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

/** \file
 * \ingroup bke
 */

#include <cmath>
#include <cstdio>
#include <cstring>

#include "DNA_mesh_types.h"
#include "DNA_meshdata_types.h"
#include "DNA_pointcloud_types.h"

#include "BLI_linklist.h"
#include "BLI_math.h"
#include "BLI_span.hh"
#include "BLI_task.h"
#include "BLI_threads.h"
#include "BLI_utildefines.h"

#include "BKE_attribute.hh"
#include "BKE_bvhutils.h"
#include "BKE_editmesh.h"
#include "BKE_mesh.h"
#include "BKE_mesh_runtime.h"

#include "MEM_guardedalloc.h"

using blender::Span;
using blender::VArray;

/* -------------------------------------------------------------------- */
/** \name BVHCache
 * \{ */

struct BVHCacheItem {
  bool is_filled;
  BVHTree *tree;
};

struct BVHCache {
  BVHCacheItem items[BVHTREE_MAX_ITEM];
  ThreadMutex mutex;
};

/**
 * Queries a bvhcache for the cache bvhtree of the request type
 *
 * When the `r_locked` is filled and the tree could not be found the caches mutex will be
 * locked. This mutex can be unlocked by calling `bvhcache_unlock`.
 *
 * When `r_locked` is used the `mesh_eval_mutex` must contain the `MeshRuntime.eval_mutex`.
 */
static bool bvhcache_find(BVHCache **bvh_cache_p,
                          BVHCacheType type,
                          BVHTree **r_tree,
                          bool *r_locked,
                          std::mutex *mesh_eval_mutex)
{
  bool do_lock = r_locked;
  if (r_locked) {
    *r_locked = false;
  }
  if (*bvh_cache_p == nullptr) {
    if (!do_lock) {
      /* Cache does not exist and no lock is requested. */
      return false;
    }
    /* Lazy initialization of the bvh_cache using the `mesh_eval_mutex`. */
    std::lock_guard lock{*mesh_eval_mutex};
    if (*bvh_cache_p == nullptr) {
      *bvh_cache_p = bvhcache_init();
    }
  }
  BVHCache *bvh_cache = *bvh_cache_p;

  if (bvh_cache->items[type].is_filled) {
    *r_tree = bvh_cache->items[type].tree;
    return true;
  }
  if (do_lock) {
    BLI_mutex_lock(&bvh_cache->mutex);
    bool in_cache = bvhcache_find(bvh_cache_p, type, r_tree, nullptr, nullptr);
    if (in_cache) {
      BLI_mutex_unlock(&bvh_cache->mutex);
      return in_cache;
    }
    *r_locked = true;
  }
  return false;
}

static void bvhcache_unlock(BVHCache *bvh_cache, bool lock_started)
{
  if (lock_started) {
    BLI_mutex_unlock(&bvh_cache->mutex);
  }
}

bool bvhcache_has_tree(const BVHCache *bvh_cache, const BVHTree *tree)
{
  if (bvh_cache == nullptr) {
    return false;
  }

  for (int i = 0; i < BVHTREE_MAX_ITEM; i++) {
    if (bvh_cache->items[i].tree == tree) {
      return true;
    }
  }
  return false;
}

BVHCache *bvhcache_init()
{
  BVHCache *cache = MEM_cnew<BVHCache>(__func__);
  BLI_mutex_init(&cache->mutex);
  return cache;
}
/**
 * Inserts a BVHTree of the given type under the cache
 * After that the caller no longer needs to worry when to free the BVHTree
 * as that will be done when the cache is freed.
 *
 * A call to this assumes that there was no previous cached tree of the given type
 * \warning The #BVHTree can be nullptr.
 */
static void bvhcache_insert(BVHCache *bvh_cache, BVHTree *tree, BVHCacheType type)
{
  BVHCacheItem *item = &bvh_cache->items[type];
  BLI_assert(!item->is_filled);
  item->tree = tree;
  item->is_filled = true;
}

void bvhcache_free(BVHCache *bvh_cache)
{
  for (int index = 0; index < BVHTREE_MAX_ITEM; index++) {
    BVHCacheItem *item = &bvh_cache->items[index];
    BLI_bvhtree_free(item->tree);
    item->tree = nullptr;
  }
  BLI_mutex_end(&bvh_cache->mutex);
  MEM_freeN(bvh_cache);
}

/**
 * BVH-tree balancing inside a mutex lock must be run in isolation. Balancing
 * is multithreaded, and we do not want the current thread to start another task
 * that may involve acquiring the same mutex lock that it is waiting for.
 */
static void bvhtree_balance_isolated(void *userdata)
{
  BLI_bvhtree_balance((BVHTree *)userdata);
}

static void bvhtree_balance(BVHTree *tree, const bool isolate)
{
  if (tree) {
    if (isolate) {
      BLI_task_isolate(bvhtree_balance_isolated, tree);
    }
    else {
      BLI_bvhtree_balance(tree);
    }
  }
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Local Callbacks
 * \{ */

/* Math stuff for ray casting on mesh faces and for nearest surface */

float bvhtree_ray_tri_intersection(const BVHTreeRay *ray,
                                   const float /*m_dist*/,
                                   const float v0[3],
                                   const float v1[3],
                                   const float v2[3])
{
  float dist;

#ifdef USE_KDOPBVH_WATERTIGHT
  if (isect_ray_tri_watertight_v3(ray->origin, ray->isect_precalc, v0, v1, v2, &dist, nullptr))
#else
  if (isect_ray_tri_epsilon_v3(
          ray->origin, ray->direction, v0, v1, v2, &dist, nullptr, FLT_EPSILON))
#endif
  {
    return dist;
  }

  return FLT_MAX;
}

float bvhtree_sphereray_tri_intersection(const BVHTreeRay *ray,
                                         float radius,
                                         const float m_dist,
                                         const float v0[3],
                                         const float v1[3],
                                         const float v2[3])
{

  float idist;
  float p1[3];
  float hit_point[3];

  madd_v3_v3v3fl(p1, ray->origin, ray->direction, m_dist);
  if (isect_sweeping_sphere_tri_v3(ray->origin, p1, radius, v0, v1, v2, &idist, hit_point)) {
    return idist * m_dist;
  }

