/*
 * ***** 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) 2004 by Blender Foundation.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Joseph Eagar
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/editors/mesh/editmesh_utils.c
 *  \ingroup edmesh
 */

#include "MEM_guardedalloc.h"

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

#include "BLI_math.h"
#include "BLI_alloca.h"

#include "BKE_DerivedMesh.h"
#include "BKE_context.h"
#include "BKE_global.h"
#include "BKE_depsgraph.h"
#include "BKE_key.h"
#include "BKE_main.h"
#include "BKE_mesh.h"
#include "BKE_mesh_mapping.h"
#include "BKE_report.h"
#include "BKE_editmesh.h"
#include "BKE_editmesh_bvh.h"

#include "BKE_object.h"  /* XXX. only for EDBM_mesh_ensure_valid_dm_hack() which will be removed */

#include "WM_api.h"
#include "WM_types.h"

#include "ED_mesh.h"
#include "ED_screen.h"
#include "ED_util.h"
#include "ED_view3d.h"

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

/* mesh backup implementation. This would greatly benefit from some sort of binary diffing
 * just as the undo stack would. So leaving this as an interface for further work */

BMBackup EDBM_redo_state_store(BMEditMesh *em)
{
	BMBackup backup;
	backup.bmcopy = BM_mesh_copy(em->bm);
	return backup;
}

void EDBM_redo_state_restore(BMBackup backup, BMEditMesh *em, int recalctess)
{
	BMesh *tmpbm;
	if (!em || !backup.bmcopy)
		return;

	BM_mesh_data_free(em->bm);
	tmpbm = BM_mesh_copy(backup.bmcopy);
	*em->bm = *tmpbm;
	MEM_freeN(tmpbm);
	tmpbm = NULL;

	if (recalctess)
		BKE_editmesh_tessface_calc(em);
}

void EDBM_redo_state_free(BMBackup *backup, BMEditMesh *em, int recalctess)
{
	if (em && backup->bmcopy) {
		BM_mesh_data_free(em->bm);
		*em->bm = *backup->bmcopy;
	}
	else if (backup->bmcopy) {
		BM_mesh_data_free(backup->bmcopy);
	}

	if (backup->bmcopy)
		MEM_freeN(backup->bmcopy);
	backup->bmcopy = NULL;

	if (recalctess && em)
		BKE_editmesh_tessface_calc(em);
}

/* hack to workaround multiple operators being called within the same event loop without an update
 * see: [#31811] */
void EDBM_mesh_ensure_valid_dm_hack(Scene *scene, BMEditMesh *em)
{
	if ((((ID *)em->ob->data)->flag & LIB_ID_RECALC) ||
	    (em->ob->recalc & OB_RECALC_DATA))
	{
		/* since we may not have done selection flushing */
		if ((em->ob->recalc & OB_RECALC_DATA) == 0) {
			DAG_id_tag_update(&em->ob->id, OB_RECALC_DATA);
		}
		BKE_object_handle_update(G.main->eval_ctx, scene, em->ob);
	}
}

void EDBM_mesh_normals_update(BMEditMesh *em)
{
	BM_mesh_normals_update(em->bm);
}

void EDBM_mesh_clear(BMEditMesh *em)
{
	/* clear bmesh */
	BM_mesh_clear(em->bm);
	
	/* free derived meshes */
	BKE_editmesh_free_derivedmesh(em);
	
	/* free tessellation data */
	em->tottri = 0;
	if (em->looptris) {
		MEM_freeN(em->looptris);
		em->looptris = NULL;
	}
}

void EDBM_stats_update(BMEditMesh *em)
{
	const char iter_types[3] = {BM_VERTS_OF_MESH,
	                            BM_EDGES_OF_MESH,
	                            BM_FACES_OF_MESH};

	BMIter iter;
	BMElem *ele;
	int *tots[3];
	int i;

	tots[0] = &em->bm->totvertsel;
	tots[1] = &em->bm->totedgesel;
	tots[2] = &em->bm->totfacesel;
	
	em->bm->totvertsel = em->bm->totedgesel = em->bm->totfacesel = 0;

	for (i = 0; i < 3; i++) {
		ele = BM_iter_new(&iter, em->bm, iter_types[i], NULL);
		for ( ; ele; ele = BM_iter_step(&iter)) {
			if (BM_elem_flag_test(ele, BM_ELEM_SELECT)) {
				(*tots[i])++;
			}
		}
	}
}

DerivedMesh *EDBM_mesh_deform_dm_get(BMEditMesh *em)
{
	return ((em->derivedFinal != NULL) &&
	        (em->derivedFinal->type == DM_TYPE_EDITBMESH) &&
	        (em->derivedFinal->deformedOnly != false)) ? em->derivedFinal : NULL;
}

bool EDBM_op_init(BMEditMesh *em, BMOperator *bmop, wmOperator *op, const char *fmt, ...)
{
	BMesh *bm = em->bm;
	va_list list;

	va_start(list, fmt);

	if (!BMO_op_vinitf(bm, bmop, BMO_FLAG_DEFAULTS, fmt, list)) {
		BKE_reportf(op->reports, RPT_ERROR, "Parse error in %s", __func__);
		va_end(list);
		return false;
	}
	
	if (!em->emcopy)
		em->emcopy = BKE_editmesh_copy(em);
	em->emcopyusers++;

	va_end(list);

	return true;
}


/* returns 0 on error, 1 on success.  executes and finishes a bmesh operator */
bool EDBM_op_finish(BMEditMesh *em, BMOperator *bmop, wmOperator *op, const bool do_report)
{
	const char *errmsg;
	
	BMO_op_finish(em->bm, bmop);

	if (BMO_error_get(em->bm, &errmsg, NULL)) {
		BMEditMesh *emcopy = em->emcopy;

		if (do_report) {
			BKE_report(op->reports, RPT_ERROR, errmsg);
		}

		EDBM_mesh_free(em);
		*em = *emcopy;

