/**************************************************************************/
/*  nav_utils_3d.h                                                        */
/**************************************************************************/
/*                         This file is part of:                          */
/*                             GODOT ENGINE                               */
/*                        https://godotengine.org                         */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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/* Permission is hereby granted, free of charge, to any person obtaining  */
/* a copy of this software and associated documentation files (the        */
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#pragma once

#include "core/math/vector3.h"
#include "core/templates/hashfuncs.h"
#include "core/templates/local_vector.h"
#include "core/templates/rid.h"

#include <cfloat> // FLT_MAX

class NavBaseIteration3D;

namespace Nav3D {
struct Polygon;

union PointKey {
	struct {
		int64_t x : 21;
		int64_t y : 22;
		int64_t z : 21;
	};

	uint64_t key = 0;
};

struct EdgeKey {
	PointKey a;
	PointKey b;

	static uint32_t hash(const EdgeKey &p_val) {
		return hash_one_uint64(p_val.a.key) ^ hash_one_uint64(p_val.b.key);
	}

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

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

struct ConnectableEdge {
	EdgeKey ek;
	uint32_t polygon_index;
	int edge = -1;
	Vector3 pathway_start;
	Vector3 pathway_end;
};

struct Connection {
	/// Polygon that this connection leads to.
	Polygon *polygon = nullptr;

	/// Edge of the source polygon where this connection starts from.
	int edge = -1;

	/// Point on the edge where the gateway leading to the poly starts.
	Vector3 pathway_start;

	/// Point on the edge where the gateway leading to the poly ends.
	Vector3 pathway_end;
};

struct Polygon {
	uint32_t id = UINT32_MAX;

	/// Navigation region or link that contains this polygon.
	const NavBaseIteration3D *owner = nullptr;

	LocalVector<Vector3> vertices;

	real_t surface_area = 0.0;
};

struct NavigationPoly {
	/// This poly.
	const Polygon *poly = nullptr;

	/// Index in the heap of traversable polygons.
	uint32_t traversable_poly_index = UINT32_MAX;

	/// Those 4 variables are used to travel the path backwards.
	int back_navigation_poly_id = -1;
	int back_navigation_edge = -1;
	Vector3 back_navigation_edge_pathway_start;
	Vector3 back_navigation_edge_pathway_end;

	/// The entry position of this poly.
	Vector3 entry;
	/// The distance traveled until now (g cost).
	real_t traveled_distance = 0.0;
	/// The distance to the destination (h cost).
	real_t distance_to_destination = 0.0;

	/// The total travel cost (f cost).
	real_t total_travel_cost() const {
		return traveled_distance + distance_to_destination;
	}

	bool operator==(const NavigationPoly &p_other) const {
		return poly == p_other.poly;
	}

	bool operator!=(const NavigationPoly &p_other) const {
		return !(*this == p_other);
	}

	void reset() {
		poly = nullptr;
		traversable_poly_index = UINT32_MAX;
		back_navigation_poly_id = -1;
		back_navigation_edge = -1;
		traveled_distance = FLT_MAX;
		distance_to_destination = 0.0;
	}
};

struct NavPolyTravelCostGreaterThan {
	// Returns `true` if the travel cost of `a` is higher than that of `b`.
	bool operator()(const NavigationPoly *p_poly_a, const NavigationPoly *p_poly_b) const {
		real_t f_cost_a = p_poly_a->total_travel_cost();
		real_t h_cost_a = p_poly_a->distance_to_destination;
		real_t f_cost_b = p_poly_b->total_travel_cost();
		real_t h_cost_b = p_poly_b->distance_to_destination;

		if (f_cost_a != f_cost_b) {
			return f_cost_a > f_cost_b;
		} else {
			return h_cost_a > h_cost_b;
		}
	}
};

struct NavPolyHeapIndexer {
	void operator()(NavigationPoly *p_poly, uint32_t p_heap_index) const {
		p_poly->traversable_poly_index = p_heap_index;
	}
};

struct ClosestPointQueryResult {
	Vector3 point;
	Vector3 normal;
	RID owner;
};

struct EdgeConnectionPair {
	Connection connections[2];
	int size = 0;
};

struct PerformanceData {
	int pm_region_count = 0;
	int pm_agent_count = 0;
	int pm_link_count = 0;
	int pm_polygon_count = 0;
	int pm_edge_count = 0;
	int pm_edge_merge_count = 0;
	int pm_edge_connection_count = 0;
	int pm_edge_free_count = 0;
	int pm_obstacle_count = 0;

	void reset() {
		pm_region_count = 0;
		pm_agent_count = 0;
		pm_link_count = 0;
		pm_polygon_count = 0;
		pm_edge_count = 0;
		pm_edge_merge_count = 0;
		pm_edge_connection_count = 0;
		pm_edge_free_count = 0;
		pm_obstacle_count = 0;
	}
};

} // namespace Nav3D
