/*
 * 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
 */

#include "BLI_utildefines.h"

#include "BLI_math.h"

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

#include "MEM_guardedalloc.h"

#include "BKE_collision.h"
#include "BKE_global.h"
#include "BKE_lib_id.h"
#include "BKE_mesh.h"
#include "BKE_mesh_runtime.h"
#include "BKE_modifier.h"
#include "BKE_pointcache.h"
#include "BKE_scene.h"

#include "MOD_modifiertypes.h"
#include "MOD_util.h"

#include "DEG_depsgraph_query.h"

static void initData(ModifierData *md)
{
  CollisionModifierData *collmd = (CollisionModifierData *)md;

  collmd->x = NULL;
  collmd->xnew = NULL;
  collmd->current_x = NULL;
  collmd->current_xnew = NULL;
  collmd->current_v = NULL;
  collmd->time_x = collmd->time_xnew = -1000;
  collmd->mvert_num = 0;
  collmd->tri_num = 0;
  collmd->is_static = false;
  collmd->bvhtree = NULL;
}

static void freeData(ModifierData *md)
{
  CollisionModifierData *collmd = (CollisionModifierData *)md;

  if (collmd) { /* Seriously? */
    if (collmd->bvhtree) {
      BLI_bvhtree_free(collmd->bvhtree);
      collmd->bvhtree = NULL;
    }

    MEM_SAFE_FREE(collmd->x);
    MEM_SAFE_FREE(collmd->xnew);
    MEM_SAFE_FREE(collmd->current_x);
    MEM_SAFE_FREE(collmd->current_xnew);
    MEM_SAFE_FREE(collmd->current_v);

    MEM_SAFE_FREE(collmd->tri);

    collmd->time_x = collmd->time_xnew = -1000;
    collmd->mvert_num = 0;
    collmd->tri_num = 0;
    collmd->is_static = false;
  }
}

static bool dependsOnTime(ModifierData *UNUSED(md))
{
  return true;
}

static void deformVerts(ModifierData *md,
                        const ModifierEvalContext *ctx,
                        Mesh *mesh,
                        float (*vertexCos)[3],
                        int numVerts)
{
  CollisionModifierData *collmd = (CollisionModifierData *)md;
  Mesh *mesh_src;
  MVert *tempVert = NULL;
  Object *ob = ctx->object;

  if (mesh == NULL) {
    mesh_src = MOD_deform_mesh_eval_get(ob, NULL, NULL, NULL, numVerts, false, false);
  }
  else {
    /* Not possible to use get_mesh() in this case as we'll modify its vertices
     * and get_mesh() would return 'mesh' directly. */
    BKE_id_copy_ex(NULL, (ID *)mesh, (ID **)&mesh_src, LIB_ID_COPY_LOCALIZE);
  }

  if (!ob->pd) {
    printf("CollisionModifier deformVerts: Should not happen!\n");
    return;
  }

  if (mesh_src) {
    float current_time = 0;
    uint mvert_num = 0;

    BKE_mesh_vert_coords_apply(mesh_src, vertexCos);
    BKE_mesh_calc_normals(mesh_src);

    current_time = DEG_get_ctime(ctx->depsgraph);

    if (G.debug & G_DEBUG_SIMDATA) {
      printf("current_time %f, collmd->time_xnew %f\n", current_time, collmd->time_xnew);
    }

    mvert_num = mesh_src->totvert;

    if (current_time < collmd->time_xnew) {
      freeData((ModifierData *)collmd);
    }
    else if (current_time == collmd->time_xnew) {
      if (mvert_num != collmd->mvert_num) {
        freeData((ModifierData *)collmd);
      }
    }

