extends CharacterBody3D

## NS-23: `NavigationAgent3D` path-follow for click-to-move visuals. Server owns `PositionState` /
## `MoveCommand` (NS-16, NS-19); boot snap vs post-verify nav goal from `main.gd`.

const MOVE_SPEED: float = 5.0
## If the nav mesh is missing or the agent gives up, steer on XZ toward `target_position`.
const FALLBACK_ARRIVE_EPS: float = 0.4

@onready var _nav_agent: NavigationAgent3D = $NavigationAgent3D


func _ready() -> void:
	_nav_agent.set_target_position(global_position)


## After successful move POST + GET: walk to server target without teleporting.
func set_authoritative_nav_goal(world_pos: Vector3) -> void:
	_nav_agent.set_target_position(world_pos)


## NS-19 rejection or cancel pending path without moving the body.
func clear_nav_goal() -> void:
	velocity = Vector3.ZERO
	_nav_agent.set_target_position(global_position)


## Boot (and any hard reconcile): teleport to server position and reset agent.
func snap_to_server(world_pos: Vector3) -> void:
	global_position = world_pos
	velocity = Vector3.ZERO
	_nav_agent.set_target_position(world_pos)


func _physics_process(_delta: float) -> void:
	var nav_map: RID = _nav_agent.get_navigation_map()
	if NavigationServer3D.map_get_iteration_id(nav_map) == 0:
		velocity = Vector3.ZERO
		move_and_slide()
		return
	if _nav_agent.is_navigation_finished():
		var target: Vector3 = _nav_agent.target_position
		var flat_target := Vector3(target.x, global_position.y, target.z)
		var to_target: Vector3 = flat_target - global_position
		to_target.y = 0.0
		if to_target.length_squared() > FALLBACK_ARRIVE_EPS * FALLBACK_ARRIVE_EPS:
			velocity = to_target.normalized() * MOVE_SPEED
			velocity.y = 0.0
		else:
			velocity = Vector3.ZERO
		move_and_slide()
		return

	var next_path_position: Vector3 = _nav_agent.get_next_path_position()
	var to_next: Vector3 = next_path_position - global_position
	to_next.y = 0.0
	if to_next.length_squared() < 0.0001:
		var to_final: Vector3 = _nav_agent.target_position - global_position
		to_final.y = 0.0
		if to_final.length_squared() > 0.0001:
			velocity = to_final.normalized() * MOVE_SPEED
			velocity.y = 0.0
		else:
			velocity = Vector3.ZERO
	else:
		velocity = to_next.normalized() * MOVE_SPEED
		velocity.y = 0.0
	move_and_slide()