  return FLT_MAX;
}

/*
 * BVH from meshes callbacks
 */

/**
 * Callback to BVH-tree nearest point.
 * The tree must have been built using #bvhtree_from_mesh_faces.
 *
 * \param userdata: Must be a #BVHMeshCallbackUserdata built from the same mesh as the tree.
 */
static void mesh_faces_nearest_point(void *userdata,
                                     int index,
                                     const float co[3],
                                     BVHTreeNearest *nearest)
{
  const BVHTreeFromMesh *data = (BVHTreeFromMesh *)userdata;
  const MVert *vert = data->vert;
  const MFace *face = data->face + index;

  const float *t0, *t1, *t2, *t3;
  t0 = vert[face->v1].co;
  t1 = vert[face->v2].co;
  t2 = vert[face->v3].co;
  t3 = face->v4 ? vert[face->v4].co : nullptr;

  do {
    float nearest_tmp[3], dist_sq;

    closest_on_tri_to_point_v3(nearest_tmp, co, t0, t1, t2);
    dist_sq = len_squared_v3v3(co, nearest_tmp);

    if (dist_sq < nearest->dist_sq) {
      nearest->index = index;
      nearest->dist_sq = dist_sq;
      copy_v3_v3(nearest->co, nearest_tmp);
      normal_tri_v3(nearest->no, t0, t1, t2);
    }

    t1 = t2;
    t2 = t3;
    t3 = nullptr;

  } while (t2);
}
/* copy of function above */
static void mesh_looptri_nearest_point(void *userdata,
                                       int index,
                                       const float co[3],
                                       BVHTreeNearest *nearest)
{
  const BVHTreeFromMesh *data = (BVHTreeFromMesh *)userdata;
  const MVert *vert = data->vert;
  const MLoopTri *lt = &data->looptri[index];
  const float *vtri_co[3] = {
      vert[data->loop[lt->tri[0]].v].co,
      vert[data->loop[lt->tri[1]].v].co,
      vert[data->loop[lt->tri[2]].v].co,
  };
  float nearest_tmp[3], dist_sq;

  closest_on_tri_to_point_v3(nearest_tmp, co, UNPACK3(vtri_co));
  dist_sq = len_squared_v3v3(co, nearest_tmp);

  if (dist_sq < nearest->dist_sq) {
    nearest->index = index;
    nearest->dist_sq = dist_sq;
    copy_v3_v3(nearest->co, nearest_tmp);
    normal_tri_v3(nearest->no, UNPACK3(vtri_co));
  }
}
/* copy of function above (warning, should de-duplicate with editmesh_bvh.c) */
static void editmesh_looptri_nearest_point(void *userdata,
                                           int index,
                                           const float co[3],
                                           BVHTreeNearest *nearest)
{
  const BVHTreeFromEditMesh *data = (const BVHTreeFromEditMesh *)userdata;
  BMEditMesh *em = data->em;
  const BMLoop **ltri = (const BMLoop **)em->looptris[index];

  const float *t0, *t1, *t2;
  t0 = ltri[0]->v->co;
  t1 = ltri[1]->v->co;
  t2 = ltri[2]->v->co;

  {
    float nearest_tmp[3], dist_sq;

    closest_on_tri_to_point_v3(nearest_tmp, co, t0, t1, t2);
    dist_sq = len_squared_v3v3(co, nearest_tmp);

    if (dist_sq < nearest->dist_sq) {
      nearest->index = index;
      nearest->dist_sq = dist_sq;
      copy_v3_v3(nearest->co, nearest_tmp);
      normal_tri_v3(nearest->no, t0, t1, t2);
    }
  }
}

/**
 * Callback to BVH-tree ray-cast.
 * The tree must have been built using bvhtree_from_mesh_faces.
 *
 * \param userdata: Must be a #BVHMeshCallbackUserdata built from the same mesh as the tree.
 */
static void mesh_faces_spherecast(void *userdata,
                                  int index,
                                  const BVHTreeRay *ray,
                                  BVHTreeRayHit *hit)
{
  const BVHTreeFromMesh *data = (BVHTreeFromMesh *)userdata;
  const MVert *vert = data->vert;
  const MFace *face = &data->face[index];

  const float *t0, *t1, *t2, *t3;
  t0 = vert[face->v1].co;
  t1 = vert[face->v2].co;
  t2 = vert[face->v3].co;
  t3 = face->v4 ? vert[face->v4].co : nullptr;

  do {
    float dist;
    if (ray->radius == 0.0f) {
      dist = bvhtree_ray_tri_intersection(ray, hit->dist, t0, t1, t2);
    }
    else {
      dist = bvhtree_sphereray_tri_intersection(ray, ray->radius, hit->dist, t0, t1, t2);
    }

    if (dist >= 0 && dist < hit->dist) {
      hit->index = index;
      hit->dist = dist;
      madd_v3_v3v3fl(hit->co, ray->origin, ray->direction, dist);

      normal_tri_v3(hit->no, t0, t1, t2);
    }

    t1 = t2;
    t2 = t3;
    t3 = nullptr;

  } while (t2);
}
/* copy of function above */
static void mesh_looptri_spherecast(void *userdata,
                                    int index,
                                    const BVHTreeRay *ray,
                                    BVHTreeRayHit *hit)
{
  const BVHTreeFromMesh *data = (BVHTreeFromMesh *)userdata;
  const MVert *vert = data->vert;
  const MLoopTri *lt = &data->looptri[index];
  const float *vtri_co[3] = {
      vert[data->loop[lt->tri[0]].v].co,
      vert[data->loop[lt->tri[1]].v].co,
      vert[data->loop[lt->tri[2]].v].co,
  };
  float dist;

  if (ray->radius == 0.0f) {
    dist = bvhtree_ray_tri_intersection(ray, hit->dist, UNPACK3(vtri_co));
  }
  else {
    dist = bvhtree_sphereray_tri_intersection(ray, ray->radius, hit->dist, UNPACK3(vtri_co));
  }

  if (dist >= 0 && dist < hit->dist) {
    hit->index = index;
    hit->dist = dist;
    madd_v3_v3v3fl(hit->co, ray->origin, ray->direction, dist);

    normal_tri_v3(hit->no, UNPACK3(vtri_co));
  }
}
/* copy of function above (warning, should de-duplicate with editmesh_bvh.c) */
static void editmesh_looptri_spherecast(void *userdata,
                                        int index,
                                        const BVHTreeRay *ray,
                                        BVHTreeRayHit *hit)
{
  const BVHTreeFromEditMesh *data = (BVHTreeFromEditMesh *)userdata;
  BMEditMesh *em = data->em;
  const BMLoop **ltri = (const BMLoop **)em->looptris[index];

  const float *t0, *t1, *t2;
  t0 = ltri[0]->v->co;
  t1 = ltri[1]->v->co;
  t2 = ltri[2]->v->co;

