/*************************************************************************/
/*  navigation_agent_2d.cpp                                              */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
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#include "navigation_agent_2d.h"

#include "core/config/engine.h"
#include "core/containers/vector.h"
#include "scene/2d/navigation_2d.h"
#include "scene/resources/world_2d.h"
#include "servers/navigation_2d_server.h"

void NavigationAgent2D::_bind_methods() {
	ClassDB::bind_method(D_METHOD("get_rid"), &NavigationAgent2D::get_rid);

	ClassDB::bind_method(D_METHOD("set_avoidance_enabled", "enabled"), &NavigationAgent2D::set_avoidance_enabled);
	ClassDB::bind_method(D_METHOD("get_avoidance_enabled"), &NavigationAgent2D::get_avoidance_enabled);

	ClassDB::bind_method(D_METHOD("set_path_desired_distance", "desired_distance"), &NavigationAgent2D::set_path_desired_distance);
	ClassDB::bind_method(D_METHOD("get_path_desired_distance"), &NavigationAgent2D::get_path_desired_distance);

	ClassDB::bind_method(D_METHOD("set_target_desired_distance", "desired_distance"), &NavigationAgent2D::set_target_desired_distance);
	ClassDB::bind_method(D_METHOD("get_target_desired_distance"), &NavigationAgent2D::get_target_desired_distance);

	ClassDB::bind_method(D_METHOD("set_radius", "radius"), &NavigationAgent2D::set_radius);
	ClassDB::bind_method(D_METHOD("get_radius"), &NavigationAgent2D::get_radius);

	ClassDB::bind_method(D_METHOD("set_navigation", "navigation"), &NavigationAgent2D::set_navigation_node);
	ClassDB::bind_method(D_METHOD("get_navigation"), &NavigationAgent2D::get_navigation_node);

	ClassDB::bind_method(D_METHOD("set_neighbor_dist", "neighbor_dist"), &NavigationAgent2D::set_neighbor_dist);
	ClassDB::bind_method(D_METHOD("get_neighbor_dist"), &NavigationAgent2D::get_neighbor_dist);

	ClassDB::bind_method(D_METHOD("set_max_neighbors", "max_neighbors"), &NavigationAgent2D::set_max_neighbors);
	ClassDB::bind_method(D_METHOD("get_max_neighbors"), &NavigationAgent2D::get_max_neighbors);

	ClassDB::bind_method(D_METHOD("set_time_horizon", "time_horizon"), &NavigationAgent2D::set_time_horizon);
	ClassDB::bind_method(D_METHOD("get_time_horizon"), &NavigationAgent2D::get_time_horizon);

	ClassDB::bind_method(D_METHOD("set_max_speed", "max_speed"), &NavigationAgent2D::set_max_speed);
	ClassDB::bind_method(D_METHOD("get_max_speed"), &NavigationAgent2D::get_max_speed);

	ClassDB::bind_method(D_METHOD("set_path_max_distance", "max_speed"), &NavigationAgent2D::set_path_max_distance);
	ClassDB::bind_method(D_METHOD("get_path_max_distance"), &NavigationAgent2D::get_path_max_distance);

	ClassDB::bind_method(D_METHOD("set_navigation_layers", "navigation_layers"), &NavigationAgent2D::set_navigation_layers);
	ClassDB::bind_method(D_METHOD("get_navigation_layers"), &NavigationAgent2D::get_navigation_layers);

	ClassDB::bind_method(D_METHOD("set_navigation_map", "navigation_map"), &NavigationAgent2D::set_navigation_map);
	ClassDB::bind_method(D_METHOD("get_navigation_map"), &NavigationAgent2D::get_navigation_map);

