/*============================================================================
 * Write a nodal representation associated with a mesh and associated
 * variables to Catalyst objects
 *============================================================================*/

/*
  This file is part of Code_Saturne, a general-purpose CFD tool.

  Copyright (C) 1998-2013 EDF S.A.

  This program is free software; you can redistribute it and/or modify it under
  the terms of the GNU General Public License as published by the Free Software
  Foundation; either version 2 of the License, or (at your option) any later
  version.

  This program is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  details.

  You should have received a copy of the GNU General Public License along with
  this program; if not, write to the Free Software Foundation, Inc., 51 Franklin
  Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/

/*----------------------------------------------------------------------------*/

/* On glibc-based systems, define _GNU_SOURCE so as to enable
   modification of floating-point error exceptions handling;
   _GNU_SOURCE must be defined before including any headers, to ensure
   the correct feature macros are defined first. */

#if defined(__linux__) || defined(__linux) || defined(linux)
#define CS_FPE_TRAP
#if !defined(_GNU_SOURCE)
#define _GNU_SOURCE
#endif
#endif

#include "cs_defs.h"

#if defined(HAVE_CATALYST)

/*----------------------------------------------------------------------------
 * Standard C library headers
 *----------------------------------------------------------------------------*/

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if defined(CS_FPE_TRAP)
#include <fenv.h>
#endif

/*----------------------------------------------------------------------------
 * Catalyst and VTK library headers
 *----------------------------------------------------------------------------*/

#include <vtkCellType.h>

#include <vtkCellData.h>
#include <vtkCharArray.h>
#include <vtkFloatArray.h>
#include <vtkMultiBlockDataSet.h>
#include <vtkIdList.h>
#include <vtkIdTypeArray.h>
#include <vtkImageData.h>
#include <vtkInformation.h>
#include <vtkObjectFactory.h>
#include <vtkPointData.h>
#include <vtkPolyData.h>
#include <vtkUnstructuredGrid.h>

#include <vtkCPDataDescription.h>
#include <vtkCPInputDataDescription.h>
#include <vtkCPProcessor.h>
#include <vtkCPPythonScriptPipeline.h>
#include <vtkSmartPointer.h>

#include <vtkXMLUnstructuredGridWriter.h>
#include <vtkUnstructuredGridWriter.h>
#include <vtkGenericDataObjectWriter.h>
#include <vtkDoubleArray.h>

/*----------------------------------------------------------------------------
 *  Local headers
 *----------------------------------------------------------------------------*/

#include "bft_error.h"
#include "bft_mem.h"
#include "bft_printf.h"

#include "fvm_defs.h"
#include "fvm_convert_array.h"
#include "fvm_io_num.h"
#include "fvm_nodal.h"
#include "fvm_nodal_priv.h"
#include "fvm_writer_priv.h"

#include "cs_block_dist.h"
#include "cs_file.h"
#include "cs_parall.h"
#include "cs_part_to_block.h"

/*----------------------------------------------------------------------------
 *  Header for the current file
 *----------------------------------------------------------------------------*/

#include "fvm_to_catalyst.h"

/*----------------------------------------------------------------------------
 * Catalyst field structure
 *----------------------------------------------------------------------------*/

typedef struct {

  int                   mesh_id;       /* Associated mesh structure id */
  int                   dim;           /* Field dimension */
  vtkUnstructuredGrid  *f;             /* Pointer to VTK writer fields */

} fvm_catalyst_field_t;

/*----------------------------------------------------------------------------
 * Catalyst writer/reader structure
 *----------------------------------------------------------------------------*/

typedef struct {

  char                       *name;           /* Writer name */

  int                         rank;           /* Rank of current process
                                                 in communicator */
  int                         n_ranks;        /* Size of communicator */

  vtkMultiBlockDataSet       *mb;             /* Associated dataset */

  fvm_writer_time_dep_t       time_dependency; /* Mesh time dependency */

  int                         n_fields;       /* Number of fields */
  fvm_catalyst_field_t      **fields;         /* Array of field helper
                                                 structures */

  int                         time_step;      /* Latest time step */
  double                      time_value;    /* Latest time value */

#if defined(HAVE_MPI)
  MPI_Comm                    comm;           /* Associated MPI communicator */
#endif

  vtkCPProcessor             *processor;      /* Co processor */
  vtkCPDataDescription       *datadesc;       /* Data description */

  bool                        private_comm;   /* Use private communicator */
  bool                        ensight_names;  /* Use EnSight rules for
                                                 field names */

  bool                        modified;       /* Has output been added since
                                                 las coprocessing ? */

} fvm_to_catalyst_t;

/*============================================================================
 * Static global variables
 *============================================================================*/

#if defined(CS_FPE_TRAP)
static int    _fenv_save = 0;
static fenv_t _fenv_old;     /* Old exception mask */
#endif

/*============================================================================
 * Private function definitions
 *============================================================================*/

/*----------------------------------------------------------------------------
 * Disable floating-point exception handling.
 *
 * Uses a counter to handle nested calls.
 *----------------------------------------------------------------------------*/

static void
_disable_fe_exceptions(void)
{
#if defined(CS_FPE_TRAP)
  if (_fenv_save == 0) {
    if (fegetenv(&_fenv_old) == 0)
      _fenv_save += 1;
    fedisableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW);
  }
  else
    _fenv_save += 1;
#endif
}