  {
    float dist;
    if (ray->radius == 0.0f) {
      dist = bvhtree_ray_tri_intersection(ray, hit->dist, t0, t1, t2);
    }
    else {
      dist = bvhtree_sphereray_tri_intersection(ray, ray->radius, hit->dist, t0, t1, t2);
    }

    if (dist >= 0 && dist < hit->dist) {
      hit->index = index;
      hit->dist = dist;
      madd_v3_v3v3fl(hit->co, ray->origin, ray->direction, dist);

      normal_tri_v3(hit->no, t0, t1, t2);
    }
  }
}

/**
 * Callback to BVH-tree nearest point.
 * The tree must have been built using #bvhtree_from_mesh_edges.
 *
 * \param userdata: Must be a #BVHMeshCallbackUserdata built from the same mesh as the tree.
 */
static void mesh_edges_nearest_point(void *userdata,
                                     int index,
                                     const float co[3],
                                     BVHTreeNearest *nearest)
{
  const BVHTreeFromMesh *data = (BVHTreeFromMesh *)userdata;
  const MVert *vert = data->vert;
  const MEdge *edge = data->edge + index;
  float nearest_tmp[3], dist_sq;

  const float *t0, *t1;
  t0 = vert[edge->v1].co;
  t1 = vert[edge->v2].co;

  closest_to_line_segment_v3(nearest_tmp, co, t0, t1);
  dist_sq = len_squared_v3v3(nearest_tmp, co);

  if (dist_sq < nearest->dist_sq) {
    nearest->index = index;
    nearest->dist_sq = dist_sq;
    copy_v3_v3(nearest->co, nearest_tmp);
    sub_v3_v3v3(nearest->no, t0, t1);
    normalize_v3(nearest->no);
  }
}

/* Helper, does all the point-sphere-cast work actually. */
static void mesh_verts_spherecast_do(int index,
                                     const float v[3],
                                     const BVHTreeRay *ray,
                                     BVHTreeRayHit *hit)
{
  float dist;
  const float *r1;
  float r2[3], i1[3];
  r1 = ray->origin;
  add_v3_v3v3(r2, r1, ray->direction);

  closest_to_line_segment_v3(i1, v, r1, r2);

  /* No hit if closest point is 'behind' the origin of the ray, or too far away from it. */
  if ((dot_v3v3v3(r1, i1, r2) >= 0.0f) && ((dist = len_v3v3(r1, i1)) < hit->dist)) {
    hit->index = index;
    hit->dist = dist;
    copy_v3_v3(hit->co, i1);
  }
}

static void editmesh_verts_spherecast(void *userdata,
                                      int index,
                                      const BVHTreeRay *ray,
                                      BVHTreeRayHit *hit)
{
  const BVHTreeFromEditMesh *data = (const BVHTreeFromEditMesh *)userdata;
  BMVert *eve = BM_vert_at_index(data->em->bm, index);

  mesh_verts_spherecast_do(index, eve->co, ray, hit);
}

/**
 * Callback to BVH-tree ray-cast.
 * The tree must have been built using bvhtree_from_mesh_verts.
 *
 * \param userdata: Must be a #BVHMeshCallbackUserdata built from the same mesh as the tree.
 */
static void mesh_verts_spherecast(void *userdata,
                                  int index,
                                  const BVHTreeRay *ray,
                                  BVHTreeRayHit *hit)
{
  const BVHTreeFromMesh *data = (BVHTreeFromMesh *)userdata;
  const float *v = data->vert[index].co;

  mesh_verts_spherecast_do(index, v, ray, hit);
}

/**
 * Callback to BVH-tree ray-cast.
 * The tree must have been built using bvhtree_from_mesh_edges.
 *
 * \param userdata: Must be a #BVHMeshCallbackUserdata built from the same mesh as the tree.
 */
static void mesh_edges_spherecast(void *userdata,
                                  int index,
                                  const BVHTreeRay *ray,
                                  BVHTreeRayHit *hit)
{
  const BVHTreeFromMesh *data = (BVHTreeFromMesh *)userdata;
  const MVert *vert = data->vert;
  const MEdge *edge = &data->edge[index];

  const float radius_sq = square_f(ray->radius);
  float dist;
  const float *v1, *v2, *r1;
  float r2[3], i1[3], i2[3];
  v1 = vert[edge->v1].co;
  v2 = vert[edge->v2].co;

  /* In case we get a zero-length edge, handle it as a point! */
  if (equals_v3v3(v1, v2)) {
    mesh_verts_spherecast_do(index, v1, ray, hit);
    return;
  }

  r1 = ray->origin;
  add_v3_v3v3(r2, r1, ray->direction);

  if (isect_line_line_v3(v1, v2, r1, r2, i1, i2)) {
    /* No hit if intersection point is 'behind' the origin of the ray, or too far away from it. */
    if ((dot_v3v3v3(r1, i2, r2) >= 0.0f) && ((dist = len_v3v3(r1, i2)) < hit->dist)) {
      const float e_fac = line_point_factor_v3(i1, v1, v2);
      if (e_fac < 0.0f) {
        copy_v3_v3(i1, v1);
      }
      else if (e_fac > 1.0f) {
        copy_v3_v3(i1, v2);
      }
      /* Ensure ray is really close enough from edge! */
      if (len_squared_v3v3(i1, i2) <= radius_sq) {
        hit->index = index;
        hit->dist = dist;
        copy_v3_v3(hit->co, i2);
      }
    }
  }
}

