/*
 * ***** 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.
 *
 * Contributor(s): Campbell Barton.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/bmesh/operators/bmo_fill_edgeloop.c
 *  \ingroup bmesh
 *
 * Fill discreet edge loop(s) with faces.
 */

#include "MEM_guardedalloc.h"

#include "BLI_listbase.h"

#include "bmesh.h"

#include "intern/bmesh_operators_private.h" /* own include */

#define VERT_USED	1
#define EDGE_MARK	2
#define ELE_OUT		4

void bmo_edgeloop_fill_exec(BMesh *bm, BMOperator *op)
{
	/* first collect an array of unique from the edges */
	const int tote = BMO_slot_buffer_count(op->slots_in, "edges");
	const int totv = tote;  /* these should be the same */
	BMVert **verts = MEM_mallocN(sizeof(*verts) * totv, __func__);

	BMVert *v;
	BMEdge *e;
	int i;
	bool ok = true;

	BMOIter oiter;

	const short mat_nr     = BMO_slot_int_get(op->slots_in,  "mat_nr");
	const bool use_smooth  = BMO_slot_bool_get(op->slots_in, "use_smooth");

	/* 'VERT_USED' will be disabled, so enable and fill the array */
	i = 0;
	BMO_ITER (e, &oiter, op->slots_in, "edges", BM_EDGE) {
		BMIter viter;
		BMO_elem_flag_enable(bm, e, EDGE_MARK);
		BM_ITER_ELEM (v, &viter, e, BM_VERTS_OF_EDGE) {
			if (BMO_elem_flag_test(bm, v, VERT_USED) == false) {
				if (i == tote) {
					goto cleanup;
				}

				BMO_elem_flag_enable(bm, v, VERT_USED);
				verts[i++] = v;
			}
		}
	}

	/* we have a different number of verts to edges */
	if (i != tote) {
		goto cleanup;
	}

	/* loop over connected flagged edges and fill in faces,  this is made slightly more
	 * complicated because there may be multiple disconnected loops to fill. */

	/* sanity check - that each vertex has 2 edge users */
	for (i = 0; i < totv; i++) {
		v = verts[i];
		/* count how many flagged edges this vertex uses */
		if (BMO_iter_elem_count_flag(bm, BM_EDGES_OF_VERT, v, EDGE_MARK, true) != 2) {
			ok = false;
			break;
		}
	}

	if (ok) {
		/* note: in the case of multiple loops, this over-allocs (which is fine) */
		BMVert **f_verts  = MEM_mallocN(sizeof(*verts) * totv, __func__);
		BMIter eiter;

		/* build array of connected verts and edges */
		BMEdge *e_prev = NULL;
		BMEdge *e_next = NULL;
		int totv_used = 0;

		while (totv_used < totv) {
			for (i = 0; i < totv; i++) {
				v = verts[i];
				if (BMO_elem_flag_test(bm, v, VERT_USED)) {
					break;
				}
			}

			/* this should never fail, as long as (totv_used < totv)
			 * we should have marked verts available */
			BLI_assert(BMO_elem_flag_test(bm, v, VERT_USED));

			/* watch it, 'i' is used for final face length */
			i = 0;
			do {
				/* we know that there are 2 edges per vertex so no need to check */
				BM_ITER_ELEM (e, &eiter, v, BM_EDGES_OF_VERT) {
					if (BMO_elem_flag_test(bm, e, EDGE_MARK)) {
						if (e != e_prev) {
							e_next = e;
							break;
						}
					}
				}

				/* fill in the array */
				f_verts[i] = v;
				BMO_elem_flag_disable(bm, v, VERT_USED);
				totv_used++;

				/* step over the edges */
				v = BM_edge_other_vert(e_next, v);
				e_prev = e_next;
				i++;
			} while ((v != f_verts[0]));

			if (BM_face_exists(f_verts, i, NULL) == false) {
				BMFace *f;

				/* don't use calc_edges option because we already have the edges */
				f = BM_face_create_ngon_verts(bm, f_verts, i, NULL, BM_CREATE_NOP, true, false);
				BMO_elem_flag_enable(bm, f, ELE_OUT);
				f->mat_nr = mat_nr;
				if (use_smooth) {
					BM_elem_flag_enable(f, BM_ELEM_SMOOTH);
				}
			}
		}
		MEM_freeN(f_verts);

		BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "faces.out", BM_FACE, ELE_OUT);
	}

cleanup:
	MEM_freeN(verts);
}