		MEM_freeN(emcopy);
		em->emcopyusers = 0;
		em->emcopy = NULL;

		/* when copying, tessellation isn't to for faster copying,
		 * but means we need to re-tessellate here */
		if (em->looptris == NULL) {
			BKE_editmesh_tessface_calc(em);
		}

		return false;
	}
	else {
		em->emcopyusers--;
		if (em->emcopyusers < 0) {
			printf("warning: em->emcopyusers was less then zero.\n");
		}

		if (em->emcopyusers <= 0) {
			BKE_editmesh_free(em->emcopy);
			MEM_freeN(em->emcopy);
			em->emcopy = NULL;
		}

		return true;
	}
}

bool EDBM_op_callf(BMEditMesh *em, wmOperator *op, const char *fmt, ...)
{
	BMesh *bm = em->bm;
	BMOperator bmop;
	va_list list;

	va_start(list, fmt);

	if (!BMO_op_vinitf(bm, &bmop, BMO_FLAG_DEFAULTS, fmt, list)) {
		BKE_reportf(op->reports, RPT_ERROR, "Parse error in %s", __func__);
		va_end(list);
		return false;
	}

	if (!em->emcopy)
		em->emcopy = BKE_editmesh_copy(em);
	em->emcopyusers++;

	BMO_op_exec(bm, &bmop);

	va_end(list);
	return EDBM_op_finish(em, &bmop, op, true);
}

bool EDBM_op_call_and_selectf(BMEditMesh *em, wmOperator *op,
                              const char *select_slot_out, const bool select_extend,
                              const char *fmt, ...)
{
	BMOpSlot *slot_select_out;
	BMesh *bm = em->bm;
	BMOperator bmop;
	va_list list;
	char hflag;

	va_start(list, fmt);

	if (!BMO_op_vinitf(bm, &bmop, BMO_FLAG_DEFAULTS, fmt, list)) {
		BKE_reportf(op->reports, RPT_ERROR, "Parse error in %s", __func__);
		va_end(list);
		return false;
	}

	if (!em->emcopy)
		em->emcopy = BKE_editmesh_copy(em);
	em->emcopyusers++;

	BMO_op_exec(bm, &bmop);

	slot_select_out = BMO_slot_get(bmop.slots_out, select_slot_out);
	hflag = slot_select_out->slot_subtype.elem & BM_ALL_NOLOOP;
	BLI_assert(hflag != 0);

	if (select_extend == false) {
		BM_mesh_elem_hflag_disable_all(em->bm, BM_VERT | BM_EDGE | BM_FACE, BM_ELEM_SELECT, false);
	}

	BMO_slot_buffer_hflag_enable(em->bm, bmop.slots_out, select_slot_out, hflag, BM_ELEM_SELECT, true);

	va_end(list);
	return EDBM_op_finish(em, &bmop, op, true);
}

bool EDBM_op_call_silentf(BMEditMesh *em, const char *fmt, ...)
{
	BMesh *bm = em->bm;
	BMOperator bmop;
	va_list list;

	va_start(list, fmt);

	if (!BMO_op_vinitf(bm, &bmop, BMO_FLAG_DEFAULTS, fmt, list)) {
		va_end(list);
		return false;
	}

	if (!em->emcopy)
		em->emcopy = BKE_editmesh_copy(em);
	em->emcopyusers++;

	BMO_op_exec(bm, &bmop);

	va_end(list);
	return EDBM_op_finish(em, &bmop, NULL, false);
}

void EDBM_selectmode_to_scene(bContext *C)
{
	Scene *scene = CTX_data_scene(C);
	Object *obedit = CTX_data_edit_object(C);
	BMEditMesh *em = BKE_editmesh_from_object(obedit);

	if (!em)
		return;

	scene->toolsettings->selectmode = em->selectmode;

	/* Request redraw of header buttons (to show new select mode) */
	WM_event_add_notifier(C, NC_SCENE | ND_TOOLSETTINGS, scene);
}

void EDBM_mesh_make(ToolSettings *ts, Object *ob)
{
	Mesh *me = ob->data;
	BMesh *bm;

	if (UNLIKELY(!me->mpoly && me->totface)) {
		BKE_mesh_convert_mfaces_to_mpolys(me);
	}

	bm = BKE_mesh_to_bmesh(me, ob);

	if (me->edit_btmesh) {
		/* this happens when switching shape keys */
		EDBM_mesh_free(me->edit_btmesh);
		MEM_freeN(me->edit_btmesh);
	}

	/* currently executing operators re-tessellates, so we can avoid doing here
	 * but at some point it may need to be added back. */
#if 0
	me->edit_btmesh = BKE_editmesh_create(bm, true);
#else
	me->edit_btmesh = BKE_editmesh_create(bm, false);
#endif

	me->edit_btmesh->selectmode = me->edit_btmesh->bm->selectmode = ts->selectmode;
	me->edit_btmesh->mat_nr = (ob->actcol > 0) ? ob->actcol - 1 : 0;
	me->edit_btmesh->ob = ob;

	/* we need to flush selection because the mode may have changed from when last in editmode */
	EDBM_selectmode_flush(me->edit_btmesh);
}

void EDBM_mesh_load(Object *ob)
{
	Mesh *me = ob->data;
	BMesh *bm = me->edit_btmesh->bm;

	BM_mesh_bm_to_me(bm, me, false);

#ifdef USE_TESSFACE_DEFAULT
	BKE_mesh_tessface_calc(me);
#endif

	/* free derived mesh. usually this would happen through depsgraph but there
	 * are exceptions like file save that will not cause this, and we want to
	 * avoid ending up with an invalid derived mesh then */
	BKE_object_free_derived_caches(ob);
}

/**
 * Should only be called on the active editmesh, otherwise call #BKE_editmesh_free
 */
void EDBM_mesh_free(BMEditMesh *em)
{
	/* These tables aren't used yet, so it's not strictly necessary
	 * to 'end' them (with 'e' param) but if someone tries to start
	 * using them, having these in place will save a lot of pain */
	ED_mesh_mirror_spatial_table(NULL, NULL, NULL, 'e');
	ED_mesh_mirror_topo_table(NULL, 'e');

