/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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) 2007 Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Geoffrey Bantle.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/bmesh/intern/bmesh_construct.c
 *  \ingroup bmesh
 *
 * BM construction functions.
 */

#include "MEM_guardedalloc.h"

#include "BLI_array.h"
#include "BLI_math.h"

#include "BKE_customdata.h"

#include "DNA_meshdata_types.h"

#include "bmesh.h"
#include "intern/bmesh_private.h"

#define SELECT 1

/* prototypes */
static void bm_loop_attrs_copy(BMesh *source_mesh, BMesh *target_mesh,
                               const BMLoop *source_loop, BMLoop *target_loop);

/**
 * \brief Make Quad/Triangle
 *
 * Creates a new quad or triangle from a list of 3 or 4 vertices.
 * If \a no_double is true, then a check is done to see if a face
 * with these vertices already exists and returns it instead.
 *
 * If a pointer to an example face is provided, it's custom data
 * and properties will be copied to the new face.
 *
 * \note The winding of the face is determined by the order
 * of the vertices in the vertex array.
 */

BMFace *BM_face_create_quad_tri(BMesh *bm,
                                BMVert *v1, BMVert *v2, BMVert *v3, BMVert *v4,
                                const BMFace *example, const bool no_double)
{
	BMVert *vtar[4] = {v1, v2, v3, v4};
	return BM_face_create_quad_tri_v(bm, vtar, v4 ? 4 : 3, example, no_double);
}

BMFace *BM_face_create_quad_tri_v(BMesh *bm, BMVert **verts, int len, const BMFace *example, const bool no_double)
{
	BMFace *f = NULL;
	bool is_overlap = false;

	/* sanity check - debug mode only */
	if (len == 3) {
		BLI_assert(verts[0] != verts[1]);
		BLI_assert(verts[0] != verts[2]);
		BLI_assert(verts[1] != verts[2]);
	}
	else if (len == 4) {
		BLI_assert(verts[0] != verts[1]);
		BLI_assert(verts[0] != verts[2]);
		BLI_assert(verts[0] != verts[3]);

		BLI_assert(verts[1] != verts[2]);
		BLI_assert(verts[1] != verts[3]);

		BLI_assert(verts[2] != verts[3]);
	}
	else {
		BLI_assert(0);
	}


	if (no_double) {
		/* check if face exists or overlaps */
		is_overlap = BM_face_exists(verts, len, &f);
	}

	/* make new face */
	if ((f == NULL) && (!is_overlap)) {
		BMEdge *edar[4] = {NULL};
		edar[0] = BM_edge_create(bm, verts[0], verts[1], NULL, BM_CREATE_NO_DOUBLE);
		edar[1] = BM_edge_create(bm, verts[1], verts[2], NULL, BM_CREATE_NO_DOUBLE);
		if (len == 4) {
			edar[2] = BM_edge_create(bm, verts[2], verts[3], NULL, BM_CREATE_NO_DOUBLE);
			edar[3] = BM_edge_create(bm, verts[3], verts[0], NULL, BM_CREATE_NO_DOUBLE);
		}
		else {
			edar[2] = BM_edge_create(bm, verts[2], verts[0], NULL, BM_CREATE_NO_DOUBLE);
		}

		f = BM_face_create(bm, verts, edar, len, 0);

		if (example && f) {
			BM_elem_attrs_copy(bm, bm, example, f);
		}
	}

	return f;
}

/**
 * \brief copies face loop data from shared adjacent faces.
 * \note when a matching edge is found, both loops of that edge are copied
 * this is done since the face may not be completely surrounded by faces,
 * this way: a quad with 2 connected quads on either side will still get all 4 loops updated */
void BM_face_copy_shared(BMesh *bm, BMFace *f)
{
	BMLoop *l_first;
	BMLoop *l_iter;

	l_iter = l_first = BM_FACE_FIRST_LOOP(f);
	do {
		BMLoop *l_other = l_iter->radial_next;

		if (l_other && l_other != l_iter) {
			if (l_other->v == l_iter->v) {
				bm_loop_attrs_copy(bm, bm, l_other, l_iter);
				bm_loop_attrs_copy(bm, bm, l_other->next, l_iter->next);
			}
			else {
				bm_loop_attrs_copy(bm, bm, l_other->next, l_iter);
				bm_loop_attrs_copy(bm, bm, l_other, l_iter->next);
			}
			/* since we copy both loops of the shared edge, step over the next loop here */
			if ((l_iter = l_iter->next) == l_first) {
				break;
			}
		}
	} while ((l_iter = l_iter->next) != l_first);
}