	ClassDB::bind_method(D_METHOD("set_target_location", "location"), &NavigationAgent2D::set_target_location);
	ClassDB::bind_method(D_METHOD("get_target_location"), &NavigationAgent2D::get_target_location);
	ClassDB::bind_method(D_METHOD("get_next_location"), &NavigationAgent2D::get_next_location);
	ClassDB::bind_method(D_METHOD("distance_to_target"), &NavigationAgent2D::distance_to_target);
	ClassDB::bind_method(D_METHOD("set_velocity", "velocity"), &NavigationAgent2D::set_velocity);
	ClassDB::bind_method(D_METHOD("get_nav_path"), &NavigationAgent2D::get_nav_path);
	ClassDB::bind_method(D_METHOD("get_nav_path_index"), &NavigationAgent2D::get_nav_path_index);
	ClassDB::bind_method(D_METHOD("is_target_reached"), &NavigationAgent2D::is_target_reached);
	ClassDB::bind_method(D_METHOD("is_target_reachable"), &NavigationAgent2D::is_target_reachable);
	ClassDB::bind_method(D_METHOD("is_navigation_finished"), &NavigationAgent2D::is_navigation_finished);
	ClassDB::bind_method(D_METHOD("get_final_location"), &NavigationAgent2D::get_final_location);

	ClassDB::bind_method(D_METHOD("_avoidance_done", "new_velocity"), &NavigationAgent2D::_avoidance_done);

	ADD_GROUP("Pathfinding", "");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "path_desired_distance", PROPERTY_HINT_RANGE, "0.1,100,0.01"), "set_path_desired_distance", "get_path_desired_distance");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "target_desired_distance", PROPERTY_HINT_RANGE, "0.1,100,0.01"), "set_target_desired_distance", "get_target_desired_distance");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "path_max_distance", PROPERTY_HINT_RANGE, "10,100,1"), "set_path_max_distance", "get_path_max_distance");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "navigation_layers", PROPERTY_HINT_LAYERS_2D_NAVIGATION), "set_navigation_layers", "get_navigation_layers");

	ADD_GROUP("Avoidance", "");
	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "avoidance_enabled"), "set_avoidance_enabled", "get_avoidance_enabled");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "radius", PROPERTY_HINT_RANGE, "0.1,500,0.01"), "set_radius", "get_radius");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "neighbor_dist", PROPERTY_HINT_RANGE, "0.1,100000,0.01"), "set_neighbor_dist", "get_neighbor_dist");
	ADD_PROPERTY(PropertyInfo(Variant::INT, "max_neighbors", PROPERTY_HINT_RANGE, "1,10000,1"), "set_max_neighbors", "get_max_neighbors");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "time_horizon", PROPERTY_HINT_RANGE, "0.1,10000,0.01"), "set_time_horizon", "get_time_horizon");
	ADD_PROPERTY(PropertyInfo(Variant::REAL, "max_speed", PROPERTY_HINT_RANGE, "0.1,100000,0.01"), "set_max_speed", "get_max_speed");

	ADD_SIGNAL(MethodInfo("path_changed"));
	ADD_SIGNAL(MethodInfo("target_reached"));
	ADD_SIGNAL(MethodInfo("navigation_finished"));
	ADD_SIGNAL(MethodInfo("velocity_computed", PropertyInfo(Variant::VECTOR2, "safe_velocity")));
}

void NavigationAgent2D::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_POST_ENTER_TREE: {
			// Search the navigation node and set it
			{
				Navigation2D *nav = nullptr;
				Node *p = get_parent();
				while (p != nullptr) {
					nav = Object::cast_to<Navigation2D>(p);
					if (nav != nullptr) {
						p = nullptr;
					} else {
						p = p->get_parent();
					}
				}