/** \} */

/*
 * BVH builders
 */

/* -------------------------------------------------------------------- */
/** \name Common Utils
 * \{ */

static void bvhtree_from_mesh_setup_data(BVHTree *tree,
                                         const BVHCacheType bvh_cache_type,
                                         const MVert *vert,
                                         const MEdge *edge,
                                         const MFace *face,
                                         const MLoop *loop,
                                         const MLoopTri *looptri,
                                         const float (*vert_normals)[3],
                                         BVHTreeFromMesh *r_data)
{
  memset(r_data, 0, sizeof(*r_data));

  r_data->tree = tree;

  r_data->vert = vert;
  r_data->edge = edge;
  r_data->face = face;
  r_data->loop = loop;
  r_data->looptri = looptri;
  r_data->vert_normals = vert_normals;

  switch (bvh_cache_type) {
    case BVHTREE_FROM_VERTS:
    case BVHTREE_FROM_LOOSEVERTS:
      /* a nullptr nearest callback works fine
       * remember the min distance to point is the same as the min distance to BV of point */
      r_data->nearest_callback = nullptr;
      r_data->raycast_callback = mesh_verts_spherecast;
      break;

    case BVHTREE_FROM_EDGES:
    case BVHTREE_FROM_LOOSEEDGES:
      r_data->nearest_callback = mesh_edges_nearest_point;
      r_data->raycast_callback = mesh_edges_spherecast;
      break;
    case BVHTREE_FROM_FACES:
      r_data->nearest_callback = mesh_faces_nearest_point;
      r_data->raycast_callback = mesh_faces_spherecast;
      break;
    case BVHTREE_FROM_LOOPTRI:
    case BVHTREE_FROM_LOOPTRI_NO_HIDDEN:
      r_data->nearest_callback = mesh_looptri_nearest_point;
      r_data->raycast_callback = mesh_looptri_spherecast;
      break;
    case BVHTREE_FROM_EM_VERTS:
    case BVHTREE_FROM_EM_EDGES:
    case BVHTREE_FROM_EM_LOOPTRI:
    case BVHTREE_MAX_ITEM:
      BLI_assert(false);
      break;
  }
}

static void bvhtree_from_editmesh_setup_data(BVHTree *tree,
                                             const BVHCacheType bvh_cache_type,
                                             struct BMEditMesh *em,
                                             BVHTreeFromEditMesh *r_data)
{
  memset(r_data, 0, sizeof(*r_data));

  r_data->tree = tree;

  r_data->em = em;

  switch (bvh_cache_type) {
    case BVHTREE_FROM_EM_VERTS:
      r_data->nearest_callback = nullptr;
      r_data->raycast_callback = editmesh_verts_spherecast;
      break;
    case BVHTREE_FROM_EM_EDGES:
      r_data->nearest_callback = nullptr; /* TODO */
      r_data->raycast_callback = nullptr; /* TODO */
      break;
    case BVHTREE_FROM_EM_LOOPTRI:
      r_data->nearest_callback = editmesh_looptri_nearest_point;
      r_data->raycast_callback = editmesh_looptri_spherecast;
      break;

    case BVHTREE_FROM_VERTS:
    case BVHTREE_FROM_LOOSEVERTS:
    case BVHTREE_FROM_EDGES:
    case BVHTREE_FROM_LOOSEEDGES:
    case BVHTREE_FROM_FACES:
    case BVHTREE_FROM_LOOPTRI:
    case BVHTREE_FROM_LOOPTRI_NO_HIDDEN:
    case BVHTREE_MAX_ITEM:
      BLI_assert(false);
      break;
  }
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Vertex Builder
 * \{ */

static BVHTree *bvhtree_from_editmesh_verts_create_tree(float epsilon,
                                                        int tree_type,
                                                        int axis,
                                                        BMEditMesh *em,
                                                        const BLI_bitmap *verts_mask,
                                                        int verts_num_active)
{
  BM_mesh_elem_table_ensure(em->bm, BM_VERT);
  const int verts_num = em->bm->totvert;
  if (verts_mask) {
    BLI_assert(IN_RANGE_INCL(verts_num_active, 0, verts_num));
  }
  else {
    verts_num_active = verts_num;
  }

  BVHTree *tree = BLI_bvhtree_new(verts_num_active, epsilon, tree_type, axis);

  if (tree) {
    for (int i = 0; i < verts_num; i++) {
      if (verts_mask && !BLI_BITMAP_TEST_BOOL(verts_mask, i)) {
        continue;
      }
      BMVert *eve = BM_vert_at_index(em->bm, i);
      BLI_bvhtree_insert(tree, i, eve->co, 1);
    }
    BLI_assert(BLI_bvhtree_get_len(tree) == verts_num_active);
  }

  return tree;
}

static BVHTree *bvhtree_from_mesh_verts_create_tree(float epsilon,
                                                    int tree_type,
                                                    int axis,
                                                    const MVert *vert,
                                                    const int verts_num,
                                                    const BLI_bitmap *verts_mask,
                                                    int verts_num_active)
{
  BVHTree *tree = nullptr;

  if (verts_mask) {
    BLI_assert(IN_RANGE_INCL(verts_num_active, 0, verts_num));
  }
  else {
    verts_num_active = verts_num;
  }

  if (verts_num_active) {
    tree = BLI_bvhtree_new(verts_num_active, epsilon, tree_type, axis);

    if (tree) {
      for (int i = 0; i < verts_num; i++) {
        if (verts_mask && !BLI_BITMAP_TEST_BOOL(verts_mask, i)) {
          continue;
        }
        BLI_bvhtree_insert(tree, i, vert[i].co, 1);
      }
      BLI_assert(BLI_bvhtree_get_len(tree) == verts_num_active);
    }
  }

  return tree;
}

BVHTree *bvhtree_from_editmesh_verts_ex(BVHTreeFromEditMesh *data,
                                        BMEditMesh *em,
                                        const BLI_bitmap *verts_mask,
                                        int verts_num_active,
                                        float epsilon,
                                        int tree_type,
                                        int axis)
{
  BVHTree *tree = nullptr;
  tree = bvhtree_from_editmesh_verts_create_tree(
      epsilon, tree_type, axis, em, verts_mask, verts_num_active);

  bvhtree_balance(tree, false);

  if (data) {
    bvhtree_from_editmesh_setup_data(tree, BVHTREE_FROM_EM_VERTS, em, data);
  }

  return tree;
}

BVHTree *bvhtree_from_editmesh_verts(
    BVHTreeFromEditMesh *data, BMEditMesh *em, float epsilon, int tree_type, int axis)
{
  return bvhtree_from_editmesh_verts_ex(data, em, nullptr, -1, epsilon, tree_type, axis);
}