	BKE_editmesh_free(em);
}

void EDBM_selectmode_flush_ex(BMEditMesh *em, const short selectmode)
{
	BM_mesh_select_mode_flush_ex(em->bm, selectmode);
}

void EDBM_selectmode_flush(BMEditMesh *em)
{
	EDBM_selectmode_flush_ex(em, em->selectmode);
}

void EDBM_deselect_flush(BMEditMesh *em)
{
	/* function below doesnt use. just do this to keep the values in sync */
	em->bm->selectmode = em->selectmode;
	BM_mesh_deselect_flush(em->bm);
}


void EDBM_select_flush(BMEditMesh *em)
{
	/* function below doesnt use. just do this to keep the values in sync */
	em->bm->selectmode = em->selectmode;
	BM_mesh_select_flush(em->bm);
}

void EDBM_select_more(BMEditMesh *em)
{
	BMOperator bmop;
	int use_faces = em->selectmode == SCE_SELECT_FACE;

	BMO_op_initf(em->bm, &bmop, BMO_FLAG_DEFAULTS,
	             "region_extend geom=%hvef use_constrict=%b use_faces=%b",
	             BM_ELEM_SELECT, false, use_faces);
	BMO_op_exec(em->bm, &bmop);
	/* don't flush selection in edge/vertex mode  */
	BMO_slot_buffer_hflag_enable(em->bm, bmop.slots_out, "geom.out", BM_ALL_NOLOOP, BM_ELEM_SELECT, use_faces ? true : false);
	BMO_op_finish(em->bm, &bmop);

	EDBM_selectmode_flush(em);
}

void EDBM_select_less(BMEditMesh *em)
{
	BMOperator bmop;
	int use_faces = em->selectmode == SCE_SELECT_FACE;

	BMO_op_initf(em->bm, &bmop, BMO_FLAG_DEFAULTS,
	             "region_extend geom=%hvef use_constrict=%b use_faces=%b",
	             BM_ELEM_SELECT, true, use_faces);
	BMO_op_exec(em->bm, &bmop);
	/* don't flush selection in edge/vertex mode  */
	BMO_slot_buffer_hflag_disable(em->bm, bmop.slots_out, "geom.out", BM_ALL_NOLOOP, BM_ELEM_SELECT, use_faces ? true : false);
	BMO_op_finish(em->bm, &bmop);

	EDBM_selectmode_flush(em);
}

void EDBM_flag_disable_all(BMEditMesh *em, const char hflag)
{
	BM_mesh_elem_hflag_disable_all(em->bm, BM_VERT | BM_EDGE | BM_FACE, hflag, false);
}

void EDBM_flag_enable_all(BMEditMesh *em, const char hflag)
{
	BM_mesh_elem_hflag_enable_all(em->bm, BM_VERT | BM_EDGE | BM_FACE, hflag, true);
}

/**************-------------- Undo ------------*****************/

/* for callbacks */

static void *getEditMesh(bContext *C)
{
	Object *obedit = CTX_data_edit_object(C);
	if (obedit && obedit->type == OB_MESH) {
		Mesh *me = obedit->data;
		return me->edit_btmesh;
	}
	return NULL;
}

typedef struct UndoMesh {
	Mesh me;
	int selectmode;

	/** \note
	 * this isn't a prefect solution, if you edit keys and change shapes this works well (fixing [#32442]),
	 * but editing shape keys, going into object mode, removing or changing their order,
	 * then go back into editmode and undo will give issues - where the old index will be out of sync
	 * with the new object index.
	 *
	 * There are a few ways this could be made to work but for now its a known limitation with mixing
	 * object and editmode operations - Campbell */
	int shapenr;
} UndoMesh;

/* undo simply makes copies of a bmesh */
static void *editbtMesh_to_undoMesh(void *emv, void *obdata)
{
	BMEditMesh *em = emv;
	Mesh *obme = obdata;
	
	UndoMesh *um = MEM_callocN(sizeof(UndoMesh), "undo Mesh");
	
	/* make sure shape keys work */
	um->me.key = obme->key ? BKE_key_copy_nolib(obme->key) : NULL;

	/* BM_mesh_validate(em->bm); */ /* for troubleshooting */

	BM_mesh_bm_to_me(em->bm, &um->me, false);

	um->selectmode = em->selectmode;
	um->shapenr = em->bm->shapenr;

	return um;
}

static void undoMesh_to_editbtMesh(void *umv, void *em_v, void *UNUSED(obdata))
{
	BMEditMesh *em = em_v, *em_tmp;
	Object *ob = em->ob;
	UndoMesh *um = umv;
	BMesh *bm;

	const BMAllocTemplate allocsize = BMALLOC_TEMPLATE_FROM_ME(&um->me);

	ob->shapenr = em->bm->shapenr = um->shapenr;

	EDBM_mesh_free(em);

	bm = BM_mesh_create(&allocsize);

	BM_mesh_bm_from_me(bm, &um->me, true, false, ob->shapenr);

	em_tmp = BKE_editmesh_create(bm, true);
	*em = *em_tmp;
	
	em->selectmode = um->selectmode;
	bm->selectmode = um->selectmode;
	em->ob = ob;

	MEM_freeN(em_tmp);
}

static void free_undo(void *me_v)
{
	Mesh *me = me_v;
	if (me->key) {
		BKE_key_free(me->key);
		MEM_freeN(me->key);
	}

	BKE_mesh_free(me, false);
	MEM_freeN(me);
}

/* and this is all the undo system needs to know */
void undo_push_mesh(bContext *C, const char *name)
{
	/* em->ob gets out of date and crashes on mesh undo,
	 * this is an easy way to ensure its OK
	 * though we could investigate the matter further. */
	Object *obedit = CTX_data_edit_object(C);
	BMEditMesh *em = BKE_editmesh_from_object(obedit);
	em->ob = obedit;

	undo_editmode_push(C, name, getEditMesh, free_undo, undoMesh_to_editbtMesh, editbtMesh_to_undoMesh, NULL);
}

