/* SPDX-FileCopyrightText: 2005 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup modifiers
 *
 * Edge Split modifier
 *
 * Splits edges in the mesh according to sharpness flag
 * or edge angle (can be used to achieve auto-smoothing)
 */

#include "BLI_math_vector.h"
#include "BLI_utildefines.h"

#include "BLT_translation.hh"

#include "DNA_defaults.h"
#include "DNA_mesh_types.h"
#include "DNA_screen_types.h"

#include "BKE_mesh.hh"
#include "BKE_modifier.hh"

#include "UI_interface.hh"
#include "UI_resources.hh"

#include "RNA_access.hh"
#include "RNA_prototypes.hh"

#include "bmesh.hh"
#include "bmesh_tools.hh"

#include "MOD_ui_common.hh"

#include "GEO_randomize.hh"

/* For edge split modifier node. */
Mesh *doEdgeSplit(const Mesh *mesh, EdgeSplitModifierData *emd);

Mesh *doEdgeSplit(const 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;

  BMeshCreateParams create_params{};
  BMeshFromMeshParams convert_params{};
  convert_params.calc_face_normal = calc_face_normals;
  convert_params.calc_vert_normal = false;
  convert_params.add_key_index = false;
  convert_params.use_shapekey = false;
  convert_params.active_shapekey = 0;
  convert_params.cd_mask_extra.vmask = CD_MASK_ORIGINDEX;
  convert_params.cd_mask_extra.emask = CD_MASK_ORIGINDEX;
  convert_params.cd_mask_extra.pmask = CD_MASK_ORIGINDEX;

  bm = BKE_mesh_to_bmesh_ex(mesh, &create_params, &convert_params);

  if (do_split_angle) {
    BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
      /* check for 1 edge having 2 face users */
      BMLoop *l1 = e->l;
      BMLoop *l2 = (e->l) ? e->l->radial_next : nullptr;
      if (l1 && l2 != l1) {
        if (/* 3+ faces on this edge, always split */
            UNLIKELY(l1 != l2->radial_next) ||
            /* O degree 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);

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

  result = BKE_mesh_from_bmesh_for_eval_nomain(bm, nullptr, mesh);
  BM_mesh_free(bm);

  blender::geometry::debug_randomize_mesh_order(result);

  return result;
}

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

  BLI_assert(MEMCMP_STRUCT_AFTER_IS_ZERO(emd, modifier));

  MEMCPY_STRUCT_AFTER(emd, DNA_struct_default_get(EdgeSplitModifierData), modifier);
}

static Mesh *modify_mesh(ModifierData *md, const ModifierEvalContext * /*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;
}

static void panel_draw(const bContext * /*C*/, Panel *panel)
{
  uiLayout *row, *sub;
  uiLayout *layout = panel->layout;

  PointerRNA *ptr = modifier_panel_get_property_pointers(panel, nullptr);

  uiLayoutSetPropSep(layout, true);

  row = &layout->row(true, IFACE_("Edge Angle"));
  row->prop(ptr, "use_edge_angle", UI_ITEM_NONE, "", ICON_NONE);
  sub = &row->row(true);
  uiLayoutSetActive(sub, RNA_boolean_get(ptr, "use_edge_angle"));
  sub->prop(ptr, "split_angle", UI_ITEM_NONE, "", ICON_NONE);

  layout->prop(ptr, "use_edge_sharp", UI_ITEM_NONE, IFACE_("Sharp Edges"), ICON_NONE);

  modifier_error_message_draw(layout, ptr);
}

static void panel_register(ARegionType *region_type)
{
  modifier_panel_register(region_type, eModifierType_EdgeSplit, panel_draw);
}

ModifierTypeInfo modifierType_EdgeSplit = {
    /*idname*/ "EdgeSplit",
    /*name*/ N_("EdgeSplit"),
    /*struct_name*/ "EdgeSplitModifierData",
    /*struct_size*/ sizeof(EdgeSplitModifierData),
    /*srna*/ &RNA_EdgeSplitModifier,
    /*type*/ ModifierTypeType::Constructive,
    /*flags*/ eModifierTypeFlag_AcceptsMesh | eModifierTypeFlag_AcceptsCVs |
        eModifierTypeFlag_SupportsMapping | eModifierTypeFlag_SupportsEditmode |
        eModifierTypeFlag_EnableInEditmode,
    /*icon*/ ICON_MOD_EDGESPLIT,

    /*copy_data*/ BKE_modifier_copydata_generic,

    /*deform_verts*/ nullptr,
    /*deform_matrices*/ nullptr,
    /*deform_verts_EM*/ nullptr,
    /*deform_matrices_EM*/ nullptr,
    /*modify_mesh*/ modify_mesh,
    /*modify_geometry_set*/ nullptr,

    /*init_data*/ init_data,
    /*required_data_mask*/ nullptr,
    /*free_data*/ nullptr,
    /*is_disabled*/ nullptr,
    /*update_depsgraph*/ nullptr,
    /*depends_on_time*/ nullptr,
    /*depends_on_normals*/ nullptr,
    /*foreach_ID_link*/ nullptr,
    /*foreach_tex_link*/ nullptr,
    /*free_runtime_data*/ nullptr,
    /*panel_register*/ panel_register,
    /*blend_write*/ nullptr,
    /*blend_read*/ nullptr,
    /*foreach_cache*/ nullptr,
};
