/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2024 Matthieu Schaller (schaller@strw.leidenuniv.nl)
 *                             Yolan Uyttenhove (Yolan.Uyttenhove@UGent.be)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 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 Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/

#ifndef SWIFTSIM_CELL_GRID_H
#define SWIFTSIM_CELL_GRID_H

/* Config parameters. */
#include <config.h>

/* Includes. */
#include <stddef.h>

/* Local includes */
#include "const.h"
#include "shadowswift/voronoi.h"
#include "timeline.h"

/*! @brief Enum indicating the completeness for the Voronoi mesh of this cell.
 *
 * A cell is considered complete when it and its neighbours on the same level in
 * the AMR have at least one particle in every 1/27th cube of the cell (obtained
 * by dividing cells in three along all axes).
 *
 * The Voronoi grid can safely be constructed on any level where the cell is
 * complete. */
enum grid_completeness {
  grid_invalidated_completeness = 0,
  grid_complete,
  grid_incomplete,
};

struct cell_grid {
  /*! Pointer to parent where the grid is constructed. */
  struct cell *construction_level;

  /*! Pointer to shallowest parent of this cell used in any pair construction
   * task. Can be above the construction level of this cell. We need to drift at
   * this level. */
  struct cell *super;

  /*! Whether this cell is complete (at least one particle in all 27 sub-cells
   * if this cell is divided in thirds along each axis). */
  enum grid_completeness self_completeness;

  /*! Whether this cell is itself complete and has directly neighbouring cell
   * on the same level in all directions which are also complete. */
  int complete;

#ifdef WITH_MPI
  /*! Flags indicating whether we should send the faces for the corresponding
   * SIDs over MPI */
  int send_flags;
#endif

  /*! Pointer to the voronoi struct of this cell (if any) */
  struct voronoi *voronoi;

  /*! Pointer to this cells construction task. */
  struct task *construction;

  /*! Linked list of this cells outgoing construction synchronization tasks
   * (i.e. for cells that need this cell for their construction task) */
  struct link *sync_out;

  /*! Linked list of this cells incoming construction synchronization tasks
   * (i.e. cells needed for this cell's construction task) */
  struct link *sync_in;

  /*! Time of last construction */
  integertime_t ti_old;
};

struct pcell_faces {
  size_t counts[27];

  struct voronoi_pair faces[];
};

/*! @brief Enum used to indicate whether a cell is above, below or on the
 * construction level. Only used in the packed cell representation */
enum grid_construction_level {
  grid_above_construction_level,
  grid_on_construction_level,
  grid_below_construction_level
};

#endif  // SWIFTSIM_CELL_GRID_H