/*----------------------------------------------------------------------------
 * Restore floating-point exception handling.
 *----------------------------------------------------------------------------*/

static void
_restore_fe_exceptions(void)
{
#if defined(CS_FPE_TRAP)
  if (_fenv_save) {
    _fenv_save -= 1;
    if (_fenv_save == 0)
      fesetenv(&_fenv_old);
  }
#endif
}

/*----------------------------------------------------------------------------
 * Return the Catalyst mesh id associated with a given mesh name,
 * or -1 if no association found.
 *
 * parameters:
 *   writer    <-- writer structure
 *   mesh_name <-- mesh name
 *
 * returns:
 *    Catalyst mesh id, or -1 if Catalyst mesh name is not associated
 *    with this writer structure in FVM
 *----------------------------------------------------------------------------*/

static int
_get_catalyst_mesh_id(fvm_to_catalyst_t  *writer,
                      const char         *mesh_name)
{
  int i;
  int retval = -1;

  assert(writer != NULL);

  int nb = writer->mb->GetNumberOfBlocks();
  for (i = 0; i < nb; i++) {
    if (strcmp
         (mesh_name,
          writer->mb->GetMetaData(i)->Get(vtkCompositeDataSet::NAME())) == 0)
      break;
  }

  if (i < nb)
    retval = i;

  return retval;
}

/*----------------------------------------------------------------------------
 * Create a Catalyst mesh structure.
 *
 * parameters:
 *   writer    <-- Catalyst structure.
 *   mesh      <-- FVM mesh  structure.
 *
 * returns:
 *   Catalyst mesh id.
 *----------------------------------------------------------------------------*/

static int
_add_catalyst_mesh(fvm_to_catalyst_t  *writer,
                   const fvm_nodal_t  *mesh)
{
  assert(writer != NULL);

  /* Add a new Catalyst mesh structure */

  int id = writer->mb->GetNumberOfBlocks();
  vtkUnstructuredGrid* ugrid = vtkUnstructuredGrid::New();

  writer->mb->SetBlock(id, ugrid);
  writer->mb->GetMetaData(id)->Set(vtkCompositeDataSet::NAME(), mesh->name);

  return id;
}

/*----------------------------------------------------------------------------
 * Define VTK geometrical element type according to FVM element type
 *
 * parameters:
 *   fvm_elt_type <-- pointer to fvm element type.
 *
 * return:
 *   med geometrical element type.
 *----------------------------------------------------------------------------*/

static VTKCellType
_get_norm_elt_type(const fvm_element_t fvm_elt_type)
{
  VTKCellType  norm_elt_type;

  switch (fvm_elt_type) {

  case FVM_EDGE:
    norm_elt_type = VTK_LINE;
    break;

  case FVM_FACE_TRIA:
    norm_elt_type = VTK_TRIANGLE;
    break;

  case FVM_FACE_QUAD:
    norm_elt_type = VTK_QUAD;
    break;

  case FVM_FACE_POLY:
    norm_elt_type = VTK_POLYGON;
    break;

  case FVM_CELL_TETRA:
    norm_elt_type = VTK_TETRA;
    break;

  case FVM_CELL_PYRAM:
    norm_elt_type = VTK_PYRAMID;
    break;

  case FVM_CELL_PRISM:
    norm_elt_type = VTK_WEDGE;
    break;

  case FVM_CELL_HEXA:
    norm_elt_type = VTK_HEXAHEDRON;
    break;

  case FVM_CELL_POLY:
    norm_elt_type = VTK_POLYHEDRON;
    break;

  default:
    norm_elt_type = VTK_EMPTY_CELL;
    bft_error(__FILE__, __LINE__, 0,
              "_get_norm_elt_type(): "
              "No association with VTK element type has been found\n"
              "FVM element type: \"%i\"\n",
              (int)fvm_elt_type);

  } /* End of switch on element type */

  return norm_elt_type;
}

/*----------------------------------------------------------------------------
 * Get vertex order to describe Catalyst element type.
 *
 * parameters:
 *   norm_elt_type  <-- Catalyst element type.
 *   vertex_order  --> Pointer to vertex order array (0 to n-1).
 *
 *----------------------------------------------------------------------------*/

static void
_get_vertex_order(VTKCellType   norm_elt_type,
                  int          *vertex_order)
{
  switch(norm_elt_type) {

  case VTK_LINE:
    vertex_order[0] = 0;
    vertex_order[1] = 1;
    break;

  case VTK_TRIANGLE:
    vertex_order[0] = 0;
    vertex_order[1] = 1;
    vertex_order[2] = 2;
    break;

  case VTK_QUAD:
    vertex_order[0] = 0;
    vertex_order[1] = 1;
    vertex_order[2] = 2;
    vertex_order[3] = 3;
    break;

  case VTK_TETRA:
    vertex_order[0] = 0;
    vertex_order[1] = 1;
    vertex_order[2] = 2;
    vertex_order[3] = 3;
    break;

  case VTK_PYRAMID:
    vertex_order[0] = 0;
    vertex_order[1] = 1;
    vertex_order[2] = 2;
    vertex_order[3] = 3;
    vertex_order[4] = 4;
    break;