/**
 * Return a new UVVertMap from the editmesh
 */
UvVertMap *BM_uv_vert_map_create(BMesh *bm, bool use_select, const float limit[2])
{
	BMVert *ev;
	BMFace *efa;
	BMLoop *l;
	BMIter iter, liter;
	/* vars from original func */
	UvVertMap *vmap;
	UvMapVert *buf;
	/* MTexPoly *tf; */ /* UNUSED */
	MLoopUV *luv;
	unsigned int a;
	int totverts, i, totuv;
	const int cd_loop_uv_offset = CustomData_get_offset(&bm->ldata, CD_MLOOPUV);

	BM_mesh_elem_index_ensure(bm, BM_VERT | BM_FACE);
	
	totverts = bm->totvert;
	totuv = 0;

	/* generate UvMapVert array */
	BM_ITER_MESH (efa, &iter, bm, BM_FACES_OF_MESH) {
		if ((use_select == false) || BM_elem_flag_test(efa, BM_ELEM_SELECT)) {
			totuv += efa->len;
		}
	}

	if (totuv == 0) {
		return NULL;
	}
	vmap = (UvVertMap *)MEM_callocN(sizeof(*vmap), "UvVertMap");
	if (!vmap) {
		return NULL;
	}

	vmap->vert = (UvMapVert **)MEM_callocN(sizeof(*vmap->vert) * totverts, "UvMapVert_pt");
	buf = vmap->buf = (UvMapVert *)MEM_callocN(sizeof(*vmap->buf) * totuv, "UvMapVert");

	if (!vmap->vert || !vmap->buf) {
		BKE_mesh_uv_vert_map_free(vmap);
		return NULL;
	}
	
	a = 0;
	BM_ITER_MESH (efa, &iter, bm, BM_FACES_OF_MESH) {
		if ((use_select == false) || BM_elem_flag_test(efa, BM_ELEM_SELECT)) {
			i = 0;
			BM_ITER_ELEM (l, &liter, efa, BM_LOOPS_OF_FACE) {
				buf->tfindex = i;
				buf->f = a;
				buf->separate = 0;
				
				buf->next = vmap->vert[BM_elem_index_get(l->v)];
				vmap->vert[BM_elem_index_get(l->v)] = buf;
				
				buf++;
				i++;
			}
		}

		a++;
	}
	
	/* sort individual uvs for each vert */
	a = 0;
	BM_ITER_MESH (ev, &iter, bm, BM_VERTS_OF_MESH) {
		UvMapVert *newvlist = NULL, *vlist = vmap->vert[a];
		UvMapVert *iterv, *v, *lastv, *next;
		float *uv, *uv2, uvdiff[2];

		while (vlist) {
			v = vlist;
			vlist = vlist->next;
			v->next = newvlist;
			newvlist = v;

			efa = BM_face_at_index(bm, v->f);
			/* tf = CustomData_bmesh_get(&bm->pdata, efa->head.data, CD_MTEXPOLY); */ /* UNUSED */
			
			l = BM_iter_at_index(bm, BM_LOOPS_OF_FACE, efa, v->tfindex);
			luv = BM_ELEM_CD_GET_VOID_P(l, cd_loop_uv_offset);
			uv = luv->uv;
			
			lastv = NULL;
			iterv = vlist;

			while (iterv) {
				next = iterv->next;
				efa = BM_face_at_index(bm, iterv->f);
				/* tf = CustomData_bmesh_get(&bm->pdata, efa->head.data, CD_MTEXPOLY); */ /* UNUSED */
				
				l = BM_iter_at_index(bm, BM_LOOPS_OF_FACE, efa, iterv->tfindex);
				luv = BM_ELEM_CD_GET_VOID_P(l, cd_loop_uv_offset);
				uv2 = luv->uv;
				
				sub_v2_v2v2(uvdiff, uv2, uv);

				if (fabsf(uvdiff[0]) < limit[0] && fabsf(uvdiff[1]) < limit[1]) {
					if (lastv) lastv->next = next;
					else vlist = next;
					iterv->next = newvlist;
					newvlist = iterv;
				}
				else {
					lastv = iterv;
				}

				iterv = next;
			}

			newvlist->separate = 1;
		}

		vmap->vert[a] = newvlist;
		a++;
	}

	return vmap;
}


UvMapVert *BM_uv_vert_map_at_index(UvVertMap *vmap, unsigned int v)
{
	return vmap->vert[v];
}

/* from editmesh_lib.c in trunk */


/* A specialized vert map used by stitch operator */
UvElementMap *BM_uv_element_map_create(BMesh *bm, const bool selected, const bool do_islands)
{
	BMVert *ev;
	BMFace *efa;
	BMLoop *l;
	BMIter iter, liter;
	/* vars from original func */
	UvElementMap *element_map;
	UvElement *buf;
	UvElement *islandbuf;
	/* island number for faces */
	int *island_number;

	MLoopUV *luv;
	int totverts, i, totuv, j, nislands = 0, islandbufsize = 0;

	unsigned int *map;
	BMFace **stack;
	int stacksize = 0;

	const int cd_loop_uv_offset = CustomData_get_offset(&bm->ldata, CD_MLOOPUV);

	BM_mesh_elem_index_ensure(bm, BM_VERT | BM_FACE);

	totverts = bm->totvert;
	totuv = 0;

	island_number = MEM_mallocN(sizeof(*stack) * bm->totface, "uv_island_number_face");
	if (!island_number) {
		return NULL;
	}

