if (isParamValid("add_subdomain_ids") && isParamValid("add_subdomain_names"))
  {
    const auto add_subdomain =
        getParam<SubdomainID, SubdomainName>("add_subdomain_ids", "add_subdomain_names");
    for (const auto & [sub_id, sub_name] : add_subdomain)
    {
      // add subdomain id
      _mesh_subdomains.insert(sub_id);
      // set name of the subdomain just added
      setSubdomainName(sub_id, sub_name);
    }
    need_subdomain_name_map_sync = true;
  }
  else if (isParamValid("add_subdomain_names"))
  {
    // the user has defined add_subdomain_names, but not add_subdomain_ids
    const auto & add_subdomain_names = getParam<std::vector<SubdomainName>>("add_subdomain_names");

    // to define subdomain ids, we need the largest subdomain id defined yet.
    subdomain_id_type offset = 0;
    if (!_mesh_subdomains.empty())
      offset = *_mesh_subdomains.rbegin();

    // add all subdomains (and auto-assign ids)
    for (const SubdomainName & sub_name : add_subdomain_names)
    {
      // to avoid two subdomains with the same ID (notably on recover)
      if (getSubdomainID(sub_name) != libMesh::Elem::invalid_subdomain_id)
        continue;
      const auto sub_id = ++offset;
      // add subdomain id
      _mesh_subdomains.insert(sub_id);
      // set name of the subdomain just added
      setSubdomainName(sub_id, sub_name);
    }
    need_subdomain_name_map_sync = true;
  }
  if (need_subdomain_name_map_sync)
    _mesh->sync_subdomain_name_map();

  // Make sure nodesets have been generated
  buildNodeListFromSideList();

  // Collect (local) boundary IDs
  const std::set<BoundaryID> & local_bids = getMesh().get_boundary_info().get_boundary_ids();
  _mesh_boundary_ids.insert(local_bids.begin(), local_bids.end());

  const std::set<BoundaryID> & local_node_bids =
      getMesh().get_boundary_info().get_node_boundary_ids();
  _mesh_nodeset_ids.insert(local_node_bids.begin(), local_node_bids.end());

  const std::set<BoundaryID> & local_side_bids =
      getMesh().get_boundary_info().get_side_boundary_ids();
  _mesh_sideset_ids.insert(local_side_bids.begin(), local_side_bids.end());

  // Add explicitly requested sidesets/nodesets
  // This is done *after* the side boundaries (e.g. "right", ...) have been generated.
  auto add_sets = [this](const bool sidesets, auto & set_ids)
  {
    const std::string type = sidesets ? "sideset" : "nodeset";
    const std::string id_param = "add_" + type + "_ids";
    const std::string name_param = "add_" + type + "_names";

    if (isParamValid(id_param))
    {
      const auto & add_ids = getParam<std::vector<BoundaryID>>(id_param);
      _mesh_boundary_ids.insert(add_ids.begin(), add_ids.end());
      set_ids.insert(add_ids.begin(), add_ids.end());
      if (isParamValid(name_param))
      {
        const auto & add_names = getParam<std::vector<BoundaryName>>(name_param);
        mooseAssert(add_names.size() == add_ids.size(),
                    "Id and name sets must be the same size when adding.");
        for (const auto i : index_range(add_ids))
          setBoundaryName(add_ids[i], add_names[i]);
      }
    }
    else if (isParamValid(name_param))
    {
      // the user has defined names, but not ids
      const auto & add_names = getParam<std::vector<BoundaryName>>(name_param);

      auto & mesh_ids = sidesets ? _mesh_sideset_ids : _mesh_nodeset_ids;

      // to define ids, we need the largest id defined yet.
      boundary_id_type offset = 0;
      if (!mesh_ids.empty())
        offset = *mesh_ids.rbegin();
      if (!_mesh_boundary_ids.empty())
        offset = std::max(offset, *_mesh_boundary_ids.rbegin());

      // add all sidesets/nodesets (and auto-assign ids)
      for (const auto & name : add_names)
      {
        // to avoid two sets with the same ID (notably on recover)
        if (getBoundaryID(name) != Moose::INVALID_BOUNDARY_ID)
          continue;
        const auto id = ++offset;
        // add sideset id
        _mesh_boundary_ids.insert(id);
        set_ids.insert(id);
        // set name of the sideset just added
        setBoundaryName(id, name);
      }
    }
  };

  add_sets(true, _mesh_sideset_ids);
  add_sets(false, _mesh_nodeset_ids);

  // Communicate subdomain and boundary IDs if this is a parallel mesh
  if (!getMesh().is_serial())
  {
    _communicator.set_union(_mesh_subdomains);
    _communicator.set_union(_mesh_boundary_ids);
    _communicator.set_union(_mesh_nodeset_ids);
    _communicator.set_union(_mesh_sideset_ids);
  }

  if (!_built_from_other_mesh)
  {
    if (!_coord_system_set)
      setCoordSystem(_provided_coord_blocks, getParam<MultiMooseEnum>("coord_type"));
    else if (_pars.isParamSetByUser("coord_type"))
      mooseError(
          "Trying to set coordinate system type information based on the user input file, but "
          "the coordinate system type information has already been set programmatically! "
          "Either remove your coordinate system type information from the input file, or contact "
          "your application developer");
  }

  // Set general axisymmetric axes if provided
  if (isParamValid("rz_coord_blocks") && isParamValid("rz_coord_origins") &&
      isParamValid("rz_coord_directions"))
  {
    const auto rz_coord_blocks = getParam<std::vector<SubdomainName>>("rz_coord_blocks");
    const auto rz_coord_origins = getParam<std::vector<Point>>("rz_coord_origins");
    const auto rz_coord_directions = getParam<std::vector<RealVectorValue>>("rz_coord_directions");
    if (rz_coord_origins.size() == rz_coord_blocks.size() &&
        rz_coord_directions.size() == rz_coord_blocks.size())
    {
      std::vector<std::pair<Point, RealVectorValue>> rz_coord_axes;
      for (unsigned int i = 0; i < rz_coord_origins.size(); ++i)
        rz_coord_axes.push_back(std::make_pair(rz_coord_origins[i], rz_coord_directions[i]));

      setGeneralAxisymmetricCoordAxes(rz_coord_blocks, rz_coord_axes);

      if (isParamSetByUser("rz_coord_axis"))
        mooseError("The parameter 'rz_coord_axis' may not be provided if 'rz_coord_blocks', "
                   "'rz_coord_origins', and 'rz_coord_directions' are provided.");
    }
    else
      mooseError("The parameters 'rz_coord_blocks', 'rz_coord_origins', and "
                 "'rz_coord_directions' must all have the same size.");
  }
  else if (isParamValid("rz_coord_blocks") || isParamValid("rz_coord_origins") ||
           isParamValid("rz_coord_directions"))
    mooseError("If any of the parameters 'rz_coord_blocks', 'rz_coord_origins', and "
               "'rz_coord_directions' are provided, then all must be provided.");

  detectOrthogonalDimRanges();

  update();

  // Check if there is subdomain name duplication for the same subdomain ID
  checkDuplicateSubdomainNames();

  _moose_mesh_prepared = true;

  return libmesh_mesh_prepared;
}

bool
MooseMesh::possiblyRebuildNodeToElemMap()
{
  // *Rebuild* the node to element map. I emphasize rebuild because if it has not been built
  // previously we won't do anything
  if (!_node_to_elem_map_built)
  {
    mooseAssert(_node_to_elem_map.empty(), "If it hasn't been built, it better well be empty");
    return false;
  }

  _node_to_elem_map.clear();
  _node_to_elem_map_built = false;
  internalNodeToElemMap();
  return true;
}

void
MooseMesh::update()
{
  TIME_SECTION("update", 3, "Updating Mesh", true);

  // Rebuild the boundary conditions
  buildNodeListFromSideList();

  buildNodeList();
  buildBndElemList();
  cacheInfo();
  buildElemIDInfo();

  // this will make moose mesh aware of p-refinement added by mesh generators including
  // a file mesh generator loading a restart checkpoint file
  _max_p_level = 0;
  _max_h_level = 0;
  for (const auto & elem : getMesh().active_local_element_ptr_range())
  {
    if (elem->p_level() > _max_p_level)
      _max_p_level = elem->p_level();
    if (elem->level() > _max_h_level)
      _max_h_level = elem->level();
  }
  comm().max(_max_p_level);
  comm().max(_max_h_level);

  // the flag might have been set by calling doingPRefinement(true)
  _doing_p_refinement = _doing_p_refinement || (_max_p_level > 0);

  computeMaxPerElemAndSide();

#ifdef MOOSE_KOKKOS_ENABLED
  if (_app.getExecutioner() && _app.feProblem().initialized() &&
      _app.feProblem().hasKokkosObjects())
    _kokkos_mesh->update();
#endif

  _finite_volume_info_dirty = true;

  possiblyRebuildNodeToElemMap();
}

void
MooseMesh::buildLowerDMesh()
{
  auto & mesh = getMesh();

  if (!mesh.is_serial())
    mooseError(
        "Hybrid finite element method must use replicated mesh.\nCurrently lower-dimensional mesh "
        "does not support mesh re-partitioning and a debug assertion being hit related with "
        "neighbors of lower-dimensional element, with distributed mesh.");

  // Lower-D element build requires neighboring element information
  if (!mesh.is_prepared())
    mesh.find_neighbors();

  // maximum number of sides of all elements
  unsigned int max_n_sides = 0;

  // remove existing lower-d element first
  std::set<Elem *> deleteable_elems;
  for (auto & elem : mesh.element_ptr_range())
    if (_lower_d_interior_blocks.count(elem->subdomain_id()) ||
        _lower_d_boundary_blocks.count(elem->subdomain_id()))
      deleteable_elems.insert(elem);
    else if (elem->n_sides() > max_n_sides)
      max_n_sides = elem->n_sides();

  for (auto & elem : deleteable_elems)
    mesh.delete_elem(elem);
  for (const auto & id : _lower_d_interior_blocks)
    _mesh_subdomains.erase(id);
  for (const auto & id : _lower_d_boundary_blocks)
    _mesh_subdomains.erase(id);
  _lower_d_interior_blocks.clear();
  _lower_d_boundary_blocks.clear();

  mesh.comm().max(max_n_sides);

  deleteable_elems.clear();

  // get all side types
  std::set<int> interior_side_types;
  std::set<int> boundary_side_types;
  for (const auto & elem : mesh.active_element_ptr_range())
    for (const auto side : elem->side_index_range())
    {
      Elem * neig = elem->neighbor_ptr(side);
      std::unique_ptr<Elem> side_elem(elem->build_side_ptr(side));
      if (neig)
        interior_side_types.insert(side_elem->type());
      else
        boundary_side_types.insert(side_elem->type());
    }
  mesh.comm().set_union(interior_side_types);
  mesh.comm().set_union(boundary_side_types);

  // assign block ids for different side types
  std::map<ElemType, SubdomainID> interior_block_ids;
  std::map<ElemType, SubdomainID> boundary_block_ids;
  // we assume this id is not used by the mesh
  auto id = libMesh::Elem::invalid_subdomain_id - 2;
  for (const auto & tpid : interior_side_types)
  {
    const auto type = ElemType(tpid);
    mesh.subdomain_name(id) = "INTERNAL_SIDE_LOWERD_SUBDOMAIN_" + Utility::enum_to_string(type);
    interior_block_ids[type] = id;
    _lower_d_interior_blocks.insert(id);
    if (_mesh_subdomains.count(id) > 0)
      mooseError("Trying to add a mesh block with id ", id, " that has existed in the mesh");
    _mesh_subdomains.insert(id);
    --id;
  }
  for (const auto & tpid : boundary_side_types)
  {
    const auto type = ElemType(tpid);
    mesh.subdomain_name(id) = "BOUNDARY_SIDE_LOWERD_SUBDOMAIN_" + Utility::enum_to_string(type);
    boundary_block_ids[type] = id;
    _lower_d_boundary_blocks.insert(id);
    if (_mesh_subdomains.count(id) > 0)
      mooseError("Trying to add a mesh block with id ", id, " that has existed in the mesh");
    _mesh_subdomains.insert(id);
    --id;
  }

  dof_id_type max_elem_id = mesh.max_elem_id();
  unique_id_type max_unique_id = mesh.parallel_max_unique_id();

  std::vector<Elem *> side_elems;
  _higher_d_elem_side_to_lower_d_elem.clear();
  for (const auto & elem : mesh.active_element_ptr_range())
  {
    // skip existing lower-d elements
    if (elem->interior_parent())
      continue;

    for (const auto side : elem->side_index_range())
    {
      Elem * neig = elem->neighbor_ptr(side);

      bool build_side = false;
      if (!neig)
        build_side = true;
      else
      {
        mooseAssert(!neig->is_remote(), "We error if the mesh is not serial");
        if (!neig->active())
          build_side = true;
        else if (neig->level() == elem->level() && elem->id() < neig->id())
          build_side = true;
      }

      if (build_side)
      {
        std::unique_ptr<Elem> side_elem(elem->build_side_ptr(side));

        // The side will be added with the same processor id as the parent.
        side_elem->processor_id() = elem->processor_id();

        // Add subdomain ID
        if (neig)
          side_elem->subdomain_id() = interior_block_ids.at(side_elem->type());
        else
          side_elem->subdomain_id() = boundary_block_ids.at(side_elem->type());

        // set ids consistently across processors (these ids will be temporary)
        side_elem->set_id(max_elem_id + elem->id() * max_n_sides + side);
        side_elem->set_unique_id(max_unique_id + elem->id() * max_n_sides + side);

        // Also assign the side's interior parent, so it is always
        // easy to figure out the Elem we came from.
        // Note: the interior parent could be a ghost element.
        side_elem->set_interior_parent(elem);

        side_elems.push_back(side_elem.release());

        // add link between higher d element to lower d element
        auto pair = std::make_pair(elem, side);
        auto link = std::make_pair(pair, side_elems.back());
        auto ilink = std::make_pair(side_elems.back(), side);
        _lower_d_elem_to_higher_d_elem_side.insert(ilink);
        _higher_d_elem_side_to_lower_d_elem.insert(link);
      }
    }
  }

  // finally, add the lower-dimensional element to the mesh
  // Note: lower-d interior element will exist on a processor if its associated interior
  //       parent exists on a processor whether or not being a ghost. Lower-d elements will
  //       get its interior parent's processor id.
  for (auto & elem : side_elems)
    mesh.add_elem(elem);

  // we do all the stuff in prepare_for_use such as renumber_nodes_and_elements(),
  // update_parallel_id_counts(), cache_elem_dims(), etc. except partitioning here.
  const bool skip_partitioning_old = mesh.skip_partitioning();
  mesh.skip_partitioning(true);
  // Finding neighbors is ambiguous for lower-dimensional elements on interior faces
  mesh.allow_find_neighbors(false);
  mesh.prepare_for_use();
  mesh.skip_partitioning(skip_partitioning_old);
}

const Node &
MooseMesh::node(const dof_id_type i) const
{
  mooseDeprecated("MooseMesh::node() is deprecated, please use MooseMesh::nodeRef() instead");
  return nodeRef(i);
}

Node &
MooseMesh::node(const dof_id_type i)
{
  mooseDeprecated("MooseMesh::node() is deprecated, please use MooseMesh::nodeRef() instead");
  return nodeRef(i);
}

const Node &
MooseMesh::nodeRef(const dof_id_type i) const
{
  const auto node_ptr = queryNodePtr(i);
  mooseAssert(node_ptr, "Missing node");
  return *node_ptr;
}

Node &
MooseMesh::nodeRef(const dof_id_type i)
{
  return const_cast<Node &>(const_cast<const MooseMesh *>(this)->nodeRef(i));
}

const Node *
MooseMesh::nodePtr(const dof_id_type i) const
{
  return &nodeRef(i);
}

Node *
MooseMesh::nodePtr(const dof_id_type i)
{
  return &nodeRef(i);
}

const Node *
MooseMesh::queryNodePtr(const dof_id_type i) const
{
  if (i > getMesh().max_node_id())
  {
    auto it = _quadrature_nodes.find(i);
    if (it == _quadrature_nodes.end())
      return nullptr;
    auto & node_ptr = it->second;
    mooseAssert(node_ptr, "Uninitialized quadrature node");
    return node_ptr;
  }

  return getMesh().query_node_ptr(i);
}

Node *
MooseMesh::queryNodePtr(const dof_id_type i)
{
  return const_cast<Node *>(const_cast<const MooseMesh *>(this)->queryNodePtr(i));
}

void
MooseMesh::meshChanged()
{
  TIME_SECTION("meshChanged", 3, "Updating Because Mesh Changed");

  update();

  // Delete all of the cached ranges
  _active_node_range.reset();
  _active_semilocal_node_range.reset();
  _local_node_range.reset();
  _bnd_node_range.reset();
  _bnd_elem_range.reset();

  // Rebuild the ranges
  getActiveLocalElementRange();
  getActiveNodeRange();
  getLocalNodeRange();
  getBoundaryNodeRange();
  getBoundaryElementRange();

  // Call the callback function onMeshChanged
  onMeshChanged();
}

void
MooseMesh::onMeshChanged()
{
}

void
MooseMesh::cacheChangedLists()
{
  TIME_SECTION("cacheChangedLists", 5, "Caching Changed Lists");

  ConstElemRange elem_range(getMesh().local_elements_begin(), getMesh().local_elements_end(), 1);
  CacheChangedListsThread cclt(*this);
  Threads::parallel_reduce(elem_range, cclt);