  case VTK_WEDGE:
    vertex_order[0] = 0;
    vertex_order[1] = 2;
    vertex_order[2] = 1;
    vertex_order[3] = 3;
    vertex_order[4] = 5;
    vertex_order[5] = 4;
    break;

  case VTK_HEXAHEDRON:
    vertex_order[0] = 0;
    vertex_order[1] = 1;
    vertex_order[2] = 2;
    vertex_order[3] = 3;
    vertex_order[4] = 4;
    vertex_order[5] = 5;
    vertex_order[6] = 6;
    vertex_order[7] = 7;
    break;

  case VTK_POLYGON:
    vertex_order[0] = -1;
    break;

  case VTK_POLYHEDRON:
    vertex_order[0] = -1;
    break;

  default:
    bft_error(__FILE__, __LINE__, 0,
              "_get_vertex_order(): No associated FVM element type known\n"
              "VTK element type: \"%i\"\n",
              (int)norm_elt_type);
  }

  return;
}

/*----------------------------------------------------------------------------
 * Return the Catalyst field id associated with given mesh and field names,
 * or -1 if no association found.
 *
 * parameters:
 *   writer    <-- Catalyst writer structure.
 *   fieldname <-- input fieldname.
 *   mesh_id   <-- id of associated mesh in structure.
 *   dim       <-- number of field components.
 *   location  <-- mesh location (cells or vertices).
 *   type      <-- field type (cells, nodes)
 *   td        <-- time discretization type
 *
 * returns
 *   field id in writer structure, or -1 if not found
 *----------------------------------------------------------------------------*/

static int
_get_catalyst_field_id(fvm_to_catalyst_t         *writer,
                       const char                *fieldname,
                       int                        mesh_id,
                       int                        dim,
                       cs_datatype_t              datatype,
                       fvm_writer_var_loc_t       location)
{
  int i;

  for (i = 0; i < writer->n_fields; ++i){

    vtkFieldData *fData_ptr ;

    if (writer->fields[i]->mesh_id != mesh_id)
      continue;

    if (location == FVM_WRITER_PER_NODE)
      fData_ptr = (writer->fields[i])->f->GetPointData();
    else
      fData_ptr = writer->fields[i]->f->GetCellData();

    if (fData_ptr->HasArray(fieldname)){
      break;
    }
  }

  if (i < writer->n_fields)
    return i;

  return -1;
}

/*----------------------------------------------------------------------------
 * Create a Catalyst field structure.
 *
 * parameters:
 *   writer     <-- Catalyst writer structure.
 *   fieldname  <-- input fieldname.
 *   mesh_id    <-- id of associated mesh in structure.
 *   dim        <-- number of field components.
 *   location   <-- mesh location (cells or vertices).
 *   time_step  <-- number of time step to add
 *   time_value <-- associated time value
 *
 * returns
 *   field id in writer structure
 *----------------------------------------------------------------------------*/

static int
_add_catalyst_field(fvm_to_catalyst_t         *writer,
                    const char                *fieldname,
                    int                        mesh_id,
                    int                        dim,
                    cs_datatype_t              datatype,
                    fvm_writer_var_loc_t       location,
                    const int                  time_step,
                    const double               time_value)
{
  int f_id = writer->n_fields;
  
  BFT_REALLOC(writer->fields,
              writer->n_fields+ 1,
              fvm_catalyst_field_t *);

  vtkUnstructuredGrid *f =  NULL;
  vtkDoubleArray *tmp = NULL;

  if (writer->mb->GetMetaData(mesh_id) != NULL) {

    f = vtkUnstructuredGrid::SafeDownCast(vtkDataSet::SafeDownCast
          (writer->mb->GetBlock(mesh_id)));

    tmp = vtkDoubleArray::New();
    tmp->SetName(fieldname);

    tmp->SetNumberOfComponents(dim);

    if (location == FVM_WRITER_PER_NODE) {
      f->GetPointData()->AllocateArrays(f->GetNumberOfPoints());
      vtkDataSetAttributes::SafeDownCast
        (f->GetPointData())->AddArray(vtkAbstractArray::SafeDownCast(tmp));
    }
    else {
      f->GetCellData()->AllocateArrays(f->GetNumberOfCells());
      /* force to AddArray, due to protection of SetArray */
      vtkDataSetAttributes::SafeDownCast
        (f->GetCellData())->AddArray(vtkAbstractArray::SafeDownCast(tmp));
    }
    tmp->Delete();

  }

  BFT_REALLOC(writer->fields,
              writer->n_fields+ 1,
              fvm_catalyst_field_t *);

  BFT_MALLOC(writer->fields[f_id], 1, fvm_catalyst_field_t);

  writer->fields[f_id]->mesh_id = mesh_id;

  writer->fields[f_id]->dim = dim;
  writer->fields[f_id]->f = f;

  writer->n_fields++;
  
  return f_id;
}

/*----------------------------------------------------------------------------
 * Write vertex coordinates to VTK.
 *
 * parameters:
 *   mesh        <-- pointer to nodal mesh structure
 *   vtk_mesh    <-- pointer to VTK Mesh object
 *----------------------------------------------------------------------------*/

static void
_export_vertex_coords(const fvm_nodal_t        *mesh,
                      vtkUnstructuredGrid      *vtk_mesh)
{
  cs_lnum_t   i, j;
  size_t stride;

  double point[3];

  double  *block_coords = NULL;

  const double  *vertex_coords = mesh->vertex_coords;
  const cs_lnum_t  n_vertices = mesh->n_vertices;