	/* generate UvElement array */
	BM_ITER_MESH (efa, &iter, bm, BM_FACES_OF_MESH) {
		if (!selected || BM_elem_flag_test(efa, BM_ELEM_SELECT)) {
			totuv += efa->len;
		}
	}

	if (totuv == 0) {
		MEM_freeN(island_number);
		return NULL;
	}
	element_map = (UvElementMap *)MEM_callocN(sizeof(*element_map), "UvElementMap");
	if (!element_map) {
		MEM_freeN(island_number);
		return NULL;
	}
	element_map->totalUVs = totuv;
	element_map->vert = (UvElement **)MEM_callocN(sizeof(*element_map->vert) * totverts, "UvElementVerts");
	buf = element_map->buf = (UvElement *)MEM_callocN(sizeof(*element_map->buf) * totuv, "UvElement");

	if (!element_map->vert || !element_map->buf) {
		BM_uv_element_map_free(element_map);
		MEM_freeN(island_number);
		return NULL;
	}

	j = 0;
	BM_ITER_MESH (efa, &iter, bm, BM_FACES_OF_MESH) {
		island_number[j++] = INVALID_ISLAND;
		if (!selected || BM_elem_flag_test(efa, BM_ELEM_SELECT)) {
			BM_ITER_ELEM_INDEX (l, &liter, efa, BM_LOOPS_OF_FACE, i) {
				buf->l = l;
				buf->separate = 0;
				buf->island = INVALID_ISLAND;
				buf->tfindex = i;

				buf->next = element_map->vert[BM_elem_index_get(l->v)];
				element_map->vert[BM_elem_index_get(l->v)] = buf;

				buf++;
			}
		}
	}

	/* sort individual uvs for each vert */
	i = 0;
	BM_ITER_MESH (ev, &iter, bm, BM_VERTS_OF_MESH) {
		UvElement *newvlist = NULL, *vlist = element_map->vert[i];
		UvElement *iterv, *v, *lastv, *next;
		float *uv, *uv2, uvdiff[2];

		while (vlist) {
			v = vlist;
			vlist = vlist->next;
			v->next = newvlist;
			newvlist = v;

			l = v->l;
			luv = BM_ELEM_CD_GET_VOID_P(l, cd_loop_uv_offset);
			uv = luv->uv;

			lastv = NULL;
			iterv = vlist;

			while (iterv) {
				next = iterv->next;

				l = iterv->l;
				luv = BM_ELEM_CD_GET_VOID_P(l, cd_loop_uv_offset);
				uv2 = luv->uv;

				sub_v2_v2v2(uvdiff, uv2, uv);

				if (fabsf(uvdiff[0]) < STD_UV_CONNECT_LIMIT && fabsf(uvdiff[1]) < STD_UV_CONNECT_LIMIT) {
					if (lastv) lastv->next = next;
					else vlist = next;
					iterv->next = newvlist;
					newvlist = iterv;
				}
				else {
					lastv = iterv;
				}

				iterv = next;
			}

			newvlist->separate = 1;
		}

		element_map->vert[i] = newvlist;
		i++;
	}

	if (do_islands) {
		/* map holds the map from current vmap->buf to the new, sorted map */
		map = MEM_mallocN(sizeof(*map) * totuv, "uvelement_remap");
		stack = MEM_mallocN(sizeof(*stack) * bm->totface, "uv_island_face_stack");
		islandbuf = MEM_callocN(sizeof(*islandbuf) * totuv, "uvelement_island_buffer");

		/* at this point, every UvElement in vert points to a UvElement sharing the same vertex. Now we should sort uv's in islands. */
		for (i = 0; i < totuv; i++) {
			if (element_map->buf[i].island == INVALID_ISLAND) {
				element_map->buf[i].island = nislands;
				stack[0] = element_map->buf[i].l->f;
				island_number[BM_elem_index_get(stack[0])] = nislands;
				stacksize = 1;

				while (stacksize > 0) {
					efa = stack[--stacksize];

					BM_ITER_ELEM (l, &liter, efa, BM_LOOPS_OF_FACE) {
						UvElement *element, *initelement = element_map->vert[BM_elem_index_get(l->v)];

						for (element = initelement; element; element = element->next) {
							if (element->separate)
								initelement = element;

							if (element->l->f == efa) {
								/* found the uv corresponding to our face and vertex. Now fill it to the buffer */
								element->island = nislands;
								map[element - element_map->buf] = islandbufsize;
								islandbuf[islandbufsize].l = element->l;
								islandbuf[islandbufsize].separate = element->separate;
								islandbuf[islandbufsize].tfindex = element->tfindex;
								islandbuf[islandbufsize].island =  nislands;
								islandbufsize++;

								for (element = initelement; element; element = element->next) {
									if (element->separate && element != initelement)
										break;

									if (island_number[BM_elem_index_get(element->l->f)] == INVALID_ISLAND) {
										stack[stacksize++] = element->l->f;
										island_number[BM_elem_index_get(element->l->f)] = nislands;
									}
								}
								break;
							}
						}
					}
				}

				nislands++;
			}
		}

		/* remap */
		for (i = 0; i < bm->totvert; i++) {
			/* important since we may do selection only. Some of these may be NULL */
			if (element_map->vert[i])
				element_map->vert[i] = &islandbuf[map[element_map->vert[i] - element_map->buf]];
		}

		element_map->islandIndices = MEM_callocN(sizeof(*element_map->islandIndices) * nislands, "UvElementMap_island_indices");
		if (!element_map->islandIndices) {
			MEM_freeN(islandbuf);
			MEM_freeN(stack);
			MEM_freeN(map);
			BM_uv_element_map_free(element_map);
			MEM_freeN(island_number);
		}

		j = 0;
		for (i = 0; i < totuv; i++) {
			UvElement *element = element_map->buf[i].next;
			if (element == NULL)
				islandbuf[map[i]].next = NULL;
			else
				islandbuf[map[i]].next = &islandbuf[map[element - element_map->buf]];

			if (islandbuf[i].island != j) {
				j++;
				element_map->islandIndices[j] = i;
			}
		}