				set_navigation(nav);
			}

			// need to use POST_ENTER_TREE cause with normal ENTER_TREE not all required Nodes are ready.
			// cannot use READY as ready does not get called if Node is readded to SceneTree
			set_agent_parent(get_parent());
			set_physics_process_internal(true);
		} break;
		case NOTIFICATION_PARENTED: {
			if (is_inside_tree() && (get_parent() != agent_parent)) {
				// only react to PARENTED notifications when already inside_tree and parent changed, e.g. users switch nodes around
				// PARENTED notification fires also when Node is added in scripts to a parent
				// this would spam transforms fails and world fails while Node is outside SceneTree
				// when node gets reparented when joining the tree POST_ENTER_TREE takes care of this
				set_agent_parent(get_parent());
				set_physics_process_internal(true);
			}
		} break;
		case NOTIFICATION_UNPARENTED: {
			// if agent has no parent no point in processing it until reparented
			set_agent_parent(nullptr);
			set_physics_process_internal(false);
		} break;
		case NOTIFICATION_PAUSED: {
			if (agent_parent && !agent_parent->can_process()) {
				map_before_pause = Navigation2DServer::get_singleton()->agent_get_map(get_rid());
				Navigation2DServer::get_singleton()->agent_set_map(get_rid(), RID());
			} else if (agent_parent && agent_parent->can_process() && !(map_before_pause == RID())) {
				Navigation2DServer::get_singleton()->agent_set_map(get_rid(), map_before_pause);
				map_before_pause = RID();
			}
		} break;
		case NOTIFICATION_UNPAUSED: {
			if (agent_parent && !agent_parent->can_process()) {
				map_before_pause = Navigation2DServer::get_singleton()->agent_get_map(get_rid());
				Navigation2DServer::get_singleton()->agent_set_map(get_rid(), RID());
			} else if (agent_parent && agent_parent->can_process() && !(map_before_pause == RID())) {
				Navigation2DServer::get_singleton()->agent_set_map(get_rid(), map_before_pause);
				map_before_pause = RID();
			}
		} break;
		case NOTIFICATION_EXIT_TREE: {
			set_agent_parent(nullptr);
			set_navigation(nullptr);
			set_physics_process_internal(false);
		} break;
		case NOTIFICATION_INTERNAL_PHYSICS_PROCESS: {
			if (agent_parent) {
				if (avoidance_enabled) {
					// agent_position on NavigationServer is avoidance only and has nothing to do with pathfinding
					// no point in flooding NavigationServer queue with agent position updates that get send to the void if avoidance is not used
					Navigation2DServer::get_singleton()->agent_set_position(agent, agent_parent->get_global_position());
				}
				_check_distance_to_target();
			}
		} break;
	}
}

NavigationAgent2D::NavigationAgent2D() {
	agent_parent = nullptr;
	navigation = nullptr;

	avoidance_enabled = false;
	navigation_layers = 1;

	path_desired_distance = 1.0;
	target_desired_distance = 1.0;
	path_max_distance = 3.0;
	velocity_submitted = false;
	target_reached = false;
	navigation_finished = true;
	agent = Navigation2DServer::get_singleton()->agent_create();

	set_neighbor_dist(0.0);
	set_max_neighbors(0);
	set_time_horizon(0.0);
	set_radius(0.0);
	set_max_speed(0.0);

	time_horizon = 0.0;

	nav_path_index = 0;
	update_frame_id = 0;
}

NavigationAgent2D::~NavigationAgent2D() {
	Navigation2DServer::get_singleton()->free(agent);
	agent = RID(); // Pointless
}

void NavigationAgent2D::set_avoidance_enabled(bool p_enabled) {
	avoidance_enabled = p_enabled;
	if (avoidance_enabled) {
		Navigation2DServer::get_singleton()->agent_set_callback(agent, get_instance_id(), "_avoidance_done");
	} else {
		Navigation2DServer::get_singleton()->agent_set_callback(agent, ObjectID(), "_avoidance_done");
	}
}

bool NavigationAgent2D::get_avoidance_enabled() const {
	return avoidance_enabled;
}

void NavigationAgent2D::set_agent_parent(Node *p_agent_parent) {
	// remove agent from any avoidance map before changing parent or there will be leftovers on the RVO map
	Navigation2DServer::get_singleton()->agent_set_callback(agent, ObjectID(), "_avoidance_done");
	if (Object::cast_to<Node2D>(p_agent_parent) != nullptr) {
		// place agent on navigation map first or else the RVO agent callback creation fails silently later
		agent_parent = Object::cast_to<Node2D>(p_agent_parent);
		if (map_override.is_valid()) {
			Navigation2DServer::get_singleton()->agent_set_map(get_rid(), map_override);
		} else if (navigation != nullptr) {
			Navigation2DServer::get_singleton()->agent_set_map(get_rid(), navigation->get_rid());
		} else {
			// no navigation node found in parent nodes, use default navigation map from world resource
			Navigation2DServer::get_singleton()->agent_set_map(get_rid(), agent_parent->get_world_2d()->get_navigation_map());
		}
		// create new avoidance callback if enabled
		set_avoidance_enabled(avoidance_enabled);
	} else {
		agent_parent = nullptr;
		Navigation2DServer::get_singleton()->agent_set_map(get_rid(), RID());
	}
}

