# res://autoload/scene_transition.gd
extends CanvasLayer

signal transition_finished

@export var fade_duration: float = 0.4
@export var color: Color = Color.BLACK

var _rect: ColorRect
var _is_transitioning := false

func _ready() -> void:
	# Couche au-dessus de tout
	layer = 128
	# Ne bloque pas les inputs quand invisible
	process_mode = Node.PROCESS_MODE_ALWAYS

	_rect = ColorRect.new()
	_rect.color = color
	_rect.modulate.a = 0.0
	_rect.visible = false
	_rect.mouse_filter = Control.MOUSE_FILTER_IGNORE
	_rect.set_anchors_preset(Control.PRESET_FULL_RECT)
	add_child(_rect)

func change_scene(scene: PackedScene, duration: float = -1.0) -> void:
	var prev := fade_duration
	if duration > 0.0:
		fade_duration = duration
	await change_scene_path(scene.resource_path)
	fade_duration = prev

func change_scene_path(path: String) -> void:
	if _is_transitioning:
		return
	_is_transitioning = true

	# 1. Fade vers le noir
	await _fade(1.0)

	# 2. Changement effectif
	var err := get_tree().change_scene_to_file(path)
	if err != OK:
		push_error("Erreur changement de scène: %s" % err)
		await _fade(0.0)
		_is_transitioning = false
		return

	# 3. Attendre que la nouvelle scène soit prête
	await get_tree().process_frame
	await get_tree().process_frame

	# 4. Fade depuis le noir
	await _fade(0.0)

	_is_transitioning = false
	transition_finished.emit()


func _fade(target_alpha: float) -> void:
	_rect.visible = true
	var tween := create_tween()
	tween.set_ease(Tween.EASE_IN_OUT)
	tween.set_trans(Tween.TRANS_SINE)
	tween.tween_property(_rect, "modulate:a", target_alpha, fade_duration)
	await tween.finished
	if is_zero_approx(target_alpha):
		_rect.visible = false