    /* check if mesh has changed */
    if (collmd->x && (mvert_num != collmd->mvert_num)) {
      freeData((ModifierData *)collmd);
    }

    if (collmd->time_xnew == -1000) { /* first time */

      collmd->x = MEM_dupallocN(mesh_src->mvert); /* frame start position */

      for (uint i = 0; i < mvert_num; i++) {
        /* we save global positions */
        mul_m4_v3(ob->obmat, collmd->x[i].co);
      }

      collmd->xnew = MEM_dupallocN(collmd->x);          // frame end position
      collmd->current_x = MEM_dupallocN(collmd->x);     // inter-frame
      collmd->current_xnew = MEM_dupallocN(collmd->x);  // inter-frame
      collmd->current_v = MEM_dupallocN(collmd->x);     // inter-frame

      collmd->mvert_num = mvert_num;

      {
        const MLoop *mloop = mesh_src->mloop;
        const MLoopTri *looptri = BKE_mesh_runtime_looptri_ensure(mesh_src);
        collmd->tri_num = BKE_mesh_runtime_looptri_len(mesh_src);
        MVertTri *tri = MEM_mallocN(sizeof(*tri) * collmd->tri_num, __func__);
        BKE_mesh_runtime_verttri_from_looptri(tri, mloop, looptri, collmd->tri_num);
        collmd->tri = tri;
      }

      /* create bounding box hierarchy */
      collmd->bvhtree = bvhtree_build_from_mvert(
          collmd->x, collmd->tri, collmd->tri_num, ob->pd->pdef_sboft);

      collmd->time_x = collmd->time_xnew = current_time;
      collmd->is_static = true;
    }
    else if (mvert_num == collmd->mvert_num) {
      /* put positions to old positions */
      tempVert = collmd->x;
      collmd->x = collmd->xnew;
      collmd->xnew = tempVert;
      collmd->time_x = collmd->time_xnew;

      memcpy(collmd->xnew, mesh_src->mvert, mvert_num * sizeof(MVert));

      bool is_static = true;

      for (uint i = 0; i < mvert_num; i++) {
        /* we save global positions */
        mul_m4_v3(ob->obmat, collmd->xnew[i].co);

        /* detect motion */
        is_static = is_static && equals_v3v3(collmd->x[i].co, collmd->xnew[i].co);
      }

      memcpy(collmd->current_xnew, collmd->x, mvert_num * sizeof(MVert));
      memcpy(collmd->current_x, collmd->x, mvert_num * sizeof(MVert));

      /* check if GUI setting has changed for bvh */
      if (collmd->bvhtree) {
        if (ob->pd->pdef_sboft != BLI_bvhtree_get_epsilon(collmd->bvhtree)) {
          BLI_bvhtree_free(collmd->bvhtree);
          collmd->bvhtree = bvhtree_build_from_mvert(
              collmd->current_x, collmd->tri, collmd->tri_num, ob->pd->pdef_sboft);
        }
      }

      /* happens on file load (ONLY when i decomment changes in readfile.c) */
      if (!collmd->bvhtree) {
        collmd->bvhtree = bvhtree_build_from_mvert(
            collmd->current_x, collmd->tri, collmd->tri_num, ob->pd->pdef_sboft);
      }
      else if (!collmd->is_static || !is_static) {
        /* recalc static bounding boxes */
        bvhtree_update_from_mvert(collmd->bvhtree,
                                  collmd->current_x,
                                  collmd->current_xnew,
                                  collmd->tri,
                                  collmd->tri_num,
                                  true);
      }

      collmd->is_static = is_static;
      collmd->time_xnew = current_time;
    }
    else if (mvert_num != collmd->mvert_num) {
      freeData((ModifierData *)collmd);
    }
  }

  if (!ELEM(mesh_src, NULL, mesh)) {
    BKE_id_free(NULL, mesh_src);
  }
}

static void updateDepsgraph(ModifierData *UNUSED(md), const ModifierUpdateDepsgraphContext *ctx)
{
  DEG_add_modifier_to_transform_relation(ctx->node, "Collision Modifier");
}

ModifierTypeInfo modifierType_Collision = {
    /* name */ "Collision",
    /* structName */ "CollisionModifierData",
    /* structSize */ sizeof(CollisionModifierData),
    /* type */ eModifierTypeType_OnlyDeform,
    /* flags */ eModifierTypeFlag_AcceptsMesh | eModifierTypeFlag_Single,

    /* copyData */ NULL,

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

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