/**
 * \brief Make NGon
 *
 * Makes an ngon from an unordered list of edges. \a v1 and \a v2
 * must be the verts defining edges[0],
 * and define the winding of the new face.
 *
 * \a edges are not required to be ordered, simply to to form
 * a single closed loop as a whole.
 *
 * \note While this function will work fine when the edges
 * are already sorted, if the edges are always going to be sorted,
 * #BM_face_create should be considered over this function as it
 * avoids some unnecessary work.
 */
BMFace *BM_face_create_ngon(BMesh *bm, BMVert *v1, BMVert *v2, BMEdge **edges, const int len, const int create_flag)
{
	BMEdge **edges_sort = BLI_array_alloca(edges_sort, len);
	BMVert **verts_sort = BLI_array_alloca(verts_sort, len + 1);
	int esort_index = 0;
	int vsort_index = 0;

	BMFace *f = NULL;
	BMEdge *e;
	BMVert *v, *ev1, *ev2;
	int i;
	bool is_v1_found, is_reverse;


	/* this code is hideous, yeek.  I'll have to think about ways of
	 *  cleaning it up.  basically, it now combines the old BM_face_create_ngon
	 *  _and_ the old bmesh_mf functions, so its kindof smashed together
	 * - joeedh */

	BLI_assert(len && v1 && v2 && edges && bm);

	/* put edges in correct order */
	for (i = 0; i < len; i++) {
		BM_ELEM_API_FLAG_ENABLE(edges[i], _FLAG_MF);
	}

	ev1 = edges[0]->v1;
	ev2 = edges[0]->v2;

	if (v1 == ev2) {
		/* Swapping here improves performance and consistency of face
		 * structure in the special case that the edges are already in
		 * the correct order and winding */
		SWAP(BMVert *, ev1, ev2);
	}

	verts_sort[vsort_index++] = ev1;
	v = ev2;
	e = edges[0];
	do {
		BMEdge *e2 = e;

		/* vertex array is (len + 1) */
		if (UNLIKELY(vsort_index > len)) {
			goto err; /* vertex in loop twice */
		}

		verts_sort[vsort_index++] = v;
		edges_sort[esort_index++] = e;

		/* we only flag the verts to check if they are in the face more than once */
		BM_ELEM_API_FLAG_ENABLE(v, _FLAG_MV);

		do {
			e2 = bmesh_disk_edge_next(e2, v);
			if (e2 != e && BM_ELEM_API_FLAG_TEST(e2, _FLAG_MF)) {
				v = BM_edge_other_vert(e2, v);
				break;
			}
		} while (e2 != e);

		if (UNLIKELY(e2 == e)) {
			goto err; /* the edges do not form a closed loop */
		}

		e = e2;
	} while (e != edges[0]);

	if (UNLIKELY(esort_index != len)) {
		goto err; /* we didn't use all edges in forming the boundary loop */
	}

	/* ok, edges are in correct order, now ensure they are going
	 * in the correct direction */
	is_v1_found = is_reverse = false;
	for (i = 0; i < len; i++) {
		if (BM_vert_in_edge(edges_sort[i], v1)) {
			/* see if v1 and v2 are in the same edge */
			if (BM_vert_in_edge(edges_sort[i], v2)) {
				/* if v1 is shared by the *next* edge, then the winding
				 * is incorrect */
				if (BM_vert_in_edge(edges_sort[(i + 1) % len], v1)) {
					is_reverse = true;
					break;
				}
			}

			is_v1_found = true;
		}

		if ((is_v1_found == false) && BM_vert_in_edge(edges_sort[i], v2)) {
			is_reverse = true;
			break;
		}
	}

	if (is_reverse) {
		for (i = 0; i < len / 2; i++) {
			v = verts_sort[i];
			verts_sort[i] = verts_sort[len - i - 1];
			verts_sort[len - i - 1] = v;
		}
	}

	for (i = 0; i < len; i++) {
		edges_sort[i] = BM_edge_exists(verts_sort[i], verts_sort[(i + 1) % len]);
		if (UNLIKELY(edges_sort[i] == NULL)) {
			goto err;
		}

		/* check if vert is in face more than once. if the flag is disabled. we've already visited */
		if (UNLIKELY(!BM_ELEM_API_FLAG_TEST(verts_sort[i], _FLAG_MV))) {
			goto err;
		}
		BM_ELEM_API_FLAG_DISABLE(verts_sort[i], _FLAG_MV);
	}

	f = BM_face_create(bm, verts_sort, edges_sort, len, create_flag);