  _coarsened_element_children.clear();

  _refined_elements = std::make_unique<ConstElemPointerRange>(cclt._refined_elements.begin(),
                                                              cclt._refined_elements.end());
  _coarsened_elements = std::make_unique<ConstElemPointerRange>(cclt._coarsened_elements.begin(),
                                                                cclt._coarsened_elements.end());
  _coarsened_element_children = cclt._coarsened_element_children;
}

ConstElemPointerRange *
MooseMesh::refinedElementRange() const
{
  return _refined_elements.get();
}

ConstElemPointerRange *
MooseMesh::coarsenedElementRange() const
{
  return _coarsened_elements.get();
}

const std::vector<const Elem *> &
MooseMesh::coarsenedElementChildren(const Elem * elem) const
{
  auto elem_to_child_pair = _coarsened_element_children.find(elem);
  mooseAssert(elem_to_child_pair != _coarsened_element_children.end(), "Missing element in map");
  return elem_to_child_pair->second;
}

void
MooseMesh::updateActiveSemiLocalNodeRange(std::set<dof_id_type> & ghosted_elems)
{
  TIME_SECTION("updateActiveSemiLocalNodeRange", 5, "Updating ActiveSemiLocalNode Range");

  _semilocal_node_list.clear();

  // First add the nodes connected to local elems
  const ConstElemRange * active_local_elems = getActiveLocalElementRange();
  for (const auto & elem : *active_local_elems)
  {
    for (unsigned int n = 0; n < elem->n_nodes(); ++n)
    {
      // Since elem is const here but we require a non-const Node * to
      // store in the _semilocal_node_list (otherwise things like
      // UpdateDisplacedMeshThread don't work), we are using a
      // const_cast. A more long-term fix would be to have
      // getActiveLocalElementRange return a non-const ElemRange.
      Node * node = const_cast<Node *>(elem->node_ptr(n));

      _semilocal_node_list.insert(node);
    }
  }

  // Now add the nodes connected to ghosted_elems
  for (const auto & ghost_elem_id : ghosted_elems)
  {
    Elem * elem = getMesh().elem_ptr(ghost_elem_id);
    for (unsigned int n = 0; n < elem->n_nodes(); n++)
    {
      Node * node = elem->node_ptr(n);

      _semilocal_node_list.insert(node);
    }
  }

  // Now create the actual range
  _active_semilocal_node_range = std::make_unique<SemiLocalNodeRange>(_semilocal_node_list.begin(),
                                                                      _semilocal_node_list.end());
}

bool
MooseMesh::isSemiLocal(Node * const node) const
{
  return _semilocal_node_list.find(node) != _semilocal_node_list.end();
}

class BndNodeCompare
{
public:
  BndNodeCompare() {}

  bool operator()(const BndNode * const & lhs, const BndNode * const & rhs)
  {
    if (lhs->_bnd_id < rhs->_bnd_id)
      return true;

    if (lhs->_bnd_id > rhs->_bnd_id)
      return false;

    if (lhs->_node->id() < rhs->_node->id())
      return true;

    if (lhs->_node->id() > rhs->_node->id())
      return false;

    return false;
  }
};

void
MooseMesh::buildNodeList()
{
  TIME_SECTION("buildNodeList", 5, "Building Node List");

  freeBndNodes();

  auto bc_tuples = getMesh().get_boundary_info().build_node_list();

  int n = bc_tuples.size();
  _bnd_nodes.clear();
  _bnd_nodes.reserve(n);
  for (const auto & t : bc_tuples)
  {
    auto node_id = std::get<0>(t);
    auto bc_id = std::get<1>(t);

    _bnd_nodes.push_back(new BndNode(getMesh().node_ptr(node_id), bc_id));
    _node_set_nodes[bc_id].push_back(node_id);
    _bnd_node_ids[bc_id].insert(node_id);
  }

  _bnd_nodes.reserve(_bnd_nodes.size() + _extra_bnd_nodes.size());
  for (unsigned int i = 0; i < _extra_bnd_nodes.size(); i++)
  {
    BndNode * bnode = new BndNode(_extra_bnd_nodes[i]._node, _extra_bnd_nodes[i]._bnd_id);
    _bnd_nodes.push_back(bnode);
    _bnd_node_ids[std::get<1>(bc_tuples[i])].insert(_extra_bnd_nodes[i]._node->id());
  }

  // This sort is here so that boundary conditions are always applied in the same order
  std::sort(_bnd_nodes.begin(), _bnd_nodes.end(), BndNodeCompare());
}

void
MooseMesh::computeMaxPerElemAndSide()
{
  auto & mesh = getMesh();

  _max_sides_per_elem = 0;
  _max_nodes_per_elem = 0;
  _max_nodes_per_side = 0;

  for (auto & elem : as_range(mesh.local_elements_begin(), mesh.local_elements_end()))
  {
    _max_sides_per_elem = std::max(_max_sides_per_elem, elem->n_sides());
    _max_nodes_per_elem = std::max(_max_nodes_per_elem, elem->n_nodes());

    for (unsigned int side = 0; side < elem->n_sides(); ++side)
      _max_nodes_per_side = std::max(_max_nodes_per_side, elem->side_ptr(side)->n_nodes());
  }

  mesh.comm().max(_max_sides_per_elem);
  mesh.comm().max(_max_nodes_per_elem);
  mesh.comm().max(_max_nodes_per_side);
}

void
MooseMesh::buildElemIDInfo()
{
  unsigned int n = getMesh().n_elem_integers() + 1;

  _block_id_mapping.clear();
  _max_ids.clear();
  _min_ids.clear();
  _id_identical_flag.clear();

  _block_id_mapping.resize(n);
  _max_ids.resize(n, std::numeric_limits<dof_id_type>::min());
  _min_ids.resize(n, std::numeric_limits<dof_id_type>::max());
  _id_identical_flag.resize(n, std::vector<bool>(n, true));
  for (const auto & elem : getMesh().active_local_element_ptr_range())
    for (unsigned int i = 0; i < n; ++i)
    {
      auto id = (i == n - 1 ? elem->subdomain_id() : elem->get_extra_integer(i));
      _block_id_mapping[i][elem->subdomain_id()].insert(id);
      if (id > _max_ids[i])
        _max_ids[i] = id;
      if (id < _min_ids[i])
        _min_ids[i] = id;
      for (unsigned int j = 0; j < n; ++j)
      {
        auto idj = (j == n - 1 ? elem->subdomain_id() : elem->get_extra_integer(j));
        if (i != j && _id_identical_flag[i][j] && id != idj)
          _id_identical_flag[i][j] = false;
      }
    }

  for (unsigned int i = 0; i < n; ++i)
  {
    for (auto & blk : meshSubdomains())
      comm().set_union(_block_id_mapping[i][blk]);
    comm().min(_id_identical_flag[i]);
  }
  comm().max(_max_ids);
  comm().min(_min_ids);
}

std::unordered_map<dof_id_type, std::set<dof_id_type>>
MooseMesh::getElemIDMapping(const std::string & from_id_name, const std::string & to_id_name) const
{
  auto & mesh_base = getMesh();

  if (!mesh_base.has_elem_integer(from_id_name))
    mooseError("Mesh does not have the element integer name '", from_id_name, "'");
  if (!mesh_base.has_elem_integer(to_id_name))
    mooseError("Mesh does not have the element integer name '", to_id_name, "'");

  const auto id1 = mesh_base.get_elem_integer_index(from_id_name);
  const auto id2 = mesh_base.get_elem_integer_index(to_id_name);

  std::unordered_map<dof_id_type, std::set<dof_id_type>> id_map;
  for (const auto id : getAllElemIDs(id1))
    id_map[id] = std::set<dof_id_type>();

  for (const auto & elem : mesh_base.active_local_element_ptr_range())
    id_map[elem->get_extra_integer(id1)].insert(elem->get_extra_integer(id2));

  for (auto & [id, ids] : id_map)
  {
    libmesh_ignore(id); // avoid overzealous gcc 9.4 unused var warning
    comm().set_union(ids);
  }

  return id_map;
}

std::set<dof_id_type>
MooseMesh::getAllElemIDs(unsigned int elem_id_index) const
{
  std::set<dof_id_type> unique_ids;
  for (auto & pair : _block_id_mapping[elem_id_index])
    for (auto & id : pair.second)
      unique_ids.insert(id);
  return unique_ids;
}

std::set<dof_id_type>
MooseMesh::getElemIDsOnBlocks(unsigned int elem_id_index, const std::set<SubdomainID> & blks) const
{
  std::set<dof_id_type> unique_ids;
  for (auto & blk : blks)
  {
    auto it = _block_id_mapping[elem_id_index].find(blk);
    if (it == _block_id_mapping[elem_id_index].end())
      mooseError("Block ", blk, " is not available on the mesh");

    for (auto & mid : it->second)
      unique_ids.insert(mid);
  }
  return unique_ids;
}

void
MooseMesh::buildBndElemList()
{
  TIME_SECTION("buildBndElemList", 5, "Building Boundary Elements List");

  freeBndElems();

  auto bc_tuples = getMesh().get_boundary_info().build_active_side_list();

  int n = bc_tuples.size();
  _bnd_elems.clear();
  _bnd_elems.reserve(n);
  for (const auto & t : bc_tuples)
  {
    auto elem_id = std::get<0>(t);
    auto side_id = std::get<1>(t);
    auto bc_id = std::get<2>(t);

    _bnd_elems.push_back(new BndElement(getMesh().elem_ptr(elem_id), side_id, bc_id));
    _bnd_elem_ids[bc_id].insert(elem_id);
  }
}

std::unordered_map<dof_id_type, std::vector<dof_id_type>> &
MooseMesh::internalNodeToElemMap()
{
  if (!_node_to_elem_map_built) // Guard the creation with a double checked lock
  {
    Threads::spin_mutex::scoped_lock lock(Threads::spin_mtx);

    if (!_node_to_elem_map_built)
    {
      // This is allowing the timing to be run even with threads
      // This is safe because all threads will be waiting on this section when it runs
      // NOTE: Do not copy this construction to other places without thinking REALLY hard about it
      // The PerfGraph is NOT threadsafe and will cause all kinds of havok if care isn't taken
      auto in_threads = Threads::in_threads;
      Threads::in_threads = false;
      TIME_SECTION("nodeToElemMap", 5, "Building Node To Elem Map");
      Threads::in_threads = in_threads;

      mooseAssert(_node_to_elem_map.empty(), "Expected empty map before building");
      for (const auto & elem : getMesh().active_element_ptr_range())
        for (unsigned int n = 0; n < elem->n_nodes(); n++)
          _node_to_elem_map[elem->node_id(n)].push_back(elem->id());

      _node_to_elem_map_built = true; // MUST be set at the end for double-checked locking to work!
    }
  }
  return _node_to_elem_map;
}

const std::unordered_map<dof_id_type, std::vector<dof_id_type>> &
MooseMesh::nodeToElemMap()
{
  return internalNodeToElemMap();
}

const ConstElemRange *
MooseMesh::getActiveLocalElementRange()
{
  return &getMesh().active_local_element_stored_range();
}

NodeRange *
MooseMesh::getActiveNodeRange()
{
  if (!_active_node_range)
  {
    TIME_SECTION("getActiveNodeRange", 5);

    _active_node_range =
        std::make_unique<NodeRange>(getMesh().active_nodes_begin(), getMesh().active_nodes_end());
  }

  return _active_node_range.get();
}

SemiLocalNodeRange *
MooseMesh::getActiveSemiLocalNodeRange() const
{
  mooseAssert(_active_semilocal_node_range,
              "_active_semilocal_node_range has not been created yet!");

  return _active_semilocal_node_range.get();
}

ConstNodeRange *
MooseMesh::getLocalNodeRange()
{
  if (!_local_node_range)
  {
    TIME_SECTION("getLocalNodeRange", 5);

    _local_node_range = std::make_unique<ConstNodeRange>(getMesh().local_nodes_begin(),
                                                         getMesh().local_nodes_end());
  }

  return _local_node_range.get();
}

ConstBndNodeRange *
MooseMesh::getBoundaryNodeRange()
{
  if (!_bnd_node_range)
  {
    TIME_SECTION("getBoundaryNodeRange", 5);

    _bnd_node_range = std::make_unique<ConstBndNodeRange>(bndNodesBegin(), bndNodesEnd());
  }

  return _bnd_node_range.get();
}

ConstBndElemRange *
MooseMesh::getBoundaryElementRange()
{
  if (!_bnd_elem_range)
  {
    TIME_SECTION("getBoundaryElementRange", 5);

    _bnd_elem_range = std::make_unique<ConstBndElemRange>(bndElemsBegin(), bndElemsEnd());
  }

  return _bnd_elem_range.get();
}

const std::unordered_map<boundary_id_type, std::unordered_set<dof_id_type>> &
MooseMesh::getBoundariesToElems() const
{
  mooseDeprecated("MooseMesh::getBoundariesToElems is deprecated, "
                  "use MooseMesh::getBoundariesToActiveSemiLocalElemIds");
  return getBoundariesToActiveSemiLocalElemIds();
}

const std::unordered_map<boundary_id_type, std::unordered_set<dof_id_type>> &
MooseMesh::getBoundariesToActiveSemiLocalElemIds() const
{
  return _bnd_elem_ids;
}

std::unordered_set<dof_id_type>
MooseMesh::getBoundaryActiveSemiLocalElemIds(BoundaryID bid) const
{
  // The boundary to element map is computed on every mesh update
  const auto it = _bnd_elem_ids.find(bid);
  if (it == _bnd_elem_ids.end())
    // Boundary is not local to this domain, return an empty set
    return std::unordered_set<dof_id_type>{};
  return it->second;
}

std::unordered_set<dof_id_type>
MooseMesh::getBoundaryActiveNeighborElemIds(BoundaryID bid) const
{
  // Vector of boundary elems is updated every mesh update
  std::unordered_set<dof_id_type> neighbor_elems;
  for (const auto & bnd_elem : _bnd_elems)
  {
    const auto & [elem_ptr, elem_side, elem_bid] = *bnd_elem;
    if (elem_bid == bid)
    {
      const auto * neighbor = elem_ptr->neighbor_ptr(elem_side);
      // Dont add fully remote elements, ghosted is fine
      if (neighbor && neighbor != libMesh::remote_elem)
      {
        // handle mesh refinement, only return active elements near the boundary
        if (neighbor->active())
          neighbor_elems.insert(neighbor->id());
        else
        {
          std::vector<const Elem *> family;
          neighbor->active_family_tree_by_neighbor(family, elem_ptr);
          for (const auto & child_neighbor : family)
            neighbor_elems.insert(child_neighbor->id());
        }
      }
    }
  }

  return neighbor_elems;
}

bool
MooseMesh::isBoundaryFullyExternalToSubdomains(BoundaryID bid,
                                               const std::set<SubdomainID> & blk_group) const
{
  mooseAssert(_bnd_elem_range, "Boundary element range is not initialized");

  // Loop over all side elements of the mesh, select those on the boundary
  for (const auto & bnd_elem : *_bnd_elem_range)
  {
    const auto & [elem_ptr, elem_side, elem_bid] = *bnd_elem;
    if (elem_bid == bid)
    {
      // If an element is internal to the group of subdomain, check the neighbor
      if (blk_group.find(elem_ptr->subdomain_id()) != blk_group.end())
      {
        const auto * const neighbor = elem_ptr->neighbor_ptr(elem_side);

        // If we did not ghost the neighbor, we cannot decide
        if (neighbor == libMesh::remote_elem)
          mooseError("Insufficient level of geometrical ghosting to determine "
                     "if a boundary is internal to the mesh");
        // If the neighbor does not exist, then we are on the edge of the mesh
        if (!neighbor)
          continue;
        // If the neighbor is also in the group of subdomain,
        // then the boundary cuts the subdomains
        if (blk_group.find(neighbor->subdomain_id()) != blk_group.end())
          return false;
      }
    }
  }
  return true;
}

void
MooseMesh::cacheInfo()
{
  TIME_SECTION("cacheInfo", 3);

  _sub_to_data.clear();
  _neighbor_subdomain_boundary_ids.clear();
  _block_node_list.clear();
  _higher_d_elem_side_to_lower_d_elem.clear();
  _lower_d_elem_to_higher_d_elem_side.clear();
  _lower_d_interior_blocks.clear();
  _lower_d_boundary_blocks.clear();

  const auto & mesh = getMesh();

  // Cache higher and lowerD element information
  for (const auto & elem : mesh.element_ptr_range())
  {
    const Elem * ip_elem = elem->interior_parent();

    if (ip_elem)
    {
      unsigned int ip_side = ip_elem->which_side_am_i(elem);

      // For some grid sequencing tests: ip_side == libMesh::invalid_uint
      if (ip_side != libMesh::invalid_uint)
      {
        auto pair = std::make_pair(ip_elem, ip_side);
        _higher_d_elem_side_to_lower_d_elem.insert(
            std::pair<std::pair<const Elem *, unsigned short int>, const Elem *>(pair, elem));
        _lower_d_elem_to_higher_d_elem_side.insert(
            std::pair<const Elem *, unsigned short int>(elem, ip_side));

        auto id = elem->subdomain_id();
        if (ip_elem->neighbor_ptr(ip_side))
        {
          if (mesh.subdomain_name(id).find("INTERNAL_SIDE_LOWERD_SUBDOMAIN_") != std::string::npos)
            _lower_d_interior_blocks.insert(id);
        }
        else
        {
          if (mesh.subdomain_name(id).find("BOUNDARY_SIDE_LOWERD_SUBDOMAIN_") != std::string::npos)
            _lower_d_boundary_blocks.insert(id);
        }
      }
    }

    for (unsigned int nd = 0; nd < elem->n_nodes(); ++nd)
    {
      const Node & node = *elem->node_ptr(nd);
      _block_node_list[node.id()].insert(elem->subdomain_id());
    }
  }
  _communicator.set_union(_lower_d_interior_blocks);
  _communicator.set_union(_lower_d_boundary_blocks);

