/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2005 Blender Foundation. All rights reserved. */

/** \file
 * \ingroup modifiers
 */

#include "MEM_guardedalloc.h"

#include "BLI_utildefines.h"

#include "BLI_ghash.h"
#include "BLI_math_vector.h"
#include "BLI_rand.h"

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

#include "DEG_depsgraph_query.h"

#include "BKE_context.h"
#include "BKE_mesh.h"
#include "BKE_modifier.h"
#include "BKE_particle.h"
#include "BKE_scene.h"
#include "BKE_screen.h"

#include "UI_interface.h"
#include "UI_resources.h"

#include "RNA_access.h"
#include "RNA_prototypes.h"

#include "MOD_modifiertypes.h"
#include "MOD_ui_common.h"

static void initData(ModifierData *md)
{
  BuildModifierData *bmd = (BuildModifierData *)md;

  BLI_assert(MEMCMP_STRUCT_AFTER_IS_ZERO(bmd, modifier));

  MEMCPY_STRUCT_AFTER(bmd, DNA_struct_default_get(BuildModifierData), modifier);
}

static bool dependsOnTime(struct Scene *UNUSED(scene), ModifierData *UNUSED(md))
{
  return true;
}

static Mesh *modifyMesh(ModifierData *md, const ModifierEvalContext *ctx, struct Mesh *mesh)
{
  Mesh *result;
  BuildModifierData *bmd = (BuildModifierData *)md;
  int i, j, k;
  int faces_dst_num, edges_dst_num, loops_dst_num = 0;
  int *vertMap, *edgeMap, *faceMap;
  float frac;
  MPoly *mpoly_dst;
  MLoop *ml_dst, *ml_src /*, *mloop_dst */;
  GHashIterator gh_iter;
  /* maps vert indices in old mesh to indices in new mesh */
  GHash *vertHash = BLI_ghash_int_new("build ve apply gh");
  /* maps edge indices in new mesh to indices in old mesh */
  GHash *edgeHash = BLI_ghash_int_new("build ed apply gh");
  /* maps edge indices in old mesh to indices in new mesh */
  GHash *edgeHash2 = BLI_ghash_int_new("build ed apply gh");

  const int vert_src_num = mesh->totvert;
  const int edge_src_num = mesh->totedge;
  const int poly_src_num = mesh->totpoly;
  MPoly *mpoly_src = mesh->mpoly;
  MLoop *mloop_src = mesh->mloop;
  MEdge *medge_src = mesh->medge;
  MVert *mvert_src = mesh->mvert;

  vertMap = MEM_malloc_arrayN(vert_src_num, sizeof(*vertMap), "build modifier vertMap");
  edgeMap = MEM_malloc_arrayN(edge_src_num, sizeof(*edgeMap), "build modifier edgeMap");
  faceMap = MEM_malloc_arrayN(poly_src_num, sizeof(*faceMap), "build modifier faceMap");

  range_vn_i(vertMap, vert_src_num, 0);
  range_vn_i(edgeMap, edge_src_num, 0);
  range_vn_i(faceMap, poly_src_num, 0);

  struct Scene *scene = DEG_get_input_scene(ctx->depsgraph);
  frac = (BKE_scene_ctime_get(scene) - bmd->start) / bmd->length;
  CLAMP(frac, 0.0f, 1.0f);
  if (bmd->flag & MOD_BUILD_FLAG_REVERSE) {
    frac = 1.0f - frac;
  }

  faces_dst_num = poly_src_num * frac;
  edges_dst_num = edge_src_num * frac;

  /* if there's at least one face, build based on faces */
  if (faces_dst_num) {
    MPoly *mpoly, *mp;
    MLoop *ml, *mloop;
    uintptr_t hash_num, hash_num_alt;

    if (bmd->flag & MOD_BUILD_FLAG_RANDOMIZE) {
      BLI_array_randomize(faceMap, sizeof(*faceMap), poly_src_num, bmd->seed);
    }