void NavigationAgent2D::set_navigation(Navigation2D *p_nav) {
	if (navigation == p_nav) {
		return; // Pointless
	}

	navigation = p_nav;
	Navigation2DServer::get_singleton()->agent_set_map(agent, navigation == nullptr ? RID() : navigation->get_rid());
}

void NavigationAgent2D::set_navigation_node(Node *p_nav) {
	Navigation2D *nav = Object::cast_to<Navigation2D>(p_nav);
	ERR_FAIL_NULL(nav);
	set_navigation(nav);
}

Node *NavigationAgent2D::get_navigation_node() const {
	return Object::cast_to<Node>(navigation);
}

void NavigationAgent2D::set_navigation_layers(uint32_t p_navigation_layers) {
	bool _navigation_layers_changed = navigation_layers != p_navigation_layers;
	navigation_layers = p_navigation_layers;
	if (_navigation_layers_changed) {
		_request_repath();
	}
}

uint32_t NavigationAgent2D::get_navigation_layers() const {
	return navigation_layers;
}

void NavigationAgent2D::set_navigation_map(RID p_navigation_map) {
	map_override = p_navigation_map;
	Navigation2DServer::get_singleton()->agent_set_map(agent, map_override);
	_request_repath();
}

RID NavigationAgent2D::get_navigation_map() const {
	if (map_override.is_valid()) {
		return map_override;
	} else if (navigation != nullptr) {
		return navigation->get_rid();
	} else if (agent_parent != nullptr) {
		return agent_parent->get_world_2d()->get_navigation_map();
	}
	return RID();
}

void NavigationAgent2D::set_path_desired_distance(real_t p_dd) {
	path_desired_distance = p_dd;
}

void NavigationAgent2D::set_target_desired_distance(real_t p_dd) {
	target_desired_distance = p_dd;
}

void NavigationAgent2D::set_radius(real_t p_radius) {
	radius = p_radius;
	Navigation2DServer::get_singleton()->agent_set_radius(agent, radius);
}

void NavigationAgent2D::set_neighbor_dist(real_t p_dist) {
	neighbor_dist = p_dist;
	Navigation2DServer::get_singleton()->agent_set_neighbor_dist(agent, neighbor_dist);
}

void NavigationAgent2D::set_max_neighbors(int p_count) {
	max_neighbors = p_count;
	Navigation2DServer::get_singleton()->agent_set_max_neighbors(agent, max_neighbors);
}

void NavigationAgent2D::set_time_horizon(real_t p_time) {
	time_horizon = p_time;
	Navigation2DServer::get_singleton()->agent_set_time_horizon(agent, time_horizon);
}

void NavigationAgent2D::set_max_speed(real_t p_max_speed) {
	max_speed = p_max_speed;
	Navigation2DServer::get_singleton()->agent_set_max_speed(agent, max_speed);
}

void NavigationAgent2D::set_path_max_distance(real_t p_pmd) {
	path_max_distance = p_pmd;
}

real_t NavigationAgent2D::get_path_max_distance() {
	return path_max_distance;
}

void NavigationAgent2D::set_target_location(Vector2 p_location) {
	target_location = p_location;
	_request_repath();
}

Vector2 NavigationAgent2D::get_target_location() const {
	return target_location;
}

Vector2 NavigationAgent2D::get_next_location() {
	update_navigation();
	if (navigation_path.size() == 0) {
		ERR_FAIL_COND_V(agent_parent == nullptr, Vector2());
		return agent_parent->get_global_transform().get_origin();
	} else {
		return navigation_path[nav_path_index];
	}
}

real_t NavigationAgent2D::distance_to_target() const {
	ERR_FAIL_COND_V(agent_parent == nullptr, 0.0);
	return agent_parent->get_global_transform().get_origin().distance_to(target_location);
}

bool NavigationAgent2D::is_target_reached() const {
	return target_reached;
}

bool NavigationAgent2D::is_target_reachable() {
	return target_desired_distance >= get_final_location().distance_to(target_location);
}

bool NavigationAgent2D::is_navigation_finished() {
	update_navigation();
	return navigation_finished;
}

