/*
 * ***** 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): Joseph Eagar, Campbell Barton.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/bmesh/operators/bmo_create.c
 *  \ingroup bmesh 
 *
 * Create faces or edges (Fkey by default).
 */

#include "MEM_guardedalloc.h"

#include "BLI_listbase.h"

#include "bmesh.h"

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

#define ELE_NEW		1
#define ELE_OUT		2

/* This is what runs when pressing the F key
 * doing the best thing here isn't always easy create vs dissolve, its nice to support
 * but it it _really_ gives issues we might have to not call dissolve. - campbell
 */
void bmo_contextual_create_exec(BMesh *bm, BMOperator *op)
{
	BMOIter oiter;
	BMHeader *h;
	int totv = 0, tote = 0, totf = 0;
	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");

	/* count number of each element type we were passe */
	BMO_ITER (h, &oiter, op->slots_in, "geom", BM_VERT | BM_EDGE | BM_FACE) {
		switch (h->htype) {
			case BM_VERT: totv++; break;
			case BM_EDGE: tote++; break;
			case BM_FACE: totf++; break;
		}

		BMO_elem_flag_enable(bm, (BMElemF *)h, ELE_NEW);
	}
	
	/* --- Support Edge Creation ---
	 * simple case when we only have 2 verts selected.
	 */
	if (totv == 2 && tote == 0 && totf == 0) {
		BMVert *verts[2];
		BMEdge *e;

		BMO_iter_as_array(op->slots_in, "geom", BM_VERT, (void **)verts, 2);

		/* create edge */
		e = BM_edge_create(bm, verts[0], verts[1], NULL, BM_CREATE_NO_DOUBLE);
		BMO_elem_flag_enable(bm, e, ELE_OUT);
		tote += 1;
		BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "edges.out", BM_EDGE, ELE_OUT);
		return;
	}


	/* --- Support for Special Case ---
	 * where there is a contiguous edge ring with one isolated vertex.
	 *
	 * This example shows 2 edges created from 3 verts
	 * with 1 free standing vertex. Dotted lines denote the 2 edges that are created.
	 *
	 * note that this works for any sided shape.
	 *
	 * +--------+
	 * |        .
	 * |        .
	 * |        .
	 * |        .
	 * +........+ <-- starts out free standing.
	 *
	 */

	/* Here we check for consistency and create 2 edges */
	if (totf == 0 && totv >= 4 && totv == tote + 2) {
		/* find a free standing vertex and 2 endpoint verts */
		BMVert *v, *v_free = NULL, *v_a = NULL, *v_b = NULL;
		bool ok = true;


		BMO_ITER (v, &oiter, op->slots_in, "geom", BM_VERT) {
			/* count how many flagged edges this vertex uses */
			const int tot_edges = BMO_iter_elem_count_flag(bm, BM_EDGES_OF_VERT, v, ELE_NEW, true);
			if (tot_edges == 0) {
				/* only accept 1 free vert */
				if (v_free == NULL)  v_free = v;
				else                 ok = false;  /* only ever want one of these */
			}
			else if (tot_edges == 1) {
				if      (v_a == NULL)  v_a = v;
				else if (v_b == NULL)  v_b = v;
				else                   ok = false;  /* only ever want 2 of these */
			}
			else if (tot_edges == 2) {
				/* do nothing, regular case */
			}
			else {
				ok = false; /* if a vertex has 3+ edge users then cancel - this is only simple cases */
			}

			if (ok == false) {
				break;
			}
		}

		if (ok == true && v_free && v_a && v_b) {
			BMEdge *e;

			e = BM_edge_create(bm, v_free, v_a, NULL, BM_CREATE_NO_DOUBLE);
			BMO_elem_flag_enable(bm, e, ELE_NEW);

			e = BM_edge_create(bm, v_free, v_b, NULL, BM_CREATE_NO_DOUBLE);
			BMO_elem_flag_enable(bm, e, ELE_NEW);
			tote += 2;
		}
	}
	/* --- end special case support, continue as normal --- */


	/* -------------------------------------------------------------------- */
	/* EdgeNet Create */
	if (tote != 0) {
		/* call edgenet prepare op so additional face creation cases work */
		BMOperator op_sub;
		BMO_op_initf(bm, &op_sub, op->flag, "edgenet_prepare edges=%fe", ELE_NEW);
		BMO_op_exec(bm, &op_sub);
		BMO_slot_buffer_flag_enable(bm, op_sub.slots_out, "edges.out", BM_EDGE, ELE_NEW);
		BMO_op_finish(bm, &op_sub);

		BMO_op_initf(bm, &op_sub, op->flag,
		             "edgenet_fill edges=%fe use_fill_check=%b mat_nr=%i use_smooth=%b",
		             ELE_NEW, true, mat_nr, use_smooth);

		BMO_op_exec(bm, &op_sub);