BVHTree *bvhtree_from_mesh_verts_ex(BVHTreeFromMesh *data,
                                    const MVert *vert,
                                    const int verts_num,
                                    const BLI_bitmap *verts_mask,
                                    int verts_num_active,
                                    float epsilon,
                                    int tree_type,
                                    int axis)
{
  BVHTree *tree = nullptr;
  tree = bvhtree_from_mesh_verts_create_tree(
      epsilon, tree_type, axis, vert, verts_num, verts_mask, verts_num_active);

  bvhtree_balance(tree, false);

  if (data) {
    /* Setup BVHTreeFromMesh */
    bvhtree_from_mesh_setup_data(
        tree, BVHTREE_FROM_VERTS, vert, nullptr, nullptr, nullptr, nullptr, nullptr, data);
  }

  return tree;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Edge Builder
 * \{ */

static BVHTree *bvhtree_from_editmesh_edges_create_tree(float epsilon,
                                                        int tree_type,
                                                        int axis,
                                                        BMEditMesh *em,
                                                        const BLI_bitmap *edges_mask,
                                                        int edges_num_active)
{
  BM_mesh_elem_table_ensure(em->bm, BM_EDGE);
  const int edges_num = em->bm->totedge;

  if (edges_mask) {
    BLI_assert(IN_RANGE_INCL(edges_num_active, 0, edges_num));
  }
  else {
    edges_num_active = edges_num;
  }

  BVHTree *tree = BLI_bvhtree_new(edges_num_active, epsilon, tree_type, axis);

  if (tree) {
    int i;
    BMIter iter;
    BMEdge *eed;
    BM_ITER_MESH_INDEX (eed, &iter, em->bm, BM_EDGES_OF_MESH, i) {
      if (edges_mask && !BLI_BITMAP_TEST_BOOL(edges_mask, i)) {
        continue;
      }
      float co[2][3];
      copy_v3_v3(co[0], eed->v1->co);
      copy_v3_v3(co[1], eed->v2->co);

      BLI_bvhtree_insert(tree, i, co[0], 2);
    }
    BLI_assert(BLI_bvhtree_get_len(tree) == edges_num_active);
  }

  return tree;
}

static BVHTree *bvhtree_from_mesh_edges_create_tree(const MVert *vert,
                                                    const MEdge *edge,
                                                    const int edge_num,
                                                    const BLI_bitmap *edges_mask,
                                                    int edges_num_active,
                                                    float epsilon,
                                                    int tree_type,
                                                    int axis)
{
  BVHTree *tree = nullptr;

  if (edges_mask) {
    BLI_assert(IN_RANGE_INCL(edges_num_active, 0, edge_num));
  }
  else {
    edges_num_active = edge_num;
  }

  if (edges_num_active) {
    /* Create a BVH-tree of the given target */
    tree = BLI_bvhtree_new(edges_num_active, epsilon, tree_type, axis);
    if (tree) {
      for (int i = 0; i < edge_num; i++) {
        if (edges_mask && !BLI_BITMAP_TEST_BOOL(edges_mask, i)) {
          continue;
        }
        float co[2][3];
        copy_v3_v3(co[0], vert[edge[i].v1].co);
        copy_v3_v3(co[1], vert[edge[i].v2].co);

        BLI_bvhtree_insert(tree, i, co[0], 2);
      }
    }
  }

  return tree;
}

BVHTree *bvhtree_from_editmesh_edges_ex(BVHTreeFromEditMesh *data,
                                        BMEditMesh *em,
                                        const BLI_bitmap *edges_mask,
                                        int edges_num_active,
                                        float epsilon,
                                        int tree_type,
                                        int axis)
{
  BVHTree *tree = nullptr;
  tree = bvhtree_from_editmesh_edges_create_tree(
      epsilon, tree_type, axis, em, edges_mask, edges_num_active);

  bvhtree_balance(tree, false);

  if (data) {
    bvhtree_from_editmesh_setup_data(tree, BVHTREE_FROM_EM_EDGES, em, data);
  }

  return tree;
}

BVHTree *bvhtree_from_editmesh_edges(
    BVHTreeFromEditMesh *data, BMEditMesh *em, float epsilon, int tree_type, int axis)
{
  return bvhtree_from_editmesh_edges_ex(data, em, nullptr, -1, epsilon, tree_type, axis);
}

BVHTree *bvhtree_from_mesh_edges_ex(BVHTreeFromMesh *data,
                                    const MVert *vert,
                                    const MEdge *edge,
                                    const int edges_num,
                                    const BLI_bitmap *edges_mask,
                                    int edges_num_active,
                                    float epsilon,
                                    int tree_type,
                                    int axis)
{
  BVHTree *tree = nullptr;
  tree = bvhtree_from_mesh_edges_create_tree(
      vert, edge, edges_num, edges_mask, edges_num_active, epsilon, tree_type, axis);

  bvhtree_balance(tree, false);

  if (data) {
    /* Setup BVHTreeFromMesh */
    bvhtree_from_mesh_setup_data(
        tree, BVHTREE_FROM_EDGES, vert, edge, nullptr, nullptr, nullptr, nullptr, data);
  }

  return tree;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Tessellated Face Builder
 * \{ */

static BVHTree *bvhtree_from_mesh_faces_create_tree(float epsilon,
                                                    int tree_type,
                                                    int axis,
                                                    const MVert *vert,
                                                    const MFace *face,
                                                    const int faces_num,
                                                    const BLI_bitmap *faces_mask,
                                                    int faces_num_active)
{
  BVHTree *tree = nullptr;

  if (faces_num) {
    if (faces_mask) {
      BLI_assert(IN_RANGE_INCL(faces_num_active, 0, faces_num));
    }
    else {
      faces_num_active = faces_num;
    }