  // Cache the boundaries next to each subdomain
  for (const auto & elem : mesh.active_local_element_ptr_range())
  {
    SubdomainID subdomain_id = elem->subdomain_id();
    auto & sub_data = _sub_to_data[subdomain_id];
    const auto elem_boundary_ids = getBoundaryIDs(elem);
    for (unsigned int side = 0; side < elem->n_sides(); side++)
    {
      const auto & boundary_ids = elem_boundary_ids[side];
      sub_data.boundary_ids.insert(boundary_ids.begin(), boundary_ids.end());

      const Elem * neig = elem->neighbor_ptr(side);
      if (neig)
      {
        _neighbor_subdomain_boundary_ids[neig->subdomain_id()].insert(boundary_ids.begin(),
                                                                      boundary_ids.end());
        SubdomainID neighbor_subdomain_id = neig->subdomain_id();
        if (neighbor_subdomain_id != subdomain_id)
          sub_data.neighbor_subs.insert(neighbor_subdomain_id);
      }
    }
  }

  for (const auto blk_id : _mesh_subdomains)
  {
    auto & sub_data = _sub_to_data[blk_id];
    _communicator.set_union(sub_data.neighbor_subs);
    _communicator.set_union(sub_data.boundary_ids);
    _communicator.set_union(_neighbor_subdomain_boundary_ids[blk_id]);
  }
}

const std::set<SubdomainID> &
MooseMesh::getNodeBlockIds(const Node & node) const
{
  auto it = _block_node_list.find(node.id());

  if (it == _block_node_list.end())
    mooseError("Unable to find node: ", node.id(), " in any block list.");

  return it->second;
}

MooseMesh::face_info_iterator
MooseMesh::ownedFaceInfoBegin()
{
  return face_info_iterator(
      _face_info.begin(),
      _face_info.end(),
      libMesh::Predicates::pid<std::vector<const FaceInfo *>::iterator>(this->processor_id()));
}

MooseMesh::face_info_iterator
MooseMesh::ownedFaceInfoEnd()
{
  return face_info_iterator(
      _face_info.end(),
      _face_info.end(),
      libMesh::Predicates::pid<std::vector<const FaceInfo *>::iterator>(this->processor_id()));
}

MooseMesh::elem_info_iterator
MooseMesh::ownedElemInfoBegin()
{
  return elem_info_iterator(_elem_info.begin(),
                            _elem_info.end(),
                            Predicates::NotNull<std::vector<const ElemInfo *>::iterator>());
}

MooseMesh::elem_info_iterator
MooseMesh::ownedElemInfoEnd()
{
  return elem_info_iterator(_elem_info.end(),
                            _elem_info.end(),
                            Predicates::NotNull<std::vector<const ElemInfo *>::iterator>());
}

// default begin() accessor
MooseMesh::bnd_node_iterator
MooseMesh::bndNodesBegin()
{
  Predicates::NotNull<bnd_node_iterator_imp> p;
  return bnd_node_iterator(_bnd_nodes.begin(), _bnd_nodes.end(), p);
}

// default end() accessor
MooseMesh::bnd_node_iterator
MooseMesh::bndNodesEnd()
{
  Predicates::NotNull<bnd_node_iterator_imp> p;
  return bnd_node_iterator(_bnd_nodes.end(), _bnd_nodes.end(), p);
}

// default begin() accessor
MooseMesh::bnd_elem_iterator
MooseMesh::bndElemsBegin()
{
  Predicates::NotNull<bnd_elem_iterator_imp> p;
  return bnd_elem_iterator(_bnd_elems.begin(), _bnd_elems.end(), p);
}

// default end() accessor
MooseMesh::bnd_elem_iterator
MooseMesh::bndElemsEnd()
{
  Predicates::NotNull<bnd_elem_iterator_imp> p;
  return bnd_elem_iterator(_bnd_elems.end(), _bnd_elems.end(), p);
}

const Node *
MooseMesh::addUniqueNode(const Point & p, Real tol)
{
  if (getMesh().n_nodes() != _node_map.size())
  {
    _node_map.clear();
    _node_map.reserve(getMesh().n_nodes());
    for (const auto & node : getMesh().node_ptr_range())
      _node_map.push_back(node);
  }

  Node * node = nullptr;
  for (unsigned int i = 0; i < _node_map.size(); ++i)
  {
    if (p.relative_fuzzy_equals(*_node_map[i], tol))
    {
      node = _node_map[i];
      break;
    }
  }
  if (node == nullptr)
  {
    node = getMesh().add_node(new Node(p));
    _node_map.push_back(node);
  }

  mooseAssert(node != nullptr, "Node is NULL");
  return node;
}

Node *
MooseMesh::addQuadratureNode(const Elem * elem,
                             const unsigned short int side,
                             const unsigned int qp,
                             BoundaryID bid,
                             const Point & point)
{
  Node * qnode;

  if (_elem_to_side_to_qp_to_quadrature_nodes[elem->id()][side].find(qp) ==
      _elem_to_side_to_qp_to_quadrature_nodes[elem->id()][side].end())
  {
    // Create a new node id starting from the max node id and counting down.  This will be the least
    // likely to collide with an existing node id.
    // Note that we are using numeric_limits<unsigned>::max even
    // though max_id is stored as a dof_id_type.  I tried this with
    // numeric_limits<dof_id_type>::max and it broke several tests in
    // MOOSE.  So, this is some kind of a magic number that we will
    // just continue to use...
    dof_id_type max_id = std::numeric_limits<unsigned int>::max() - 100;
    dof_id_type new_id = max_id - _quadrature_nodes.size();

    if (new_id <= getMesh().max_node_id())
      mooseError("Quadrature node id collides with existing node id!");

    qnode = new Node(point, new_id);

    // Keep track of this new node in two different ways for easy lookup
    _quadrature_nodes[new_id] = qnode;
    _elem_to_side_to_qp_to_quadrature_nodes[elem->id()][side][qp] = qnode;

    if (elem->active())
      internalNodeToElemMap()[new_id].push_back(elem->id());
  }
  else
    qnode = _elem_to_side_to_qp_to_quadrature_nodes[elem->id()][side][qp];

  BndNode * bnode = new BndNode(qnode, bid);
  _bnd_nodes.push_back(bnode);
  _bnd_node_ids[bid].insert(qnode->id());

  _extra_bnd_nodes.push_back(*bnode);

  // Do this so the range will be regenerated next time it is accessed
  _bnd_node_range.reset();

  return qnode;
}

Node *
MooseMesh::getQuadratureNode(const Elem * elem,
                             const unsigned short int side,
                             const unsigned int qp)
{
  mooseAssert(_elem_to_side_to_qp_to_quadrature_nodes.find(elem->id()) !=
                  _elem_to_side_to_qp_to_quadrature_nodes.end(),
              "Elem has no quadrature nodes!");
  mooseAssert(_elem_to_side_to_qp_to_quadrature_nodes[elem->id()].find(side) !=
                  _elem_to_side_to_qp_to_quadrature_nodes[elem->id()].end(),
              "Side has no quadrature nodes!");
  mooseAssert(_elem_to_side_to_qp_to_quadrature_nodes[elem->id()][side].find(qp) !=
                  _elem_to_side_to_qp_to_quadrature_nodes[elem->id()][side].end(),
              "qp not found on side!");

  return _elem_to_side_to_qp_to_quadrature_nodes[elem->id()][side][qp];
}

void
MooseMesh::clearQuadratureNodes()
{
  // Delete all the quadrature nodes
  for (auto & it : _quadrature_nodes)
    delete it.second;

  _quadrature_nodes.clear();
  _elem_to_side_to_qp_to_quadrature_nodes.clear();
  _extra_bnd_nodes.clear();

  // NOTE: this does not clear them from the nodeToElem map
}

BoundaryID
MooseMesh::getBoundaryID(const BoundaryName & boundary_name) const
{
  if (boundary_name == "ANY_BOUNDARY_ID")
    mooseError("Please use getBoundaryIDs() when passing \"ANY_BOUNDARY_ID\"");

  return MooseMeshUtils::getBoundaryID(boundary_name, getMesh());
}

const Elem *
MooseMesh::getLowerDElem(const Elem * elem, unsigned short int side) const
{
  auto it = _higher_d_elem_side_to_lower_d_elem.find(std::make_pair(elem, side));

  if (it != _higher_d_elem_side_to_lower_d_elem.end())
    return it->second;
  else
    return nullptr;
}

unsigned int
MooseMesh::getHigherDSide(const Elem * elem) const
{
  auto it = _lower_d_elem_to_higher_d_elem_side.find(elem);

  if (it != _lower_d_elem_to_higher_d_elem_side.end())
    return it->second;
  else
    return libMesh::invalid_uint;
}

std::vector<BoundaryID>
MooseMesh::getBoundaryIDs(const std::vector<BoundaryName> & boundary_name,
                          bool generate_unknown) const
{
  return MooseMeshUtils::getBoundaryIDs(
      getMesh(), boundary_name, generate_unknown, _mesh_boundary_ids);
}

SubdomainID
MooseMesh::getSubdomainID(const SubdomainName & subdomain_name) const
{
  return MooseMeshUtils::getSubdomainID(subdomain_name, getMesh());
}

std::vector<SubdomainID>
MooseMesh::getSubdomainIDs(const std::vector<SubdomainName> & subdomain_name) const
{
  return MooseMeshUtils::getSubdomainIDs(getMesh(), subdomain_name);
}

std::set<SubdomainID>
MooseMesh::getSubdomainIDs(const std::set<SubdomainName> & subdomain_name) const
{
  return MooseMeshUtils::getSubdomainIDs(getMesh(), subdomain_name);
}

void
MooseMesh::setSubdomainName(SubdomainID subdomain_id, const SubdomainName & name)
{
  mooseAssert(name != "ANY_BLOCK_ID", "Cannot set subdomain name to 'ANY_BLOCK_ID'");
  getMesh().subdomain_name(subdomain_id) = name;
}

void
MooseMesh::setSubdomainName(MeshBase & mesh, SubdomainID subdomain_id, const SubdomainName & name)
{
  mooseAssert(name != "ANY_BLOCK_ID", "Cannot set subdomain name to 'ANY_BLOCK_ID'");
  mesh.subdomain_name(subdomain_id) = name;
}

const std::string &
MooseMesh::getSubdomainName(SubdomainID subdomain_id) const
{
  return getMesh().subdomain_name(subdomain_id);
}

std::vector<SubdomainName>
MooseMesh::getSubdomainNames(const std::vector<SubdomainID> & subdomain_ids) const
{
  std::vector<SubdomainName> names(subdomain_ids.size());

  for (unsigned int i = 0; i < subdomain_ids.size(); i++)
    names[i] = getSubdomainName(subdomain_ids[i]);

  return names;
}

void
MooseMesh::setBoundaryName(BoundaryID boundary_id, BoundaryName name)
{
  BoundaryInfo & boundary_info = getMesh().get_boundary_info();

  // We need to figure out if this boundary is a sideset or nodeset
  if (boundary_info.get_side_boundary_ids().count(boundary_id))
    boundary_info.sideset_name(boundary_id) = name;
  else
    boundary_info.nodeset_name(boundary_id) = name;
}

const std::string &
MooseMesh::getBoundaryName(const BoundaryID boundary_id) const
{
  const BoundaryInfo & boundary_info = getMesh().get_boundary_info();

  // We need to figure out if this boundary is a sideset or nodeset
  if (boundary_info.get_side_boundary_ids().count(boundary_id))
    return boundary_info.get_sideset_name(boundary_id);
  else
    return boundary_info.get_nodeset_name(boundary_id);
}

std::string
MooseMesh::getBoundaryString(BoundaryID boundary_id) const
{
  const auto name = getBoundaryName(boundary_id);
  return name.size() ? name : std::to_string(boundary_id);
}

// specialization for PointListAdaptor<MooseMesh::PeriodicNodeInfo>
template <>
inline const Point &
PointListAdaptor<MooseMesh::PeriodicNodeInfo>::getPoint(
    const MooseMesh::PeriodicNodeInfo & item) const
{
  return *(item.first);
}

void
MooseMesh::buildPeriodicNodeMap(std::multimap<dof_id_type, dof_id_type> & periodic_node_map,
                                unsigned int var_number,
                                libMesh::PeriodicBoundaries * pbs) const
{
  TIME_SECTION("buildPeriodicNodeMap", 5);

  // clear existing map
  periodic_node_map.clear();

  // get periodic nodes
  std::vector<PeriodicNodeInfo> periodic_nodes;
  for (const auto & t : getMesh().get_boundary_info().build_node_list())
  {
    // unfortunately libMesh does not give us a pointer, so we have to look it up ourselves
    auto node = _mesh->node_ptr(std::get<0>(t));
    mooseAssert(node != nullptr,
                "libMesh::BoundaryInfo::build_node_list() returned an ID for a non-existing node");
    auto bc_id = std::get<1>(t);
    periodic_nodes.emplace_back(node, bc_id);
  }

  // sort by boundary id
  std::sort(periodic_nodes.begin(),
            periodic_nodes.end(),
            [](const PeriodicNodeInfo & a, const PeriodicNodeInfo & b) -> bool
            { return a.second > b.second; });

  // build kd-tree
  using KDTreeType = nanoflann::KDTreeSingleIndexAdaptor<
      nanoflann::L2_Simple_Adaptor<Real, PointListAdaptor<PeriodicNodeInfo>, Real, std::size_t>,
      PointListAdaptor<PeriodicNodeInfo>,
      LIBMESH_DIM,
      std::size_t>;
  const unsigned int max_leaf_size = 20; // slightly affects runtime
  auto point_list =
      PointListAdaptor<PeriodicNodeInfo>(periodic_nodes.begin(), periodic_nodes.end());
  auto kd_tree = std::make_unique<KDTreeType>(
      LIBMESH_DIM, point_list, nanoflann::KDTreeSingleIndexAdaptorParams(max_leaf_size));
  mooseAssert(kd_tree != nullptr, "KDTree was not properly initialized.");
  kd_tree->buildIndex();

  // data structures for kd-tree search
  nanoflann::SearchParameters search_params;
  std::vector<nanoflann::ResultItem<std::size_t, Real>> ret_matches;

  // iterate over periodic nodes (boundary ids are in contiguous blocks)
  libMesh::PeriodicBoundaryBase * periodic = nullptr;
  BoundaryID current_bc_id = BoundaryInfo::invalid_id;
  for (auto & pair : periodic_nodes)
  {
    // entering a new block of boundary IDs
    if (pair.second != current_bc_id)
    {
      current_bc_id = pair.second;
      periodic = pbs->boundary(current_bc_id);
      if (periodic && !periodic->is_my_variable(var_number))
        periodic = nullptr;
    }

    // variable is not periodic at this node, skip
    if (!periodic)
      continue;

    // clear result buffer
    ret_matches.clear();

    // id of the current node
    const auto id = pair.first->id();

    // position where we expect a periodic partner for the current node and boundary
    Point search_point = periodic->get_corresponding_pos(*pair.first);

    // search at the expected point
    kd_tree->radiusSearch(&(search_point)(0), libMesh::TOLERANCE, ret_matches, search_params);
    for (auto & match_pair : ret_matches)
    {
      const auto & match = periodic_nodes[match_pair.first];
      // add matched node if the boundary id is the corresponding id in the periodic pair
      if (match.second == periodic->pairedboundary)
        periodic_node_map.emplace(id, match.first->id());
    }
  }
}

void
MooseMesh::buildPeriodicNodeSets(std::map<BoundaryID, std::set<dof_id_type>> & periodic_node_sets,
                                 unsigned int var_number,
                                 libMesh::PeriodicBoundaries * pbs) const
{
  TIME_SECTION("buildPeriodicNodeSets", 5);

  periodic_node_sets.clear();

  // Loop over all the boundary nodes adding the periodic nodes to the appropriate set
  for (const auto & t : getMesh().get_boundary_info().build_node_list())
  {
    auto node_id = std::get<0>(t);
    auto bc_id = std::get<1>(t);

    // Is this current node on a known periodic boundary?
    if (periodic_node_sets.find(bc_id) != periodic_node_sets.end())
      periodic_node_sets[bc_id].insert(node_id);
    else // This still might be a periodic node but we just haven't seen this boundary_id yet
    {
      const libMesh::PeriodicBoundaryBase * periodic = pbs->boundary(bc_id);
      if (periodic && periodic->is_my_variable(var_number))
        periodic_node_sets[bc_id].insert(node_id);
    }
  }
}

bool
MooseMesh::detectOrthogonalDimRanges(Real tol)
{
  TIME_SECTION("detectOrthogonalDimRanges", 5);

  if (_regular_orthogonal_mesh)
    return true;

  std::vector<Real> min(3, std::numeric_limits<Real>::max());
  std::vector<Real> max(3, std::numeric_limits<Real>::min());
  unsigned int dim = getMesh().mesh_dimension();

