extends SceneTree

## 标题侧节奏音乐 + 标题背景「过去/现在」循环动画。
## 标题、难度选择、退出确认期间音乐持续播放；进入 gameplay 后停止，
## 由 RhythmManager.start() + AudioLayerController.restart_layers() 从 0 重播。

var failures: Array[String] = []


func _init() -> void:
	_run.call_deferred()


func _run() -> void:
	root.size = Vector2i(1152, 648)
	_ensure_game_settings()
	var flow: Node = load("res://autoload/game_flow_manager.gd").new()
	flow.name = "FlowUnderTest"
	flow.set("manage_scene", false)
	root.add_child(flow)
	await process_frame

	# --- 标题音乐播放器：常驻处理、走 Music 总线 ---
	var player := flow.get_node_or_null("TitleMusicPlayer") as AudioStreamPlayer
	_expect(player != null, "flow owns a TitleMusicPlayer")
	if player != null:
		_expect(player.process_mode == Node.PROCESS_MODE_ALWAYS, "title music must survive the SceneTree pause")
		_expect_equal(player.bus, &"Music", "title music routes through the Music bus")
		# headless 下不加载 mp3，注入无限长的生成器流来验证播放开关。
		player.stream = AudioStreamGenerator.new()

	# --- 标题界面同时持有两个时代背景，「现在」画在「过去」上层 ---
	var title_screen := (flow.get("_screens") as Dictionary).get(&"Title", null) as Control
	_expect(title_screen != null, "title screen exists")
	if title_screen != null:
		var past := title_screen.get_node_or_null("SceneBackgroundPast") as TextureRect
		var future := title_screen.get_node_or_null("SceneBackgroundFuture") as TextureRect
		_expect(past != null, "title keeps the past-era background")
		_expect(future != null, "title keeps the future-era background")
		if past != null and future != null:
			_expect(past.texture != null and future.texture != null, "both era textures load")
			_expect(past.get_index() < future.get_index(), "the future era paints above the past era")

	# --- 标题状态：音乐播放 + 时代循环动画运行 ---
	flow.call("_set_state", &"Title")
	flow.call("_update_title_music")
	await process_frame
	_expect(bool(flow.call("_should_play_title_music")), "title state wants the rhythm music")
	if player != null:
		_expect(player.playing, "title music plays on the title screen")
	var tween := flow.get("_title_bg_tween") as Tween
	_expect(tween != null and tween.is_valid(), "the era crossfade loop runs on the title screen")

	# --- 难度选择：音乐延续，标题动画停止 ---
	flow.call("_set_state", &"DifficultySelect")
	await process_frame
	_expect(bool(flow.call("_should_play_title_music")), "difficulty select keeps the rhythm music")
	if player != null:
		_expect(player.playing, "title music keeps playing on difficulty select")
	_expect(flow.get("_title_bg_tween") == null, "the era loop stops once the title screen hides")

	# --- 进入 gameplay：标题音乐停止 ---
	flow.call("_set_state", &"Gameplay_FrontArea")
	await process_frame
	_expect(not bool(flow.call("_should_play_title_music")), "gameplay states drop the title music")
	if player != null:
		_expect(not player.playing, "title music stops when the run starts")

	# --- 回到标题：音乐从头再播 ---
	flow.call("_set_state", &"Title")
	await process_frame
	if player != null:
		_expect(player.playing, "returning to title restarts the music")

	flow.free()
	_finish()


func _ensure_game_settings() -> Node:
	var settings := root.get_node_or_null("GameSettings")
	if settings != null:
		return settings
	settings = load("res://autoload/game_settings.gd").new()
	settings.name = "GameSettings"
	root.add_child(settings)
	return settings


func _expect(condition: bool, label: String) -> void:
	if not condition:
		failures.append(label)


func _expect_equal(actual: Variant, expected: Variant, label: String) -> void:
	if actual != expected:
		failures.append("%s: expected %s, got %s" % [label, expected, actual])


func _finish() -> void:
	paused = false
	if failures.is_empty():
		print("PASS title music and background loop")
		quit(0)
	else:
		for failure: String in failures:
			push_error(failure)
		quit(1)