/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2010 Blender Foundation. All rights reserved. */

/** \file
 * \ingroup bke
 */

#include "MEM_guardedalloc.h"

#include "BLI_kdopbvh.h"
#include "BLI_math.h"

#include "BKE_editmesh.h"

#include "BKE_editmesh_bvh.h" /* own include */

struct BMBVHTree {
  BVHTree *tree;

  BMLoop *(*looptris)[3];
  int looptris_tot;

  BMesh *bm;

  const float (*cos_cage)[3];
  bool cos_cage_free;

  int flag;
};

BMBVHTree *BKE_bmbvh_new_from_editmesh(BMEditMesh *em,
                                       int flag,
                                       const float (*cos_cage)[3],
                                       const bool cos_cage_free)
{
  return BKE_bmbvh_new(em->bm, em->looptris, em->tottri, flag, cos_cage, cos_cage_free);
}

BMBVHTree *BKE_bmbvh_new_ex(BMesh *bm,
                            BMLoop *(*looptris)[3],
                            int looptris_tot,
                            int flag,
                            const float (*cos_cage)[3],
                            const bool cos_cage_free,
                            bool (*test_fn)(BMFace *, void *user_data),
                            void *user_data)
{
  /* could become argument */
  const float epsilon = FLT_EPSILON * 2.0f;

  BMBVHTree *bmtree = MEM_callocN(sizeof(*bmtree), "BMBVHTree");
  float cos[3][3];
  int tottri;

  /* avoid testing every tri */
  BMFace *f_test, *f_test_prev;
  bool test_fn_ret;

  /* BKE_editmesh_looptri_calc() must be called already */
  BLI_assert(looptris_tot != 0 || bm->totface == 0);

  if (cos_cage) {
    BM_mesh_elem_index_ensure(bm, BM_VERT);
  }

  bmtree->looptris = looptris;
  bmtree->looptris_tot = looptris_tot;
  bmtree->bm = bm;
  bmtree->cos_cage = cos_cage;
  bmtree->cos_cage_free = cos_cage_free;
  bmtree->flag = flag;

  if (test_fn) {
    /* callback must do... */
    BLI_assert(!(flag & (BMBVH_RESPECT_SELECT | BMBVH_RESPECT_HIDDEN)));

    f_test_prev = NULL;
    test_fn_ret = false;

    tottri = 0;
    for (int i = 0; i < looptris_tot; i++) {
      f_test = looptris[i][0]->f;
      if (f_test != f_test_prev) {
        test_fn_ret = test_fn(f_test, user_data);
        f_test_prev = f_test;
      }

      if (test_fn_ret) {
        tottri++;
      }
    }
  }
  else {
    tottri = looptris_tot;
  }

  bmtree->tree = BLI_bvhtree_new(tottri, epsilon, 8, 8);

  f_test_prev = NULL;
  test_fn_ret = false;

  for (int i = 0; i < looptris_tot; i++) {
    if (test_fn) {
      /* NOTE: the arrays won't align now! Take care. */
      f_test = looptris[i][0]->f;
      if (f_test != f_test_prev) {
        test_fn_ret = test_fn(f_test, user_data);
        f_test_prev = f_test;
      }

      if (!test_fn_ret) {
        continue;
      }
    }

    if (cos_cage) {
      copy_v3_v3(cos[0], cos_cage[BM_elem_index_get(looptris[i][0]->v)]);
      copy_v3_v3(cos[1], cos_cage[BM_elem_index_get(looptris[i][1]->v)]);
      copy_v3_v3(cos[2], cos_cage[BM_elem_index_get(looptris[i][2]->v)]);
    }
    else {
      copy_v3_v3(cos[0], looptris[i][0]->v->co);
      copy_v3_v3(cos[1], looptris[i][1]->v->co);
      copy_v3_v3(cos[2], looptris[i][2]->v->co);
    }

    BLI_bvhtree_insert(bmtree->tree, i, (float *)cos, 3);
  }

  BLI_bvhtree_balance(bmtree->tree);

  return bmtree;
}

static bool bm_face_is_select(BMFace *f, void *UNUSED(user_data))
{
  return (BM_elem_flag_test(f, BM_ELEM_SELECT) != 0);
}

static bool bm_face_is_not_hidden(BMFace *f, void *UNUSED(user_data))
{
  return (BM_elem_flag_test(f, BM_ELEM_HIDDEN) == 0);
}

