/* SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup bmesh
 *
 * Wrapper around #BM_mesh_bisect_plane
 */

#include "MEM_guardedalloc.h"

#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_utildefines_stack.h"

#include "bmesh.h"
#include "bmesh_tools.h"

#include "intern/bmesh_operators_private.h" /* own include */

#define ELE_NEW 1
#define ELE_CUT 2
#define ELE_INPUT 4

void bmo_bisect_plane_exec(BMesh *bm, BMOperator *op)
{
  const float dist = BMO_slot_float_get(op->slots_in, "dist");
  const bool use_snap_center = BMO_slot_bool_get(op->slots_in, "use_snap_center");
  const bool clear_outer = BMO_slot_bool_get(op->slots_in, "clear_outer");
  const bool clear_inner = BMO_slot_bool_get(op->slots_in, "clear_inner");

  float plane_co[3];
  float plane_no[3];
  float plane[4];

  BMO_slot_vec_get(op->slots_in, "plane_co", plane_co);
  BMO_slot_vec_get(op->slots_in, "plane_no", plane_no);

  if (is_zero_v3(plane_no)) {
    BMO_error_raise(bm, op, BMO_ERROR_CANCEL, "Zero normal given");
    return;
  }

  plane_from_point_normal_v3(plane, plane_co, plane_no);

  /* tag geometry to bisect */
  BM_mesh_elem_hflag_disable_all(bm, BM_EDGE | BM_FACE, BM_ELEM_TAG, false);
  BMO_slot_buffer_hflag_enable(bm, op->slots_in, "geom", BM_EDGE | BM_FACE, BM_ELEM_TAG, false);

  BMO_slot_buffer_flag_enable(bm, op->slots_in, "geom", BM_ALL_NOLOOP, ELE_INPUT);

  BM_mesh_bisect_plane(bm, plane, use_snap_center, true, ELE_CUT, ELE_NEW, dist);

  if (clear_outer || clear_inner) {
    /* Use an array of vertices because 'geom' contains both verts and edges that may use them.
     * Removing a vert may remove and edge which is later checked by #BMO_ITER.
     * over-allocate the total possible vert count. */
    const int vert_arr_max = min_ii(bm->totvert, BMO_slot_buffer_len(op->slots_in, "geom"));
    BMVert **vert_arr = MEM_mallocN(sizeof(*vert_arr) * (size_t)vert_arr_max, __func__);
    BMOIter siter;
    BMVert *v;
    float plane_inner[4];
    float plane_outer[4];

    STACK_DECLARE(vert_arr);

    copy_v3_v3(plane_outer, plane);
    copy_v3_v3(plane_inner, plane);
    plane_outer[3] = plane[3] - dist;
    plane_inner[3] = plane[3] + dist;

    STACK_INIT(vert_arr, vert_arr_max);

    BMO_ITER (v, &siter, op->slots_in, "geom", BM_VERT) {
      if ((clear_outer && plane_point_side_v3(plane_outer, v->co) > 0.0f) ||
          (clear_inner && plane_point_side_v3(plane_inner, v->co) < 0.0f)) {
        STACK_PUSH(vert_arr, v);
      }
    }

    while ((v = STACK_POP(vert_arr))) {
      BM_vert_kill(bm, v);
    }

    MEM_freeN(vert_arr);
  }

  BMO_slot_buffer_from_enabled_flag(
      bm, op, op->slots_out, "geom.out", BM_ALL_NOLOOP, ELE_NEW | ELE_INPUT);
  BMO_slot_buffer_from_enabled_flag(
      bm, op, op->slots_out, "geom_cut.out", BM_VERT | BM_EDGE, ELE_CUT);
}