    /* Create a BVH-tree of the given target. */
    // printf("%s: building BVH, total=%d\n", __func__, numFaces);
    tree = BLI_bvhtree_new(faces_num_active, epsilon, tree_type, axis);
    if (tree) {
      if (vert && face) {
        for (int i = 0; i < faces_num; i++) {
          float co[4][3];
          if (faces_mask && !BLI_BITMAP_TEST_BOOL(faces_mask, i)) {
            continue;
          }

          copy_v3_v3(co[0], vert[face[i].v1].co);
          copy_v3_v3(co[1], vert[face[i].v2].co);
          copy_v3_v3(co[2], vert[face[i].v3].co);
          if (face[i].v4) {
            copy_v3_v3(co[3], vert[face[i].v4].co);
          }

          BLI_bvhtree_insert(tree, i, co[0], face[i].v4 ? 4 : 3);
        }
      }
      BLI_assert(BLI_bvhtree_get_len(tree) == faces_num_active);
    }
  }

  return tree;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name LoopTri Face Builder
 * \{ */

static BVHTree *bvhtree_from_editmesh_looptri_create_tree(float epsilon,
                                                          int tree_type,
                                                          int axis,
                                                          BMEditMesh *em,
                                                          const BLI_bitmap *looptri_mask,
                                                          int looptri_num_active)
{
  BVHTree *tree = nullptr;
  const int looptri_num = em->tottri;

  if (looptri_num) {
    if (looptri_mask) {
      BLI_assert(IN_RANGE_INCL(looptri_num_active, 0, looptri_num));
    }
    else {
      looptri_num_active = looptri_num;
    }

    /* Create a BVH-tree of the given target */
    // printf("%s: building BVH, total=%d\n", __func__, numFaces);
    tree = BLI_bvhtree_new(looptri_num_active, epsilon, tree_type, axis);
    if (tree) {
      const BMLoop *(*looptris)[3] = (const BMLoop *(*)[3])em->looptris;

      /* Insert BMesh-tessellation triangles into the BVH-tree, unless they are hidden
       * and/or selected. Even if the faces themselves are not selected for the snapped
       * transform, having a vertex selected means the face (and thus it's tessellated
       * triangles) will be moving and will not be a good snap targets. */
      for (int i = 0; i < looptri_num; i++) {
        const BMLoop **ltri = looptris[i];
        bool insert = looptri_mask ? BLI_BITMAP_TEST_BOOL(looptri_mask, i) : true;

        if (insert) {
          /* No reason found to block hit-testing the triangle for snap, so insert it now. */
          float co[3][3];
          copy_v3_v3(co[0], ltri[0]->v->co);
          copy_v3_v3(co[1], ltri[1]->v->co);
          copy_v3_v3(co[2], ltri[2]->v->co);

          BLI_bvhtree_insert(tree, i, co[0], 3);
        }
      }
      BLI_assert(BLI_bvhtree_get_len(tree) == looptri_num_active);
    }
  }

  return tree;
}

static BVHTree *bvhtree_from_mesh_looptri_create_tree(float epsilon,
                                                      int tree_type,
                                                      int axis,
                                                      const MVert *vert,
                                                      const MLoop *mloop,
                                                      const MLoopTri *looptri,
                                                      const int looptri_num,
                                                      const BLI_bitmap *looptri_mask,
                                                      int looptri_num_active)
{
  BVHTree *tree = nullptr;

  if (looptri_mask) {
    BLI_assert(IN_RANGE_INCL(looptri_num_active, 0, looptri_num));
  }
  else {
    looptri_num_active = looptri_num;
  }

  if (looptri_num_active) {
    /* Create a BVH-tree of the given target */
    // printf("%s: building BVH, total=%d\n", __func__, numFaces);
    tree = BLI_bvhtree_new(looptri_num_active, epsilon, tree_type, axis);
    if (tree) {
      if (vert && looptri) {
        for (int i = 0; i < looptri_num; i++) {
          float co[3][3];
          if (looptri_mask && !BLI_BITMAP_TEST_BOOL(looptri_mask, i)) {
            continue;
          }

          copy_v3_v3(co[0], vert[mloop[looptri[i].tri[0]].v].co);
          copy_v3_v3(co[1], vert[mloop[looptri[i].tri[1]].v].co);
          copy_v3_v3(co[2], vert[mloop[looptri[i].tri[2]].v].co);

          BLI_bvhtree_insert(tree, i, co[0], 3);
        }
      }
      BLI_assert(BLI_bvhtree_get_len(tree) == looptri_num_active);
    }
  }

  return tree;
}

BVHTree *bvhtree_from_editmesh_looptri_ex(BVHTreeFromEditMesh *data,
                                          BMEditMesh *em,
                                          const BLI_bitmap *looptri_mask,
                                          int looptri_num_active,
                                          float epsilon,
                                          int tree_type,
                                          int axis)
{
  /* BMESH specific check that we have tessfaces,
   * we _could_ tessellate here but rather not - campbell */

  BVHTree *tree = nullptr;
  tree = bvhtree_from_editmesh_looptri_create_tree(
      epsilon, tree_type, axis, em, looptri_mask, looptri_num_active);

  bvhtree_balance(tree, false);

  if (data) {
    bvhtree_from_editmesh_setup_data(tree, BVHTREE_FROM_EM_LOOPTRI, em, data);
  }
  return tree;
}

BVHTree *bvhtree_from_editmesh_looptri(
    BVHTreeFromEditMesh *data, BMEditMesh *em, float epsilon, int tree_type, int axis)
{
  return bvhtree_from_editmesh_looptri_ex(data, em, nullptr, -1, epsilon, tree_type, axis);
}