	/* clean up flags */
	for (i = 0; i < len; i++) {
		BM_ELEM_API_FLAG_DISABLE(edges_sort[i], _FLAG_MF);
	}

	return f;

err:
	for (i = 0; i < len; i++) {
		BM_ELEM_API_FLAG_DISABLE(edges[i], _FLAG_MF);
	}
	for (i = 0; i < vsort_index; i++) {
		BM_ELEM_API_FLAG_DISABLE(verts_sort[i], _FLAG_MV);
	}

	return NULL;
}

/**
 * Create an ngon from an array of sorted verts
 *
 * Special features this has over other functions.
 * - Optionally calculate winding based on surrounding edges.
 * - Optionally create edges between vertices.
 * - Uses verts so no need to find edges (handy when you only have verts)
 */
BMFace *BM_face_create_ngon_verts(BMesh *bm, BMVert **vert_arr, const int len, const int create_flag,
                                  const bool calc_winding, const bool create_edges)
{
	BMEdge **edge_arr = BLI_array_alloca(edge_arr, len);
	unsigned int winding[2] = {0, 0};
	int i, i_prev = len - 1;

	BLI_assert(len > 2);

	for (i = 0; i < len; i++) {
		if (create_edges) {
			edge_arr[i] = BM_edge_create(bm, vert_arr[i_prev], vert_arr[i], NULL, BM_CREATE_NO_DOUBLE);
		}
		else {
			edge_arr[i] = BM_edge_exists(vert_arr[i_prev], vert_arr[i]);
			if (edge_arr[i] == NULL) {
				return NULL;
			}
		}

		if (calc_winding) {
			/* the edge may exist already and be attached to a face
			 * in this case we can find the best winding to use for the new face */
			if (edge_arr[i]->l) {
				BMVert *test_v1, *test_v2;
				/* we want to use the reverse winding to the existing order */
				BM_edge_ordered_verts(edge_arr[i], &test_v2, &test_v1);
				winding[(vert_arr[i_prev] == test_v2)]++;
			}
		}

		i_prev = i;
	}

	/* --- */

	if (calc_winding) {
		if (winding[0] < winding[1]) {
			winding[0] = 1;
			winding[1] = 0;
		}
		else {
			winding[0] = 0;
			winding[1] = 1;
		}
	}
	else {
		winding[0] = 0;
		winding[1] = 1;
	}

	/* --- */

	/* create the face */
	return BM_face_create_ngon(bm, vert_arr[winding[0]], vert_arr[winding[1]], edge_arr, len, create_flag);
}


typedef struct AngleIndexPair {
	float angle;
	int index;
} AngleIndexPair;

static int angle_index_pair_cmp(const void *e1, const void *e2)
{
	const AngleIndexPair *p1 = e1, *p2 = e2;
	if      (p1->angle > p2->angle) return  1;
	else if (p1->angle < p2->angle) return -1;
	else return 0;
}

/**
 * Makes an NGon from an un-ordered set of verts
 *
 * assumes...
 * - that verts are only once in the list.
 * - that the verts have roughly planer bounds
 * - that the verts are roughly circular
 * there can be concave areas but overlapping folds from the center point will fail.
 *
 * a brief explanation of the method used
 * - find the center point
 * - find the normal of the vcloud
 * - order the verts around the face based on their angle to the normal vector at the center point.
 *
 * \note Since this is a vcloud there is no direction.
 */
BMFace *BM_face_create_ngon_vcloud(BMesh *bm, BMVert **vert_arr, int len, const int create_flag)
{
	BMFace *f;

	float totv_inv = 1.0f / (float)len;
	int i = 0;

	float cent[3], nor[3];

	float *far = NULL, *far_cross = NULL;

	float far_vec[3];
	float far_cross_vec[3];
	float sign_vec[3]; /* work out if we are pos/neg angle */

	float far_dist, far_best;
	float far_cross_dist, far_cross_best = 0.0f;

	AngleIndexPair *vang;

	BMVert **vert_arr_map;

	/* get the center point and collect vector array since we loop over these a lot */
	zero_v3(cent);
	for (i = 0; i < len; i++) {
		madd_v3_v3fl(cent, vert_arr[i]->co, totv_inv);
	}


	/* find the far point from cent */
	far_best = 0.0f;
	for (i = 0; i < len; i++) {
		far_dist = len_squared_v3v3(vert_arr[i]->co, cent);
		if (far_dist > far_best || far == NULL) {
			far = vert_arr[i]->co;
			far_best = far_dist;
		}
	}

	sub_v3_v3v3(far_vec, far, cent);
	// far_dist = len_v3(far_vec); /* real dist */ /* UNUSED */

	/* --- */

	/* find a point 90deg about to compare with */
	far_cross_best = 0.0f;
	for (i = 0; i < len; i++) {

		if (far == vert_arr[i]->co) {
			continue;
		}

		sub_v3_v3v3(far_cross_vec, vert_arr[i]->co, cent);
		far_cross_dist = normalize_v3(far_cross_vec);

		/* more of a weight then a distance */
		far_cross_dist = (/* first we want to have a value close to zero mapped to 1 */
		                  1.0f - fabsf(dot_v3v3(far_vec, far_cross_vec)) *