Vector2 NavigationAgent2D::get_final_location() {
	update_navigation();
	if (navigation_path.size() == 0) {
		return Vector2();
	}
	return navigation_path[navigation_path.size() - 1];
}

void NavigationAgent2D::set_velocity(Vector2 p_velocity) {
	target_velocity = p_velocity;
	Navigation2DServer::get_singleton()->agent_set_target_velocity(agent, target_velocity);
	Navigation2DServer::get_singleton()->agent_set_velocity(agent, prev_safe_velocity);
	velocity_submitted = true;
}

void NavigationAgent2D::_avoidance_done(Vector3 p_new_velocity) {
	const Vector2 velocity = Vector2(p_new_velocity.x, p_new_velocity.z);
	prev_safe_velocity = velocity;

	if (!velocity_submitted) {
		target_velocity = Vector2();
		return;
	}
	velocity_submitted = false;

	emit_signal("velocity_computed", velocity);
}

String NavigationAgent2D::get_configuration_warning() const {
	if (!Object::cast_to<Node2D>(get_parent())) {
		return TTR("The NavigationAgent2D can be used only under a Node2D inheriting parent node.");
	}

	return String();
}

void NavigationAgent2D::update_navigation() {
	if (agent_parent == nullptr) {
		return;
	}
	if (!agent_parent->is_inside_tree()) {
		return;
	}
	if (update_frame_id == Engine::get_singleton()->get_physics_frames()) {
		return;
	}

	update_frame_id = Engine::get_singleton()->get_physics_frames();

	Vector2 o = agent_parent->get_global_transform().get_origin();

	bool reload_path = false;

	if (Navigation2DServer::get_singleton()->agent_is_map_changed(agent)) {
		reload_path = true;
	} else if (navigation_path.size() == 0) {
		reload_path = true;
	} else {
		// Check if too far from the navigation path
		if (nav_path_index > 0) {
			Vector2 segment[2];
			segment[0] = navigation_path[nav_path_index - 1];
			segment[1] = navigation_path[nav_path_index];
			Vector2 p = Geometry::get_closest_point_to_segment_2d(o, segment);
			if (o.distance_to(p) >= path_max_distance) {
				// To faraway, reload path
				reload_path = true;
			}
		}
	}

	if (reload_path) {
		if (map_override.is_valid()) {
			navigation_path = Navigation2DServer::get_singleton()->map_get_path(map_override, o, target_location, true, navigation_layers);
		} else if (navigation != nullptr) {
			navigation_path = Navigation2DServer::get_singleton()->map_get_path(navigation->get_rid(), o, target_location, true, navigation_layers);
		} else {
			navigation_path = Navigation2DServer::get_singleton()->map_get_path(agent_parent->get_world_2d()->get_navigation_map(), o, target_location, true, navigation_layers);
		}

		navigation_finished = false;
		nav_path_index = 0;
		emit_signal("path_changed");
	}

	if (navigation_path.size() == 0) {
		return;
	}

	// Check if we can advance the navigation path
	if (navigation_finished == false) {
		// Advances to the next far away location.
		while (o.distance_to(navigation_path[nav_path_index]) < path_desired_distance) {
			nav_path_index += 1;
			if (nav_path_index == navigation_path.size()) {
				_check_distance_to_target();
				nav_path_index -= 1;
				navigation_finished = true;
				emit_signal("navigation_finished");
				break;
			}
		}
	}
}

void NavigationAgent2D::_request_repath() {
	navigation_path.clear();
	target_reached = false;
	navigation_finished = false;
	update_frame_id = 0;
}

void NavigationAgent2D::_check_distance_to_target() {
	if (!target_reached) {
		if (distance_to_target() < target_desired_distance) {
			target_reached = true;
			emit_signal("target_reached");
		}
	}
}