/*
 * ***** 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.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/bmesh/operators/bmo_triangulate.c
 *  \ingroup bmesh
 *
 * Triangulate faces, also defines triangle fill.
 */

#include "MEM_guardedalloc.h"

#include "DNA_listBase.h"

#include "BLI_math.h"
#include "BLI_sort_utils.h"
#include "BLI_scanfill.h"

#include "bmesh.h"
#include "bmesh_tools.h"
#include "intern/bmesh_operators_private.h"


#define ELE_NEW		1
#define EDGE_MARK	4

void bmo_triangulate_exec(BMesh *bm, BMOperator *op)
{
	const int quad_method = BMO_slot_int_get(op->slots_in, "quad_method");
	const int ngon_method = BMO_slot_int_get(op->slots_in, "ngon_method");

	BMOpSlot *slot_facemap_out = BMO_slot_get(op->slots_out, "face_map.out");

	BM_mesh_elem_hflag_disable_all(bm, BM_FACE | BM_EDGE, BM_ELEM_TAG, false);
	BMO_slot_buffer_hflag_enable(bm, op->slots_in, "faces", BM_FACE, BM_ELEM_TAG, false);

	BM_mesh_triangulate(bm, quad_method, ngon_method, true, op, slot_facemap_out);

	BMO_slot_buffer_from_enabled_hflag(bm, op, op->slots_out, "edges.out", BM_EDGE, BM_ELEM_TAG);
	BMO_slot_buffer_from_enabled_hflag(bm, op, op->slots_out, "faces.out", BM_FACE, BM_ELEM_TAG);
}

struct SortNormal {
	float value;  /* keep first */
	float no[3];
};

void bmo_triangle_fill_exec(BMesh *bm, BMOperator *op)
{
	const bool use_beauty = BMO_slot_bool_get(op->slots_in, "use_beauty");
	const bool use_dissolve = BMO_slot_bool_get(op->slots_in, "use_dissolve");
	BMOIter siter;
	BMEdge *e;
	ScanFillContext sf_ctx;
	/* ScanFillEdge *sf_edge; */ /* UNUSED */
	ScanFillFace *sf_tri;
	GHash *sf_vert_map;
	float normal[3];
	const int scanfill_flag = BLI_SCANFILL_CALC_HOLES | BLI_SCANFILL_CALC_POLYS | BLI_SCANFILL_CALC_LOOSE;
	bool calc_winding = false;

	sf_vert_map = BLI_ghash_ptr_new_ex(__func__, BMO_slot_buffer_count(op->slots_in, "edges"));

	BMO_slot_vec_get(op->slots_in, "normal", normal);
	
	BLI_scanfill_begin(&sf_ctx);
	
	BMO_ITER (e, &siter, op->slots_in, "edges", BM_EDGE) {
		ScanFillVert *sf_verts[2];
		BMVert **e_verts = &e->v1;
		unsigned int i;

		BMO_elem_flag_enable(bm, e, EDGE_MARK);

		calc_winding = (calc_winding || BM_edge_is_boundary(e));

		for (i = 0; i < 2; i++) {
			if ((sf_verts[i] = BLI_ghash_lookup(sf_vert_map, e_verts[i])) == NULL) {
				sf_verts[i] = BLI_scanfill_vert_add(&sf_ctx, e_verts[i]->co);
				sf_verts[i]->tmp.p = e_verts[i];
				BLI_ghash_insert(sf_vert_map, e_verts[i], sf_verts[i]);
			}
		}

		/* sf_edge = */ BLI_scanfill_edge_add(&sf_ctx, UNPACK2(sf_verts));
		/* sf_edge->tmp.p = e; */ /* UNUSED */
	}
	BLI_ghash_free(sf_vert_map, NULL, NULL);
	

	if (is_zero_v3(normal)) {
		/* calculate the normal from the cross product of vert-edge pairs.
		 * Since we don't know winding, just accumulate */
		ScanFillVert *sf_vert;
		struct SortNormal *nors;
		const unsigned int nors_tot = BLI_ghash_size(sf_vert_map);
		unsigned int i;
		bool is_degenerate = true;

		nors = MEM_mallocN(sizeof(*nors) * nors_tot, __func__);

		for (sf_vert = sf_ctx.fillvertbase.first, i = 0; sf_vert; sf_vert = sf_vert->next, i++) {
			BMVert *v = sf_vert->tmp.p;
			BMIter eiter;
			BMEdge *e, *e_pair[2];
			unsigned int e_index = 0;

			nors[i].value = -1.0f;

			/* only use if 'is_degenerate' stays true */
			add_v3_v3(normal, v->no);