		                  /* second  we multiply by the distance
		                   * so points close to the center are not preferred */
		                  far_cross_dist);

		if (far_cross_dist > far_cross_best || far_cross == NULL) {
			far_cross = vert_arr[i]->co;
			far_cross_best = far_cross_dist;
		}
	}

	sub_v3_v3v3(far_cross_vec, far_cross, cent);

	/* --- */

	/* now we have 2 vectors we can have a cross product */
	cross_v3_v3v3(nor, far_vec, far_cross_vec);
	normalize_v3(nor);
	cross_v3_v3v3(sign_vec, far_vec, nor); /* this vector should match 'far_cross_vec' closely */

	/* --- */

	/* now calculate every points angle around the normal (signed) */
	vang = MEM_mallocN(sizeof(AngleIndexPair) * len, __func__);

	for (i = 0; i < len; i++) {
		float co[3];
		float proj_vec[3];
		float angle;

		/* center relative vec */
		sub_v3_v3v3(co, vert_arr[i]->co, cent);

		/* align to plane */
		project_v3_v3v3(proj_vec, co, nor);
		sub_v3_v3(co, proj_vec);

		/* now 'co' is valid - we can compare its angle against the far vec */
		angle = angle_v3v3(far_vec, co);

		if (dot_v3v3(co, sign_vec) < 0.0f) {
			angle = -angle;
		}

		vang[i].angle = angle;
		vang[i].index = i;
	}

	/* sort by angle and magic! - we have our ngon */
	qsort(vang, len, sizeof(AngleIndexPair), angle_index_pair_cmp);

	/* --- */

	/* create edges and find the winding (if faces are attached to any existing edges) */
	vert_arr_map = MEM_mallocN(sizeof(BMVert **) * len, __func__);

	for (i = 0; i < len; i++) {
		vert_arr_map[i] = vert_arr[vang[i].index];
	}
	MEM_freeN(vang);

	f = BM_face_create_ngon_verts(bm, vert_arr_map, len, create_flag, true, true);

	MEM_freeN(vert_arr_map);

	return f;
}

/**
 * Called by operators to remove elements that they have marked for
 * removal.
 */
void BMO_remove_tagged_faces(BMesh *bm, const short oflag)
{
	BMFace *f;
	BMIter iter;

	BM_ITER_MESH (f, &iter, bm, BM_FACES_OF_MESH) {
		if (BMO_elem_flag_test(bm, f, oflag)) {
			BM_face_kill(bm, f);
		}
	}
}

void BMO_remove_tagged_edges(BMesh *bm, const short oflag)
{
	BMEdge *e;
	BMIter iter;

	BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
		if (BMO_elem_flag_test(bm, e, oflag)) {
			BM_edge_kill(bm, e);
		}
	}
}

void BMO_remove_tagged_verts(BMesh *bm, const short oflag)
{
	BMVert *v;
	BMIter iter;

	BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
		if (BMO_elem_flag_test(bm, v, oflag)) {
			BM_vert_kill(bm, v);
		}
	}
}

/**
 * you need to make remove tagged verts/edges/faces
 * api functions that take a filter callback.....
 * and this new filter type will be for opstack flags.
 * This is because the BM_remove_taggedXXX functions bypass iterator API.
 *  - Ops don't care about 'UI' considerations like selection state, hide state, etc.
 *    If you want to work on unhidden selections for instance,
 *    copy output from a 'select context' operator to another operator....
 */

static void bmo_remove_tagged_context_verts(BMesh *bm, const short oflag)
{
	BMVert *v;
	BMEdge *e;
	BMFace *f;

	BMIter iter;
	BMIter itersub;

	BM_ITER_MESH (v, &iter, bm, BM_VERTS_OF_MESH) {
		if (BMO_elem_flag_test(bm, v, oflag)) {
			/* Visit edge */
			BM_ITER_ELEM (e, &itersub, v, BM_EDGES_OF_VERT) {
				BMO_elem_flag_enable(bm, e, oflag);
			}
			/* Visit face */
			BM_ITER_ELEM (f, &itersub, v, BM_FACES_OF_VERT) {
				BMO_elem_flag_enable(bm, f, oflag);
			}
		}
	}

	BMO_remove_tagged_faces(bm, oflag);
	BMO_remove_tagged_edges(bm, oflag);
	BMO_remove_tagged_verts(bm, oflag);
}

static void bmo_remove_tagged_context_edges(BMesh *bm, const short oflag)
{
	BMEdge *e;
	BMFace *f;

	BMIter iter;
	BMIter itersub;

	BM_ITER_MESH (e, &iter, bm, BM_EDGES_OF_MESH) {
		if (BMO_elem_flag_test(bm, e, oflag)) {
			BM_ITER_ELEM (f, &itersub, e, BM_FACES_OF_EDGE) {
				BMO_elem_flag_enable(bm, f, oflag);
			}
		}
	}
	BMO_remove_tagged_faces(bm, oflag);
	BMO_remove_tagged_edges(bm, oflag);
}