		MEM_freeN(element_map->buf);

		element_map->buf = islandbuf;
		element_map->totalIslands = nislands;
		MEM_freeN(stack);
		MEM_freeN(map);
	}
	MEM_freeN(island_number);

	return element_map;
}

void BM_uv_vert_map_free(UvVertMap *vmap)
{
	if (vmap) {
		if (vmap->vert) MEM_freeN(vmap->vert);
		if (vmap->buf) MEM_freeN(vmap->buf);
		MEM_freeN(vmap);
	}
}

void BM_uv_element_map_free(UvElementMap *element_map)
{
	if (element_map) {
		if (element_map->vert) MEM_freeN(element_map->vert);
		if (element_map->buf) MEM_freeN(element_map->buf);
		if (element_map->islandIndices) MEM_freeN(element_map->islandIndices);
		MEM_freeN(element_map);
	}
}

UvElement *BM_uv_element_get(UvElementMap *map, BMFace *efa, BMLoop *l)
{
	UvElement *element;

	element = map->vert[BM_elem_index_get(l->v)];

	for (; element; element = element->next)
		if (element->l->f == efa)
			return element;

	return NULL;
}

/* last_sel, use em->act_face otherwise get the last selected face in the editselections
 * at the moment, last_sel is mainly useful for making sure the space image dosnt flicker */
MTexPoly *EDBM_mtexpoly_active_get(BMEditMesh *em, BMFace **r_act_efa, const bool sloppy, const bool selected)
{
	BMFace *efa = NULL;
	
	if (!EDBM_mtexpoly_check(em))
		return NULL;
	
	efa = BM_mesh_active_face_get(em->bm, sloppy, selected);

	if (efa) {
		if (r_act_efa) *r_act_efa = efa;
		return CustomData_bmesh_get(&em->bm->pdata, efa->head.data, CD_MTEXPOLY);
	}

	if (r_act_efa) *r_act_efa = NULL;
	return NULL;
}

/* can we edit UV's for this mesh?*/
bool EDBM_mtexpoly_check(BMEditMesh *em)
{
	/* some of these checks could be a touch overkill */
	return em && em->bm->totface && CustomData_has_layer(&em->bm->pdata, CD_MTEXPOLY) &&
	       CustomData_has_layer(&em->bm->ldata, CD_MLOOPUV);
}

bool EDBM_vert_color_check(BMEditMesh *em)
{
	/* some of these checks could be a touch overkill */
	return em && em->bm->totface && CustomData_has_layer(&em->bm->ldata, CD_MLOOPCOL);
}

static BMVert *cache_mirr_intptr_as_bmvert(intptr_t *index_lookup, int index)
{
	intptr_t eve_i = index_lookup[index];
	return (eve_i == -1) ? NULL : (BMVert *)eve_i;
}

/**
 * [note: I've decided to use ideasman's code for non-editmode stuff, but since
 *  it has a big "not for editmode!" disclaimer, I'm going to keep what I have here
 *  - joeedh]
 *
 * x-mirror editing api.  usage:
 *
 *  EDBM_verts_mirror_cache_begin(em);
 *  ...
 *  ...
 *  BM_ITER_MESH (v, &iter, em->bm, BM_VERTS_OF_MESH) {
 *     mirrorv = EDBM_verts_mirror_get(em, v);
 *  }
 *  ...
 *  ...
 *  EDBM_verts_mirror_cache_end(em);
 *
 * \param use_self  Allow a vertex to reference its self.
 * \param use_select  Only cache selected verts.
 *
 * \note why do we only allow x axis mirror editing?
 */

/* BM_SEARCH_MAXDIST is too big, copied from 2.6x MOC_THRESH, should become a
 * preference */
#define BM_SEARCH_MAXDIST_MIRR 0.00002f
#define BM_CD_LAYER_ID "__mirror_index"
/**
 * \param em  Editmesh.
 * \param use_self  Allow a vertex to point to its self (middle verts).
 * \param use_select  Restrict to selected verts.
 * \param use_topology  Use topology mirror.
 * \param maxdist  Distance for close point test.
 * \param r_index  Optional array to write into, as an alternative to a customdata layer (length of total verts).
 */
void EDBM_verts_mirror_cache_begin_ex(BMEditMesh *em, const int axis, const bool use_self, const bool use_select,
                                      /* extra args */
                                      const bool use_topology, float maxdist, int *r_index)
{
	Mesh *me = (Mesh *)em->ob->data;
	BMesh *bm = em->bm;
	BMIter iter;
	BMVert *v;
	int cd_vmirr_offset;
	int i;

	/* one or the other is used depending if topo is enabled */
	struct BMBVHTree *tree = NULL;
	MirrTopoStore_t mesh_topo_store = {NULL, -1, -1, -1};

	BM_mesh_elem_table_ensure(bm, BM_VERT);

	if (r_index == NULL) {
		const char *layer_id = BM_CD_LAYER_ID;
		em->mirror_cdlayer = CustomData_get_named_layer_index(&bm->vdata, CD_PROP_INT, layer_id);
		if (em->mirror_cdlayer == -1) {
			BM_data_layer_add_named(bm, &bm->vdata, CD_PROP_INT, layer_id);
			em->mirror_cdlayer = CustomData_get_named_layer_index(&bm->vdata, CD_PROP_INT, layer_id);
		}

		cd_vmirr_offset = CustomData_get_n_offset(&bm->vdata, CD_PROP_INT,
		                                          em->mirror_cdlayer - CustomData_get_layer_index(&bm->vdata, CD_PROP_INT));

		bm->vdata.layers[em->mirror_cdlayer].flag |= CD_FLAG_TEMPORARY;
	}

	BM_mesh_elem_index_ensure(bm, BM_VERT);

	if (use_topology) {
		ED_mesh_mirrtopo_init(me, -1, &mesh_topo_store, true);
	}
	else {
		tree = BKE_bmbvh_new_from_editmesh(em, 0, NULL, false);
	}

#define VERT_INTPTR(_v, _i) r_index ? &r_index[_i] : BM_ELEM_CD_GET_VOID_P(_v, cd_vmirr_offset);

