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

/** \file
 * \ingroup bmesh
 *
 * Pokes a face.
 *
 * Splits a face into a triangle fan.
 */

#include "BLI_math.h"

#include "bmesh.h"

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

#include "BKE_customdata.h"

#define ELE_NEW 1

/**
 * Pokes a face
 *
 * Splits a face into a triangle fan.
 * Iterate over all selected faces, create a new center vertex and
 * create triangles between original face edges and new center vertex.
 */
void bmo_poke_exec(BMesh *bm, BMOperator *op)
{
  const int cd_loop_mdisp_offset = CustomData_get_offset(&bm->ldata, CD_MDISPS);
  BMOIter oiter;
  BMFace *f;

  const float offset = BMO_slot_float_get(op->slots_in, "offset");
  const bool use_relative_offset = BMO_slot_bool_get(op->slots_in, "use_relative_offset");
  const int center_mode = BMO_slot_int_get(op->slots_in, "center_mode");
  void (*bm_face_calc_center_fn)(const BMFace *f, float r_cent[3]);

  switch (center_mode) {
    case BMOP_POKE_MEDIAN_WEIGHTED:
      bm_face_calc_center_fn = BM_face_calc_center_median_weighted;
      break;
    case BMOP_POKE_BOUNDS:
      bm_face_calc_center_fn = BM_face_calc_center_bounds;
      break;
    case BMOP_POKE_MEDIAN:
      bm_face_calc_center_fn = BM_face_calc_center_median;
      break;
    default:
      BLI_assert(0);
      return;
  }

  BMO_ITER (f, &oiter, op->slots_in, "faces", BM_FACE) {
    BMFace *f_new;
    float f_center[3], f_center_mean[3];
    BMVert *v_center = NULL;
    BMLoop *l_iter, *l_first;
    /* only interpolate the central loop from the face once,
     * then copy to all others in the fan */
    BMLoop *l_center_example;

    /* 1.0 or the average length from the center to the face verts */
    float offset_fac;

    int i;

    bm_face_calc_center_fn(f, f_center);
    v_center = BM_vert_create(bm, f_center, NULL, BM_CREATE_NOP);
    BMO_vert_flag_enable(bm, v_center, ELE_NEW);

    if (cd_loop_mdisp_offset != -1) {
      if (center_mode == BMOP_POKE_MEDIAN) {
        copy_v3_v3(f_center_mean, f_center);
      }
      else {
        BM_face_calc_center_median(f, f_center_mean);
      }
    }

    /* handled by BM_loop_interp_from_face */
    // BM_vert_interp_from_face(bm, v_center, f);

    if (use_relative_offset) {
      offset_fac = 0.0f;
    }
    else {
      offset_fac = 1.0f;
    }

    i = 0;
    l_iter = l_first = BM_FACE_FIRST_LOOP(f);
    do {
      BMLoop *l_new;

      f_new = BM_face_create_quad_tri(
          bm, l_iter->v, l_iter->next->v, v_center, NULL, f, BM_CREATE_NOP);
      l_new = BM_FACE_FIRST_LOOP(f_new);

      if (i == 0) {
        l_center_example = l_new->prev;
        BM_loop_interp_from_face(bm, l_center_example, f, true, false);
      }
      else {
        BM_elem_attrs_copy(bm, bm, l_center_example, l_new->prev);
      }

      /* Copy Loop Data */
      BM_elem_attrs_copy(bm, bm, l_iter, l_new);
      BM_elem_attrs_copy(bm, bm, l_iter->next, l_new->next);

      BMO_face_flag_enable(bm, f_new, ELE_NEW);

      if (cd_loop_mdisp_offset != -1) {
        float f_new_center[3];
        BM_face_calc_center_median(f_new, f_new_center);
        BM_face_interp_multires_ex(bm, f_new, f, f_new_center, f_center, cd_loop_mdisp_offset);
      }

      if (use_relative_offset) {
        offset_fac += len_v3v3(f_center, l_iter->v->co);
      }

    } while ((void)i++, (l_iter = l_iter->next) != l_first);

    if (use_relative_offset) {
      offset_fac /= (float)f->len;
    }
    /* else remain at 1.0 */

    copy_v3_v3(v_center->no, f->no);
    madd_v3_v3fl(v_center->co, v_center->no, offset * offset_fac);

    /* Kill Face */
    BM_face_kill(bm, f);
  }

  BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "verts.out", BM_VERT, ELE_NEW);
  BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "faces.out", BM_FACE, ELE_NEW);
}