extends RefCounted
class_name Promise

signal resolved
signal denied

var waited_signals: Array[Signal] = []
var triggered: Dictionary[Signal, bool] = {}
var _denied: bool = false

static func from_signals(...sigs: Array) -> Promise:
	var promise := Promise.new()
	promise.waited_signals.assign(sigs)
	for sig: Signal in sigs:
		promise.triggered[sig] = false
	return promise

func _connect_signals() -> void:
	for sig: Signal in waited_signals:
		sig.connect(_handle_signal.bind(sig))

func _disconnect_signals() -> void:
	for sig: Signal in waited_signals:
		sig.disconnect(_handle_signal)

func _handle_signal(sig: Signal, ...args: Array) -> void:
	assert(triggered.has(sig), "Signal is not promised!")
	triggered[sig] = true

func any() -> void:
	while await Engine.get_main_loop().process_frame:
		if _denied:
			_disconnect_signals()
			denied.emit()
			return
		if triggered.values().any(func(x): return x):
			_disconnect_signals()
			resolved.emit()
			return

func all() -> void:
	while await Engine.get_main_loop().process_frame:
		if _denied:
			_disconnect_signals()
			denied.emit()
			return
		if triggered.values().all(func(x): return x):
			_disconnect_signals()
			resolved.emit()
			return

func deny() -> void:
	_denied = true