extends Node2D

## 2026-07-07 视差修正：当前美术图里地面/步道和远景烙在同一张图上。
## 为了让角色脚下参照物保持 1:1 世界坐标，ArtLayer 先作为 WorldGroundLayer
## 固定不随相机做视差。未来美术拆出天空/夕阳后，把远景节点放入
## SkyParallaxLayer，即可继续按 0.2 倍世界滚动（80% 跟随相机）。
## 勿用 Parallax2D（历史上因 CanvasModulate/wipe 兼容性移除过，见 decisions.md）。
const PARALLAX_SCROLL_SCALE := 0.2
const PARALLAX_ANCHOR_X := 1734.5

@onready var past_background: CanvasItem = $ArtLayer/PastBackground
@onready var future_background: CanvasItem = $ArtLayer/FutureBackground
@onready var _world_ground_layer: Node2D = $ArtLayer
@onready var _sky_parallax_layer: Node2D = get_node_or_null("SkyParallaxLayer") as Node2D

var _world_ground_base_x := 0.0
var _sky_parallax_base_x := 0.0


func _ready() -> void:
	_world_ground_base_x = _world_ground_layer.position.x
	if _sky_parallax_layer != null:
		_sky_parallax_base_x = _sky_parallax_layer.position.x
	_set_time_phase(_current_time_phase())
	var bus := _event_bus_or_null()
	if bus != null and bus.has_signal("time_phase_changed") and not bus.is_connected("time_phase_changed", _on_time_phase_changed):
		bus.connect("time_phase_changed", _on_time_phase_changed)


func _process(_delta: float) -> void:
	_world_ground_layer.position.x = _world_ground_base_x
	if _sky_parallax_layer == null:
		return
	var camera := get_viewport().get_camera_2d()
	if camera == null:
		# headless 测试/无相机场景：远景层也保持原位。
		_sky_parallax_layer.position.x = _sky_parallax_base_x
		return
	# get_screen_center_position 含 limit 夹取，玩家贴墙时远景不会继续滑。
	var center_x := camera.get_screen_center_position().x
	_sky_parallax_layer.position.x = _sky_parallax_base_x + (center_x - PARALLAX_ANCHOR_X) * (1.0 - PARALLAX_SCROLL_SCALE)


func _on_time_phase_changed(_previous: StringName, current: StringName, _reason: StringName) -> void:
	_set_time_phase(current)


func _set_time_phase(time_phase: StringName) -> void:
	var use_future := time_phase == &"future"
	if past_background != null:
		past_background.visible = not use_future
	if future_background != null:
		future_background.visible = use_future


func _current_time_phase() -> StringName:
	if not is_inside_tree():
		return &"past"
	var manager := get_tree().root.get_node_or_null("TimePhaseManager")
	if manager != null:
		return StringName(str(manager.get("current_time_phase")))
	return &"past"


func _event_bus_or_null() -> Node:
	if not is_inside_tree():
		return null
	return get_tree().root.get_node_or_null("EventBus")