  // Find the bounding box of our mesh
  for (const auto & node : getMesh().node_ptr_range())
    // Check all coordinates, we don't know if this mesh might be lying in a higher dim even if the
    // mesh dimension is lower.
    for (const auto i : make_range(Moose::dim))
    {
      if ((*node)(i) < min[i])
        min[i] = (*node)(i);
      if ((*node)(i) > max[i])
        max[i] = (*node)(i);
    }

  this->comm().max(max);
  this->comm().min(min);

  _extreme_nodes.resize(8); // 2^LIBMESH_DIM
  // Now make sure that there are actual nodes at all of the extremes
  std::vector<bool> extreme_matches(8, false);
  std::vector<unsigned int> comp_map(3);
  for (const auto & node : getMesh().node_ptr_range())
  {
    // See if the current node is located at one of the extremes
    unsigned int coord_match = 0;

    for (const auto i : make_range(Moose::dim))
    {
      if (std::abs((*node)(i)-min[i]) < tol)
      {
        comp_map[i] = MIN;
        ++coord_match;
      }
      else if (std::abs((*node)(i)-max[i]) < tol)
      {
        comp_map[i] = MAX;
        ++coord_match;
      }
    }

    if (coord_match == LIBMESH_DIM) // Found a coordinate at one of the extremes
    {
      _extreme_nodes[comp_map[X] * 4 + comp_map[Y] * 2 + comp_map[Z]] = node;
      extreme_matches[comp_map[X] * 4 + comp_map[Y] * 2 + comp_map[Z]] = true;
    }
  }

  // See if we matched all of the extremes for the mesh dimension
  this->comm().max(extreme_matches);
  if (std::count(extreme_matches.begin(), extreme_matches.end(), true) == (1 << dim))
    _regular_orthogonal_mesh = true;

  // Set the bounds
  _bounds.resize(LIBMESH_DIM);
  for (const auto i : make_range(Moose::dim))
  {
    _bounds[i].resize(2);
    _bounds[i][MIN] = min[i];
    _bounds[i][MAX] = max[i];
  }

  return _regular_orthogonal_mesh;
}

void
MooseMesh::detectPairedSidesets()
{
  TIME_SECTION("detectPairedSidesets", 5);

  _paired_boundary = std::vector<std::pair<BoundaryID, BoundaryID>>();

  // Loop over level-0 elements (since boundary condition information
  // is only directly stored for them) and find sidesets with normals
  // that point in the -x, +x, -y, +y, and -z, +z direction.  If there
  // is a unique sideset id for each direction, then the paired
  // sidesets consist of (-x,+x), (-y,+y), (-z,+z).  If there are
  // multiple sideset ids for a given direction, then we can't pick a
  // single pair for that direction.  In that case, we'll just return
  // as was done in the original algorithm.

  // we need to test all element dimensions from dim down to 1
  const unsigned int mesh_dim = getMesh().mesh_dimension();

  // Helper for iterating through unit dimensions (0=x, 1=y, 2=z)
  static constexpr std::array<std::size_t, 3> unit_dims{0, 1, 2};
  // Helper for mapping from unit dim -> name
  static const std::array<std::string, 3> unit_dim_names{"x", "y", "z"};

  // Boundary id sets for elements of different dimensions
  // First index: side dimension; 0=1D, 1=2D, 2=3D
  // Second index: unit dimension; 0=x, 1=y, 2=z
  // Third index: false for minus, true for plus
  std::array<std::array<std::array<std::set<BoundaryID>, 2>, 3>, 3> ids{};

  // Build quadrature needed to evaluate side normals
  std::array<std::unique_ptr<FEBase>, 3> fe_faces{};
  std::array<std::unique_ptr<libMesh::QGauss>, 3> qfaces{};
  for (const auto side_dim : make_range(mesh_dim))
  {
    // Face is assumed to be flat, therefore normal is assumed to be
    // constant over the face, therefore only compute it at 1 qp.
    qfaces[side_dim] = std::unique_ptr<libMesh::QGauss>(new libMesh::QGauss(side_dim, CONSTANT));

    // A first-order Lagrange FE for the face.
    fe_faces[side_dim] = FEBase::build(side_dim + 1, FEType(FIRST, libMesh::LAGRANGE));
    fe_faces[side_dim]->attach_quadrature_rule(qfaces[side_dim].get());
    fe_faces[side_dim]->get_normals();
  }

  // Get boundary IDs for each dimension that are in the unit normal
  const auto & boundary_info = getMesh().get_boundary_info();
  // Temporary for evaluating boundary_ids
  std::vector<boundary_id_type> face_ids;
  // The side dimensions we've come across, so that we only report
  // warnings for side dimensions that we have
  std::set<unsigned int> side_dims;
  // Normal dimensions that we found that were nonzero; lets us
  // skip warnings for dimensions that we don't have
  std::array<bool, 3> nonzero_dims = periodic_dim_default;
  for (auto & elem : as_range(getMesh().level_elements_begin(0), getMesh().level_elements_end(0)))
  {
    // If not on the boundary, nothing to do
    if (!elem->on_boundary())
      continue;

    const auto side_dim = elem->dim() - 1;
    side_dims.insert(side_dim);

    // Check for unit normals on each boundary side
    for (const auto s : elem->side_index_range())
      if (!elem->neighbor_ptr(s))
      {
        // Reinit to get the normal
        fe_faces[side_dim]->reinit(elem, s);
        const auto & normal = fe_faces[side_dim]->get_normals()[0];

        // Get the boundary ID(s) for this side.  If there is more
        // than 1 boundary id, then we already can't determine a
        // unique pairing of sides in this direction, but we'll just
        // keep going to keep the logic simple.
        boundary_info.boundary_ids(elem, s, face_ids);

        bool found = false;
        for (const auto unit_dim : unit_dims)
        {
          if (libMesh::absolute_fuzzy_equals(normal(unit_dim), 0.0))
            continue;
          nonzero_dims[unit_dim] = true;
          if (!found)
            for (const auto plus : {false, true})
            {
              if (libMesh::absolute_fuzzy_equals(normal(unit_dim), plus ? 1.0 : -1.0))
              {
                ids[side_dim][unit_dim][plus].insert(face_ids.begin(), face_ids.end());
                found = true;
                break;
              }
            }
        }
      }
  }

  // For a distributed mesh, boundaries may be distributed as well. We therefore collect information
  // from everyone. If the mesh is already serial, then there is no need to do an allgather. Note
  // that this is just going to gather information about what the periodic bc ids are. We are not
  // gathering any remote elements or anything like that. It's just that the GhostPointNeighbors
  // ghosting functor currently relies on the fact that every process agrees on whether we have
  // periodic boundaries; every process that thinks there are periodic boundaries will call
  // MeshBase::sub_point_locator which makes a parallel_object_only() assertion (right or wrong). So
  // we all need to go there (or not go there)
  if (_use_distributed_mesh && !_mesh->is_serial())
  {
    // Communicate id data by packing as [side dim, unit dim, plus (as a char), boundary id]
    std::vector<std::tuple<unsigned int, unsigned int, unsigned char, boundary_id_type>> id_data;
    for (const auto side_dim : side_dims)
      for (const auto unit_dim : unit_dims)
        for (const auto plus : {false, true})
          for (const auto bd : ids[side_dim][unit_dim][plus])
            id_data.emplace_back(side_dim, unit_dim, plus, bd);
    _communicator.allgather(id_data, false);
    for (const auto & [side_dim, unit_dim, plus_char, bd] : id_data)
      ids[side_dim][unit_dim][bool(plus_char)].insert(bd);

    // Gather true-ness of nonzero_dims
    for (auto & entry : nonzero_dims)
      _communicator.max(entry);

    // Gather found side dimensions
    _communicator.set_union(side_dims);
  } // end if (_use_distributed_mesh && !_need_ghost_ghosted_boundaries)

  // Find pairings that have exactly one boundary on each side
  std::ostringstream oss_found, oss_missing;
  for (const auto side_dim : side_dims)
  {
    for (const auto unit_dim : unit_dims)
      if (nonzero_dims[unit_dim])
      {
        const auto & unit_name = unit_dim_names[unit_dim];
        const auto & minus = ids[side_dim][unit_dim][false];
        const auto & plus = ids[side_dim][unit_dim][true];

        if (minus.size() == 1 && plus.size() == 1)
        {
          const auto get_boundary_name = [this](const auto id)
          {
            const auto & name = getBoundaryName(id);
            return name.size() ? name : std::to_string(id);
          };

          oss_found << "\n  " << side_dim + 1 << "D " << unit_name
                    << "-direction: " << get_boundary_name(*minus.begin()) << " <-> "
                    << get_boundary_name(*plus.begin());
          _paired_boundary->emplace_back(std::make_pair(*minus.begin(), *plus.begin()));
        }
        else
          oss_missing << "\n  " << side_dim + 1 << "D -" << unit_name << "/+" << unit_name
                      << ": Found " << minus.size() << " -" << unit_name << " boundaries and "
                      << plus.size() << " +" << unit_name << " boundaries";
      }
  }

  std::ostringstream oss;
  const auto found = oss_found.str();
  const auto missing = oss_missing.str();
  if (found.size())
    oss << "The following paired boundaries were automatically detected for periodicity:\n"
        << found << "\n";
  if (missing.size())
  {
    if (found.size())
      oss << "\n";
    oss << "Paired boundaries were not automatically detected for the following:\n"
        << missing
        << "\n\nAutomatic detection requires that exactly one boundary is found in each unit "
           "direction.\n";
  }

  mooseInfoRepeated(oss.str());
}

Real
MooseMesh::dimensionWidth(unsigned int component) const
{
  return getMaxInDimension(component) - getMinInDimension(component);
}

Real
MooseMesh::getMinInDimension(unsigned int component) const
{
  mooseAssert(_mesh, "The MeshBase has not been constructed");
  mooseAssert(component < _bounds.size(), "Requested dimension out of bounds");

  return _bounds[component][MIN];
}

Real
MooseMesh::getMaxInDimension(unsigned int component) const
{
  mooseAssert(_mesh, "The MeshBase has not been constructed");
  mooseAssert(component < _bounds.size(), "Requested dimension out of bounds");

  return _bounds[component][MAX];
}

void
MooseMesh::addPeriodicVariable(const unsigned int sys_num,
                               const unsigned int var_num,
                               const BoundaryID primary,
                               const BoundaryID secondary)
{
  if (!_regular_orthogonal_mesh)
    return;

  const auto key = std::make_pair(sys_num, var_num);
  auto & entry = _periodic_dim.try_emplace(key, periodic_dim_default).first->second;

  _half_range = Point(dimensionWidth(0) / 2.0, dimensionWidth(1) / 2.0, dimensionWidth(2) / 2.0);

  bool component_found = false;
  for (const auto component : make_range(dimension()))
  {
    const std::pair<BoundaryID, BoundaryID> * boundary_ids = getPairedBoundaryMapping(component);

    if (boundary_ids && ((boundary_ids->first == primary && boundary_ids->second == secondary) ||
                         (boundary_ids->first == secondary && boundary_ids->second == primary)))
    {
      entry[component] = true;
      component_found = true;
    }
  }

  if (!component_found)
    mooseWarning("Could not find a match between boundary '",
                 getBoundaryName(primary),
                 "' and '",
                 getBoundaryName(secondary),
                 "' to set periodic boundary conditions for variable (index:",
                 var_num,
                 ") in either the X, Y or Z direction. The periodic dimension of the mesh for this "
                 "variable will not be stored.");
}

const std::array<bool, 3> &
MooseMesh::queryPeriodicDimensions(const unsigned int sys_num, const unsigned int var_num) const
{
  const auto key = std::make_pair(sys_num, var_num);
  if (const auto it = _periodic_dim.find(key); it != _periodic_dim.end())
    return it->second;
  return periodic_dim_default;
}

const std::array<bool, 3> &
MooseMesh::queryPeriodicDimensions(const MooseVariableBase & var) const
{
  return queryPeriodicDimensions(var.sys().number(), var.number());
}

bool
MooseMesh::isTranslatedPeriodic(const unsigned int sys_num,
                                const unsigned int var_num,
                                const unsigned int component) const
{
  mooseAssert(component < dimension(), "Requested dimension out of bounds");
  return queryPeriodicDimensions(sys_num, var_num)[component];
}

bool
MooseMesh::isTranslatedPeriodic(const MooseVariableBase & var, const unsigned int component) const
{
  return isTranslatedPeriodic(var.sys().number(), var.number(), component);
}

bool
MooseMesh::isTranslatedPeriodic(const unsigned int var_num, const unsigned int component) const
{
  mooseDoOnce(mooseDeprecated(
      "MooseMesh::isTranslatedPeriodic(const unsigned int, const unsigned int) is deprecated. Use "
      "the method that additionally takes the system number or the MooseVariableBase instead."));
  return isTranslatedPeriodic(0, var_num, component);
}

RealVectorValue
MooseMesh::minPeriodicVector(const unsigned int sys_num,
                             const unsigned int var_num,
                             Point p,
                             Point q) const
{
  const auto & periodic_dims = queryPeriodicDimensions(sys_num, var_num);

  for (const auto i : make_range(dimension()))
  {
    // check to see if we're closer in real or periodic space in x, y, and z
    if (periodic_dims[i])
    {
      // Need to test order before differencing
      if (p(i) > q(i))
      {
        if (p(i) - q(i) > _half_range(i))
          p(i) -= _half_range(i) * 2;
      }
      else
      {
        if (q(i) - p(i) > _half_range(i))
          p(i) += _half_range(i) * 2;
      }
    }
  }

  return q - p;
}

RealVectorValue
MooseMesh::minPeriodicVector(const MooseVariableBase & var, const Point & p, const Point & q) const
{
  return minPeriodicVector(var.sys().number(), var.number(), p, q);
}

RealVectorValue
MooseMesh::minPeriodicVector(const unsigned int var_num, const Point & p, const Point & q) const
{
  mooseDoOnce(mooseDeprecated("MooseMesh::minPeriodicVector(const unsigned int, const Point &, "
                              "const Point &) is deprecated. Use the method that additionally "
                              "takes the system number or the MooseVariableBase instead."));
  return minPeriodicVector(0, var_num, p, q);
}

Real
MooseMesh::minPeriodicDistance(const unsigned int sys_num,
                               const unsigned int var_num,
                               const Point & p,
                               const Point & q) const
{
  return minPeriodicVector(sys_num, var_num, p, q).norm();
}

Real
MooseMesh::minPeriodicDistance(const MooseVariableBase & var,
                               const Point & p,
                               const Point & q) const
{
  return minPeriodicDistance(var.sys().number(), var.number(), p, q);
}

Real
MooseMesh::minPeriodicDistance(const unsigned int var_num, const Point & p, const Point & q) const
{
  mooseDoOnce(mooseDeprecated("MooseMesh::minPeriodicDistance(const unsigned int, const Point &, "
                              "const Point &) is deprecated. Use the method that additionally "
                              "takes the system number or the MooseVariableBase instead."));
  return minPeriodicDistance(0, var_num, p, q);
}

const std::pair<BoundaryID, BoundaryID> *
MooseMesh::getPairedBoundaryMapping(unsigned int component) const
{
  if (!_regular_orthogonal_mesh)
    mooseError("Trying to retrieve automatic paired mapping for a mesh that is not regular and "
               "orthogonal");

  mooseAssert(component < dimension(), "Requested dimension out of bounds");

  if (!hasDetectedPairedSidesets())
    mooseError("MooseMesh::getPairedBoundaryMapping(): Paired boundaries not built; must call "
               "detectPairedSidesets() first");

  if (component < _paired_boundary->size())
    return &(*_paired_boundary)[component];
  else
    return nullptr;
}

void
MooseMesh::buildHRefinementAndCoarseningMaps(Assembly * const assembly)
{
  std::map<ElemType, Elem *> canonical_elems;

  // First, loop over all elements and find a canonical element for each type
  // Doing it this way guarantees that this is going to work in parallel
  for (const auto & elem : getMesh().element_ptr_range()) // TODO: Thread this
  {
    ElemType type = elem->type();

    if (canonical_elems.find(type) ==
        canonical_elems.end()) // If we haven't seen this type of elem before save it
      canonical_elems[type] = elem;
    else
    {
      Elem * stored = canonical_elems[type];
      if (elem->id() < stored->id()) // Arbitrarily keep the one with a lower id
        canonical_elems[type] = elem;
    }
  }
  // Now build the maps using these templates
  // Note: This MUST be done NOT threaded!
  for (const auto & can_it : canonical_elems)
  {
    Elem * elem = can_it.second;

    // Need to do this just once to get the right qrules put in place
    assembly->setCurrentSubdomainID(elem->subdomain_id());
    assembly->reinit(elem);
    assembly->reinit(elem, 0);
    auto && qrule = assembly->writeableQRule();
    auto && qrule_face = assembly->writeableQRuleFace();

    // Volume to volume projection for refinement
    buildRefinementMap(*elem, *qrule, *qrule_face, -1, -1, -1);

    // Volume to volume projection for coarsening
    buildCoarseningMap(*elem, *qrule, *qrule_face, -1);

    // Map the sides of children
    for (unsigned int side = 0; side < elem->n_sides(); side++)
    {
      // Side to side for sides that match parent's sides
      buildRefinementMap(*elem, *qrule, *qrule_face, side, -1, side);
      buildCoarseningMap(*elem, *qrule, *qrule_face, side);
    }