#define DEL_WIREVERT	(1 << 10)

/**
 * \warning oflag applies to different types in some contexts,
 * not just the type being removed.
 *
 * \warning take care, uses operator flag DEL_WIREVERT
 */
void BMO_remove_tagged_context(BMesh *bm, const short oflag, const int type)
{
	BMVert *v;
	BMEdge *e;
	BMFace *f;

	BMIter viter;
	BMIter eiter;
	BMIter fiter;

	switch (type) {
		case DEL_VERTS:
		{
			bmo_remove_tagged_context_verts(bm, oflag);

			break;
		}
		case DEL_EDGES:
		{
			/* flush down to vert */
			BM_ITER_MESH (e, &eiter, bm, BM_EDGES_OF_MESH) {
				if (BMO_elem_flag_test(bm, e, oflag)) {
					BMO_elem_flag_enable(bm, e->v1, oflag);
					BMO_elem_flag_enable(bm, e->v2, oflag);
				}
			}
			bmo_remove_tagged_context_edges(bm, oflag);
			/* remove loose vertice */
			BM_ITER_MESH (v, &viter, bm, BM_VERTS_OF_MESH) {
				if (BMO_elem_flag_test(bm, v, oflag) && (!(v->e)))
					BMO_elem_flag_enable(bm, v, DEL_WIREVERT);
			}
			BMO_remove_tagged_verts(bm, DEL_WIREVERT);

			break;
		}
		case DEL_EDGESFACES:
		{
			bmo_remove_tagged_context_edges(bm, oflag);

			break;
		}
		case DEL_ONLYFACES:
		{
			BMO_remove_tagged_faces(bm, oflag);

			break;
		}
		case DEL_ONLYTAGGED:
		{
			BMO_remove_tagged_faces(bm, oflag);
			BMO_remove_tagged_edges(bm, oflag);
			BMO_remove_tagged_verts(bm, oflag);

			break;
		}
		case DEL_FACES:
		{
			/* go through and mark all edges and all verts of all faces for delete */
			BM_ITER_MESH (f, &fiter, bm, BM_FACES_OF_MESH) {
				if (BMO_elem_flag_test(bm, f, oflag)) {
					for (e = BM_iter_new(&eiter, bm, BM_EDGES_OF_FACE, f); e; e = BM_iter_step(&eiter))
						BMO_elem_flag_enable(bm, e, oflag);
					for (v = BM_iter_new(&viter, bm, BM_VERTS_OF_FACE, f); v; v = BM_iter_step(&viter))
						BMO_elem_flag_enable(bm, v, oflag);
				}
			}
			/* now go through and mark all remaining faces all edges for keeping */
			BM_ITER_MESH (f, &fiter, bm, BM_FACES_OF_MESH) {
				if (!BMO_elem_flag_test(bm, f, oflag)) {
					for (e = BM_iter_new(&eiter, bm, BM_EDGES_OF_FACE, f); e; e = BM_iter_step(&eiter)) {
						BMO_elem_flag_disable(bm, e, oflag);
					}
					for (v = BM_iter_new(&viter, bm, BM_VERTS_OF_FACE, f); v; v = BM_iter_step(&viter)) {
						BMO_elem_flag_disable(bm, v, oflag);
					}
				}
			}
			/* also mark all the vertices of remaining edges for keeping */
			BM_ITER_MESH (e, &eiter, bm, BM_EDGES_OF_MESH) {
				if (!BMO_elem_flag_test(bm, e, oflag)) {
					BMO_elem_flag_disable(bm, e->v1, oflag);
					BMO_elem_flag_disable(bm, e->v2, oflag);
				}
			}
			/* now delete marked face */
			BMO_remove_tagged_faces(bm, oflag);
			/* delete marked edge */
			BMO_remove_tagged_edges(bm, oflag);
			/* remove loose vertice */
			BMO_remove_tagged_verts(bm, oflag);

			break;
		}
		case DEL_ALL:
		{
			/* does this option even belong in here? */
			BM_ITER_MESH (f, &fiter, bm, BM_FACES_OF_MESH) {
				BMO_elem_flag_enable(bm, f, oflag);
			}
			BM_ITER_MESH (e, &eiter, bm, BM_EDGES_OF_MESH) {
				BMO_elem_flag_enable(bm, e, oflag);
			}
			BM_ITER_MESH (v, &viter, bm, BM_VERTS_OF_MESH) {
				BMO_elem_flag_enable(bm, v, oflag);
			}