BMBVHTree *BKE_bmbvh_new(BMesh *bm,
                         BMLoop *(*looptris)[3],
                         int looptris_tot,
                         int flag,
                         const float (*cos_cage)[3],
                         const bool cos_cage_free)
{
  bool (*test_fn)(BMFace *, void *user_data);

  if (flag & BMBVH_RESPECT_SELECT) {
    test_fn = bm_face_is_select;
  }
  else if (flag & BMBVH_RESPECT_HIDDEN) {
    test_fn = bm_face_is_not_hidden;
  }
  else {
    test_fn = NULL;
  }

  flag &= ~(BMBVH_RESPECT_SELECT | BMBVH_RESPECT_HIDDEN);

  return BKE_bmbvh_new_ex(
      bm, looptris, looptris_tot, flag, cos_cage, cos_cage_free, test_fn, NULL);
}

void BKE_bmbvh_free(BMBVHTree *bmtree)
{
  BLI_bvhtree_free(bmtree->tree);

  if (bmtree->cos_cage && bmtree->cos_cage_free) {
    MEM_freeN((void *)bmtree->cos_cage);
  }

  MEM_freeN(bmtree);
}

BVHTree *BKE_bmbvh_tree_get(BMBVHTree *bmtree)
{
  return bmtree->tree;
}

/* -------------------------------------------------------------------- */
/* Utility BMesh cast/intersect functions */

/**
 * Return the coords from a triangle.
 */
static void bmbvh_tri_from_face(const float *cos[3],
                                const BMLoop **ltri,
                                const float (*cos_cage)[3])
{
  if (cos_cage == NULL) {
    cos[0] = ltri[0]->v->co;
    cos[1] = ltri[1]->v->co;
    cos[2] = ltri[2]->v->co;
  }
  else {
    cos[0] = cos_cage[BM_elem_index_get(ltri[0]->v)];
    cos[1] = cos_cage[BM_elem_index_get(ltri[1]->v)];
    cos[2] = cos_cage[BM_elem_index_get(ltri[2]->v)];
  }
}

/* Taken from `bvhutils.c`. */

/* -------------------------------------------------------------------- */
/* BKE_bmbvh_ray_cast */

struct RayCastUserData {
  /* from the bmtree */
  const BMLoop *(*looptris)[3];
  const float (*cos_cage)[3];

  /* from the hit */
  float uv[2];
};

static BMFace *bmbvh_ray_cast_handle_hit(BMBVHTree *bmtree,
                                         struct RayCastUserData *bmcb_data,
                                         const BVHTreeRayHit *hit,
                                         float *r_dist,
                                         float r_hitout[3],
                                         float r_cagehit[3])
{
  if (r_hitout) {
    if (bmtree->flag & BMBVH_RETURN_ORIG) {
      BMLoop **ltri = bmtree->looptris[hit->index];
      interp_v3_v3v3v3_uv(r_hitout, ltri[0]->v->co, ltri[1]->v->co, ltri[2]->v->co, bmcb_data->uv);
    }
    else {
      copy_v3_v3(r_hitout, hit->co);
    }

    if (r_cagehit) {
      copy_v3_v3(r_cagehit, hit->co);
    }
  }

  if (r_dist) {
    *r_dist = hit->dist;
  }

  return bmtree->looptris[hit->index][0]->f;
}

static void bmbvh_ray_cast_cb(void *userdata, int index, const BVHTreeRay *ray, BVHTreeRayHit *hit)
{
  struct RayCastUserData *bmcb_data = userdata;
  const BMLoop **ltri = bmcb_data->looptris[index];
  float dist, uv[2];
  const float *tri_cos[3];
  bool isect;

  bmbvh_tri_from_face(tri_cos, ltri, bmcb_data->cos_cage);