		/* return if edge net create did something */
		if (BMO_slot_buffer_count(op_sub.slots_out, "faces.out")) {
			BMO_slot_copy(&op_sub, slots_out, "faces.out",
			              op,   slots_out, "faces.out");
			BMO_op_finish(bm, &op_sub);
			return;
		}

		BMO_op_finish(bm, &op_sub);
	}


	/* -------------------------------------------------------------------- */
	/* Dissolve Face */
	if (totf != 0) {  /* should be (totf > 1)... see below */
		/* note: allow this to run on single faces so running on a single face
		 * won't go on to create a face, treating them as random */
		BMOperator op_sub;
		BMO_op_initf(bm, &op_sub, op->flag, "dissolve_faces faces=%ff", ELE_NEW);
		BMO_op_exec(bm, &op_sub);

		/* if we dissolved anything, then return */
		if (BMO_slot_buffer_count(op_sub.slots_out, "region.out")) {
			BMO_slot_copy(&op_sub, slots_out, "region.out",
			              op,   slots_out,  "faces.out");
			BMO_op_finish(bm, &op_sub);
			return;
		}

		BMO_op_finish(bm, &op_sub);
	}


	/* -------------------------------------------------------------------- */
	/* Fill EdgeLoop's - fills isolated loops, different from edgenet */
	if (tote > 2) {
		BMOperator op_sub;
		/* note: in most cases 'edgenet_fill' will handle this case since in common cases
		 * users fill in empty spaces, however its possible to have an edge selection around
		 * existing geometry that makes 'edgenet_fill' fail. */
		BMO_op_initf(bm, &op_sub, op->flag, "edgeloop_fill edges=%fe", ELE_NEW);
		BMO_op_exec(bm, &op_sub);

		/* return if edge loop fill did something */
		if (BMO_slot_buffer_count(op_sub.slots_out, "faces.out")) {
			BMO_slot_copy(&op_sub, slots_out, "faces.out",
			              op,   slots_out, "faces.out");
			BMO_op_finish(bm, &op_sub);
			return;
		}

		BMO_op_finish(bm, &op_sub);
	}



	/* -------------------------------------------------------------------- */
	/* Continue with ad-hoc fill methods since operators fail,
	 * edge, vcloud... may add more */

	 if (0) { /* nice feature but perhaps it should be a different tool? */

		/* tricky feature for making a line/edge from selection history...
		 *
		 * Rather then do nothing, when 5+ verts are selected, check if they are in our history,
		 * when this is so, we can make edges from them, but _not_ a face,
		 * if it is the intention to make a face the user can just hit F again since there will be edges next
		 * time around.
		 *
		 * if all history verts have ELE_NEW flagged and the total number of history verts == totv,
		 * then we know the history contains all verts here and we can continue...
		 */

		BMEditSelection *ese;
		int tot_ese_v = 0;

		for (ese = bm->selected.first; ese; ese = ese->next) {
			if (ese->htype == BM_VERT) {
				if (BMO_elem_flag_test(bm, (BMElemF *)ese->ele, ELE_NEW)) {
					tot_ese_v++;
				}
				else {
					/* unflagged vert means we are not in sync */
					tot_ese_v = -1;
					break;
				}
			}
		}

		if (tot_ese_v == totv) {
			BMVert *v_prev = NULL;
			/* yes, all select-history verts are accounted for, now make edges */

			for (ese = bm->selected.first; ese; ese = ese->next) {
				if (ese->htype == BM_VERT) {
					BMVert *v = (BMVert *)ese->ele;
					if (v_prev) {
						BMEdge *e = BM_edge_create(bm, v, v_prev, NULL, BM_CREATE_NO_DOUBLE);
						BMO_elem_flag_enable(bm, e, ELE_OUT);
					}
					v_prev = v;
				}
			}
		}
		BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "edges.out", BM_EDGE, ELE_OUT);
		/* done creating edges */

		return;
	}


	/* -------------------------------------------------------------------- */
	/* Fill Vertex Cloud
	 *
	 * last resort when all else fails.
	 */
	if (totv > 2) {
		/* TODO, some of these vertes may be connected by edges,
		 * this connectivity could be used rather then treating
		 * them as a bunch of isolated verts. */

		BMVert **vert_arr = MEM_mallocN(sizeof(BMVert **) * totv, __func__);
		BMFace *f;

		BMO_iter_as_array(op->slots_in, "geom", BM_VERT, (void **)vert_arr, totv);
		f = BM_face_create_ngon_vcloud(bm, vert_arr, totv, BM_CREATE_NO_DOUBLE);

		if (f) {
			BMO_elem_flag_enable(bm, f, ELE_OUT);
			f->mat_nr = mat_nr;
			if (use_smooth) {
				BM_elem_flag_enable(f, BM_ELEM_SMOOTH);
			}
			BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "faces.out", BM_FACE, ELE_OUT);
		}

		MEM_freeN(vert_arr);
	}
}