    /* get the set of all vert indices that will be in the final mesh,
     * mapped to the new indices
     */
    mpoly = mpoly_src;
    mloop = mloop_src;
    hash_num = 0;
    for (i = 0; i < faces_dst_num; i++) {
      mp = mpoly + faceMap[i];
      ml = mloop + mp->loopstart;

      for (j = 0; j < mp->totloop; j++, ml++) {
        void **val_p;
        if (!BLI_ghash_ensure_p(vertHash, POINTER_FROM_INT(ml->v), &val_p)) {
          *val_p = (void *)hash_num;
          hash_num++;
        }
      }

      loops_dst_num += mp->totloop;
    }
    BLI_assert(hash_num == BLI_ghash_len(vertHash));

    /* get the set of edges that will be in the new mesh (i.e. all edges
     * that have both verts in the new mesh)
     */
    hash_num = 0;
    hash_num_alt = 0;
    for (i = 0; i < edge_src_num; i++, hash_num_alt++) {
      MEdge *me = medge_src + i;

      if (BLI_ghash_haskey(vertHash, POINTER_FROM_INT(me->v1)) &&
          BLI_ghash_haskey(vertHash, POINTER_FROM_INT(me->v2))) {
        BLI_ghash_insert(edgeHash, (void *)hash_num, (void *)hash_num_alt);
        BLI_ghash_insert(edgeHash2, (void *)hash_num_alt, (void *)hash_num);
        hash_num++;
      }
    }
    BLI_assert(hash_num == BLI_ghash_len(edgeHash));
  }
  else if (edges_dst_num) {
    MEdge *medge, *me;
    uintptr_t hash_num;

    if (bmd->flag & MOD_BUILD_FLAG_RANDOMIZE) {
      BLI_array_randomize(edgeMap, sizeof(*edgeMap), edge_src_num, bmd->seed);
    }

    /* get the set of all vert indices that will be in the final mesh,
     * mapped to the new indices
     */
    medge = medge_src;
    hash_num = 0;
    BLI_assert(hash_num == BLI_ghash_len(vertHash));
    for (i = 0; i < edges_dst_num; i++) {
      void **val_p;
      me = medge + edgeMap[i];

      if (!BLI_ghash_ensure_p(vertHash, POINTER_FROM_INT(me->v1), &val_p)) {
        *val_p = (void *)hash_num;
        hash_num++;
      }
      if (!BLI_ghash_ensure_p(vertHash, POINTER_FROM_INT(me->v2), &val_p)) {
        *val_p = (void *)hash_num;
        hash_num++;
      }
    }
    BLI_assert(hash_num == BLI_ghash_len(vertHash));

    /* get the set of edges that will be in the new mesh */
    for (i = 0; i < edges_dst_num; i++) {
      j = BLI_ghash_len(edgeHash);

      BLI_ghash_insert(edgeHash, POINTER_FROM_INT(j), POINTER_FROM_INT(edgeMap[i]));
      BLI_ghash_insert(edgeHash2, POINTER_FROM_INT(edgeMap[i]), POINTER_FROM_INT(j));
    }
  }
  else {
    int verts_num = vert_src_num * frac;

    if (bmd->flag & MOD_BUILD_FLAG_RANDOMIZE) {
      BLI_array_randomize(vertMap, sizeof(*vertMap), vert_src_num, bmd->seed);
    }

    /* get the set of all vert indices that will be in the final mesh,
     * mapped to the new indices
     */
    for (i = 0; i < verts_num; i++) {
      BLI_ghash_insert(vertHash, POINTER_FROM_INT(vertMap[i]), POINTER_FROM_INT(i));
    }
  }

  /* now we know the number of verts, edges and faces, we can create the mesh. */
  result = BKE_mesh_new_nomain_from_template(
      mesh, BLI_ghash_len(vertHash), BLI_ghash_len(edgeHash), 0, loops_dst_num, faces_dst_num);

  /* copy the vertices across */
  GHASH_ITER (gh_iter, vertHash) {
    MVert source;
    MVert *dest;
    int oldIndex = POINTER_AS_INT(BLI_ghashIterator_getKey(&gh_iter));
    int newIndex = POINTER_AS_INT(BLI_ghashIterator_getValue(&gh_iter));

    source = mvert_src[oldIndex];
    dest = &result->mvert[newIndex];

    CustomData_copy_data(&mesh->vdata, &result->vdata, oldIndex, newIndex, 1);
    *dest = source;
  }