			BMO_remove_tagged_faces(bm, oflag);
			BMO_remove_tagged_edges(bm, oflag);
			BMO_remove_tagged_verts(bm, oflag);

			break;
		}
	}
}
/*************************************************************/


static void bm_vert_attrs_copy(BMesh *source_mesh, BMesh *target_mesh,
                               const BMVert *source_vertex, BMVert *target_vertex)
{
	if ((source_mesh == target_mesh) && (source_vertex == target_vertex)) {
		BLI_assert(!"BMVert: source and targer match");
		return;
	}
	copy_v3_v3(target_vertex->no, source_vertex->no);
	CustomData_bmesh_free_block_data(&target_mesh->vdata, &target_vertex->head.data);
	CustomData_bmesh_copy_data(&source_mesh->vdata, &target_mesh->vdata,
	                           source_vertex->head.data, &target_vertex->head.data);
}

static void bm_edge_attrs_copy(BMesh *source_mesh, BMesh *target_mesh,
                               const BMEdge *source_edge, BMEdge *target_edge)
{
	if ((source_mesh == target_mesh) && (source_edge == target_edge)) {
		BLI_assert(!"BMEdge: source and targer match");
		return;
	}
	CustomData_bmesh_free_block_data(&target_mesh->edata, &target_edge->head.data);
	CustomData_bmesh_copy_data(&source_mesh->edata, &target_mesh->edata,
	                           source_edge->head.data, &target_edge->head.data);
}

static void bm_loop_attrs_copy(BMesh *source_mesh, BMesh *target_mesh,
                               const BMLoop *source_loop, BMLoop *target_loop)
{
	if ((source_mesh == target_mesh) && (source_loop == target_loop)) {
		BLI_assert(!"BMLoop: source and targer match");
		return;
	}
	CustomData_bmesh_free_block_data(&target_mesh->ldata, &target_loop->head.data);
	CustomData_bmesh_copy_data(&source_mesh->ldata, &target_mesh->ldata,
	                           source_loop->head.data, &target_loop->head.data);
}

static void bm_face_attrs_copy(BMesh *source_mesh, BMesh *target_mesh,
                               const BMFace *source_face, BMFace *target_face)
{
	if ((source_mesh == target_mesh) && (source_face == target_face)) {
		BLI_assert(!"BMFace: source and targer match");
		return;
	}
	copy_v3_v3(target_face->no, source_face->no);
	CustomData_bmesh_free_block_data(&target_mesh->pdata, &target_face->head.data);
	CustomData_bmesh_copy_data(&source_mesh->pdata, &target_mesh->pdata,
	                           source_face->head.data, &target_face->head.data);
	target_face->mat_nr = source_face->mat_nr;
}

/* BMESH_TODO: Special handling for hide flags? */
/* BMESH_TODO: swap src/dst args, everywhere else in bmesh does other way round */

/**
 * Copies attributes, e.g. customdata, header flags, etc, from one element
 * to another of the same type.
 */
void BM_elem_attrs_copy_ex(BMesh *bm_src, BMesh *bm_dst, const void *ele_src_v, void *ele_dst_v,
                           const char hflag_mask)
{
	const BMHeader *ele_src = ele_src_v;
	BMHeader *ele_dst = ele_dst_v;

	BLI_assert(ele_src->htype == ele_dst->htype);

	if (ele_src->htype != ele_dst->htype) {
		BLI_assert(!"type mismatch");
		return;
	}

	if ((hflag_mask & BM_ELEM_SELECT) == 0) {
		/* First we copy select */
		if (BM_elem_flag_test((BMElem *)ele_src, BM_ELEM_SELECT)) {
			BM_elem_select_set(bm_dst, (BMElem *)ele_dst, true);
		}
	}

	/* Now we copy flags */
	if (hflag_mask == 0) {
		ele_dst->hflag = ele_src->hflag;
	}
	else {
		ele_dst->hflag = ((ele_dst->hflag & hflag_mask) | (ele_src->hflag & ~hflag_mask));
	}

	/* Copy specific attributes */
	switch (ele_dst->htype) {
		case BM_VERT:
			bm_vert_attrs_copy(bm_src, bm_dst, (const BMVert *)ele_src, (BMVert *)ele_dst);
			break;
		case BM_EDGE:
			bm_edge_attrs_copy(bm_src, bm_dst, (const BMEdge *)ele_src, (BMEdge *)ele_dst);
			break;
		case BM_LOOP:
			bm_loop_attrs_copy(bm_src, bm_dst, (const BMLoop *)ele_src, (BMLoop *)ele_dst);
			break;
		case BM_FACE:
			bm_face_attrs_copy(bm_src, bm_dst, (const BMFace *)ele_src, (BMFace *)ele_dst);
			break;
		default:
			BLI_assert(0);
	}
}

void BM_elem_attrs_copy(BMesh *bm_src, BMesh *bm_dst, const void *ele_src, void *ele_dst)
{
	/* BMESH_TODO, default 'use_flags' to false */
	BM_elem_attrs_copy_ex(bm_src, bm_dst, ele_src, ele_dst, 0);
}