    // Child side to parent volume mapping for "internal" child sides
    for (unsigned int child = 0; child < elem->n_children(); ++child)
      for (unsigned int side = 0; side < elem->n_sides();
           ++side)                                // Assume children have the same number of sides!
        if (!elem->is_child_on_side(child, side)) // Otherwise we already computed that map
          buildRefinementMap(*elem, *qrule, *qrule_face, -1, child, side);
  }
}

void
MooseMesh::buildPRefinementAndCoarseningMaps(Assembly * const assembly)
{
  _elem_type_to_p_refinement_map.clear();
  _elem_type_to_p_refinement_side_map.clear();
  _elem_type_to_p_coarsening_map.clear();
  _elem_type_to_p_coarsening_side_map.clear();

  std::map<ElemType, std::pair<Elem *, unsigned int>> elems_and_max_p_level;

  for (const auto & elem : getMesh().active_element_ptr_range())
  {
    const auto type = elem->type();
    auto & [picked_elem, max_p_level] = elems_and_max_p_level[type];
    if (!picked_elem)
      picked_elem = elem;
    max_p_level = std::max(max_p_level, elem->p_level());
  }

  // The only requirement on the FEType is that it can be arbitrarily p-refined
  const FEType p_refinable_fe_type(CONSTANT, libMesh::MONOMIAL);
  std::vector<Point> volume_ref_points_coarse, volume_ref_points_fine, face_ref_points_coarse,
      face_ref_points_fine;
  std::vector<unsigned int> p_levels;

  for (auto & [elem_type, elem_p_level_pair] : elems_and_max_p_level)
  {
    auto & [moose_elem, max_p_level] = elem_p_level_pair;
    const auto dim = moose_elem->dim();
    // Need to do this just once to get the right qrules put in place
    assembly->setCurrentSubdomainID(moose_elem->subdomain_id());
    assembly->reinit(moose_elem);
    assembly->reinit(moose_elem, 0);
    auto & qrule = assembly->writeableQRule();
    auto & qrule_face = assembly->writeableQRuleFace();

    libMesh::Parallel::Communicator self_comm{};
    ReplicatedMesh mesh(self_comm);
    mesh.set_mesh_dimension(dim);
    for (const auto & nd : moose_elem->node_ref_range())
      mesh.add_point(nd);

    Elem * const elem = mesh.add_elem(Elem::build(elem_type).release());
    for (const auto i : elem->node_index_range())
      elem->set_node(i, mesh.node_ptr(i));

    std::unique_ptr<FEBase> fe_face(FEBase::build(dim, p_refinable_fe_type));
    fe_face->get_phi();
    const auto & face_phys_points = fe_face->get_xyz();
    fe_face->attach_quadrature_rule(qrule_face);

    qrule->init(*elem);
    volume_ref_points_coarse = qrule->get_points();
    fe_face->reinit(elem, (unsigned int)0);
    libMesh::FEMap::inverse_map(dim, elem, face_phys_points, face_ref_points_coarse);

    p_levels.resize(max_p_level + 1);
    std::iota(p_levels.begin(), p_levels.end(), 0);
    libMesh::MeshRefinement mesh_refinement(mesh);

    for (const auto p_level : p_levels)
    {
      mesh_refinement.uniformly_p_refine(1);
      qrule->init(*elem);
      volume_ref_points_fine = qrule->get_points();
      fe_face->reinit(elem, (unsigned int)0);
      libMesh::FEMap::inverse_map(dim, elem, face_phys_points, face_ref_points_fine);

      const auto map_key = std::make_pair(elem_type, p_level);
      auto & volume_refine_map = _elem_type_to_p_refinement_map[map_key];
      auto & face_refine_map = _elem_type_to_p_refinement_side_map[map_key];
      auto & volume_coarsen_map = _elem_type_to_p_coarsening_map[map_key];
      auto & face_coarsen_map = _elem_type_to_p_coarsening_side_map[map_key];

      auto fill_maps = [this](const auto & coarse_ref_points,
                              const auto & fine_ref_points,
                              auto & coarsen_map,
                              auto & refine_map)
      {
        mapPoints(fine_ref_points, coarse_ref_points, refine_map);
        mapPoints(coarse_ref_points, fine_ref_points, coarsen_map);
      };

      fill_maps(
          volume_ref_points_coarse, volume_ref_points_fine, volume_coarsen_map, volume_refine_map);
      fill_maps(face_ref_points_coarse, face_ref_points_fine, face_coarsen_map, face_refine_map);

      // With this level's maps filled our fine points now become our coarse points
      volume_ref_points_fine.swap(volume_ref_points_coarse);
      face_ref_points_fine.swap(face_ref_points_coarse);
    }
  }
}

void
MooseMesh::buildRefinementAndCoarseningMaps(Assembly * const assembly)
{
  TIME_SECTION("buildRefinementAndCoarseningMaps", 5, "Building Refinement And Coarsening Maps");
  if (doingPRefinement())
    buildPRefinementAndCoarseningMaps(assembly);
  else
    buildHRefinementAndCoarseningMaps(assembly);
}

void
MooseMesh::buildRefinementMap(const Elem & elem,
                              QBase & qrule,
                              QBase & qrule_face,
                              int parent_side,
                              int child,
                              int child_side)
{
  TIME_SECTION("buildRefinementMap", 5, "Building Refinement Map");

  if (child == -1) // Doing volume mapping or parent side mapping
  {
    mooseAssert(parent_side == child_side,
                "Parent side must match child_side if not passing a specific child!");

    std::pair<int, ElemType> the_pair(parent_side, elem.type());

    if (_elem_type_to_refinement_map.find(the_pair) != _elem_type_to_refinement_map.end())
      mooseError("Already built a qp refinement map!");

    std::vector<std::pair<unsigned int, QpMap>> coarsen_map;
    std::vector<std::vector<QpMap>> & refinement_map = _elem_type_to_refinement_map[the_pair];
    findAdaptivityQpMaps(
        &elem, qrule, qrule_face, refinement_map, coarsen_map, parent_side, child, child_side);
  }
  else // Need to map a child side to parent volume qps
  {
    std::pair<int, int> child_pair(child, child_side);

    if (_elem_type_to_child_side_refinement_map.find(elem.type()) !=
            _elem_type_to_child_side_refinement_map.end() &&
        _elem_type_to_child_side_refinement_map[elem.type()].find(child_pair) !=
            _elem_type_to_child_side_refinement_map[elem.type()].end())
      mooseError("Already built a qp refinement map!");

    std::vector<std::pair<unsigned int, QpMap>> coarsen_map;
    std::vector<std::vector<QpMap>> & refinement_map =
        _elem_type_to_child_side_refinement_map[elem.type()][child_pair];
    findAdaptivityQpMaps(
        &elem, qrule, qrule_face, refinement_map, coarsen_map, parent_side, child, child_side);
  }
}

const std::vector<std::vector<QpMap>> &
MooseMesh::getRefinementMap(const Elem & elem, int parent_side, int child, int child_side)
{
  if (child == -1) // Doing volume mapping or parent side mapping
  {
    mooseAssert(parent_side == child_side,
                "Parent side must match child_side if not passing a specific child!");

    std::pair<int, ElemType> the_pair(parent_side, elem.type());

    if (_elem_type_to_refinement_map.find(the_pair) == _elem_type_to_refinement_map.end())
      mooseError("Could not find a suitable qp refinement map!");

    return _elem_type_to_refinement_map[the_pair];
  }
  else // Need to map a child side to parent volume qps
  {
    std::pair<int, int> child_pair(child, child_side);

    if (_elem_type_to_child_side_refinement_map.find(elem.type()) ==
            _elem_type_to_child_side_refinement_map.end() ||
        _elem_type_to_child_side_refinement_map[elem.type()].find(child_pair) ==
            _elem_type_to_child_side_refinement_map[elem.type()].end())
      mooseError("Could not find a suitable qp refinement map!");

    return _elem_type_to_child_side_refinement_map[elem.type()][child_pair];
  }

}

void
MooseMesh::buildCoarseningMap(const Elem & elem, QBase & qrule, QBase & qrule_face, int input_side)
{
  TIME_SECTION("buildCoarseningMap", 5, "Building Coarsening Map");

  std::pair<int, ElemType> the_pair(input_side, elem.type());

  if (_elem_type_to_coarsening_map.find(the_pair) != _elem_type_to_coarsening_map.end())
    mooseError("Already built a qp coarsening map!");

  std::vector<std::vector<QpMap>> refinement_map;
  std::vector<std::pair<unsigned int, QpMap>> & coarsen_map =
      _elem_type_to_coarsening_map[the_pair];

  // The -1 here is for a specific child.  We don't do that for coarsening maps
  // Also note that we're always mapping the same side to the same side (which is guaranteed by
  // libMesh).
  findAdaptivityQpMaps(
      &elem, qrule, qrule_face, refinement_map, coarsen_map, input_side, -1, input_side);

}

const std::vector<std::pair<unsigned int, QpMap>> &
MooseMesh::getCoarseningMap(const Elem & elem, int input_side)
{
  std::pair<int, ElemType> the_pair(input_side, elem.type());

  if (_elem_type_to_coarsening_map.find(the_pair) == _elem_type_to_coarsening_map.end())
    mooseError("Could not find a suitable qp refinement map!");

  return _elem_type_to_coarsening_map[the_pair];
}

void
MooseMesh::mapPoints(const std::vector<Point> & from,
                     const std::vector<Point> & to,
                     std::vector<QpMap> & qp_map)
{
  unsigned int n_from = from.size();
  unsigned int n_to = to.size();

  qp_map.resize(n_from);

  for (unsigned int i = 0; i < n_from; ++i)
  {
    const Point & from_point = from[i];

    QpMap & current_map = qp_map[i];

    for (unsigned int j = 0; j < n_to; ++j)
    {
      const Point & to_point = to[j];
      Real distance = (from_point - to_point).norm();

      if (distance < current_map._distance)
      {
        current_map._distance = distance;
        current_map._from = i;
        current_map._to = j;
      }
    }
  }
}

void
MooseMesh::findAdaptivityQpMaps(const Elem * template_elem,
                                QBase & qrule,
                                QBase & qrule_face,
                                std::vector<std::vector<QpMap>> & refinement_map,
                                std::vector<std::pair<unsigned int, QpMap>> & coarsen_map,
                                int parent_side,
                                int child,
                                int child_side)
{
  TIME_SECTION("findAdaptivityQpMaps", 5);

  ReplicatedMesh mesh(_communicator);
  mesh.skip_partitioning(true);

  unsigned int dim = template_elem->dim();
  mesh.set_mesh_dimension(dim);

  for (unsigned int i = 0; i < template_elem->n_nodes(); ++i)
    mesh.add_point(template_elem->point(i));

  Elem * elem = mesh.add_elem(Elem::build(template_elem->type()).release());

  for (unsigned int i = 0; i < template_elem->n_nodes(); ++i)
    elem->set_node(i, mesh.node_ptr(i));

  std::unique_ptr<FEBase> fe(FEBase::build(dim, FEType()));
  fe->get_phi();
  const std::vector<Point> & q_points_volume = fe->get_xyz();

  std::unique_ptr<FEBase> fe_face(FEBase::build(dim, FEType()));
  fe_face->get_phi();
  const std::vector<Point> & q_points_face = fe_face->get_xyz();

  fe->attach_quadrature_rule(&qrule);
  fe_face->attach_quadrature_rule(&qrule_face);

  // The current q_points (locations in *physical* space)
  const std::vector<Point> * q_points;

  if (parent_side != -1)
  {
    fe_face->reinit(elem, parent_side);
    q_points = &q_points_face;
  }
  else
  {
    fe->reinit(elem);
    q_points = &q_points_volume;
  }

  std::vector<Point> parent_ref_points;

  libMesh::FEMap::inverse_map(elem->dim(), elem, *q_points, parent_ref_points);
  libMesh::MeshRefinement mesh_refinement(mesh);
  mesh_refinement.uniformly_refine(1);

  // A map from the child element index to the locations of all the child's quadrature points in
  // *reference* space. Note that we use a map here instead of a vector because the caller can
  // pass an explicit child index. We are not guaranteed to have a sequence from [0, n_children)
  std::map<unsigned int, std::vector<Point>> child_to_ref_points;

  unsigned int n_children = elem->n_children();

  refinement_map.resize(n_children);

  std::vector<unsigned int> children;

  if (child != -1) // Passed in a child explicitly
    children.push_back(child);
  else
  {
    children.resize(n_children);
    for (unsigned int child = 0; child < n_children; ++child)
      children[child] = child;
  }

  for (unsigned int i = 0; i < children.size(); ++i)
  {
    unsigned int child = children[i];

    if ((parent_side != -1 && !elem->is_child_on_side(child, parent_side)))
      continue;

    const Elem * child_elem = elem->child_ptr(child);

    if (child_side != -1)
    {
      fe_face->reinit(child_elem, child_side);
      q_points = &q_points_face;
    }
    else
    {
      fe->reinit(child_elem);
      q_points = &q_points_volume;
    }

    std::vector<Point> child_ref_points;

    libMesh::FEMap::inverse_map(elem->dim(), elem, *q_points, child_ref_points);
    child_to_ref_points[child] = child_ref_points;

    std::vector<QpMap> & qp_map = refinement_map[child];

    // Find the closest parent_qp to each child_qp
    mapPoints(child_ref_points, parent_ref_points, qp_map);
  }

  coarsen_map.resize(parent_ref_points.size());

  // For each parent qp find the closest child qp
  for (unsigned int child = 0; child < n_children; child++)
  {
    if (parent_side != -1 && !elem->is_child_on_side(child, child_side))
      continue;

    std::vector<Point> & child_ref_points = child_to_ref_points[child];

    std::vector<QpMap> qp_map;

    // Find all of the closest points from parent_qp to _THIS_ child's qp
    mapPoints(parent_ref_points, child_ref_points, qp_map);

    // Check those to see if they are closer than what we currently have for each point
    for (unsigned int parent_qp = 0; parent_qp < parent_ref_points.size(); ++parent_qp)
    {
      std::pair<unsigned int, QpMap> & child_and_map = coarsen_map[parent_qp];
      unsigned int & closest_child = child_and_map.first;
      QpMap & closest_map = child_and_map.second;

      QpMap & current_map = qp_map[parent_qp];

      if (current_map._distance < closest_map._distance)
      {
        closest_child = child;
        closest_map = current_map;
      }
    }
  }
}

void
MooseMesh::changeBoundaryId(const boundary_id_type old_id,
                            const boundary_id_type new_id,
                            bool delete_prev)
{
  TIME_SECTION("changeBoundaryId", 6);
  changeBoundaryId(getMesh(), old_id, new_id, delete_prev);
}

void
MooseMesh::changeBoundaryId(MeshBase & mesh,
                            const boundary_id_type old_id,
                            const boundary_id_type new_id,
                            bool delete_prev)
{
  // Get a reference to our BoundaryInfo object, we will use it several times below...
  BoundaryInfo & boundary_info = mesh.get_boundary_info();

  // Container to catch ids passed back from BoundaryInfo
  std::vector<boundary_id_type> old_ids;

  // Only level-0 elements store BCs.  Loop over them.
  for (auto & elem : as_range(mesh.level_elements_begin(0), mesh.level_elements_end(0)))
  {
    unsigned int n_sides = elem->n_sides();
    for (unsigned int s = 0; s != n_sides; ++s)
    {
      boundary_info.boundary_ids(elem, s, old_ids);
      if (std::find(old_ids.begin(), old_ids.end(), old_id) != old_ids.end())
      {
        std::vector<boundary_id_type> new_ids(old_ids);
        std::replace(new_ids.begin(), new_ids.end(), old_id, new_id);
        if (delete_prev)
        {
          boundary_info.remove_side(elem, s);
          boundary_info.add_side(elem, s, new_ids);
        }
        else
          boundary_info.add_side(elem, s, new_ids);
      }
    }
  }

  // Remove any remaining references to the old ID from the
  // BoundaryInfo object.  This prevents things like empty sidesets
  // from showing up when printing information, etc.
  if (delete_prev)
    boundary_info.remove_id(old_id);

  // The cached boundary id sets will need re-preparation
  mesh.unset_has_boundary_id_sets();
}

const RealVectorValue &
MooseMesh::getNormalByBoundaryID(BoundaryID id) const
{
  mooseAssert(_boundary_to_normal_map.get() != nullptr, "Boundary To Normal Map not built!");

  // Note: Boundaries that are not in the map (existing boundaries) will default
  // construct a new RealVectorValue - (x,y,z)=(0, 0, 0)
  return (*_boundary_to_normal_map)[id];
}

MooseMesh &
MooseMesh::clone() const
{
  mooseError("MooseMesh::clone() is no longer supported, use MooseMesh::safeClone() instead.");
}

void
MooseMesh::determineUseDistributedMesh()
{
  switch (_parallel_type)
  {
    case ParallelType::DEFAULT:
      // The user did not specify 'parallel_type = XYZ' in the input file,
      // so we allow the --distributed-mesh command line arg to possibly turn
      // on DistributedMesh.  If the command line arg is not present, we pick ReplicatedMesh.
      if (_app.getDistributedMeshOnCommandLine())
        _use_distributed_mesh = true;
      break;
    case ParallelType::REPLICATED:
      if (_app.getDistributedMeshOnCommandLine() || _is_nemesis || _is_split)
        _parallel_type_overridden = true;
      _use_distributed_mesh = false;
      break;
    case ParallelType::DISTRIBUTED:
      _use_distributed_mesh = true;
      break;
  }