	BM_ITER_MESH_INDEX (v, &iter, bm, BM_VERTS_OF_MESH, i) {
		BLI_assert(BM_elem_index_get(v) == i);

		/* temporary for testing, check for selection */
		if (use_select && !BM_elem_flag_test(v, BM_ELEM_SELECT)) {
			/* do nothing */
		}
		else {
			BMVert *v_mirr;
			int *idx = VERT_INTPTR(v, i);

			if (use_topology) {
				v_mirr = cache_mirr_intptr_as_bmvert(mesh_topo_store.index_lookup, i);
			}
			else {
				float co[3];
				copy_v3_v3(co, v->co);
				co[axis] *= -1.0f;
				v_mirr = BKE_bmbvh_find_vert_closest(tree, co, maxdist);
			}

			if (v_mirr && (use_self || (v_mirr != v))) {
				const int i_mirr = BM_elem_index_get(v_mirr);
				*idx = i_mirr;
				idx = VERT_INTPTR(v_mirr, i_mirr);
				*idx = i;
			}
			else {
				*idx = -1;
			}
		}

	}

#undef VERT_INTPTR

	if (use_topology) {
		ED_mesh_mirrtopo_free(&mesh_topo_store);
	}
	else {
		BKE_bmbvh_free(tree);
	}
}

void EDBM_verts_mirror_cache_begin(BMEditMesh *em, const int axis,
                                   const bool use_self, const bool use_select,
                                   const bool use_topology)
{
	EDBM_verts_mirror_cache_begin_ex(em, axis,
	                                 use_self, use_select,
	                                 /* extra args */
	                                 use_topology, BM_SEARCH_MAXDIST_MIRR, NULL);
}

BMVert *EDBM_verts_mirror_get(BMEditMesh *em, BMVert *v)
{
	const int *mirr = CustomData_bmesh_get_layer_n(&em->bm->vdata, v->head.data, em->mirror_cdlayer);

	BLI_assert(em->mirror_cdlayer != -1); /* invalid use */

	if (mirr && *mirr >= 0 && *mirr < em->bm->totvert) {
		if (!em->bm->vtable) {
			printf("err: should only be called between "
			       "EDBM_verts_mirror_cache_begin and EDBM_verts_mirror_cache_end");
			return NULL;
		}

		return em->bm->vtable[*mirr];
	}

	return NULL;
}

BMEdge *EDBM_verts_mirror_get_edge(BMEditMesh *em, BMEdge *e)
{
	BMVert *v1_mirr = EDBM_verts_mirror_get(em, e->v1);
	if (v1_mirr) {
		BMVert *v2_mirr = EDBM_verts_mirror_get(em, e->v2);
		if (v2_mirr) {
			return BM_edge_exists(v1_mirr, v2_mirr);
		}
	}

	return NULL;
}

BMFace *EDBM_verts_mirror_get_face(BMEditMesh *em, BMFace *f)
{
	BMFace *f_mirr = NULL;
	BMVert **v_mirr_arr = BLI_array_alloca(v_mirr_arr, f->len);

	BMLoop *l_iter, *l_first;
	unsigned int i = 0;

	l_iter = l_first = BM_FACE_FIRST_LOOP(f);
	do {
		if ((v_mirr_arr[i++] = EDBM_verts_mirror_get(em, l_iter->v)) == NULL) {
			return NULL;
		}
	} while ((l_iter = l_iter->next) != l_first);

	BM_face_exists(v_mirr_arr, f->len, &f_mirr);
	return f_mirr;
}

void EDBM_verts_mirror_cache_clear(BMEditMesh *em, BMVert *v)
{
	int *mirr = CustomData_bmesh_get_layer_n(&em->bm->vdata, v->head.data, em->mirror_cdlayer);

	BLI_assert(em->mirror_cdlayer != -1); /* invalid use */

	if (mirr) {
		*mirr = -1;
	}
}

void EDBM_verts_mirror_cache_end(BMEditMesh *em)
{
	em->mirror_cdlayer = -1;
}

void EDBM_verts_mirror_apply(BMEditMesh *em, const int sel_from, const int sel_to)
{
	BMIter iter;
	BMVert *v;

	BLI_assert((em->bm->vtable != NULL) && ((em->bm->elem_table_dirty & BM_VERT) == 0));

	BM_ITER_MESH (v, &iter, em->bm, BM_VERTS_OF_MESH) {
		if (BM_elem_flag_test(v, BM_ELEM_SELECT) == sel_from) {
			BMVert *mirr = EDBM_verts_mirror_get(em, v);
			if (mirr) {
				if (BM_elem_flag_test(mirr, BM_ELEM_SELECT) == sel_to) {
					copy_v3_v3(mirr->co, v->co);
					mirr->co[0] *= -1.0f;
				}
			}
		}
	}
}


/* swap is 0 or 1, if 1 it hides not selected */
void EDBM_mesh_hide(BMEditMesh *em, bool swap)
{
	BMIter iter;
	BMElem *ele;
	int itermode;
	char hflag_swap = swap ? BM_ELEM_SELECT : 0;

	if (em == NULL) return;

	if (em->selectmode & SCE_SELECT_VERTEX)
		itermode = BM_VERTS_OF_MESH;
	else if (em->selectmode & SCE_SELECT_EDGE)
		itermode = BM_EDGES_OF_MESH;
	else
		itermode = BM_FACES_OF_MESH;

	BM_ITER_MESH (ele, &iter, em->bm, itermode) {
		if (BM_elem_flag_test(ele, BM_ELEM_SELECT) ^ hflag_swap)
			BM_elem_hide_set(em->bm, ele, true);
	}

	EDBM_selectmode_flush(em);