  /* Vertex coordinates */
  /*--------------------*/

  stride = (size_t)(mesh->dim);

  vtkPoints *points = vtkPoints::New();

  points->Allocate(mesh->n_vertices);

  if (mesh->parent_vertex_num != NULL) {
    const cs_lnum_t  *parent_vertex_num = mesh->parent_vertex_num;
    for (i = 0; i < n_vertices; i++) {
      for (j = 0; j < mesh->dim; j++)
        point[j] = vertex_coords[(parent_vertex_num[i]-1)*stride + j];
      for (; j < 3; j++)
        point[j] = 0.;
      points->InsertNextPoint(point[0], point[1], point[2]);
    }
  }
  else {
    for (i = 0; i < n_vertices; i++) {
      for (j = 0; j < mesh->dim; j++)
        point[j] = vertex_coords[i*stride + j];
      for (; j < 3; j++)
        point[j] = 0.;
      points->InsertNextPoint(point[0], point[1], point[2]);
    }
  }

  if (mesh->global_vertex_num != NULL) {

    const cs_gnum_t *g_vtx_num
      = fvm_io_num_get_global_num(mesh->global_vertex_num);

    vtkIdTypeArray *g_vtx_id = vtkIdTypeArray::New();

    g_vtx_id->SetNumberOfComponents(1);
    g_vtx_id->SetName("GlobalNodeId");
    g_vtx_id->SetNumberOfTuples(n_vertices);

    for (i = 0; i < n_vertices; i++) {
      vtkIdType ii = g_vtx_num[i]-1;
      g_vtx_id->SetTupleValue(i, &ii);
    }

    vtk_mesh->GetPointData()->SetGlobalIds(g_vtx_id);

    g_vtx_id->Delete();

  }

  vtk_mesh->SetPoints(points);
  points->Delete();
}

/*----------------------------------------------------------------------------
 * Write strided connectivity block to VTK.
 *
 * The connectivity on input may use 1 to n numbering, so it is shifted
 * by -1 here.
 *
 * parameters:
 *   type     <-- FVM element type
 *   n_elts   <-- number of elements in block
 *   connect  <-- connectivity array
 *   vtk_mesh <-> pointer to VTK mesh object
 *----------------------------------------------------------------------------*/

static void
_write_connect_block(fvm_element_t         type,
                     cs_lnum_t             n_elts,
                     const cs_lnum_t       connect[],
                     vtkUnstructuredGrid  *vtk_mesh)
{
  int vertex_order[8];
  cs_lnum_t  i;
  int  j;
  
  vtkIdType *vtx_ids = new vtkIdType[8];

  const int  stride = fvm_nodal_n_vertices_element[type];
  VTKCellType vtk_type = _get_norm_elt_type(type);

  _get_vertex_order(vtk_type, vertex_order);

  assert(vtk_mesh != NULL);

  for (i = 0; i < n_elts; i++) {
    for (j = 0; j < stride; j++)
      vtx_ids[j] = connect[i*stride + vertex_order[j]] - 1;
    vtk_mesh->InsertNextCell(vtk_type, stride, vtx_ids);
  }

  delete [] vtx_ids;
}

/*----------------------------------------------------------------------------
 * Write polygons from a nodal mesh to VTK.
 *
 * parameters:
 *   export_section <-- pointer to Catalyst section helper structure
 *   vtk_mesh       <-> pointer to VTK mesh object
 *----------------------------------------------------------------------------*/

static void
_export_nodal_polygons(const fvm_nodal_section_t  *section,
                       vtkUnstructuredGrid        *vtk_mesh)
{
  cs_lnum_t   i, j;

  int vtx_ids_size = 8;
  vtkIdType *vtx_ids = NULL;

  BFT_MALLOC(vtx_ids, vtx_ids_size, vtkIdType);

  /* Loop on all polygonal faces */
  /*-----------------------------*/

  for (i = 0; i < section->n_elements; i++) {

    int k = 0;

    int face_size = section->vertex_index[i+1] - section->vertex_index[i];
    while (vtx_ids_size < face_size) {
      vtx_ids_size *= 2;
      BFT_REALLOC(vtx_ids, vtx_ids_size, vtkIdType);
    }

    for (j = section->vertex_index[i];
         j < section->vertex_index[i+1];
         j++)
      vtx_ids[k++] = section->vertex_num[j] - 1;

    vtk_mesh->InsertNextCell(VTK_POLYGON, k, vtx_ids);

  } /* End of loop on polygonal faces */

  BFT_FREE(vtx_ids);
}

/*----------------------------------------------------------------------------
 * Write polyhedra from a nodal mesh to VTK.
 *
 * parameters:
 *   n_vertices <-- number of vertices in FVM mesh
 *   section    <-- pointer to Catalyst section helper structure
 *   vtk_mesh   <-> VTK mesh object
 *----------------------------------------------------------------------------*/

static void
_export_nodal_polyhedra(cs_lnum_t                   n_vertices,
                        const fvm_nodal_section_t  *section,
                        vtkUnstructuredGrid        *vtk_mesh)
{
  int  face_sgn;
  int  buf_size = 8;
  cs_lnum_t  i, j, k, l;

  cs_lnum_t  face_length, face_id;

  int *vtx_marker = NULL;
  vtkIdType *face_array = NULL;
  vtkIdType *vtx_ids = NULL;