BVHTree *bvhtree_from_mesh_looptri_ex(BVHTreeFromMesh *data,
                                      const struct MVert *vert,
                                      const struct MLoop *mloop,
                                      const struct MLoopTri *looptri,
                                      const int looptri_num,
                                      const BLI_bitmap *looptri_mask,
                                      int looptri_num_active,
                                      float epsilon,
                                      int tree_type,
                                      int axis)
{
  BVHTree *tree = nullptr;
  tree = bvhtree_from_mesh_looptri_create_tree(epsilon,
                                               tree_type,
                                               axis,
                                               vert,
                                               mloop,
                                               looptri,
                                               looptri_num,
                                               looptri_mask,
                                               looptri_num_active);

  bvhtree_balance(tree, false);

  if (data) {
    /* Setup BVHTreeFromMesh */
    bvhtree_from_mesh_setup_data(
        tree, BVHTREE_FROM_LOOPTRI, vert, nullptr, nullptr, mloop, looptri, nullptr, data);
  }

  return tree;
}

static BLI_bitmap *loose_verts_map_get(const MEdge *medge,
                                       int edges_num,
                                       const MVert * /*mvert*/,
                                       int verts_num,
                                       int *r_loose_vert_num)
{
  BLI_bitmap *loose_verts_mask = BLI_BITMAP_NEW(verts_num, __func__);
  BLI_bitmap_set_all(loose_verts_mask, true, verts_num);

  const MEdge *e = medge;
  int num_linked_verts = 0;
  for (; edges_num--; e++) {
    if (BLI_BITMAP_TEST(loose_verts_mask, e->v1)) {
      BLI_BITMAP_DISABLE(loose_verts_mask, e->v1);
      num_linked_verts++;
    }
    if (BLI_BITMAP_TEST(loose_verts_mask, e->v2)) {
      BLI_BITMAP_DISABLE(loose_verts_mask, e->v2);
      num_linked_verts++;
    }
  }

  *r_loose_vert_num = verts_num - num_linked_verts;

  return loose_verts_mask;
}

static BLI_bitmap *loose_edges_map_get(const MEdge *medge,
                                       const int edges_len,
                                       int *r_loose_edge_len)
{
  BLI_bitmap *loose_edges_mask = BLI_BITMAP_NEW(edges_len, __func__);

  int loose_edges_len = 0;
  const MEdge *e = medge;
  for (int i = 0; i < edges_len; i++, e++) {
    if (e->flag & ME_LOOSEEDGE) {
      BLI_BITMAP_ENABLE(loose_edges_mask, i);
      loose_edges_len++;
    }
    else {
      BLI_BITMAP_DISABLE(loose_edges_mask, i);
    }
  }

  *r_loose_edge_len = loose_edges_len;

  return loose_edges_mask;
}

static BLI_bitmap *looptri_no_hidden_map_get(const MPoly *mpoly,
                                             const VArray<bool> &hide_poly,
                                             const int looptri_len,
                                             int *r_looptri_active_len)
{
  if (hide_poly.is_single() && !hide_poly.get_internal_single()) {
    return nullptr;
  }
  BLI_bitmap *looptri_mask = BLI_BITMAP_NEW(looptri_len, __func__);

  int looptri_no_hidden_len = 0;
  int looptri_iter = 0;
  int i_poly = 0;
  while (looptri_iter != looptri_len) {
    int mp_totlooptri = mpoly[i_poly].totloop - 2;
    if (hide_poly[i_poly]) {
      looptri_iter += mp_totlooptri;
    }
    else {
      while (mp_totlooptri--) {
        BLI_BITMAP_ENABLE(looptri_mask, looptri_iter);
        looptri_iter++;
        looptri_no_hidden_len++;
      }
    }
    i_poly++;
  }

  *r_looptri_active_len = looptri_no_hidden_len;

  return looptri_mask;
}

BVHTree *BKE_bvhtree_from_mesh_get(struct BVHTreeFromMesh *data,
                                   const struct Mesh *mesh,
                                   const BVHCacheType bvh_cache_type,
                                   const int tree_type)
{
  BVHCache **bvh_cache_p = (BVHCache **)&mesh->runtime->bvh_cache;

  const MLoopTri *looptri = nullptr;
  int looptri_len = 0;
  if (ELEM(bvh_cache_type, BVHTREE_FROM_LOOPTRI, BVHTREE_FROM_LOOPTRI_NO_HIDDEN)) {
    looptri = BKE_mesh_runtime_looptri_ensure(mesh);
    looptri_len = BKE_mesh_runtime_looptri_len(mesh);
  }
  const Span<MVert> verts = mesh->verts();
  const Span<MEdge> edges = mesh->edges();
  const Span<MLoop> loops = mesh->loops();

  /* Setup BVHTreeFromMesh */
  bvhtree_from_mesh_setup_data(nullptr,
                               bvh_cache_type,
                               verts.data(),
                               edges.data(),
                               (const MFace *)CustomData_get_layer(&mesh->fdata, CD_MFACE),
                               loops.data(),
                               looptri,
                               BKE_mesh_vertex_normals_ensure(mesh),
                               data);

  bool lock_started = false;
  data->cached = bvhcache_find(
      bvh_cache_p, bvh_cache_type, &data->tree, &lock_started, &mesh->runtime->eval_mutex);

  if (data->cached) {
    BLI_assert(lock_started == false);

    /* NOTE: #data->tree can be nullptr. */
    return data->tree;
  }

  /* Create BVHTree. */

  BLI_bitmap *mask = nullptr;
  int mask_bits_act_len = -1;

  switch (bvh_cache_type) {
    case BVHTREE_FROM_LOOSEVERTS:
      mask = loose_verts_map_get(
          edges.data(), mesh->totedge, verts.data(), mesh->totvert, &mask_bits_act_len);
      ATTR_FALLTHROUGH;
    case BVHTREE_FROM_VERTS:
      data->tree = bvhtree_from_mesh_verts_create_tree(
          0.0f, tree_type, 6, verts.data(), mesh->totvert, mask, mask_bits_act_len);
      break;

    case BVHTREE_FROM_LOOSEEDGES:
      mask = loose_edges_map_get(edges.data(), mesh->totedge, &mask_bits_act_len);
      ATTR_FALLTHROUGH;
    case BVHTREE_FROM_EDGES:
      data->tree = bvhtree_from_mesh_edges_create_tree(
          verts.data(), edges.data(), mesh->totedge, mask, mask_bits_act_len, 0.0f, tree_type, 6);
      break;

    case BVHTREE_FROM_FACES:
      BLI_assert(!(mesh->totface == 0 && mesh->totpoly != 0));
      data->tree = bvhtree_from_mesh_faces_create_tree(
          0.0f,
          tree_type,
          6,
          verts.data(),
          (const MFace *)CustomData_get_layer(&mesh->fdata, CD_MFACE),
          mesh->totface,
          nullptr,
          -1);
      break;

