/*
 * 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.
 *
 * The Original Code is Copyright (C) 2005 by the Blender Foundation.
 * All rights reserved.
 */

/** \file
 * \ingroup modifiers
 *
 * EdgeSplit modifier
 *
 * Splits edges in the mesh according to sharpness flag
 * or edge angle (can be used to achieve autosmoothing)
 */

#include "BLI_utildefines.h"

#include "BLI_math.h"

#include "DNA_mesh_types.h"
#include "DNA_object_types.h"

#include "BKE_mesh.h"
#include "BKE_modifier.h"

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

#include "MOD_modifiertypes.h"

static Mesh *doEdgeSplit(Mesh *mesh, EdgeSplitModifierData *emd)
{
  Mesh *result;
  BMesh *bm;
  BMIter iter;
  BMEdge *e;
  const float threshold = cosf(emd->split_angle + 0.000000175f);
  const bool do_split_angle = (emd->flags & MOD_EDGESPLIT_FROMANGLE) != 0 &&
                              emd->split_angle < (float)M_PI;
  const bool do_split_all = do_split_angle && emd->split_angle < FLT_EPSILON;
  const bool calc_face_normals = do_split_angle && !do_split_all;

  bm = BKE_mesh_to_bmesh_ex(mesh,
                            &(struct BMeshCreateParams){0},
                            &(struct BMeshFromMeshParams){
                                .calc_face_normal = calc_face_normals,
                                .add_key_index = false,
                                .use_shapekey = false,
                                .active_shapekey = 0,
                                .cd_mask_extra = {.vmask = CD_MASK_ORIGINDEX,
                                                  .emask = CD_MASK_ORIGINDEX,
                                                  .pmask = CD_MASK_ORIGINDEX},
                            });

  if (do_split_angle) {
    BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
      /* check for 1 edge having 2 face users */
      BMLoop *l1, *l2;
      if ((l1 = e->l) && (l2 = e->l->radial_next) != l1) {
        if (/* 3+ faces on this edge, always split */
            UNLIKELY(l1 != l2->radial_next) ||
            /* O° angle setting, we want to split on all edges. */
            do_split_all ||
            /* 2 face edge - check angle*/
            (dot_v3v3(l1->f->no, l2->f->no) < threshold)) {
          BM_elem_flag_enable(e, BM_ELEM_TAG);
        }
      }
    }
  }

  if (emd->flags & MOD_EDGESPLIT_FROMFLAG) {
    BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
      /* check for 2 or more edge users */
      if ((e->l) && (e->l->next != e->l)) {
        if (!BM_elem_flag_test(e, BM_ELEM_SMOOTH)) {
          BM_elem_flag_enable(e, BM_ELEM_TAG);
        }
      }
    }
  }

  BM_mesh_edgesplit(bm, false, true, false);

  /* BM_mesh_validate(bm); */ /* for troubleshooting */

  result = BKE_mesh_from_bmesh_for_eval_nomain(bm, NULL);
  BM_mesh_free(bm);

  result->runtime.cd_dirty_vert |= CD_MASK_NORMAL;
  return result;
}

static void initData(ModifierData *md)
{
  EdgeSplitModifierData *emd = (EdgeSplitModifierData *)md;

  /* default to 30-degree split angle, sharpness from both angle & flag */
  emd->split_angle = DEG2RADF(30.0f);
  emd->flags = MOD_EDGESPLIT_FROMANGLE | MOD_EDGESPLIT_FROMFLAG;
}

static Mesh *applyModifier(ModifierData *md, const ModifierEvalContext *UNUSED(ctx), Mesh *mesh)
{
  Mesh *result;
  EdgeSplitModifierData *emd = (EdgeSplitModifierData *)md;

  if (!(emd->flags & (MOD_EDGESPLIT_FROMANGLE | MOD_EDGESPLIT_FROMFLAG))) {
    return mesh;
  }

  result = doEdgeSplit(mesh, emd);

  return result;
}

ModifierTypeInfo modifierType_EdgeSplit = {
    /* name */ "EdgeSplit",
    /* structName */ "EdgeSplitModifierData",
    /* structSize */ sizeof(EdgeSplitModifierData),
    /* type */ eModifierTypeType_Constructive,
    /* flags */ eModifierTypeFlag_AcceptsMesh | eModifierTypeFlag_AcceptsCVs |
        eModifierTypeFlag_SupportsMapping | eModifierTypeFlag_SupportsEditmode |
        eModifierTypeFlag_EnableInEditmode,

    /* copyData */ modifier_copyData_generic,

    /* deformVerts */ NULL,
    /* deformMatrices */ NULL,
    /* deformVertsEM */ NULL,
    /* deformMatricesEM */ NULL,
    /* applyModifier */ applyModifier,

    /* initData */ initData,
    /* requiredDataMask */ NULL,
    /* freeData */ NULL,
    /* isDisabled */ NULL,
    /* updateDepsgraph */ NULL,
    /* dependsOnTime */ NULL,
    /* dependsOnNormals */ NULL,
    /* foreachObjectLink */ NULL,
    /* foreachIDLink */ NULL,
    /* foreachTexLink */ NULL,
    /* freeRuntimeData */ NULL,
};