/* helper function for 'BM_mesh_copy' */
static BMFace *bm_mesh_copy_new_face(BMesh *bm_new, BMesh *bm_old,
                                     BMVert **vtable, BMEdge **etable,
                                     BMFace *f)
{
	BMLoop **loops = BLI_array_alloca(loops, f->len);
	BMVert **verts = BLI_array_alloca(verts, f->len);
	BMEdge **edges = BLI_array_alloca(edges, f->len);

	BMFace *f_new;
	BMLoop *l_iter, *l_first;
	int j;

	j = 0;
	l_iter = l_first = BM_FACE_FIRST_LOOP(f);
	do {
		loops[j] = l_iter;
		verts[j] = vtable[BM_elem_index_get(l_iter->v)];
		edges[j] = etable[BM_elem_index_get(l_iter->e)];
		j++;
	} while ((l_iter = l_iter->next) != l_first);

	f_new = BM_face_create(bm_new, verts, edges, f->len, BM_CREATE_SKIP_CD);

	if (UNLIKELY(f_new == NULL)) {
		return NULL;
	}

	/* use totface in case adding some faces fails */
	BM_elem_index_set(f_new, (bm_new->totface - 1)); /* set_inline */

	BM_elem_attrs_copy(bm_old, bm_new, f, f_new);

	j = 0;
	l_iter = l_first = BM_FACE_FIRST_LOOP(f_new);
	do {
		BM_elem_attrs_copy(bm_old, bm_new, loops[j], l_iter);
		j++;
	} while ((l_iter = l_iter->next) != l_first);

	return f_new;
}

void BM_mesh_copy_init_customdata(BMesh *bm_dst, BMesh *bm_src, const BMAllocTemplate *allocsize)
{
	if (allocsize == NULL) {
		allocsize = &bm_mesh_allocsize_default;
	}

	CustomData_copy(&bm_src->vdata, &bm_dst->vdata, CD_MASK_BMESH, CD_CALLOC, 0);
	CustomData_copy(&bm_src->edata, &bm_dst->edata, CD_MASK_BMESH, CD_CALLOC, 0);
	CustomData_copy(&bm_src->ldata, &bm_dst->ldata, CD_MASK_BMESH, CD_CALLOC, 0);
	CustomData_copy(&bm_src->pdata, &bm_dst->pdata, CD_MASK_BMESH, CD_CALLOC, 0);

	CustomData_bmesh_init_pool(&bm_dst->vdata, allocsize->totvert, BM_VERT);
	CustomData_bmesh_init_pool(&bm_dst->edata, allocsize->totedge, BM_EDGE);
	CustomData_bmesh_init_pool(&bm_dst->ldata, allocsize->totloop, BM_LOOP);
	CustomData_bmesh_init_pool(&bm_dst->pdata, allocsize->totface, BM_FACE);
}


BMesh *BM_mesh_copy(BMesh *bm_old)
{
	BMesh *bm_new;
	BMVert *v, *v_new, **vtable = NULL;
	BMEdge *e, *e_new, **etable = NULL;
	BMFace *f, *f_new, **ftable = NULL;
	BMElem **eletable;
	BMEditSelection *ese;
	BMIter iter;
	int i;
	const BMAllocTemplate allocsize = {bm_old->totvert,
	                                   bm_old->totedge,
	                                   bm_old->totloop,
	                                   bm_old->totface};

	/* allocate a bmesh */
	bm_new = BM_mesh_create(&allocsize);

	BM_mesh_copy_init_customdata(bm_new, bm_old, &allocsize);

	vtable = MEM_mallocN(sizeof(BMVert *) * bm_old->totvert, "BM_mesh_copy vtable");
	etable = MEM_mallocN(sizeof(BMEdge *) * bm_old->totedge, "BM_mesh_copy etable");
	ftable = MEM_mallocN(sizeof(BMFace *) * bm_old->totface, "BM_mesh_copy ftable");

	BM_ITER_MESH_INDEX (v, &iter, bm_old, BM_VERTS_OF_MESH, i) {
		/* copy between meshes so cant use 'example' argument */
		v_new = BM_vert_create(bm_new, v->co, NULL, BM_CREATE_SKIP_CD);
		BM_elem_attrs_copy(bm_old, bm_new, v, v_new);
		vtable[i] = v_new;
		BM_elem_index_set(v, i); /* set_inline */
		BM_elem_index_set(v_new, i); /* set_inline */
	}
	bm_old->elem_index_dirty &= ~BM_VERT;
	bm_new->elem_index_dirty &= ~BM_VERT;

	/* safety check */
	BLI_assert(i == bm_old->totvert);
	