    case BVHTREE_FROM_LOOPTRI_NO_HIDDEN: {
      blender::bke::AttributeAccessor attributes = mesh->attributes();
      mask = looptri_no_hidden_map_get(
          mesh->polys().data(),
          attributes.lookup_or_default(".hide_poly", ATTR_DOMAIN_FACE, false),
          looptri_len,
          &mask_bits_act_len);
      ATTR_FALLTHROUGH;
    }
    case BVHTREE_FROM_LOOPTRI:
      data->tree = bvhtree_from_mesh_looptri_create_tree(0.0f,
                                                         tree_type,
                                                         6,
                                                         verts.data(),
                                                         loops.data(),
                                                         looptri,
                                                         looptri_len,
                                                         mask,
                                                         mask_bits_act_len);
      break;
    case BVHTREE_FROM_EM_VERTS:
    case BVHTREE_FROM_EM_EDGES:
    case BVHTREE_FROM_EM_LOOPTRI:
    case BVHTREE_MAX_ITEM:
      BLI_assert(false);
      break;
  }

  if (mask != nullptr) {
    MEM_freeN(mask);
  }

  bvhtree_balance(data->tree, lock_started);

  /* Save on cache for later use */
  // printf("BVHTree built and saved on cache\n");
  BLI_assert(data->cached == false);
  data->cached = true;
  bvhcache_insert(*bvh_cache_p, data->tree, bvh_cache_type);
  bvhcache_unlock(*bvh_cache_p, lock_started);

#ifdef DEBUG
  if (data->tree != nullptr) {
    if (BLI_bvhtree_get_tree_type(data->tree) != tree_type) {
      printf("tree_type %d obtained instead of %d\n",
             BLI_bvhtree_get_tree_type(data->tree),
             tree_type);
    }
  }
#endif

  return data->tree;
}

BVHTree *BKE_bvhtree_from_editmesh_get(BVHTreeFromEditMesh *data,
                                       struct BMEditMesh *em,
                                       const int tree_type,
                                       const BVHCacheType bvh_cache_type,
                                       BVHCache **bvh_cache_p,
                                       std::mutex *mesh_eval_mutex)
{
  bool lock_started = false;

  bvhtree_from_editmesh_setup_data(nullptr, bvh_cache_type, em, data);

  if (bvh_cache_p) {
    data->cached = bvhcache_find(
        bvh_cache_p, bvh_cache_type, &data->tree, &lock_started, mesh_eval_mutex);

    if (data->cached) {
      BLI_assert(lock_started == false);
      return data->tree;
    }
  }

  switch (bvh_cache_type) {
    case BVHTREE_FROM_EM_VERTS:
      data->tree = bvhtree_from_editmesh_verts_create_tree(0.0f, tree_type, 6, em, nullptr, -1);
      break;
    case BVHTREE_FROM_EM_EDGES:
      data->tree = bvhtree_from_editmesh_edges_create_tree(0.0f, tree_type, 6, em, nullptr, -1);
      break;
    case BVHTREE_FROM_EM_LOOPTRI:
      data->tree = bvhtree_from_editmesh_looptri_create_tree(0.0f, tree_type, 6, em, nullptr, -1);
      break;
    case BVHTREE_FROM_VERTS:
    case BVHTREE_FROM_EDGES:
    case BVHTREE_FROM_FACES:
    case BVHTREE_FROM_LOOPTRI:
    case BVHTREE_FROM_LOOPTRI_NO_HIDDEN:
    case BVHTREE_FROM_LOOSEVERTS:
    case BVHTREE_FROM_LOOSEEDGES:
    case BVHTREE_MAX_ITEM:
      BLI_assert(false);
      break;
  }

  bvhtree_balance(data->tree, lock_started);

  if (bvh_cache_p) {
    /* Save on cache for later use */
    // printf("BVHTree built and saved on cache\n");
    BLI_assert(data->cached == false);
    data->cached = true;
    bvhcache_insert(*bvh_cache_p, data->tree, bvh_cache_type);
    bvhcache_unlock(*bvh_cache_p, lock_started);
  }

#ifdef DEBUG
  if (data->tree != nullptr) {
    if (BLI_bvhtree_get_tree_type(data->tree) != tree_type) {
      printf("tree_type %d obtained instead of %d\n",
             BLI_bvhtree_get_tree_type(data->tree),
             tree_type);
    }
  }
#endif

  return data->tree;
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Free Functions
 * \{ */

void free_bvhtree_from_editmesh(struct BVHTreeFromEditMesh *data)
{
  if (data->tree) {
    if (!data->cached) {
      BLI_bvhtree_free(data->tree);
    }
    memset(data, 0, sizeof(*data));
  }
}

void free_bvhtree_from_mesh(struct BVHTreeFromMesh *data)
{
  if (data->tree && !data->cached) {
    BLI_bvhtree_free(data->tree);
  }

  memset(data, 0, sizeof(*data));
}

/** \} */

/* -------------------------------------------------------------------- */
/** \name Point Cloud BVH Building
 * \{ */

BVHTree *BKE_bvhtree_from_pointcloud_get(BVHTreeFromPointCloud *data,
                                         const PointCloud *pointcloud,
                                         const int tree_type)
{
  BVHTree *tree = BLI_bvhtree_new(pointcloud->totpoint, 0.0f, tree_type, 6);
  if (!tree) {
    return nullptr;
  }

  blender::bke::AttributeAccessor attributes = pointcloud->attributes();
  blender::VArraySpan<blender::float3> positions = attributes.lookup_or_default<blender::float3>(
      "position", ATTR_DOMAIN_POINT, blender::float3(0));

  for (const int i : positions.index_range()) {
    BLI_bvhtree_insert(tree, i, positions[i], 1);
  }
  BLI_assert(BLI_bvhtree_get_len(tree) == pointcloud->totpoint);
  bvhtree_balance(tree, false);

  data->coords = (const float(*)[3])positions.data();
  data->tree = tree;
  data->nearest_callback = nullptr;

  return tree;
}

void free_bvhtree_from_pointcloud(BVHTreeFromPointCloud *data)
{
  if (data->tree) {
    BLI_bvhtree_free(data->tree);
  }
  memset(data, 0, sizeof(*data));
}

/** \} */