class_name BasePopup
extends Control
## A window shown on top of the main window, such as Settings or About.
##
## Clicking outside [member panel] closes it. Popups that need to prepare or clean up
## override [method open] or [method close] and call [code]super()[/code].
##
## The panel fades in while growing from [constant START_SCALE] of its size, and closing
## does the reverse; the popup is hidden once that has finished. See [Anim].

## Emitted when the popup opens, also when it is opened again while closing.
signal opening
## Emitted when the popup starts closing, before it is hidden, so the backdrop can fade
## out with it.
signal closing

## How big the panel starts when it opens, and ends when it closes.
const START_SCALE: float = 0.95

## The visible part of the popup. Clicks outside it close the popup.
@export var panel: Control

## True while the popup is fading out after [method close].
var is_closing: bool = false


## Shows the popup.
func open() -> void:
	is_closing = false
	visible = true
	opening.emit()
	var open_tween: Tween = Anim.tween(panel, &"popup")
	panel.modulate.a = 1.0
	panel.scale = Vector2.ONE
	if open_tween == null:
		return
	Anim.center_pivot(panel)
	panel.modulate.a = 0.0
	panel.scale = Vector2.ONE * START_SCALE
	open_tween.set_parallel()
	open_tween.tween_property(panel, "modulate:a", 1.0, Anim.NORMAL)
	open_tween.tween_property(panel, "scale", Vector2.ONE, Anim.NORMAL) \
			.set_trans(Tween.TRANS_QUAD).set_ease(Tween.EASE_OUT)


## Hides the popup.
func close() -> void:
	if !visible || is_closing:
		return
	is_closing = true
	closing.emit()
	var close_tween: Tween = Anim.tween(panel, &"popup")
	if close_tween == null:
		_hide()
		return
	Anim.center_pivot(panel)
	close_tween.set_parallel()
	close_tween.tween_property(panel, "modulate:a", 0.0, Anim.FAST)
	close_tween.tween_property(panel, "scale", Vector2.ONE * START_SCALE, Anim.FAST)
	close_tween.chain().tween_callback(_hide)


## Opens the popup if it is closed and closes it if it is open.
func toggle() -> void:
	if visible && !is_closing:
		close()
	else:
		open()


func _hide() -> void:
	is_closing = false
	visible = false
	panel.modulate.a = 1.0
	panel.scale = Vector2.ONE


func _input(event: InputEvent) -> void:
	if !visible || is_closing || !(event is InputEventMouseButton) || !event.pressed:
		return
	var click: InputEventMouseButton = panel.make_input_local(event)
	if !Rect2(Vector2.ZERO, panel.size).has_point(click.position):
		close()
		# The click only closes the popup; it must not also press what is behind it
		get_viewport().set_input_as_handled()