  isect =
      (ray->radius > 0.0f ?
           isect_ray_tri_epsilon_v3(ray->origin,
                                    ray->direction,
                                    tri_cos[0],
                                    tri_cos[1],
                                    tri_cos[2],
                                    &dist,
                                    uv,
                                    ray->radius) :
#ifdef USE_KDOPBVH_WATERTIGHT
           isect_ray_tri_watertight_v3(
               ray->origin, ray->isect_precalc, tri_cos[0], tri_cos[1], tri_cos[2], &dist, uv));
#else
           isect_ray_tri_v3(
               ray->origin, ray->direction, tri_cos[0], tri_cos[1], tri_cos[2], &dist, uv));
#endif

  if (isect && dist < hit->dist) {
    hit->dist = dist;
    hit->index = index;

    copy_v3_v3(hit->no, ltri[0]->f->no);

    madd_v3_v3v3fl(hit->co, ray->origin, ray->direction, dist);

    copy_v2_v2(bmcb_data->uv, uv);
  }
}

BMFace *BKE_bmbvh_ray_cast(BMBVHTree *bmtree,
                           const float co[3],
                           const float dir[3],
                           const float radius,
                           float *r_dist,
                           float r_hitout[3],
                           float r_cagehit[3])
{
  BVHTreeRayHit hit;
  struct RayCastUserData bmcb_data;
  const float dist = r_dist ? *r_dist : FLT_MAX;

  if (bmtree->cos_cage) {
    BLI_assert(!(bmtree->bm->elem_index_dirty & BM_VERT));
  }

  hit.dist = dist;
  hit.index = -1;

  /* ok to leave 'uv' uninitialized */
  bmcb_data.looptris = (const BMLoop *(*)[3])bmtree->looptris;
  bmcb_data.cos_cage = (const float(*)[3])bmtree->cos_cage;

  BLI_bvhtree_ray_cast(bmtree->tree, co, dir, radius, &hit, bmbvh_ray_cast_cb, &bmcb_data);

  if (hit.index != -1 && hit.dist != dist) {
    return bmbvh_ray_cast_handle_hit(bmtree, &bmcb_data, &hit, r_dist, r_hitout, r_cagehit);
  }

  return NULL;
}

/* -------------------------------------------------------------------- */
/* bmbvh_ray_cast_cb_filter */

/* Same as BKE_bmbvh_ray_cast but takes a callback to filter out faces.
 */

struct RayCastUserData_Filter {
  struct RayCastUserData bmcb_data;

  BMBVHTree_FaceFilter filter_cb;
  void *filter_userdata;
};

static void bmbvh_ray_cast_cb_filter(void *userdata,
                                     int index,
                                     const BVHTreeRay *ray,
                                     BVHTreeRayHit *hit)
{
  struct RayCastUserData_Filter *bmcb_data_filter = userdata;
  struct RayCastUserData *bmcb_data = &bmcb_data_filter->bmcb_data;
  const BMLoop **ltri = bmcb_data->looptris[index];
  if (bmcb_data_filter->filter_cb(ltri[0]->f, bmcb_data_filter->filter_userdata)) {
    bmbvh_ray_cast_cb(bmcb_data, index, ray, hit);
  }
}

BMFace *BKE_bmbvh_ray_cast_filter(BMBVHTree *bmtree,
                                  const float co[3],
                                  const float dir[3],
                                  const float radius,
                                  float *r_dist,
                                  float r_hitout[3],
                                  float r_cagehit[3],
                                  BMBVHTree_FaceFilter filter_cb,
                                  void *filter_userdata)
{
  BVHTreeRayHit hit;
  struct RayCastUserData_Filter bmcb_data_filter;
  struct RayCastUserData *bmcb_data = &bmcb_data_filter.bmcb_data;

  const float dist = r_dist ? *r_dist : FLT_MAX;

  bmcb_data_filter.filter_cb = filter_cb;
  bmcb_data_filter.filter_userdata = filter_userdata;

  if (bmtree->cos_cage) {
    BLI_assert(!(bmtree->bm->elem_index_dirty & BM_VERT));
  }

  hit.dist = dist;
  hit.index = -1;

  /* ok to leave 'uv' uninitialized */
  bmcb_data->looptris = (const BMLoop *(*)[3])bmtree->looptris;
  bmcb_data->cos_cage = (const float(*)[3])bmtree->cos_cage;

