/*************************************************************************/
/*  navigation_2d.h                                                      */
/*************************************************************************/
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
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#ifndef NAVIGATION_2D_H
#define NAVIGATION_2D_H

#include "scene/2d/navigation_polygon.h"
#include "scene/2d/node_2d.h"

class Navigation2D : public Node2D {

	GDCLASS(Navigation2D, Node2D);

	union Point {

		struct {
			int64_t x : 32;
			int64_t y : 32;
		};

		uint64_t key;
		bool operator<(const Point &p_key) const { return key < p_key.key; }
	};

	struct EdgeKey {

		Point a;
		Point b;

		bool operator<(const EdgeKey &p_key) const {
			return (a.key == p_key.a.key) ? (b.key < p_key.b.key) : (a.key < p_key.a.key);
		};

		EdgeKey(const Point &p_a = Point(), const Point &p_b = Point()) :
				a(p_a),
				b(p_b) {
			if (a.key > b.key) {
				SWAP(a, b);
			}
		}
	};

	struct NavMesh;
	struct Polygon;

	struct ConnectionPending {

		Polygon *polygon;
		int edge;
	};

	struct Polygon {

		struct Edge {
			Point point;
			Polygon *C; //connection
			int C_edge;
			List<ConnectionPending>::Element *P;
			Edge() {
				C = NULL;
				C_edge = -1;
				P = NULL;
			}
		};

		Vector<Edge> edges;

		Vector2 center;
		Vector2 entry;

		float distance;
		int prev_edge;

		bool clockwise;

		NavMesh *owner;
	};

	struct Connection {

		Polygon *A;
		int A_edge;
		Polygon *B;
		int B_edge;

		List<ConnectionPending> pending;

		Connection() {
			A = NULL;
			B = NULL;
			A_edge = -1;
			B_edge = -1;
		}
	};

	Map<EdgeKey, Connection> connections;

	struct NavMesh {

		Object *owner;
		Transform2D xform;
		bool linked;
		Ref<NavigationPolygon> navpoly;
		List<Polygon> polygons;
	};

	_FORCE_INLINE_ Point _get_point(const Vector2 &p_pos) const {

		int x = int(Math::floor(p_pos.x / cell_size));
		int y = int(Math::floor(p_pos.y / cell_size));

		Point p;
		p.key = 0;
		p.x = x;
		p.y = y;
		return p;
	}

	_FORCE_INLINE_ Vector2 _get_vertex(const Point &p_point) const {

		return Vector2(p_point.x, p_point.y) * cell_size;
	}

	void _navpoly_link(int p_id);
	void _navpoly_unlink(int p_id);

	float cell_size;
	Map<int, NavMesh> navpoly_map;
	int last_id;

protected:
	static void _bind_methods();

public:
	//API should be as dynamic as possible
	int navpoly_add(const Ref<NavigationPolygon> &p_mesh, const Transform2D &p_xform, Object *p_owner = NULL);
	void navpoly_set_transform(int p_id, const Transform2D &p_xform);
	void navpoly_remove(int p_id);

	Vector<Vector2> get_simple_path(const Vector2 &p_start, const Vector2 &p_end, bool p_optimize = true);
	Vector2 get_closest_point(const Vector2 &p_point);
	Object *get_closest_point_owner(const Vector2 &p_point);

	Navigation2D();
};

#endif // NAVIGATION_2D_H