  // If the user specifies 'nemesis = true' in the Mesh block, or they are using --use-split,
  // we must use DistributedMesh.
  if (_is_nemesis || _is_split)
    _use_distributed_mesh = true;
}

std::unique_ptr<MeshBase>
MooseMesh::buildMeshBaseObject(unsigned int dim)
{
  std::unique_ptr<MeshBase> mesh;
  if (_use_distributed_mesh)
    mesh = buildTypedMesh<DistributedMesh>(dim);
  else
    mesh = buildTypedMesh<ReplicatedMesh>(dim);

  return mesh;
}

void
MooseMesh::setMeshBase(std::unique_ptr<MeshBase> mesh_base)
{
  _mesh = std::move(mesh_base);
  _mesh->allow_remote_element_removal(_allow_remote_element_removal);
}

void
MooseMesh::init()
{
  if (!_mesh)
    _mesh = buildMeshBaseObject();

  if (_app.isSplitMesh() && _use_distributed_mesh)
    mooseError("You cannot use the mesh splitter capability with DistributedMesh!");

  TIME_SECTION("init", 2);

  if (_app.isRecovering() && _allow_recovery && _app.isUltimateMaster())
  {
    // Some partitioners are not idempotent.  Some recovery data
    // files require partitioning to match mesh partitioning.  This
    // means that, when recovering, we can't safely repartition.
    const bool skip_partitioning_later = getMesh().skip_partitioning();
    getMesh().skip_partitioning(true);
    const bool allow_renumbering_later = getMesh().allow_renumbering();
    getMesh().allow_renumbering(false);

    // For now, only read the recovery mesh on the Ultimate Master..
    // sub-apps need to just build their mesh like normal
    {
      TIME_SECTION("readRecoveredMesh", 2);
      getMesh().read(_app.getRestartRecoverFileBase() + MooseApp::checkpointSuffix());
    }

    getMesh().allow_renumbering(allow_renumbering_later);
    getMesh().skip_partitioning(skip_partitioning_later);
  }
  else // Normally just build the mesh
  {
    // Don't allow partitioning during building
    if (_app.isSplitMesh())
      getMesh().skip_partitioning(true);
    buildMesh();

    if (getParam<bool>("build_all_side_lowerd_mesh"))
      buildLowerDMesh();
  }
}

std::vector<std::filesystem::path>
MooseMesh::writeRecoveryFiles(const std::filesystem::path & file_base)
{
  CheckpointIO io(getMesh(), false);
  io.write(file_base);
  return {};
}

unsigned int
MooseMesh::dimension() const
{
  return getMesh().mesh_dimension();
}

unsigned int
MooseMesh::effectiveSpatialDimension() const
{
  const Real abs_zero = 1e-12;

  // See if the mesh is completely containd in the z and y planes to calculate effective spatial
  // dim
  for (unsigned int dim = LIBMESH_DIM; dim >= 1; --dim)
    if (dimensionWidth(dim - 1) >= abs_zero)
      return dim;

  // If we get here, we have a 1D mesh on the x-axis.
  return 1;
}

unsigned int
MooseMesh::getBlocksMaxDimension(const std::vector<SubdomainName> & blocks) const
{
  const auto & mesh = getMesh();

  // Take a shortcut if possible
  if (const auto & elem_dims = mesh.elem_dimensions(); mesh.is_prepared() && elem_dims.size() == 1)
    return *elem_dims.begin();

  unsigned short dim = 0;
  const auto subdomain_ids = getSubdomainIDs(blocks);
  const std::set<SubdomainID> subdomain_ids_set(subdomain_ids.begin(), subdomain_ids.end());
  for (const auto & elem : mesh.active_subdomain_set_elements_ptr_range(subdomain_ids_set))
    dim = std::max(dim, elem->dim());

  // Get the maximumal globally
  _communicator.max(dim);
  return dim;
}

std::vector<BoundaryID>
MooseMesh::getBoundaryIDs(const Elem * const elem, const unsigned short int side) const
{
  std::vector<BoundaryID> ids;
  getMesh().get_boundary_info().boundary_ids(elem, side, ids);
  return ids;
}

std::vector<std::vector<BoundaryID>>
MooseMesh::getBoundaryIDs(const Elem * const elem) const
{
  std::vector<std::vector<BoundaryID>> ids;
  getMesh().get_boundary_info().side_boundary_ids(elem, ids);
  return ids;
}

const std::set<BoundaryID> &
MooseMesh::getBoundaryIDs() const
{
  return getMesh().get_boundary_info().get_boundary_ids();
}

void
MooseMesh::buildNodeListFromSideList()
{
  auto & boundary_info = getMesh().get_boundary_info();

  if (_construct_node_list_from_side_list)
  {
    const std::set<boundary_id_type> & side_bcids = boundary_info.get_side_boundary_ids();

    if (_displace_node_list_by_side_list)
    {
      // Don't want to use auto here - the rbegin trick relies on a
      // sorted set and we want the compiler to scream if libMesh ever
      // switches type
      const std::set<boundary_id_type> & node_bcids = boundary_info.get_node_boundary_ids();

      // If we've got a reasonable largest BC id, we can just use the
      // subsequent unused ones
      boundary_id_type next_bcid = 0;
      if (!node_bcids.empty())
        next_bcid = std::max(next_bcid, cast_int<boundary_id_type>(*node_bcids.rbegin() + 1));
      if (!side_bcids.empty())
        next_bcid = std::max(next_bcid, cast_int<boundary_id_type>(*side_bcids.rbegin() + 1));

      // We need all processors to agree on the id to use, even when
      // each only sees the bcids on their own portions of a
      // distributed mesh.
      _communicator.max(next_bcid);

      // If we've got an unreasonably high largest BC id, we should
      // probably just search for unused ones with moderate values, so we
      // don't risk wrapping.
      if (next_bcid > 1000 || next_bcid <= 0)
        next_bcid = 1000;

      // If any side bcid is already a node bcid with a different name,
      // that's a different boundary condition that we need to reassign
      // rather than overwrite or merge to.
      for (auto bcid : side_bcids)
        if (node_bcids.count(bcid) &&
            (boundary_info.get_sideset_name(bcid) != boundary_info.get_nodeset_name(bcid)))
        {
          boundary_info.renumber_node_id(bcid, next_bcid);
          do
          {
            ++next_bcid;
          } while (node_bcids.count(next_bcid) || side_bcids.count(next_bcid));
        }
    }

    // For any side bcid that has a name, make sure that our new node
    // bcid is given the same name.  We need to iterate over the
    // actual name map (which is global) here, not over side_bcids
    // (which only includes local ids on a distributed mesh).
    for (auto & [id, name] : boundary_info.get_sideset_name_map())
      boundary_info.nodeset_name(id) = name;

    boundary_info.build_node_list_from_side_list();
  }
}

std::vector<std::tuple<dof_id_type, unsigned short int, boundary_id_type>>
MooseMesh::buildSideList()
{
  return getMesh().get_boundary_info().build_side_list();
}

std::vector<std::tuple<dof_id_type, unsigned short int, boundary_id_type>>
MooseMesh::buildActiveSideList() const
{
  return getMesh().get_boundary_info().build_active_side_list();
}

unsigned int
MooseMesh::sideWithBoundaryID(const Elem * const elem, const BoundaryID boundary_id) const
{
  return getMesh().get_boundary_info().side_with_boundary_id(elem, boundary_id);
}

MeshBase::node_iterator
MooseMesh::localNodesBegin()
{
  return getMesh().local_nodes_begin();
}

MeshBase::node_iterator
MooseMesh::localNodesEnd()
{
  return getMesh().local_nodes_end();
}

MeshBase::const_node_iterator
MooseMesh::localNodesBegin() const
{
  return getMesh().local_nodes_begin();
}

MeshBase::const_node_iterator
MooseMesh::localNodesEnd() const
{
  return getMesh().local_nodes_end();
}

MeshBase::element_iterator
MooseMesh::activeLocalElementsBegin()
{
  return getMesh().active_local_elements_begin();
}

const MeshBase::element_iterator
MooseMesh::activeLocalElementsEnd()
{
  return getMesh().active_local_elements_end();
}

MeshBase::const_element_iterator
MooseMesh::activeLocalElementsBegin() const
{
  return getMesh().active_local_elements_begin();
}

const MeshBase::const_element_iterator
MooseMesh::activeLocalElementsEnd() const
{
  return getMesh().active_local_elements_end();
}

dof_id_type
MooseMesh::nNodes() const
{
  return getMesh().n_nodes();
}

dof_id_type
MooseMesh::nElem() const
{
  return getMesh().n_elem();
}

dof_id_type
MooseMesh::maxNodeId() const
{
  return getMesh().max_node_id();
}

dof_id_type
MooseMesh::maxElemId() const
{
  return getMesh().max_elem_id();
}

Elem *
MooseMesh::elem(const dof_id_type i)
{
  mooseDeprecated("MooseMesh::elem() is deprecated, please use MooseMesh::elemPtr() instead");
  return elemPtr(i);
}

const Elem *
MooseMesh::elem(const dof_id_type i) const
{
  mooseDeprecated("MooseMesh::elem() is deprecated, please use MooseMesh::elemPtr() instead");
  return elemPtr(i);
}

Elem *
MooseMesh::elemPtr(const dof_id_type i)
{
  return getMesh().elem_ptr(i);
}

const Elem *
MooseMesh::elemPtr(const dof_id_type i) const
{
  return getMesh().elem_ptr(i);
}

Elem *
MooseMesh::queryElemPtr(const dof_id_type i)
{
  return getMesh().query_elem_ptr(i);
}

const Elem *
MooseMesh::queryElemPtr(const dof_id_type i) const
{
  return getMesh().query_elem_ptr(i);
}

bool
MooseMesh::prepared() const
{
  return _mesh->is_prepared() && _moose_mesh_prepared;
}

void
MooseMesh::prepared(bool state)
{
  if (state)
    mooseError("We don't have any right to tell the libmesh mesh that it *is* prepared. Only a "
               "call to prepare_for_use should tell us that");

  // Some people may call this even before we have a MeshBase object. This isn't dangerous really
  // because when the MeshBase object is born, it knows it's in an unprepared state
  if (_mesh)
    _mesh->unset_is_prepared();

  // If the libMesh mesh isn't preparead, then our MooseMesh wrapper is also no longer prepared
  _moose_mesh_prepared = false;

  _regular_orthogonal_mesh = false;
}

void
MooseMesh::needsPrepareForUse()
{
  prepared(false);
}

const std::set<SubdomainID> &
MooseMesh::meshSubdomains() const
{
  return _mesh_subdomains;
}

const std::set<BoundaryID> &
MooseMesh::meshBoundaryIds() const
{
  return _mesh_boundary_ids;
}

const std::set<BoundaryID> &
MooseMesh::meshSidesetIds() const
{
  return _mesh_sideset_ids;
}

const std::set<BoundaryID> &
MooseMesh::meshNodesetIds() const
{
  return _mesh_nodeset_ids;
}

void
MooseMesh::setMeshBoundaryIDs(std::set<BoundaryID> boundary_IDs)
{
  _mesh_boundary_ids = boundary_IDs;
}

void
MooseMesh::setBoundaryToNormalMap(
    std::unique_ptr<std::map<BoundaryID, RealVectorValue>> boundary_map)
{
  _boundary_to_normal_map = std::move(boundary_map);
}

void
MooseMesh::setBoundaryToNormalMap(std::map<BoundaryID, RealVectorValue> * boundary_map)
{
  mooseDeprecated("setBoundaryToNormalMap(std::map<BoundaryID, RealVectorValue> * boundary_map) is "
                  "deprecated, use the unique_ptr version instead");
  _boundary_to_normal_map.reset(boundary_map);
}

unsigned int
MooseMesh::uniformRefineLevel() const
{
  return _uniform_refine_level;
}

void
MooseMesh::setUniformRefineLevel(unsigned int level, bool deletion)
{
  _uniform_refine_level = level;
  _skip_deletion_repartition_after_refine = deletion;
}

void
MooseMesh::addGhostedBoundary(BoundaryID boundary_id)
{
  _ghosted_boundaries.insert(boundary_id);
}

void
MooseMesh::setGhostedBoundaryInflation(const std::vector<Real> & inflation)
{
  _ghosted_boundaries_inflation = inflation;
}

const std::set<unsigned int> &
MooseMesh::getGhostedBoundaries() const
{
  return _ghosted_boundaries;
}

const std::vector<Real> &
MooseMesh::getGhostedBoundaryInflation() const
{
  return _ghosted_boundaries_inflation;
}

namespace // Anonymous namespace for helpers
{
// A class for templated methods that expect output iterator
// arguments, which adds objects to the Mesh.
// Although extra_ghost_elem_inserter can add any object, we
// template it around object type so that type inference and
// iterator_traits will work.
// This object specifically is used to insert extra ghost elems into the mesh
template <typename T>
struct extra_ghost_elem_inserter
{
  using iterator_category = std::output_iterator_tag;
  using value_type = T;

  extra_ghost_elem_inserter(DistributedMesh & m) : mesh(m) {}

  void operator=(const Elem * e) { mesh.add_extra_ghost_elem(const_cast<Elem *>(e)); }

  void operator=(Node * n) { mesh.add_node(n); }

  void operator=(Point * p) { mesh.add_point(*p); }

  extra_ghost_elem_inserter & operator++() { return *this; }

  extra_ghost_elem_inserter operator++(int) { return extra_ghost_elem_inserter(*this); }

  // We don't return a reference-to-T here because we don't want to
  // construct one or have any of its methods called.  We just want
  // to allow the returned object to be able to do mesh insertions
  // with operator=().
  extra_ghost_elem_inserter & operator*() { return *this; }

private:
  DistributedMesh & mesh;
};

struct CompareElemsByLevel
{
  bool operator()(const Elem * a, const Elem * b) const
  {
    libmesh_assert(a);
    libmesh_assert(b);
    const unsigned int al = a->level(), bl = b->level();
    const dof_id_type aid = a->id(), bid = b->id();

    return (al == bl) ? aid < bid : al < bl;
  }
};

} // anonymous namespace

void
MooseMesh::ghostGhostedBoundaries()
{
  // No need to do this if using a serial mesh
  // We do not need to ghost boundary elements when _need_ghost_ghosted_boundaries
  // is not true. _need_ghost_ghosted_boundaries can be set by a mesh generator
  // where boundaries are already ghosted accordingly
  if (!_use_distributed_mesh || !_need_ghost_ghosted_boundaries)
    return;

  TIME_SECTION("GhostGhostedBoundaries", 3);

  parallel_object_only();

  DistributedMesh & mesh = dynamic_cast<DistributedMesh &>(getMesh());

  // We clear ghosted elements that were added by previous invocations of this
  // method but leave ghosted elements that were added by other code, e.g.
  // OversampleOutput, untouched
  mesh.clear_extra_ghost_elems(_ghost_elems_from_ghost_boundaries);
  _ghost_elems_from_ghost_boundaries.clear();

  std::set<const Elem *, CompareElemsByLevel> boundary_elems_to_ghost;
  std::set<Node *> connected_nodes_to_ghost;

  std::vector<const Elem *> family_tree;

  for (const auto & t : mesh.get_boundary_info().build_side_list())
  {
    auto elem_id = std::get<0>(t);
    auto bc_id = std::get<2>(t);

    if (_ghosted_boundaries.find(bc_id) != _ghosted_boundaries.end())
    {
      Elem * elem = mesh.elem_ptr(elem_id);

#ifdef LIBMESH_ENABLE_AMR
      elem->family_tree(family_tree);
      Elem * parent = elem->parent();
      while (parent)
      {
        family_tree.push_back(parent);
        parent = parent->parent();
      }
#else
      family_tree.clear();
      family_tree.push_back(elem);
#endif
      for (const auto & felem : family_tree)
      {
        boundary_elems_to_ghost.insert(felem);

        // The entries of connected_nodes_to_ghost need to be
        // non-constant, so that they will work in things like
        // UpdateDisplacedMeshThread. The container returned by
        // family_tree contains const Elems even when the Elem
        // it is called on is non-const, so once that interface
        // gets fixed we can remove this const_cast.
        for (unsigned int n = 0; n < felem->n_nodes(); ++n)
          connected_nodes_to_ghost.insert(const_cast<Node *>(felem->node_ptr(n)));
      }
    }
  }

  // We really do want to store this by value instead of by reference
  const auto prior_ghost_elems = mesh.extra_ghost_elems();

  mesh.comm().allgather_packed_range(&mesh,
                                     connected_nodes_to_ghost.begin(),
                                     connected_nodes_to_ghost.end(),
                                     extra_ghost_elem_inserter<Node>(mesh));

  mesh.comm().allgather_packed_range(&mesh,
                                     boundary_elems_to_ghost.begin(),
                                     boundary_elems_to_ghost.end(),
                                     extra_ghost_elem_inserter<Elem>(mesh));

  const auto & current_ghost_elems = mesh.extra_ghost_elems();

  std::set_difference(current_ghost_elems.begin(),
                      current_ghost_elems.end(),
                      prior_ghost_elems.begin(),
                      prior_ghost_elems.end(),
                      std::inserter(_ghost_elems_from_ghost_boundaries,
                                    _ghost_elems_from_ghost_boundaries.begin()));
}

unsigned int
MooseMesh::getPatchSize() const
{
  return _patch_size;
}

void
MooseMesh::setPatchUpdateStrategy(Moose::PatchUpdateType patch_update_strategy)
{
  _patch_update_strategy = patch_update_strategy;
}

const Moose::PatchUpdateType &
MooseMesh::getPatchUpdateStrategy() const
{
  return _patch_update_strategy;
}