  BLI_bvhtree_ray_cast(
      bmtree->tree, co, dir, radius, &hit, bmbvh_ray_cast_cb_filter, &bmcb_data_filter);
  if (hit.index != -1 && hit.dist != dist) {
    return bmbvh_ray_cast_handle_hit(bmtree, bmcb_data, &hit, r_dist, r_hitout, r_cagehit);
  }

  return NULL;
}

/* -------------------------------------------------------------------- */
/* BKE_bmbvh_find_vert_closest */

struct VertSearchUserData {
  /* from the bmtree */
  const BMLoop *(*looptris)[3];
  const float (*cos_cage)[3];

  /* from the hit */
  float dist_max_sq;
  int index_tri;
};

static void bmbvh_find_vert_closest_cb(void *userdata,
                                       int index,
                                       const float co[3],
                                       BVHTreeNearest *hit)
{
  struct VertSearchUserData *bmcb_data = userdata;
  const BMLoop **ltri = bmcb_data->looptris[index];
  const float dist_max_sq = bmcb_data->dist_max_sq;

  const float *tri_cos[3];
  bmbvh_tri_from_face(tri_cos, ltri, bmcb_data->cos_cage);

  for (int i = 0; i < 3; i++) {
    const float dist_sq = len_squared_v3v3(co, tri_cos[i]);
    if (dist_sq < hit->dist_sq && dist_sq < dist_max_sq) {
      copy_v3_v3(hit->co, tri_cos[i]);
      /* XXX, normal ignores cage */
      copy_v3_v3(hit->no, ltri[i]->v->no);
      hit->dist_sq = dist_sq;
      hit->index = index;
      bmcb_data->index_tri = i;
    }
  }
}

BMVert *BKE_bmbvh_find_vert_closest(BMBVHTree *bmtree, const float co[3], const float dist_max)
{
  BVHTreeNearest hit;
  struct VertSearchUserData bmcb_data;
  const float dist_max_sq = dist_max * dist_max;

  if (bmtree->cos_cage) {
    BLI_assert(!(bmtree->bm->elem_index_dirty & BM_VERT));
  }

  hit.dist_sq = dist_max_sq;
  hit.index = -1;

  bmcb_data.looptris = (const BMLoop *(*)[3])bmtree->looptris;
  bmcb_data.cos_cage = (const float(*)[3])bmtree->cos_cage;
  bmcb_data.dist_max_sq = dist_max_sq;

  BLI_bvhtree_find_nearest(bmtree->tree, co, &hit, bmbvh_find_vert_closest_cb, &bmcb_data);
  if (hit.index != -1) {
    BMLoop **ltri = bmtree->looptris[hit.index];
    return ltri[bmcb_data.index_tri]->v;
  }

  return NULL;
}

struct FaceSearchUserData {
  /* from the bmtree */
  const BMLoop *(*looptris)[3];
  const float (*cos_cage)[3];

  /* from the hit */
  float dist_max_sq;
};

static void bmbvh_find_face_closest_cb(void *userdata,
                                       int index,
                                       const float co[3],
                                       BVHTreeNearest *hit)
{
  struct FaceSearchUserData *bmcb_data = userdata;
  const BMLoop **ltri = bmcb_data->looptris[index];
  const float dist_max_sq = bmcb_data->dist_max_sq;

  const float *tri_cos[3];

  bmbvh_tri_from_face(tri_cos, ltri, bmcb_data->cos_cage);

  float co_close[3];
  closest_on_tri_to_point_v3(co_close, co, UNPACK3(tri_cos));
  const float dist_sq = len_squared_v3v3(co, co_close);
  if (dist_sq < hit->dist_sq && dist_sq < dist_max_sq) {
    /* XXX, normal ignores cage */
    copy_v3_v3(hit->no, ltri[0]->f->no);
    hit->dist_sq = dist_sq;
    hit->index = index;
  }
}

struct BMFace *BKE_bmbvh_find_face_closest(BMBVHTree *bmtree,
                                           const float co[3],
                                           const float dist_max)
{
  BVHTreeNearest hit;
  struct FaceSearchUserData bmcb_data;
  const float dist_max_sq = dist_max * dist_max;

  if (bmtree->cos_cage) {
    BLI_assert(!(bmtree->bm->elem_index_dirty & BM_VERT));
  }

  hit.dist_sq = dist_max_sq;
  hit.index = -1;

  bmcb_data.looptris = (const BMLoop *(*)[3])bmtree->looptris;
  bmcb_data.cos_cage = (const float(*)[3])bmtree->cos_cage;
  bmcb_data.dist_max_sq = dist_max_sq;