	BM_ITER_MESH_INDEX (e, &iter, bm_old, BM_EDGES_OF_MESH, i) {
		e_new = BM_edge_create(bm_new,
		                       vtable[BM_elem_index_get(e->v1)],
		                       vtable[BM_elem_index_get(e->v2)],
		                       e, BM_CREATE_SKIP_CD);

		BM_elem_attrs_copy(bm_old, bm_new, e, e_new);
		etable[i] = e_new;
		BM_elem_index_set(e, i); /* set_inline */
		BM_elem_index_set(e_new, i); /* set_inline */
	}
	bm_old->elem_index_dirty &= ~BM_EDGE;
	bm_new->elem_index_dirty &= ~BM_EDGE;

	/* safety check */
	BLI_assert(i == bm_old->totedge);
	
	BM_ITER_MESH_INDEX (f, &iter, bm_old, BM_FACES_OF_MESH, i) {
		BM_elem_index_set(f, i); /* set_inline */

		f_new = bm_mesh_copy_new_face(bm_new, bm_old, vtable, etable, f);

		ftable[i] = f_new;

		if (f == bm_old->act_face) bm_new->act_face = f_new;
	}
	bm_old->elem_index_dirty &= ~BM_FACE;
	bm_new->elem_index_dirty &= ~BM_FACE;

	/* safety check */
	BLI_assert(i == bm_old->totface);

	/* copy over edit selection history */
	for (ese = bm_old->selected.first; ese; ese = ese->next) {
		BMElem *ele = NULL;

		switch (ese->htype) {
			case BM_VERT:
				eletable = (BMElem **)vtable;
				break;
			case BM_EDGE:
				eletable = (BMElem **)etable;
				break;
			case BM_FACE:
				eletable = (BMElem **)ftable;
				break;
			default:
				eletable = NULL;
				break;
		}

		if (eletable) {
			ele = eletable[BM_elem_index_get(ese->ele)];
			if (ele) {
				BM_select_history_store(bm_new, ele);
			}
		}
	}

	MEM_freeN(etable);
	MEM_freeN(vtable);
	MEM_freeN(ftable);

	return bm_new;
}

/* ME -> BM */
char BM_vert_flag_from_mflag(const char  meflag)
{
	return ( ((meflag & SELECT)       ? BM_ELEM_SELECT : 0) |
	         ((meflag & ME_HIDE)      ? BM_ELEM_HIDDEN : 0)
	         );
}
char BM_edge_flag_from_mflag(const short meflag)
{
	return ( ((meflag & SELECT)        ? BM_ELEM_SELECT : 0) |
	         ((meflag & ME_SEAM)       ? BM_ELEM_SEAM   : 0) |
	         ((meflag & ME_EDGEDRAW)   ? BM_ELEM_DRAW   : 0) |
	         ((meflag & ME_SHARP) == 0 ? BM_ELEM_SMOOTH : 0) | /* invert */
	         ((meflag & ME_HIDE)       ? BM_ELEM_HIDDEN : 0)
	         );
}
char BM_face_flag_from_mflag(const char  meflag)
{
	return ( ((meflag & ME_FACE_SEL)  ? BM_ELEM_SELECT : 0) |
	         ((meflag & ME_SMOOTH)    ? BM_ELEM_SMOOTH : 0) |
	         ((meflag & ME_HIDE)      ? BM_ELEM_HIDDEN : 0)
	         );
}

/* BM -> ME */
char  BM_vert_flag_to_mflag(BMVert *eve)
{
	const char hflag = eve->head.hflag;

	return ( ((hflag & BM_ELEM_SELECT)  ? SELECT  : 0) |
	         ((hflag & BM_ELEM_HIDDEN)  ? ME_HIDE : 0)
	         );
}

short BM_edge_flag_to_mflag(BMEdge *eed)
{
	const char hflag = eed->head.hflag;

	return ( ((hflag & BM_ELEM_SELECT)       ? SELECT       : 0) |
	         ((hflag & BM_ELEM_SEAM)         ? ME_SEAM      : 0) |
	         ((hflag & BM_ELEM_DRAW)         ? ME_EDGEDRAW  : 0) |
	         ((hflag & BM_ELEM_SMOOTH) == 0  ? ME_SHARP     : 0) |
	         ((hflag & BM_ELEM_HIDDEN)       ? ME_HIDE      : 0) |
	         ((BM_edge_is_wire(eed))         ? ME_LOOSEEDGE : 0) | /* not typical */
	         ME_EDGERENDER
	         );
}
char  BM_face_flag_to_mflag(BMFace *efa)
{
	const char hflag = efa->head.hflag;

	return ( ((hflag & BM_ELEM_SELECT) ? ME_FACE_SEL : 0) |
	         ((hflag & BM_ELEM_SMOOTH) ? ME_SMOOTH   : 0) |
	         ((hflag & BM_ELEM_HIDDEN) ? ME_HIDE     : 0)
	         );
}