  /* copy the edges across, remapping indices */
  for (i = 0; i < BLI_ghash_len(edgeHash); i++) {
    MEdge source;
    MEdge *dest;
    int oldIndex = POINTER_AS_INT(BLI_ghash_lookup(edgeHash, POINTER_FROM_INT(i)));

    source = medge_src[oldIndex];
    dest = &result->medge[i];

    source.v1 = POINTER_AS_INT(BLI_ghash_lookup(vertHash, POINTER_FROM_INT(source.v1)));
    source.v2 = POINTER_AS_INT(BLI_ghash_lookup(vertHash, POINTER_FROM_INT(source.v2)));

    CustomData_copy_data(&mesh->edata, &result->edata, oldIndex, i, 1);
    *dest = source;
  }

  mpoly_dst = result->mpoly;
  ml_dst = result->mloop;

  /* copy the faces across, remapping indices */
  k = 0;
  for (i = 0; i < faces_dst_num; i++) {
    MPoly *source;
    MPoly *dest;

    source = mpoly_src + faceMap[i];
    dest = mpoly_dst + i;
    CustomData_copy_data(&mesh->pdata, &result->pdata, faceMap[i], i, 1);

    *dest = *source;
    dest->loopstart = k;
    CustomData_copy_data(
        &mesh->ldata, &result->ldata, source->loopstart, dest->loopstart, dest->totloop);

    ml_src = mloop_src + source->loopstart;
    for (j = 0; j < source->totloop; j++, k++, ml_src++, ml_dst++) {
      ml_dst->v = POINTER_AS_INT(BLI_ghash_lookup(vertHash, POINTER_FROM_INT(ml_src->v)));
      ml_dst->e = POINTER_AS_INT(BLI_ghash_lookup(edgeHash2, POINTER_FROM_INT(ml_src->e)));
    }
  }

  BLI_ghash_free(vertHash, NULL, NULL);
  BLI_ghash_free(edgeHash, NULL, NULL);
  BLI_ghash_free(edgeHash2, NULL, NULL);

  MEM_freeN(vertMap);
  MEM_freeN(edgeMap);
  MEM_freeN(faceMap);

  /* TODO(sybren): also copy flags & tags? */
  return result;
}

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

  PointerRNA *ptr = modifier_panel_get_property_pointers(panel, NULL);

  uiLayoutSetPropSep(layout, true);

  uiItemR(layout, ptr, "frame_start", 0, NULL, ICON_NONE);
  uiItemR(layout, ptr, "frame_duration", 0, NULL, ICON_NONE);
  uiItemR(layout, ptr, "use_reverse", 0, NULL, ICON_NONE);

  modifier_panel_end(layout, ptr);
}

static void random_panel_header_draw(const bContext *UNUSED(C), Panel *panel)
{
  uiLayout *layout = panel->layout;

  PointerRNA *ptr = modifier_panel_get_property_pointers(panel, NULL);

  uiItemR(layout, ptr, "use_random_order", 0, NULL, ICON_NONE);
}

static void random_panel_draw(const bContext *UNUSED(C), Panel *panel)
{
  uiLayout *layout = panel->layout;

  PointerRNA *ptr = modifier_panel_get_property_pointers(panel, NULL);

  uiLayoutSetPropSep(layout, true);

  uiLayoutSetActive(layout, RNA_boolean_get(ptr, "use_random_order"));
  uiItemR(layout, ptr, "seed", 0, NULL, ICON_NONE);
}

static void panelRegister(ARegionType *region_type)
{
  PanelType *panel_type = modifier_panel_register(region_type, eModifierType_Build, panel_draw);
  modifier_subpanel_register(
      region_type, "randomize", "", random_panel_header_draw, random_panel_draw, panel_type);
}

ModifierTypeInfo modifierType_Build = {
    /* name */ "Build",
    /* structName */ "BuildModifierData",
    /* structSize */ sizeof(BuildModifierData),
    /* srna */ &RNA_BuildModifier,
    /* type */ eModifierTypeType_Nonconstructive,
    /* flags */ eModifierTypeFlag_AcceptsMesh | eModifierTypeFlag_AcceptsCVs,
    /* icon */ ICON_MOD_BUILD,

    /* copyData */ BKE_modifier_copydata_generic,

    /* deformVerts */ NULL,
    /* deformMatrices */ NULL,
    /* deformVertsEM */ NULL,
    /* deformMatricesEM */ NULL,
    /* modifyMesh */ modifyMesh,
    /* modifyGeometrySet */ NULL,

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