  BFT_MALLOC(vtx_marker, n_vertices, int);
  BFT_MALLOC(face_array, buf_size, vtkIdType);
  BFT_MALLOC(vtx_ids, buf_size, vtkIdType);

  for (i = 0; i < n_vertices; i++)
    vtx_marker[i] = -1;

  /* Write cell/vertex connectivity */
  /*--------------------------------*/

  for (i = 0; i < section->n_elements; i++) {

    int  m = 0;
    int  cell_vtx_count = 0;
    int  n_elt_faces = section->face_index[i+1] - section->face_index[i];

    for (j = section->face_index[i];
         j < section->face_index[i+1];
         j++) {

      if (section->face_num[j] > 0) {
        face_id = section->face_num[j] - 1;
        face_sgn = 1;
      }
      else {
        face_id = -section->face_num[j] - 1;
        face_sgn = -1;
      }

      face_length = (  section->vertex_index[face_id+1]
                     - section->vertex_index[face_id]);

      while (m + face_length + 1 > buf_size) {
        buf_size *= 2;
        BFT_REALLOC(face_array, buf_size, vtkIdType);
        BFT_REALLOC(vtx_ids, buf_size, vtkIdType);
      }

      face_array[m++] = face_length;

      for (k = 0; k < face_length; k++) {
        int vtx_id;
        l =    section->vertex_index[face_id]
            + (face_length + (k*face_sgn))%face_length;
        vtx_id = section->vertex_num[l] - 1;
        face_array[m++] = vtx_id;
        if (vtx_marker[vtx_id] < i) {
          vtx_ids[cell_vtx_count] = vtx_id;
          vtx_marker[vtx_id] = i;
          cell_vtx_count += 1;
        }
      }

    } /* End of loop on cell faces */

    vtk_mesh->InsertNextCell(VTK_POLYHEDRON, cell_vtx_count,
                             vtx_ids, n_elt_faces, face_array);

  } /* End of loop on polyhedral cells */

  BFT_FREE(vtx_ids);
  BFT_FREE(face_array);
  BFT_FREE(vtx_marker);
}

/*----------------------------------------------------------------------------
 * Write field values associated with nodal values of a nodal mesh to VTK.
 *
 * Output fields ar either scalar or 3d vectors or scalars, and are
 * non interlaced. Input arrays may be less than 2d, in which case the z
 * values are set to 0, and may be interlaced or not.
 *
 * parameters:
 *   mesh             <-- pointer to nodal mesh structure
 *   dim              <-- field dimension
 *   interlace        <-- indicates if field in memory is interlaced
 *   n_parent_lists   <-- indicates if field values are to be obtained
 *                        directly through the local entity index (when 0) or
 *                        through the parent entity numbers (when 1 or more)
 *   parent_num_shift <-- parent list to common number index shifts;
 *                        size: n_parent_lists
 *   datatype         <-- input data type (output is real)
 *   field_values     <-- array of associated field value arrays
 *   f                <-- associated vtkUnstructuredGrid object
 *----------------------------------------------------------------------------*/

static void
_export_field_values_n(const fvm_nodal_t     *mesh,
                       const char            *fieldname,
                       int                   dim,
                       cs_interlace_t        interlace,
                       int                   n_parent_lists,
                       const cs_lnum_t       parent_num_shift[],
                       cs_datatype_t         datatype,
                       const void           *const field_values[],
                       vtkUnstructuredGrid  *f)
{
  assert(f != NULL);

  void *values;
  values = vtkDoubleArray::SafeDownCast
    (f->GetPointData()->GetArray(fieldname))
    ->WritePointer(0, f->GetNumberOfPoints());

  fvm_convert_array(dim,
                    0,
                    dim, 
                    0, 
                    mesh->n_vertices, 
                    interlace,
                    datatype,
                    CS_DOUBLE,
                    n_parent_lists,
                    parent_num_shift,
                    mesh->parent_vertex_num,
                    field_values,
                    values);
}

/*----------------------------------------------------------------------------
 * Write field values associated with element values of a nodal mesh to VTK.
 *
 * Output fields are non interlaced. Input arrays may be interlaced or not.
 *
 * parameters:
 *   mesh             <-- pointer to nodal mesh structure
 *   dim              <-- field dimension
 *   interlace        <-- indicates if field in memory is interlaced
 *   n_parent_lists   <-- indicates if field values are to be obtained
 *                        directly through the local entity index (when 0) or
 *                        through the parent entity numbers (when 1 or more)
 *   parent_num_shift <-- parent list to common number index shifts;
 *                        size: n_parent_lists
 *   datatype         <-- indicates the data type of (source) field values
 *   field_values     <-- array of associated field value arrays
 *   f                <-- associated object handle
 *----------------------------------------------------------------------------*/

static void
_export_field_values_e(const fvm_nodal_t         *mesh,
                       const char                *fieldname,
                       int                        dim,
                       cs_interlace_t             interlace,
                       int                        n_parent_lists,
                       const cs_lnum_t            parent_num_shift[],
                       cs_datatype_t              datatype,
                       const void          *const field_values[],
                       vtkUnstructuredGrid       *f)
{
  assert(f != NULL);

  int  section_id;
  double  *values = NULL;

  values = vtkDoubleArray::SafeDownCast
    (f->GetCellData()->GetArray(fieldname))
    ->WritePointer(0, dim*f->GetNumberOfCells());

  assert(values != NULL);

