extends CanvasLayer

@onready var transition_rect : ColorRect   = $TransitionRect
@onready var status_label : Label          = %StatusLabel
@onready var progress_bar : ProgressBar    = %ProgressBar

const FADE_DURATION := 0.6
const MIN_DISPLAY_TIME := 0.4   # évite le flash sur les chargements instantanés

func _ready() -> void:
	transition_rect.visible = false
	process_mode = Node.PROCESS_MODE_ALWAYS

func change_scene(scene_path : String, message : String = "Chargement...") -> void:
	var start_ms := Time.get_ticks_msec()

	# --- 1. Afficher l'écran de chargement (fade in) ---
	status_label.text = message
	progress_bar.value = 0
	transition_rect.modulate.a = 0.0
	transition_rect.visible = true

	var fade_in := create_tween()
	fade_in.tween_property(transition_rect, "modulate:a", 1.0, FADE_DURATION)
	await fade_in.finished

	# --- 2. Lancer le chargement en arrière-plan ---
	var err := ResourceLoader.load_threaded_request(scene_path)
	if err != OK:
		push_error("Échec du lancement du chargement : %s (err %d)" % [scene_path, err])
		await _fade_out()
		return

	# --- 3. Boucle jusqu'à ce que la scène soit prête ---
	var prog : Array = []
	while true:
		var status := ResourceLoader.load_threaded_get_status(scene_path, prog)
		match status:
			ResourceLoader.THREAD_LOAD_IN_PROGRESS:
				if prog.size() > 0:
					progress_bar.value = prog[0] * 100.0
				await get_tree().process_frame
			ResourceLoader.THREAD_LOAD_LOADED:
				break
			_:
				push_error("Échec du chargement de %s" % scene_path)
				await _fade_out()
				return

	var packed : PackedScene = ResourceLoader.load_threaded_get(scene_path)
	if packed == null:
		push_error("PackedScene nulle pour %s" % scene_path)
		await _fade_out()
		return

	# --- 4. Durée minimale visible (anti-flash) ---
	var elapsed := (Time.get_ticks_msec() - start_ms) / 1000.0
	if elapsed < MIN_DISPLAY_TIME:
		await get_tree().create_timer(MIN_DISPLAY_TIME - elapsed).timeout

	# --- 5. Changer de scène ---
	get_tree().change_scene_to_packed(packed)

	# --- 6. Laisser la nouvelle scène s'initialiser, puis fade out ---
	await get_tree().process_frame
	await get_tree().process_frame
	await _fade_out()

func _fade_out() -> void:
	var tween := create_tween()
	tween.tween_property(transition_rect, "modulate:a", 0.0, FADE_DURATION)
	await tween.finished
	transition_rect.visible = false