			BM_ITER_ELEM (e, &eiter, v, BM_EDGES_OF_VERT) {
				if (BMO_elem_flag_test(bm, e, EDGE_MARK)) {
					if (e_index == 2) {
						e_index = 0;
						break;
					}
					e_pair[e_index++] = e;
				}
			}

			if (e_index == 2) {
				float dir_a[3], dir_b[3];

				is_degenerate = false;

				sub_v3_v3v3(dir_a, v->co, BM_edge_other_vert(e_pair[0], v)->co);
				sub_v3_v3v3(dir_b, v->co, BM_edge_other_vert(e_pair[1], v)->co);

				cross_v3_v3v3(nors[i].no, dir_a, dir_b);
				nors[i].value = len_squared_v3(nors[i].no);

				/* only to get deterministic behavior (for initial normal) */
				if (len_squared_v3(dir_a) > len_squared_v3(dir_b)) {
					negate_v3(nors[i].no);
				}
			}
		}

		if (UNLIKELY(is_degenerate)) {
			/* no vertices have 2 edges?
			 * in this case fall back to the average vertex normals */
		}
		else {
			qsort(nors, nors_tot, sizeof(*nors), BLI_sortutil_cmp_float_reverse);

			copy_v3_v3(normal, nors[0].no);
			for (i = 0; i < nors_tot; i++) {
				if (UNLIKELY(nors[i].value == -1.0f)) {
					break;
				}
				if (dot_v3v3(normal, nors[i].no) < 0.0f) {
					negate_v3(nors[i].no);
				}
				add_v3_v3(normal, nors[i].no);
			}
			normalize_v3(normal);
		}

		MEM_freeN(nors);
	}
	else {
		calc_winding = false;
	}

	normalize_v3(normal);

	BLI_scanfill_calc_ex(&sf_ctx, scanfill_flag, normal);


	/* if we have existing faces, base winding on those */
	if (calc_winding) {
		int winding_votes = 0;
		for (sf_tri = sf_ctx.fillfacebase.first; sf_tri; sf_tri = sf_tri->next) {
			BMVert *v_tri[3] = {sf_tri->v1->tmp.p, sf_tri->v2->tmp.p, sf_tri->v3->tmp.p};
			unsigned int i, i_prev;

			for (i = 0, i_prev = 2; i < 3; i_prev = i++) {
				e = BM_edge_exists(v_tri[i], v_tri[i_prev]);
				if (e && BM_edge_is_boundary(e) && BMO_elem_flag_test(bm, e, EDGE_MARK)) {
					winding_votes += (e->l->v == v_tri[i]) ? 1 : -1;
				}
			}
		}

		if (winding_votes < 0) {
			for (sf_tri = sf_ctx.fillfacebase.first; sf_tri; sf_tri = sf_tri->next) {
				SWAP(struct ScanFillVert *, sf_tri->v2, sf_tri->v3);
			}
		}
	}


	for (sf_tri = sf_ctx.fillfacebase.first; sf_tri; sf_tri = sf_tri->next) {
		BMFace *f;
		BMLoop *l;
		BMIter liter;

		f = BM_face_create_quad_tri(bm,
		                            sf_tri->v1->tmp.p, sf_tri->v2->tmp.p, sf_tri->v3->tmp.p, NULL,
		                            NULL, BM_CREATE_NO_DOUBLE);
		
		BMO_elem_flag_enable(bm, f, ELE_NEW);
		BM_ITER_ELEM (l, &liter, f, BM_LOOPS_OF_FACE) {
			if (!BMO_elem_flag_test(bm, l->e, EDGE_MARK)) {
				BMO_elem_flag_enable(bm, l->e, ELE_NEW);
			}
		}
	}
	
	BLI_scanfill_end(&sf_ctx);
	
	if (use_beauty) {
		BMOperator bmop;

		BMO_op_initf(bm, &bmop, op->flag, "beautify_fill faces=%ff edges=%Fe", ELE_NEW, EDGE_MARK);
		BMO_op_exec(bm, &bmop);
		BMO_slot_buffer_flag_enable(bm, bmop.slots_out, "geom.out", BM_FACE | BM_EDGE, ELE_NEW);
		BMO_op_finish(bm, &bmop);
	}
	
	BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "geom.out", BM_EDGE | BM_FACE, ELE_NEW);

	if (use_dissolve) {
		BMO_ITER (e, &siter, op->slots_out, "geom.out", BM_EDGE) {
			if (LIKELY(e->l)) {  /* in rare cases the edges face will have already been removed from the edge */
				BMFace *f_new;
				f_new = BM_faces_join_pair(bm, e->l->f,
				                           e->l->radial_next->f, e,
				                           false); /* join faces */
				if (f_new) {
					BMO_elem_flag_enable(bm, f_new, ELE_NEW);
					BM_edge_kill(bm, e);
				}
				else {
					BMO_error_clear(bm);
				}
			}
			else {
				BM_edge_kill(bm, e);
			}
		}

		BMO_slot_buffer_from_enabled_flag(bm, op, op->slots_out, "geom.out", BM_EDGE | BM_FACE, ELE_NEW);
	}
}