  /* Distribute partition to block values */

  cs_lnum_t start_id = 0;
  cs_lnum_t src_shift = 0;

  /* loop on sections which should be appended */

  const int  elt_dim = fvm_nodal_get_max_entity_dim(mesh);

  for (section_id = 0; section_id < mesh->n_sections; section_id++) {

    const fvm_nodal_section_t  *section = mesh->sections[section_id];

    if (section->entity_dim < elt_dim)
      continue;

    fvm_convert_array(dim,
                      0,
                      dim,
                      src_shift,
                      section->n_elements + src_shift,
                      interlace,
                      datatype,
                      CS_DOUBLE,
                      n_parent_lists,
                      parent_num_shift,
                      section->parent_element_num,
                      field_values,
                      values + start_id);

    start_id += section->n_elements*dim;
    if (n_parent_lists == 0)
      src_shift += section->n_elements;

  }
}

/*============================================================================
 * Public function definitions
 *============================================================================*/

BEGIN_C_DECLS

/*----------------------------------------------------------------------------
 * Initialize FVM to Catalyst object writer.
 *
 * Options are:
 *   private_comm        use private MPI communicator (default: false)
 *   names=<fmt>         use same naming rules as <fmt> format
 *                       (default: ensight)
 *
 * parameters:
 *   name           <-- base output case name.
 *   options        <-- whitespace separated, lowercase options list
 *   time_dependecy <-- indicates if and how meshes will change with time
 *   comm           <-- associated MPI communicator.
 *
 * returns:
 *   pointer to opaque Catalyst writer structure.
 *----------------------------------------------------------------------------*/

#if defined(HAVE_MPI)
void *
fvm_to_catalyst_init_writer(const char             *name,
                            const char             *path,
                            const char             *options,
                            fvm_writer_time_dep_t   time_dependency,
                            MPI_Comm                comm)
#else
void *
fvm_to_catalyst_init_writer(const char             *name,
                            const char             *path,
                            const char             *options,
                            fvm_writer_time_dep_t   time_dependency)
#endif
{
  fvm_to_catalyst_t  *w = NULL;

  _disable_fe_exceptions();

  /* Initialize writer */

  BFT_MALLOC(w, 1, fvm_to_catalyst_t);

  w->rank = 0;
  w->n_ranks = 1;

  w->mb = vtkMultiBlockDataSet::New();

  w->n_fields  = 0;
  w->fields = NULL;

  w->time_step  = -1;
  w->time_value = 0.0;

  w->private_comm = false;
  w->ensight_names = true;

  /* Writer name */

  if (name != NULL) {
    BFT_MALLOC(w->name, strlen(name) + 1, char);
    strcpy(w->name, name);
  }
  else {
    const char _name[] = "catalyst_writer";
    BFT_MALLOC(w->name, strlen(_name) + 1, char);
    strcpy(w->name, _name);
  }

  /* Parse options */

  if (options != NULL) {

    int i1, i2, l_opt;
    int l_tot = strlen(options);

    i1 = 0; i2 = 0;
    while (i1 < l_tot) {

      for (i2 = i1; i2 < l_tot && options[i2] != ' '; i2++);
      l_opt = i2 - i1;

      if ((l_opt == 12) && (strncmp(options + i1, "private_comm", l_opt) == 0))
        w->private_comm = true;
      else if ((l_opt == 6) && (strncmp(options + i1, "names=", l_opt) == 0)) {
        if ((l_opt == 6+7) && (strncmp(options + i1 + 6, "ensight", 7) == 0))
          w->ensight_names = true;
        else
          w->ensight_names = false;
      }

    }

  }

  /* Parallel parameters */

#if defined(HAVE_MPI)
  if (w->private_comm) {
    int mpi_flag;
    MPI_Initialized(&mpi_flag);

    if (mpi_flag && comm != MPI_COMM_NULL) {
      MPI_Comm_dup(comm, &(w->comm));
      MPI_Comm_rank(w->comm, &(w->rank));
      MPI_Comm_size(w->comm, &(w->n_ranks));
    }
    else
      w->comm = MPI_COMM_NULL;
  }
  else
    w->comm = comm;
#endif /* defined(HAVE_MPI) */

  /* Catalyst pipeline */

  w->processor = vtkCPProcessor::New();
  w->processor->Initialize();

  vtkCPPythonScriptPipeline  *pipeline = vtkCPPythonScriptPipeline::New();
 
  /* read the coprocessing Python file */

  char *script_path = NULL;

  int l = strlen(w->name);
  BFT_MALLOC(script_path, strlen(w->name) + 4, char);
  strcpy(script_path, w->name);
  for (int i = 0; i < l; i++) {
    if (script_path[i] == ' ')
      script_path[i] = '_';
  }
  strcat(script_path, ".py");

  /* check file's existence */

  if (cs_file_isreg(script_path)) {

    if (pipeline->Initialize(script_path) == 0)
      bft_error(__FILE__, __LINE__, 0,
                _("Error initializing pipeline from \"%s\":\n\n"), script_path);
 
