class_name StateReentrometer extends RefCounted

signal entered
signal descended
signal ascended
signal exited

var _depth: int = 0

func descend() -> void:
	assert(_depth >= 0)
	if _depth <= 0:
		entered.emit()
	descended.emit()
	_depth += 1

func ascend() -> void:
	assert(_depth > 0)
	_depth -= 1
	ascended.emit()
	if _depth <= 0:
		exited.emit()

func active() -> bool:
	return _depth > 0

func depth() -> int:
	return _depth

func valid() -> bool:
	return _depth >= 0