BoundingBox
MooseMesh::getInflatedProcessorBoundingBox(Real inflation_multiplier) const
{
  // Grab a bounding box to speed things up.  Note that
  // local_bounding_box is *not* equivalent to processor_bounding_box
  // with processor_id() except in serial.
  BoundingBox bbox = MeshTools::create_local_bounding_box(getMesh());

  // Inflate the bbox just a bit to deal with roundoff
  // Adding 1% of the diagonal size in each direction on each end
  Real inflation_amount = inflation_multiplier * (bbox.max() - bbox.min()).norm();
  Point inflation(inflation_amount, inflation_amount, inflation_amount);

  bbox.first -= inflation;  // min
  bbox.second += inflation; // max

  return bbox;
}

MooseMesh::operator libMesh::MeshBase &() { return getMesh(); }

MooseMesh::operator const libMesh::MeshBase &() const { return getMesh(); }

const MeshBase *
MooseMesh::getMeshPtr() const
{
  return _mesh.get();
}

MeshBase &
MooseMesh::getMesh()
{
  mooseAssert(_mesh, "Mesh hasn't been created");
  return *_mesh;
}

const MeshBase &
MooseMesh::getMesh() const
{
  mooseAssert(_mesh, "Mesh hasn't been created");
  return *_mesh;
}

void
MooseMesh::printInfo(std::ostream & os, const unsigned int verbosity /* = 0 */) const
{
  os << '\n';
  getMesh().print_info(os, verbosity);
  os << std::flush;
}

const std::vector<dof_id_type> &
MooseMesh::getNodeList(boundary_id_type nodeset_id) const
{
  std::map<boundary_id_type, std::vector<dof_id_type>>::const_iterator it =
      _node_set_nodes.find(nodeset_id);

  if (it == _node_set_nodes.end())
  {
    // On a distributed mesh we might not know about a remote nodeset,
    // so we'll return an empty vector and hope the nodeset exists
    // elsewhere.
    if (!getMesh().is_serial())
    {
      static const std::vector<dof_id_type> empty_vec;
      return empty_vec;
    }
    // On a replicated mesh we should know about every nodeset and if
    // we're asked for one that doesn't exist then it must be a bug.
    else
    {
      mooseError("Unable to nodeset ID: ", nodeset_id, '.');
    }
  }

  return it->second;
}

const std::set<BoundaryID> &
MooseMesh::getSubdomainBoundaryIds(const SubdomainID subdomain_id) const
{
  const auto it = _sub_to_data.find(subdomain_id);

  if (it == _sub_to_data.end())
    mooseError("Unable to find subdomain ID: ", subdomain_id, '.');

  return it->second.boundary_ids;
}

std::set<BoundaryID>
MooseMesh::getSubdomainInterfaceBoundaryIds(const SubdomainID subdomain_id) const
{
  const auto & bnd_ids = getSubdomainBoundaryIds(subdomain_id);
  std::set<BoundaryID> boundary_ids(bnd_ids.begin(), bnd_ids.end());
  std::unordered_map<SubdomainID, std::set<BoundaryID>>::const_iterator it =
      _neighbor_subdomain_boundary_ids.find(subdomain_id);

  boundary_ids.insert(it->second.begin(), it->second.end());

  return boundary_ids;
}

std::set<SubdomainID>
MooseMesh::getBoundaryConnectedBlocks(const BoundaryID bid) const
{
  std::set<SubdomainID> subdomain_ids;
  for (const auto & [sub_id, data] : _sub_to_data)
    if (data.boundary_ids.find(bid) != data.boundary_ids.end())
      subdomain_ids.insert(sub_id);

  return subdomain_ids;
}

std::set<SubdomainID>
MooseMesh::getBoundaryConnectedSecondaryBlocks(const BoundaryID bid) const
{
  std::set<SubdomainID> subdomain_ids;
  for (const auto & it : _neighbor_subdomain_boundary_ids)
    if (it.second.find(bid) != it.second.end())
      subdomain_ids.insert(it.first);

  return subdomain_ids;
}

std::set<SubdomainID>
MooseMesh::getInterfaceConnectedBlocks(const BoundaryID bid) const
{
  std::set<SubdomainID> subdomain_ids = getBoundaryConnectedBlocks(bid);
  for (const auto & it : _neighbor_subdomain_boundary_ids)
    if (it.second.find(bid) != it.second.end())
      subdomain_ids.insert(it.first);

  return subdomain_ids;
}

const std::set<SubdomainID> &
MooseMesh::getBlockConnectedBlocks(const SubdomainID subdomain_id) const
{
  const auto it = _sub_to_data.find(subdomain_id);

  if (it == _sub_to_data.end())
    mooseError("Unable to find subdomain ID: ", subdomain_id, '.');

  return it->second.neighbor_subs;
}

bool
MooseMesh::isBoundaryNode(dof_id_type node_id) const
{
  bool found_node = false;
  for (const auto & it : _bnd_node_ids)
  {
    if (it.second.find(node_id) != it.second.end())
    {
      found_node = true;
      break;
    }
  }
  return found_node;
}

bool
MooseMesh::isBoundaryNode(dof_id_type node_id, BoundaryID bnd_id) const
{
  bool found_node = false;
  std::map<boundary_id_type, std::set<dof_id_type>>::const_iterator it = _bnd_node_ids.find(bnd_id);
  if (it != _bnd_node_ids.end())
    if (it->second.find(node_id) != it->second.end())
      found_node = true;
  return found_node;
}

bool
MooseMesh::isBoundaryElem(dof_id_type elem_id) const
{
  bool found_elem = false;
  for (const auto & it : _bnd_elem_ids)
  {
    if (it.second.find(elem_id) != it.second.end())
    {
      found_elem = true;
      break;
    }
  }
  return found_elem;
}

bool
MooseMesh::isBoundaryElem(dof_id_type elem_id, BoundaryID bnd_id) const
{
  bool found_elem = false;
  auto it = _bnd_elem_ids.find(bnd_id);
  if (it != _bnd_elem_ids.end())
    if (it->second.find(elem_id) != it->second.end())
      found_elem = true;
  return found_elem;
}

void
MooseMesh::errorIfDistributedMesh(std::string name) const
{
  if (_use_distributed_mesh)
    mooseError("Cannot use ",
               name,
               " with DistributedMesh!\n",
               "Consider specifying parallel_type = 'replicated' in your input file\n",
               "to prevent it from being run with DistributedMesh.");
}

void
MooseMesh::setPartitionerHelper(MeshBase * const mesh)
{
  if (_use_distributed_mesh && (_partitioner_name != "default" && _partitioner_name != "parmetis"))
  {
    _partitioner_name = "parmetis";
    _partitioner_overridden = true;
  }

  setPartitioner(mesh ? *mesh : getMesh(), _partitioner_name, _use_distributed_mesh, _pars, *this);
}

void
MooseMesh::setPartitioner(MeshBase & mesh_base,
                          MooseEnum & partitioner,
                          bool use_distributed_mesh,
                          const InputParameters & params,
                          MooseObject & context_obj)
{
  // Set the partitioner based on partitioner name
  switch (partitioner)
  {
    case -3: // default
      // We'll use the default partitioner, but notify the user of which one is being used...
      if (use_distributed_mesh)
        partitioner = "parmetis";
      else
        partitioner = "metis";
      break;

    // No need to explicitily create the metis or parmetis partitioners,
    // They are the default for serial and parallel mesh respectively
    case -2: // metis
    case -1: // parmetis
      break;

    case 0: // linear
      mesh_base.partitioner().reset(new libMesh::LinearPartitioner);
      break;
    case 1: // centroid
    {
      if (!params.isParamValid("centroid_partitioner_direction"))
        context_obj.paramError(
            "centroid_partitioner_direction",
            "If using the centroid partitioner you _must_ specify centroid_partitioner_direction!");

      MooseEnum direction = params.get<MooseEnum>("centroid_partitioner_direction");

      if (direction == "x")
        mesh_base.partitioner().reset(
            new libMesh::CentroidPartitioner(libMesh::CentroidPartitioner::X));
      else if (direction == "y")
        mesh_base.partitioner().reset(
            new libMesh::CentroidPartitioner(libMesh::CentroidPartitioner::Y));
      else if (direction == "z")
        mesh_base.partitioner().reset(
            new libMesh::CentroidPartitioner(libMesh::CentroidPartitioner::Z));
      else if (direction == "radial")
        mesh_base.partitioner().reset(
            new libMesh::CentroidPartitioner(libMesh::CentroidPartitioner::RADIAL));
      break;
    }
    case 2: // hilbert_sfc
      mesh_base.partitioner().reset(new libMesh::HilbertSFCPartitioner);
      break;
    case 3: // morton_sfc
      mesh_base.partitioner().reset(new libMesh::MortonSFCPartitioner);
      break;
  }
}

void
MooseMesh::setCustomPartitioner(Partitioner * partitioner)
{
  _custom_partitioner = partitioner->clone();
  setIsCustomPartitionerRequested(true);
  if (_mesh)
    _mesh->partitioner() = _custom_partitioner->clone();
  _partitioner_name = "custom";
}

bool
MooseMesh::isCustomPartitionerRequested() const
{
  return _custom_partitioner_requested;
}

bool
MooseMesh::hasSecondOrderElements()
{
  bool mesh_has_second_order_elements = false;
  for (auto it = activeLocalElementsBegin(), end = activeLocalElementsEnd(); it != end; ++it)
    if ((*it)->default_order() == SECOND)
    {
      mesh_has_second_order_elements = true;
      break;
    }

  // We checked our local elements, so take the max over all processors.
  comm().max(mesh_has_second_order_elements);
  return mesh_has_second_order_elements;
}

void
MooseMesh::setIsCustomPartitionerRequested(bool cpr)
{
  _custom_partitioner_requested = cpr;
}

std::unique_ptr<libMesh::PointLocatorBase>
MooseMesh::getPointLocator() const
{
  return getMesh().sub_point_locator();
}

void
MooseMesh::buildFiniteVolumeInfo() const
{
  mooseAssert(!Threads::in_threads,
              "This routine has not been implemented for threads. Please query this routine before "
              "a threaded region or contact a MOOSE developer to discuss.");
  _finite_volume_info_dirty = false;

  using Keytype = std::pair<const Elem *, unsigned short int>;

  // create a map from elem/side --> boundary ids
  std::vector<std::tuple<dof_id_type, unsigned short int, boundary_id_type>> side_list =
      buildActiveSideList();
  std::map<Keytype, std::set<boundary_id_type>> side_map;
  for (auto & [elem_id, side, bc_id] : side_list)
  {
    const Elem * elem = _mesh->elem_ptr(elem_id);
    Keytype key(elem, side);
    auto & bc_set = side_map[key];
    bc_set.insert(bc_id);
  }

  _face_info.clear();
  _all_face_info.clear();
  _elem_side_to_face_info.clear();

  _elem_to_elem_info.clear();
  _elem_info.clear();

  // by performing the element ID comparison check in the below loop, we are ensuring that we never
  // double count face contributions. If a face lies along a process boundary, the only process that
  // will contribute to both sides of the face residuals/Jacobians will be the process that owns the
  // element with the lower ID.
  auto begin = getMesh().active_elements_begin();
  auto end = getMesh().active_elements_end();

  // We prepare a map connecting the Elem* and the corresponding ElemInfo
  // for the active elements.
  _elem_to_elem_info.reserve(nActiveLocalElem());
  unsigned int num_sides = 0;
  for (const Elem * elem : as_range(begin, end))
  {
    _elem_to_elem_info.emplace(elem->id(), elem);
    num_sides += elem->n_sides();
  }

  // Used to speed up FaceInfo creation:
  // - element side builder that caches per type of element
  libMesh::ElemSideBuilder side_builder;

  _all_face_info.reserve(num_sides / 2);
  dof_id_type face_index = 0;
  for (const Elem * elem : as_range(begin, end))
  {
    for (unsigned int side = 0; side < elem->n_sides(); ++side)
    {
      // get the neighbor element
      const Elem * neighbor = elem->neighbor_ptr(side);

      // Check if the FaceInfo shall belong to the element. If yes,
      // create and initialize the FaceInfo. We need this to ensure that
      // we do not duplicate FaceInfo-s.
      if (Moose::FV::elemHasFaceInfo(*elem, neighbor))
      {
        mooseAssert(!neighbor || (neighbor->level() < elem->level() ? neighbor->active() : true),
                    "If the neighbor is coarser than the element, we expect that the neighbor must "
                    "be active.");

        // We construct the faceInfo using the elementinfo and side index
        mooseAssert(elem->default_order() < 4, "Did not expect such high element orders in FV");
        _all_face_info.emplace_back(
            &_elem_to_elem_info[elem->id()], side, face_index++, side_builder);

        auto & fi = _all_face_info.back();

        // get all the sidesets that this face is contained in and cache them
        // in the face info.
        std::set<boundary_id_type> & boundary_ids = fi.boundaryIDs();
        boundary_ids.clear();

        // We initialize the weights/other information in faceInfo. If the neighbor does not exist
        // or is remote (so when we are on some sort of mesh boundary), we initialize the ghost
        // cell and use it to compute the weights corresponding to the faceInfo.
        if (!neighbor || neighbor == libMesh::remote_elem)
          fi.computeBoundaryCoefficients();
        else
          fi.computeInternalCoefficients(&_elem_to_elem_info[neighbor->id()]);

        auto lit = side_map.find(Keytype(&fi.elem(), fi.elemSideID()));
        if (lit != side_map.end())
          boundary_ids.insert(lit->second.begin(), lit->second.end());

        if (fi.neighborPtr())
        {
          auto rit = side_map.find(Keytype(fi.neighborPtr(), fi.neighborSideID()));
          if (rit != side_map.end())
            boundary_ids.insert(rit->second.begin(), rit->second.end());
        }
      }
    }
  }

  // Build the local face info and elem_side to face info maps. We need to do this after
  // _all_face_info is finished being constructed because emplace_back invalidates all iterators and
  // references if ever the new size exceeds capacity
  _elem_side_to_face_info.reserve(_all_face_info.size());
  // heuristic to avoid resizing too much
  _face_info.reserve(_all_face_info.size());
  for (auto & fi : _all_face_info)
  {
    const Elem * const elem = &fi.elem();
    const auto side = fi.elemSideID();

#ifndef NDEBUG
    auto pair_it =
#endif
        _elem_side_to_face_info.emplace(std::make_pair(elem, side), &fi);
    mooseAssert(pair_it.second, "We should be adding unique FaceInfo objects.");

    // We will add the faces on processor boundaries to the list of face infos on each
    // associated processor.
    if (fi.elem().processor_id() == this->processor_id() ||
        (fi.neighborPtr() && (fi.neighborPtr()->processor_id() == this->processor_id())))
      _face_info.push_back(&fi);
  }

  _elem_info.reserve(nActiveLocalElem());
  for (auto & ei : _elem_to_elem_info)
    if (ei.second.elem()->processor_id() == this->processor_id())
      _elem_info.push_back(&ei.second);
}

const FaceInfo *
MooseMesh::faceInfo(const Elem * elem, unsigned int side) const
{
  auto it = _elem_side_to_face_info.find(std::make_pair(elem, side));

  if (it == _elem_side_to_face_info.end())
    return nullptr;
  else
  {
    mooseAssert(it->second,
                "For some reason, the FaceInfo object is NULL! Try calling "
                "`buildFiniteVolumeInfo()` before using this accessor!");
    return it->second;
  }
}

const ElemInfo &
MooseMesh::elemInfo(const dof_id_type id) const
{
  return libmesh_map_find(_elem_to_elem_info, id);
}

void
MooseMesh::computeFiniteVolumeCoords() const
{
  if (_finite_volume_info_dirty)
    mooseError("Trying to compute face- and elem-info coords when the information is dirty");

  for (auto & fi : _all_face_info)
  {
    // get elem & neighbor elements, and set subdomain ids
    const SubdomainID elem_subdomain_id = fi.elemSubdomainID();
    const SubdomainID neighbor_subdomain_id = fi.neighborSubdomainID();

    coordTransformFactor(
        *this, elem_subdomain_id, fi.faceCentroid(), fi.faceCoord(), neighbor_subdomain_id);
  }

  for (auto & ei : _elem_to_elem_info)
    coordTransformFactor(
        *this, ei.second.subdomain_id(), ei.second.centroid(), ei.second.coordFactor());
}

MooseEnum
MooseMesh::partitioning()
{
  MooseEnum partitioning(
      "default=-3 metis=-2 parmetis=-1 linear=0 centroid hilbert_sfc morton_sfc custom", "default");
  return partitioning;
}

MooseEnum
MooseMesh::elemTypes()
{
  MooseEnum elemTypes(
      "EDGE EDGE2 EDGE3 EDGE4 QUAD QUAD4 QUAD8 QUAD9 TRI3 TRI6 HEX HEX8 HEX20 HEX27 TET4 TET10 "
      "PRISM6 PRISM15 PRISM18 PYRAMID5 PYRAMID13 PYRAMID14");
  return elemTypes;
}

void
MooseMesh::allowRemoteElementRemoval(const bool allow_remote_element_removal)
{
  _allow_remote_element_removal = allow_remote_element_removal;
  if (_mesh)
    _mesh->allow_remote_element_removal(allow_remote_element_removal);

  if (!allow_remote_element_removal)
    // If we're not allowing remote element removal now, then we will need deletion later after
    // late geoemetric ghosting functors have been added (late geometric ghosting functor addition
    // happens when algebraic ghosting functors are added)
    _need_delete = true;
}

void
MooseMesh::deleteRemoteElements()
{
  _allow_remote_element_removal = true;
  if (!_mesh)
    mooseError("Cannot delete remote elements because we have not yet attached a MeshBase");