    /* pipeline->SetGhostLevel(1); */
    w->processor->AddPipeline(pipeline);
    pipeline->Delete();
 
  }
  else
    bft_error(__FILE__, __LINE__, 0,
              _("Missing Catalyst pipeline file \"%s\":\n\n"), script_path);

  BFT_FREE(script_path);

  w->datadesc = vtkCPDataDescription::New();
  w->datadesc->AddInput("input");

  w->modified = true;

#if defined(CS_FPE_TRAP) && !defined(HAVE_CATALYST)
  if (_fenv_set == 0) {
    if (fegetenv(&_fenv_old) == 0) {
      feenableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW);
      _fenv_set = 1;
      /* To revert to initial behavior: fesetenv(&_fenv_old); */
    }
  }
#endif

  _restore_fe_exceptions();

  return w;
}

/*----------------------------------------------------------------------------
 * Finalize FVM to Catalyst object writer.
 *
 * parameters:
 *   this_writer_p <-- pointer to opaque writer structure.
 *
 * returns:
 *   NULL pointer
 *----------------------------------------------------------------------------*/

void *
fvm_to_catalyst_finalize_writer(void  *this_writer_p)
{
  int i;

  fvm_to_catalyst_t  *w = (fvm_to_catalyst_t *)this_writer_p;

  assert(w != NULL);

  _disable_fe_exceptions();

  /* Write output if not done already */

  fvm_to_catalyst_flush(this_writer_p);

  /* Free structures */

  BFT_FREE(w->name);

  /* Free vtkUnstructuredGrid and field structures
     (reference counters should go to 0) */

  w->processor->Finalize();
  w->processor->Delete();
  w->datadesc->Delete();
  w->mb->Delete();

  for (i = 0; i < w->n_fields; i++) {
    w->fields[i]->f = NULL; // delete w->fields[i]->f;
    BFT_FREE(w->fields[i]);
  }

  BFT_FREE(w->fields);

#if defined(HAVE_MPI)
  {
    if (w->private_comm && w->comm != MPI_COMM_NULL)
      MPI_Comm_free(&(w->comm));
  }
#endif /* defined(HAVE_MPI) */

  /* Free fvm_to_catalyst_t structure */

  BFT_FREE(w);

  _restore_fe_exceptions();

  return NULL;
}

/*----------------------------------------------------------------------------
 * Associate new time step with an Catalyst geometry.
 *
 * parameters:
 *   this_writer_p <-- pointer to associated writer
 *   time_step     <-- time step number
 *   time_value    <-- time_value number
 *----------------------------------------------------------------------------*/

void
fvm_to_catalyst_set_mesh_time(void    *this_writer_p,
                              int      time_step,
                              double   time_value)
{
  fvm_to_catalyst_t  *w = (fvm_to_catalyst_t *)this_writer_p;

  int _time_step = (time_step > -1) ? time_step : 0;
  double _time_value = (time_value > 0.0) ? time_value : 0.0;

  _disable_fe_exceptions();

  if (_time_step > w->time_step) {
    w->time_step = _time_step;
    assert(time_value >= w->time_value);
    w->time_value = _time_value;
    w->datadesc->SetTimeData(w->time_value, w->time_step);
  }

  _restore_fe_exceptions();
}

/*----------------------------------------------------------------------------
 * Write nodal mesh to a Catalyst object
 *
 * parameters:
 *   this_writer_p <-- pointer to associated writer
 *   mesh          <-- pointer to nodal mesh structure that should be written
 *----------------------------------------------------------------------------*/

void
fvm_to_catalyst_export_nodal(void               *this_writer_p,
                             const fvm_nodal_t  *mesh)
{
  int  mesh_id, section_id;

  fvm_to_catalyst_t  *w = (fvm_to_catalyst_t *)this_writer_p;

  const int  elt_dim = fvm_nodal_get_max_entity_dim(mesh);

  _disable_fe_exceptions();

  /* Initialization */
  /*----------------*/

  /* Get matching mesh */

  mesh_id = _get_catalyst_mesh_id(w, mesh->name);

  if (mesh_id < 0)
    mesh_id = _add_catalyst_mesh(w, mesh);

  vtkUnstructuredGrid *ugrid
    = vtkUnstructuredGrid::SafeDownCast
        (vtkDataSet::SafeDownCast(w->mb->GetBlock(mesh_id)));

  /* Vertex coordinates */
  /*--------------------*/

  _export_vertex_coords(mesh, ugrid);

  /* Element connectivity size */
  /*---------------------------*/

  cs_lnum_t  n_elts = 0;

  for (section_id = 0; section_id < mesh->n_sections; section_id++) {

    const fvm_nodal_section_t  *section = mesh->sections[section_id];

    if (section->entity_dim < elt_dim)
      continue;

    n_elts += section->n_elements;

  } /* End of loop on sections */

  if (n_elts > 0)
    ugrid->Allocate(n_elts);