	/* original hide flushing comment (OUTDATED):
	 * hide happens on least dominant select mode, and flushes up, not down! (helps preventing errors in subsurf) */
	/* - vertex hidden, always means edge is hidden too
	 * - edge hidden, always means face is hidden too
	 * - face hidden, only set face hide
	 * - then only flush back down what's absolute hidden
	 */
}


void EDBM_mesh_reveal(BMEditMesh *em)
{
	const char iter_types[3] = {BM_VERTS_OF_MESH,
	                            BM_EDGES_OF_MESH,
	                            BM_FACES_OF_MESH};

	const bool sels[3] = {
	    (em->selectmode & SCE_SELECT_VERTEX) != 0,
	    (em->selectmode & SCE_SELECT_EDGE) != 0,
	    (em->selectmode & SCE_SELECT_FACE) != 0,
	};
	int i;

	/* Use tag flag to remember what was hidden before all is revealed.
	 * BM_ELEM_HIDDEN --> BM_ELEM_TAG */
#pragma omp parallel for schedule(static) if (em->bm->totvert + em->bm->totedge + em->bm->totface >= BM_OMP_LIMIT)
	for (i = 0; i < 3; i++) {
		BMIter iter;
		BMElem *ele;

		BM_ITER_MESH (ele, &iter, em->bm, iter_types[i]) {
			BM_elem_flag_set(ele, BM_ELEM_TAG, BM_elem_flag_test(ele, BM_ELEM_HIDDEN));
		}
	}

	/* Reveal everything */
	EDBM_flag_disable_all(em, BM_ELEM_HIDDEN);

	/* Select relevant just-revealed elements */
	for (i = 0; i < 3; i++) {
		BMIter iter;
		BMElem *ele;

		if (!sels[i]) {
			continue;
		}

		BM_ITER_MESH (ele, &iter, em->bm, iter_types[i]) {
			if (BM_elem_flag_test(ele, BM_ELEM_TAG)) {
				BM_elem_select_set(em->bm, ele, true);
			}
		}
	}

	EDBM_selectmode_flush(em);

	/* hidden faces can have invalid normals */
	EDBM_mesh_normals_update(em);
}

/* so many tools call these that we better make it a generic function.
 */
void EDBM_update_generic(BMEditMesh *em, const bool do_tessface, const bool is_destructive)
{
	Object *ob = em->ob;
	/* order of calling isn't important */
	DAG_id_tag_update(ob->data, OB_RECALC_DATA);
	WM_main_add_notifier(NC_GEOM | ND_DATA, ob->data);

	if (do_tessface) {
		BKE_editmesh_tessface_calc(em);
	}

	if (is_destructive) {
		/* TODO. we may be able to remove this now! - Campbell */
		// BM_mesh_elem_table_free(em->bm, BM_ALL_NOLOOP);
	}
	else {
		/* in debug mode double check we didn't need to recalculate */
		BLI_assert(BM_mesh_elem_table_check(em->bm) == true);
	}

	/* don't keep stale derivedMesh data around, see: [#38872] */
	BKE_editmesh_free_derivedmesh(em);
}

/* poll call for mesh operators requiring a view3d context */
int EDBM_view3d_poll(bContext *C)
{
	if (ED_operator_editmesh(C) && ED_operator_view3d_active(C))
		return 1;

	return 0;
}



/* -------------------------------------------------------------------- */
/* BMBVH functions */
// XXX
#if 0 //BMESH_TODO: not implemented yet
int BMBVH_VertVisible(BMBVHTree *tree, BMEdge *e, RegionView3D *r3d)
{

}
#endif

static BMFace *edge_ray_cast(struct BMBVHTree *tree, const float co[3], const float dir[3], float *r_hitout, BMEdge *e)
{
	BMFace *f = BKE_bmbvh_ray_cast(tree, co, dir, 0.0f, NULL, r_hitout, NULL);

	if (f && BM_edge_in_face(e, f))
		return NULL;

	return f;
}

static void scale_point(float c1[3], const float p[3], const float s)
{
	sub_v3_v3(c1, p);
	mul_v3_fl(c1, s);
	add_v3_v3(c1, p);
}

bool BMBVH_EdgeVisible(struct BMBVHTree *tree, BMEdge *e, ARegion *ar, View3D *v3d, Object *obedit)
{
	BMFace *f;
	float co1[3], co2[3], co3[3], dir1[3], dir2[3], dir3[3];
	float origin[3], invmat[4][4];
	float epsilon = 0.01f;
	float end[3];
	const float mval_f[2] = {ar->winx / 2.0f,
	                         ar->winy / 2.0f};

	ED_view3d_win_to_segment(ar, v3d, mval_f, origin, end, false);

	invert_m4_m4(invmat, obedit->obmat);
	mul_m4_v3(invmat, origin);

	copy_v3_v3(co1, e->v1->co);
	mid_v3_v3v3(co2, e->v1->co, e->v2->co);
	copy_v3_v3(co3, e->v2->co);

	scale_point(co1, co2, 0.99);
	scale_point(co3, co2, 0.99);

	/* ok, idea is to generate rays going from the camera origin to the
	 * three points on the edge (v1, mid, v2)*/
	sub_v3_v3v3(dir1, origin, co1);
	sub_v3_v3v3(dir2, origin, co2);
	sub_v3_v3v3(dir3, origin, co3);

	normalize_v3(dir1);
	normalize_v3(dir2);
	normalize_v3(dir3);

	mul_v3_fl(dir1, epsilon);
	mul_v3_fl(dir2, epsilon);
	mul_v3_fl(dir3, epsilon);

	/* offset coordinates slightly along view vectors, to avoid
	 * hitting the faces that own the edge.*/
	add_v3_v3v3(co1, co1, dir1);
	add_v3_v3v3(co2, co2, dir2);
	add_v3_v3v3(co3, co3, dir3);

	normalize_v3(dir1);
	normalize_v3(dir2);
	normalize_v3(dir3);

	/* do three samplings: left, middle, right */
	f = edge_ray_cast(tree, co1, dir1, NULL, e);
	if (f && !edge_ray_cast(tree, co2, dir2, NULL, e))
		return true;
	else if (f && !edge_ray_cast(tree, co3, dir3, NULL, e))
		return true;
	else if (!f)
		return true;

	return false;
}