  _mesh->allow_remote_element_removal(true);

  _mesh->delete_remote_elements();
}

void
MooseMesh::cacheFaceInfoVariableOwnership() const
{
  mooseAssert(
      !Threads::in_threads,
      "Performing writes to faceInfo variable association maps. This must be done unthreaded!");

  const unsigned int num_eqs = _app.feProblem().es().n_systems();

  auto face_lambda = [this](const SubdomainID elem_subdomain_id,
                            const SubdomainID neighbor_subdomain_id,
                            SystemBase & sys,
                            std::vector<std::vector<FaceInfo::VarFaceNeighbors>> & face_type_vector)
  {
    face_type_vector[sys.number()].resize(sys.nVariables(), FaceInfo::VarFaceNeighbors::NEITHER);
    const auto & variables = sys.getVariables(0);

    for (const auto & var : variables)
    {
      const unsigned int var_num = var->number();
      const unsigned int sys_num = var->sys().number();
      std::set<SubdomainID> var_subdomains = var->blockIDs();
      bool var_defined_elem = var_subdomains.find(elem_subdomain_id) != var_subdomains.end();
      bool var_defined_neighbor =
          var_subdomains.find(neighbor_subdomain_id) != var_subdomains.end();
      if (var_defined_elem && var_defined_neighbor)
        face_type_vector[sys_num][var_num] = FaceInfo::VarFaceNeighbors::BOTH;
      else if (!var_defined_elem && !var_defined_neighbor)
        face_type_vector[sys_num][var_num] = FaceInfo::VarFaceNeighbors::NEITHER;
      else
      {
        // this is a boundary face for this variable, set elem or neighbor
        if (var_defined_elem)
          face_type_vector[sys_num][var_num] = FaceInfo::VarFaceNeighbors::ELEM;
        else if (var_defined_neighbor)
          face_type_vector[sys_num][var_num] = FaceInfo::VarFaceNeighbors::NEIGHBOR;
        else
          mooseError("Should never get here");
      }
    }
  };

  // We loop through the faces and check if they are internal, boundary or external to
  // the variables in the problem
  for (FaceInfo & face : _all_face_info)
  {
    const SubdomainID elem_subdomain_id = face.elemSubdomainID();
    const SubdomainID neighbor_subdomain_id = face.neighborSubdomainID();

    auto & face_type_vector = face.faceType();

    face_type_vector.clear();
    face_type_vector.resize(num_eqs);

    // First, we check the variables in the solver systems (linear/nonlinear)
    for (const auto i : make_range(_app.feProblem().numSolverSystems()))
      face_lambda(elem_subdomain_id,
                  neighbor_subdomain_id,
                  _app.feProblem().getSolverSystem(i),
                  face_type_vector);

    // Then we check the variables in the auxiliary system
    face_lambda(elem_subdomain_id,
                neighbor_subdomain_id,
                _app.feProblem().getAuxiliarySystem(),
                face_type_vector);
  }
}

void
MooseMesh::cacheFVElementalDoFs() const
{
  mooseAssert(!Threads::in_threads,
              "Performing writes to elemInfo dof indices. This must be done unthreaded!");

  auto elem_lambda = [](const ElemInfo & elem_info,
                        SystemBase & sys,
                        std::vector<std::vector<dof_id_type>> & dof_vector)
  {
    if (sys.nFVVariables())
    {
      dof_vector[sys.number()].resize(sys.nVariables(), libMesh::DofObject::invalid_id);
      const auto & variables = sys.getVariables(0);

      for (const auto & var : variables)
        if (var->isFV())
        {
          const auto & var_subdomains = var->blockIDs();

          // We will only cache for FV variables and if they live on the current subdomain
          if (var_subdomains.find(elem_info.subdomain_id()) != var_subdomains.end())
          {
            std::vector<dof_id_type> indices;
            var->dofMap().dof_indices(elem_info.elem(), indices, var->number());
            mooseAssert(indices.size() == 1, "We expect to have only one dof per element!");
            dof_vector[sys.number()][var->number()] = indices[0];
          }
        }
    }
  };

  const unsigned int num_eqs = _app.feProblem().es().n_systems();

  // We loop through the elements in the mesh and cache the dof indices
  // for the corresponding variables.
  for (auto & ei_pair : _elem_to_elem_info)
  {
    auto & elem_info = ei_pair.second;
    auto & dof_vector = elem_info.dofIndices();

    dof_vector.clear();
    dof_vector.resize(num_eqs);

    // First, we cache the dof indices for the variables in the solver systems (linear, nonlinear)
    for (const auto i : make_range(_app.feProblem().numSolverSystems()))
      elem_lambda(elem_info, _app.feProblem().getSolverSystem(i), dof_vector);

    // Then we cache the dof indices for the auxvariables
    elem_lambda(elem_info, _app.feProblem().getAuxiliarySystem(), dof_vector);
  }
}

void
MooseMesh::setupFiniteVolumeMeshData() const
{
  buildFiniteVolumeInfo();
  computeFiniteVolumeCoords();
  cacheFaceInfoVariableOwnership();
  cacheFVElementalDoFs();
}

void
MooseMesh::setCoordSystem(const std::vector<SubdomainName> & blocks,
                          const MultiMooseEnum & coord_sys)
{
  TIME_SECTION("setCoordSystem", 5, "Setting Coordinate System");
  if (!_provided_coord_blocks.empty() && (_provided_coord_blocks != blocks))
  {
    const std::string param_name = isParamValid("coord_block") ? "coord_block" : "block";
    mooseWarning("Supplied blocks in the 'setCoordSystem' method do not match the value of the "
                 "'Mesh/",
                 param_name,
                 "' parameter. Did you provide different parameter values for 'Mesh/",
                 param_name,
                 "' and 'Problem/block'?. We will honor the parameter value from 'Mesh/",
                 param_name,
                 "'");
    mooseAssert(_coord_system_set,
                "If we are arriving here due to a bad specification in the Problem block, then we "
                "should have already set our coordinate system subdomains from the Mesh block");
    return;
  }
  if (_pars.isParamSetByUser("coord_type") && getParam<MultiMooseEnum>("coord_type") != coord_sys)
    mooseError("Supplied coordinate systems in the 'setCoordSystem' method do not match the value "
               "of the 'Mesh/coord_type' parameter. Did you provide different parameter values for "
               "'coord_type' to 'Mesh' and 'Problem'?");

  // If blocks contain ANY_BLOCK_ID, it should be the only block specified, and coord_sys should
  // have one and only one entry. In that case, the same coordinate system will be set for all
  // subdomains.
  if (blocks.size() == 1 && blocks[0] == "ANY_BLOCK_ID")
  {
    if (coord_sys.size() > 1)
      mooseError("If you specify ANY_BLOCK_ID as the only block, you must also specify a single "
                 "coordinate system for it.");
    if (!_mesh->is_prepared())
      mooseError(
          "You cannot set the coordinate system for ANY_BLOCK_ID before the mesh is prepared. "
          "Please call this method after the mesh is prepared.");
    const auto coord_type = coord_sys.size() == 0
                                ? Moose::COORD_XYZ
                                : Moose::stringToEnum<Moose::CoordinateSystemType>(coord_sys[0]);
    for (const auto sid : meshSubdomains())
      _coord_sys[sid] = coord_type;
    return;
  }

  // If multiple blocks are specified, but one of them is ANY_BLOCK_ID, let's emit a helpful error
  if (std::find(blocks.begin(), blocks.end(), "ANY_BLOCK_ID") != blocks.end())
    mooseError("You cannot specify ANY_BLOCK_ID together with other blocks in the "
               "setCoordSystem() method. If you want to set the same coordinate system for all "
               "blocks, use ANY_BLOCK_ID as the only block.");

  auto subdomains = meshSubdomains();
  // It's possible that a user has called this API before the mesh is prepared and consequently we
  // don't yet have the subdomains in meshSubdomains()
  for (const auto & sub_name : blocks)
  {
    const auto sub_id = getSubdomainID(sub_name);
    subdomains.insert(sub_id);
  }

  if (coord_sys.size() <= 1)
  {
    // We will specify the same coordinate system for all blocks
    const auto coord_type = coord_sys.size() == 0
                                ? Moose::COORD_XYZ
                                : Moose::stringToEnum<Moose::CoordinateSystemType>(coord_sys[0]);
    for (const auto sid : subdomains)
      _coord_sys[sid] = coord_type;
  }
  else
  {
    if (blocks.size() != coord_sys.size())
      mooseError("Number of blocks and coordinate systems does not match.");

    for (const auto i : index_range(blocks))
    {
      SubdomainID sid = getSubdomainID(blocks[i]);
      Moose::CoordinateSystemType coord_type =
          Moose::stringToEnum<Moose::CoordinateSystemType>(coord_sys[i]);
      _coord_sys[sid] = coord_type;
    }

    for (const auto & sid : subdomains)
      if (_coord_sys.find(sid) == _coord_sys.end())
        mooseError("Subdomain '" + Moose::stringify(sid) +
                   "' does not have a coordinate system specified.");
  }

  _coord_system_set = true;

  updateCoordTransform();
}

Moose::CoordinateSystemType
MooseMesh::getCoordSystem(SubdomainID sid) const
{
  auto it = _coord_sys.find(sid);
  if (it != _coord_sys.end())
    return (*it).second;
  else
    mooseError("Requested subdomain ", sid, " does not exist.");
}

Moose::CoordinateSystemType
MooseMesh::getUniqueCoordSystem() const
{
  const auto unique_system = _coord_sys.find(*meshSubdomains().begin())->second;
  // Check that it is actually unique
  bool result = std::all_of(
      std::next(_coord_sys.begin()),
      _coord_sys.end(),
      [unique_system](
          typename std::unordered_map<SubdomainID, Moose::CoordinateSystemType>::const_reference
              item) { return (item.second == unique_system); });
  if (!result)
    mooseError("The unique coordinate system of the mesh was requested by the mesh contains "
               "multiple blocks with different coordinate systems");

  if (usingGeneralAxisymmetricCoordAxes())
    mooseError("General axisymmetric coordinate axes are being used, and it is currently "
               "conservatively assumed that in this case there is no unique coordinate system.");

  return unique_system;
}

const std::map<SubdomainID, Moose::CoordinateSystemType> &
MooseMesh::getCoordSystem() const
{
  return _coord_sys;
}

void
MooseMesh::setAxisymmetricCoordAxis(const MooseEnum & rz_coord_axis)
{
  _rz_coord_axis = rz_coord_axis;

  updateCoordTransform();
}

void
MooseMesh::setGeneralAxisymmetricCoordAxes(
    const std::vector<SubdomainName> & blocks,
    const std::vector<std::pair<Point, RealVectorValue>> & axes)
{
  // Set the axes for the given blocks
  mooseAssert(blocks.size() == axes.size(), "Blocks and axes vectors must be the same length.");
  for (const auto i : index_range(blocks))
  {
    const auto subdomain_id = getSubdomainID(blocks[i]);
    const auto it = _coord_sys.find(subdomain_id);
    if (it == _coord_sys.end())
      mooseError("The block '",
                 blocks[i],
                 "' has not set a coordinate system. Make sure to call setCoordSystem() before "
                 "setGeneralAxisymmetricCoordAxes().");
    else
    {
      if (it->second == Moose::COORD_RZ)
      {
        const auto direction = axes[i].second;
        if (direction.is_zero())
          mooseError("Only nonzero vectors may be supplied for RZ directions.");

        _subdomain_id_to_rz_coord_axis[subdomain_id] =
            std::make_pair(axes[i].first, direction.unit());
      }
      else
        mooseError("The block '",
                   blocks[i],
                   "' was provided in setGeneralAxisymmetricCoordAxes(), but the coordinate system "
                   "for this block is not 'RZ'.");
    }
  }

  // Make sure there are no RZ blocks that still do not have axes
  const auto all_subdomain_ids = meshSubdomains();
  for (const auto subdomain_id : all_subdomain_ids)
    if (getCoordSystem(subdomain_id) == Moose::COORD_RZ &&
        !_subdomain_id_to_rz_coord_axis.count(subdomain_id))
      mooseError("The block '",
                 getSubdomainName(subdomain_id),
                 "' was specified to use the 'RZ' coordinate system but was not given in "
                 "setGeneralAxisymmetricCoordAxes().");

  updateCoordTransform();
}

const std::pair<Point, RealVectorValue> &
MooseMesh::getGeneralAxisymmetricCoordAxis(SubdomainID subdomain_id) const
{
  auto it = _subdomain_id_to_rz_coord_axis.find(subdomain_id);
  if (it != _subdomain_id_to_rz_coord_axis.end())
    return (*it).second;
  else
    mooseError("Requested subdomain ", subdomain_id, " does not exist.");
}

bool
MooseMesh::usingGeneralAxisymmetricCoordAxes() const
{
  return _subdomain_id_to_rz_coord_axis.size() > 0;
}

void
MooseMesh::updateCoordTransform()
{
  if (!_coord_transform)
    _coord_transform = std::make_unique<MooseAppCoordTransform>(*this);
  else
    _coord_transform->setCoordinateSystem(*this);
}

unsigned int
MooseMesh::getAxisymmetricRadialCoord() const
{
  if (usingGeneralAxisymmetricCoordAxes())
    mooseError("getAxisymmetricRadialCoord() should not be called if "
               "setGeneralAxisymmetricCoordAxes() has been called.");

  if (_rz_coord_axis == 0)
    return 1; // if the rotation axis is x (0), then the radial direction is y (1)
  else
    return 0; // otherwise the radial direction is assumed to be x, i.e., the rotation axis is y
}

void
MooseMesh::checkCoordinateSystems()
{
  for (const auto & elem : getMesh().element_ptr_range())
  {
    SubdomainID sid = elem->subdomain_id();
    if (_coord_sys[sid] == Moose::COORD_RZ && elem->dim() == 3)
      mooseError("An RZ coordinate system was requested for subdomain " + Moose::stringify(sid) +
                 " which contains 3D elements.");
    if (_coord_sys[sid] == Moose::COORD_RSPHERICAL && elem->dim() > 1)
      mooseError("An RSPHERICAL coordinate system was requested for subdomain " +
                 Moose::stringify(sid) + " which contains 2D or 3D elements.");
  }
}

void
MooseMesh::setCoordData(const MooseMesh & other_mesh)
{
  _coord_sys = other_mesh._coord_sys;
  _rz_coord_axis = other_mesh._rz_coord_axis;
  _subdomain_id_to_rz_coord_axis = other_mesh._subdomain_id_to_rz_coord_axis;
}

const MooseUnits &
MooseMesh::lengthUnit() const
{
  mooseAssert(_coord_transform, "This must be non-null");
  return _coord_transform->lengthUnit();
}

void
MooseMesh::checkDuplicateSubdomainNames()
{
  std::map<SubdomainName, SubdomainID> subdomain;
  for (const auto & sbd_id : _mesh_subdomains)
  {
    std::string sub_name = getSubdomainName(sbd_id);
    if (!sub_name.empty() && subdomain.count(sub_name) > 0)
      mooseError("The subdomain name ",
                 sub_name,
                 " is used for both subdomain with ID=",
                 subdomain[sub_name],
                 " and ID=",
                 sbd_id,
                 ", Please rename one of them!");
    else
      subdomain[sub_name] = sbd_id;
  }
}

const std::vector<QpMap> &
MooseMesh::getPRefinementMapHelper(
    const Elem & elem,
    const std::map<std::pair<ElemType, unsigned int>, std::vector<QpMap>> & map) const
{
  // We are actually seeking the map stored with the p_level - 1 key, e.g. the refinement map that
  // maps from the previous p_level to this element's p_level
  return libmesh_map_find(map,
                          std::make_pair(elem.type(), cast_int<unsigned int>(elem.p_level() - 1)));
}

const std::vector<QpMap> &
MooseMesh::getPCoarseningMapHelper(
    const Elem & elem,
    const std::map<std::pair<ElemType, unsigned int>, std::vector<QpMap>> & map) const
{
  mooseAssert(elem.active() && elem.p_refinement_flag() == Elem::JUST_COARSENED,
              "These are the conditions that should be met for requesting a coarsening map");
  return libmesh_map_find(map, std::make_pair(elem.type(), elem.p_level()));
}

const std::vector<QpMap> &
MooseMesh::getPRefinementMap(const Elem & elem) const
{
  return getPRefinementMapHelper(elem, _elem_type_to_p_refinement_map);
}

const std::vector<QpMap> &
MooseMesh::getPRefinementSideMap(const Elem & elem) const
{
  return getPRefinementMapHelper(elem, _elem_type_to_p_refinement_side_map);
}

const std::vector<QpMap> &
MooseMesh::getPCoarseningMap(const Elem & elem) const
{
  return getPCoarseningMapHelper(elem, _elem_type_to_p_coarsening_map);
}

const std::vector<QpMap> &
MooseMesh::getPCoarseningSideMap(const Elem & elem) const
{
  return getPCoarseningMapHelper(elem, _elem_type_to_p_coarsening_side_map);
}

bool
MooseMesh::skipNoncriticalPartitioning() const
{
  return _mesh->skip_noncritical_partitioning();
}