extends Control
## 画脸面板：把 FaceRig 的笔画层显示出来，并把鼠标坐标换算成画布坐标喂给画笔。
##
## 面板自己不画任何东西 —— 笔画直接落在 FaceRig 的画笔上，所以关掉面板后角色脸上立刻就是刚画的。
## 打开时拍一张快照，点「取消」还原；点「完成」才写进存档。

signal finished
signal cancelled

## 画布在屏幕上的显示边长。真实画布是 rig.canvas_size 见方，坐标按比例换算
const VIEW_SIZE := 420

@onready var _canvas_rect: TextureRect = %StrokeRect
@onready var _preset_rect: TextureRect = %PresetRect
@onready var _color_button: ColorPickerButton = %ColorButton
@onready var _width_slider: HSlider = %WidthSlider
@onready var _width_label: Label = %WidthLabel
@onready var _eraser_toggle: CheckButton = %EraserToggle
@onready var _name_edit: LineEdit = %NameEdit

var _rig: FaceRig
## 打开面板时的笔画层快照，取消时还原
var _snapshot: PackedByteArray
## 打开面板时选中的表情 ID，取消时还原
var _expression_before: String = ""
## 左键是不是按着 —— 拖拽判定用这个，不看 motion 事件里的 button_mask
var _drawing := false


func _ready() -> void:
	visible = false
	_canvas_rect.custom_minimum_size = Vector2(VIEW_SIZE, VIEW_SIZE)
	_canvas_rect.gui_input.connect(_on_canvas_input)
	_color_button.color_changed.connect(_on_color_changed)
	_width_slider.value_changed.connect(_on_width_changed)
	_eraser_toggle.toggled.connect(_on_eraser_toggled)
	%ClearButton.pressed.connect(_on_clear)
	%DoneButton.pressed.connect(_on_done)
	%CancelButton.pressed.connect(_on_cancel)
	_on_width_changed(_width_slider.value)


# ---------------- 对外接口 ----------------

## 打开面板并绑定到 FaceRig。start_blank = true 时先快照再清空，取消可完整还原。
func open(rig: FaceRig, start_blank: bool = false) -> void:
	if rig == null or rig.painter == null:
		push_warning("画脸面板没拿到可用的 FaceRig")
		return
	_rig = rig
	_snapshot = rig.painter.snapshot()
	_expression_before = rig.selected_expression_id
	if start_blank:
		rig.select_blank(true)
	_canvas_rect.texture = rig.painter.texture
	%SkinRect.color = rig.skin_color
	_preset_rect.texture = rig.selected_expression_texture
	_name_edit.text = ""
	rig.painter.brush_color = _color_button.color
	rig.painter.brush_width = _width_slider.value
	rig.painter.erasing = _eraser_toggle.button_pressed
	visible = true


# ---------------- 画布输入 ----------------

## 屏幕坐标 → 画布坐标。显示尺寸和画布尺寸不一致时按比例缩
func _canvas_pos(event: InputEventMouse) -> Vector2:
	var scale := float(_rig.painter.canvas_size) / maxf(1.0, _canvas_rect.size.x)
	return event.position * scale


func _on_canvas_input(event: InputEvent) -> void:
	if _rig == null:
		return
	if event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT:
		# 自己记「按没按下」，不靠 motion 事件里的 button_mask —— 那个字段不总是可靠
		_drawing = event.pressed
		if event.pressed:
			_rig.painter.begin_stroke(_canvas_pos(event))
		else:
			_rig.painter.end_stroke()
	elif event is InputEventMouseMotion and _drawing:
		_rig.painter.extend_stroke(_canvas_pos(event))


# ---------------- 工具条 ----------------

func _on_color_changed(c: Color) -> void:
	if _rig != null:
		_rig.painter.brush_color = c
	# 选了颜色就顺手退出橡皮 —— 不然「我选了红色怎么还是擦」
	_eraser_toggle.set_pressed_no_signal(false)
	if _rig != null:
		_rig.painter.erasing = false


func _on_width_changed(w: float) -> void:
	if _rig != null:
		_rig.painter.brush_width = w
	_width_label.text = "%d px" % int(w)


func _on_eraser_toggled(on: bool) -> void:
	if _rig != null:
		_rig.painter.erasing = on


func _on_clear() -> void:
	if _rig != null:
		_rig.painter.clear()


func _on_done() -> void:
	if _rig == null:
		return
	var saved := _rig.save_drawing_as_expression(_name_edit.text)
	if saved.is_empty():
		push_warning("表情保存失败，请检查本地磁盘空间和写入权限")
		return
	visible = false
	finished.emit()


func _on_cancel() -> void:
	if _rig != null:
		if not _expression_before.is_empty():
			_rig.select_expression(_expression_before, false)
		else:
			_rig.select_blank(false)
		if _snapshot.size() > 0:
			_rig.painter.restore(_snapshot)
	visible = false
	cancelled.emit()