  /* Element connectivity */
  /*----------------------*/

  for (section_id = 0; section_id < mesh->n_sections; section_id++) {

    const fvm_nodal_section_t  *section = mesh->sections[section_id];

    if (section->entity_dim < elt_dim)
      continue;

    if (section->stride > 0)
      _write_connect_block(section->type,
                           section->n_elements,
                           section->vertex_num,
                           ugrid);

    else if (section->type == FVM_FACE_POLY)
      _export_nodal_polygons(section, ugrid);

    else if (section->type == FVM_CELL_POLY)
      _export_nodal_polyhedra(mesh->n_vertices, section, ugrid);

  } /* End of loop on sections */

  w->modified = true;

  _restore_fe_exceptions();
}

/*----------------------------------------------------------------------------
 * Write field associated with a nodal mesh to a Catalyst object.
 *
 * Assigning a negative value to the time step indicates a time-independent
 * field (in which case the time_value argument is unused).
 *
 * parameters:
 *   this_writer_p    <-- pointer to associated writer
 *   mesh             <-- pointer to associated nodal mesh structure
 *   name             <-- variable name
 *   location         <-- variable definition location (nodes or elements)
 *   dimension        <-- variable dimension (0: constant, 1: scalar,
 *                        3: vector, 6: sym. tensor, 9: asym. tensor)
 *   interlace        <-- indicates if variable in memory is interlaced
 *   n_parent_lists   <-- indicates if variable values are to be obtained
 *                        directly through the local entity index (when 0) or
 *                        through the parent entity numbers (when 1 or more)
 *   parent_num_shift <-- parent number to value array index shifts;
 *                        size: n_parent_lists
 *   datatype         <-- indicates the data type of (source) field values
 *   time_step        <-- number of the current time step
 *   time_value       <-- associated time value
 *   field_values     <-- array of associated field value arrays
 *----------------------------------------------------------------------------*/

void
fvm_to_catalyst_export_field(void                  *this_writer_p,
                             const fvm_nodal_t     *mesh,
                             const char            *name,
                             fvm_writer_var_loc_t   location,
                             int                    dimension,
                             cs_interlace_t         interlace,
                             int                    n_parent_lists,
                             const cs_lnum_t        parent_num_shift[],
                             cs_datatype_t          datatype,
                             int                    time_step,
                             double                 time_value,
                             const void      *const field_values[])
{
  int  mesh_id, field_id;
  char _name[128];

  fvm_to_catalyst_t *w = (fvm_to_catalyst_t *)this_writer_p;

  _disable_fe_exceptions();

  /* Initialization */
  /*----------------*/

  mesh_id = _get_catalyst_mesh_id(w, mesh->name);

  strncpy(_name, name, 127);
  _name[127] = '\0';
  if (w->ensight_names) {
    for (int i = 0; i < 127 && _name[i] != '\0'; i++) {
      switch (_name[i]) {
      case '(':
      case ')':
      case ']':
      case '[':
      case '+':
      case '-':
      case '@':
      case ' ':
      case '\t':
      case '!':
      case '#':
      case '*':
      case '^':
      case '$':
      case '/':
        _name[i] = '_';
        break;
      default:
        break;
      }
      if (_name[i] == ' ')
        _name[i] = '_';
    }
  }

  if (mesh_id < 0) {
    mesh_id = _add_catalyst_mesh(w, mesh);
    fvm_to_catalyst_export_nodal(w, mesh);
  }

  /* Get field id */

  field_id = _get_catalyst_field_id(w,
                                    _name,
                                    mesh_id,
                                    dimension,
                                    datatype,
                                    location);

  if (field_id < 0)
    field_id = _add_catalyst_field(w,
                                   _name,
                                   mesh_id,
                                   dimension,
                                   datatype,
                                   location,
                                   time_step,
                                   time_value);

  vtkUnstructuredGrid  *f = w->fields[field_id]->f;

  /* Per node variable */
  /*-------------------*/

  if (location == FVM_WRITER_PER_NODE)
    _export_field_values_n(mesh,
                           _name,
                           dimension,
                           interlace,
                           n_parent_lists,
                           parent_num_shift,
                           datatype,
                           field_values,
                           f);


  /* Per element variable */
  /*----------------------*/

  else if (location == FVM_WRITER_PER_ELEMENT)
    _export_field_values_e(mesh,
                           _name,
                           dimension,
                           interlace,
                           n_parent_lists,
                           parent_num_shift,
                           datatype,
                           field_values,
                           f);

  /* Update field status */
  /*---------------------*/

  fvm_to_catalyst_set_mesh_time(w, time_step, time_value);

  w->modified = true;

  _restore_fe_exceptions();
}

/*----------------------------------------------------------------------------
 * Flush files associated with a given writer.
 *
 * In this case, the effective call to coprocessing is done.
 *
 * parameters:
 *   this_writer_p    <-- pointer to associated writer
 *----------------------------------------------------------------------------*/

void
fvm_to_catalyst_flush(void  *this_writer_p)
{
  fvm_to_catalyst_t *w = (fvm_to_catalyst_t *)this_writer_p;

  _disable_fe_exceptions();

  if (w->processor->RequestDataDescription(w->datadesc) != 0 && w->modified) {
    w->datadesc->GetInputDescriptionByName("input")->SetGrid(w->mb);
    w->processor->CoProcess(w->datadesc);
    w->modified = false;
  }

  _restore_fe_exceptions();
}

/*----------------------------------------------------------------------------*/

END_C_DECLS

#endif /* HAVE_CATALYST */