  BLI_bvhtree_find_nearest(bmtree->tree, co, &hit, bmbvh_find_face_closest_cb, &bmcb_data);
  if (hit.index != -1) {
    BMLoop **ltri = bmtree->looptris[hit.index];
    return ltri[0]->f;
  }

  return NULL;
}

/* -------------------------------------------------------------------- */
/* BKE_bmbvh_overlap */

struct BMBVHTree_OverlapData {
  const BMBVHTree *tree_pair[2];
  float epsilon;
};

static bool bmbvh_overlap_cb(void *userdata, int index_a, int index_b, int UNUSED(thread))
{
  struct BMBVHTree_OverlapData *data = userdata;
  const BMBVHTree *bmtree_a = data->tree_pair[0];
  const BMBVHTree *bmtree_b = data->tree_pair[1];

  BMLoop **tri_a = bmtree_a->looptris[index_a];
  BMLoop **tri_b = bmtree_b->looptris[index_b];
  const float *tri_a_co[3] = {tri_a[0]->v->co, tri_a[1]->v->co, tri_a[2]->v->co};
  const float *tri_b_co[3] = {tri_b[0]->v->co, tri_b[1]->v->co, tri_b[2]->v->co};
  float ix_pair[2][3];
  int verts_shared = 0;

  if (bmtree_a->looptris == bmtree_b->looptris) {
    if (UNLIKELY(tri_a[0]->f == tri_b[0]->f)) {
      return false;
    }

    verts_shared = (ELEM(tri_a_co[0], UNPACK3(tri_b_co)) + ELEM(tri_a_co[1], UNPACK3(tri_b_co)) +
                    ELEM(tri_a_co[2], UNPACK3(tri_b_co)));

    /* if 2 points are shared, bail out */
    if (verts_shared >= 2) {
      return false;
    }
  }

  return (isect_tri_tri_v3(UNPACK3(tri_a_co), UNPACK3(tri_b_co), ix_pair[0], ix_pair[1]) &&
          /* if we share a vertex, check the intersection isn't a 'point' */
          ((verts_shared == 0) || (len_squared_v3v3(ix_pair[0], ix_pair[1]) > data->epsilon)));
}

BVHTreeOverlap *BKE_bmbvh_overlap(const BMBVHTree *bmtree_a,
                                  const BMBVHTree *bmtree_b,
                                  uint *r_overlap_tot)
{
  struct BMBVHTree_OverlapData data;

  data.tree_pair[0] = bmtree_a;
  data.tree_pair[1] = bmtree_b;
  data.epsilon = max_ff(BLI_bvhtree_get_epsilon(bmtree_a->tree),
                        BLI_bvhtree_get_epsilon(bmtree_b->tree));

  return BLI_bvhtree_overlap(
      bmtree_a->tree, bmtree_b->tree, r_overlap_tot, bmbvh_overlap_cb, &data);
}

static bool bmbvh_overlap_self_cb(void *userdata, int index_a, int index_b, int thread)
{
  if (index_a < index_b) {
    return bmbvh_overlap_cb(userdata, index_a, index_b, thread);
  }
  return false;
}

BVHTreeOverlap *BKE_bmbvh_overlap_self(const BMBVHTree *bmtree, uint *r_overlap_tot)
{
  struct BMBVHTree_OverlapData data;

  data.tree_pair[0] = bmtree;
  data.tree_pair[1] = bmtree;
  data.epsilon = BLI_bvhtree_get_epsilon(bmtree->tree);

  return BLI_bvhtree_overlap(
      bmtree->tree, bmtree->tree, r_overlap_tot, bmbvh_overlap_self_cb, &data);
}