class_name Anim
extends RefCounted
## Short animations made with tweens, used all over the game: popping, fading, flashing
## and pulsing.
##
## Every animation is short so a quiz never waits for one. With
## [member Settings.reduce_animations] on, nothing moves: each helper jumps straight to
## where the animation would end.

## How long quick feedback, such as a button press, takes.
const FAST: float = 0.12
## How long most animations take.
const NORMAL: float = 0.2
## How long flashes and bigger moments take.
const SLOW: float = 0.45


## Whether animations are on.
static func enabled() -> bool:
	return !Settings.reduce_animations


## A new tween on [param node] for the animation called [param key], stopping an earlier
## one with the same key so they don't fight. Returns null when animations are off or the
## node is not in the tree.
static func tween(node: Node, key: StringName = &"anim") -> Tween:
	stop(node, key)
	if !enabled() || !node.is_inside_tree():
		return null
	var new_tween: Tween = node.create_tween()
	node.set_meta(StringName("_tween_" + key), new_tween)
	return new_tween


## Stops the animation called [param key] on [param node], if one is running.
static func stop(node: Node, key: StringName = &"anim") -> void:
	var meta: StringName = StringName("_tween_" + key)
	var old: Variant = node.get_meta(meta) if node.has_meta(meta) else null
	if old is Tween && (old as Tween).is_valid():
		(old as Tween).kill()


## Makes [param control] grow from its middle.
static func center_pivot(control: Control) -> void:
	control.pivot_offset = control.size / 2


## Makes [param control] jump to [param peak] times its size and spring back.
static func pop(control: Control, peak: float = 1.3, duration: float = NORMAL) -> void:
	var pop_tween: Tween = tween(control, &"pop")
	control.scale = Vector2.ONE
	if pop_tween == null:
		return
	center_pivot(control)
	control.scale = Vector2.ONE * peak
	pop_tween.tween_property(control, "scale", Vector2.ONE, duration) \
			.set_trans(Tween.TRANS_BACK).set_ease(Tween.EASE_OUT)


## Makes [param control] grow from [param from] times its size with a bounce.
static func bounce_in(control: Control, from: float = 0.4, duration: float = SLOW) -> void:
	var bounce_tween: Tween = tween(control, &"pop")
	control.scale = Vector2.ONE
	if bounce_tween == null:
		return
	center_pivot(control)
	control.scale = Vector2.ONE * from
	bounce_tween.tween_property(control, "scale", Vector2.ONE, duration * 1.6) \
			.set_trans(Tween.TRANS_ELASTIC).set_ease(Tween.EASE_OUT)


## Fades [param item] in from invisible.
static func fade_in(item: CanvasItem, duration: float = NORMAL) -> void:
	var fade_tween: Tween = tween(item, &"fade")
	item.modulate.a = 1.0
	if fade_tween == null:
		return
	item.modulate.a = 0.0
	fade_tween.tween_property(item, "modulate:a", 1.0, duration)


## Slides [param control] in from [param offset] away from where it is, fading in.
static func slide_in(control: Control, offset: Vector2, duration: float = NORMAL) -> void:
	var slide_tween: Tween = tween(control, &"slide")
	if control.has_meta(&"_slide_home"):
		control.position = control.get_meta(&"_slide_home")
	control.modulate.a = 1.0
	if slide_tween == null:
		return
	var home: Vector2 = control.position
	control.set_meta(&"_slide_home", home)
	control.position = home + offset
	control.modulate.a = 0.0
	slide_tween.set_parallel()
	slide_tween.tween_property(control, "position", home, duration) \
			.set_trans(Tween.TRANS_QUAD).set_ease(Tween.EASE_OUT)
	slide_tween.tween_property(control, "modulate:a", 1.0, duration)
	slide_tween.chain().tween_callback(func() -> void: control.remove_meta(&"_slide_home"))


## Scales [param control] to [param target] times its size, e.g. a little bigger under
## the mouse.
static func scale_to(control: Control, target: float, duration: float = FAST) -> void:
	var scale_tween: Tween = tween(control, &"scale")
	if scale_tween == null:
		control.scale = Vector2.ONE
		return
	center_pivot(control)
	scale_tween.tween_property(control, "scale", Vector2.ONE * target, duration) \
			.set_trans(Tween.TRANS_QUAD).set_ease(Tween.EASE_OUT)


## Lights up [param container] with [param colour] for a moment, e.g. a row that just
## changed. A coloured layer is laid over the container and fades away.
static func flash(container: Container, colour: Color, duration: float = SLOW) -> void:
	if !enabled() || !container.is_inside_tree():
		return
	var layer: ColorRect = _layer(container, colour)
	var flash_tween: Tween = layer.create_tween()
	flash_tween.tween_property(layer, "color:a", 0.0, duration) \
			.set_trans(Tween.TRANS_QUAD).set_ease(Tween.EASE_IN)
	flash_tween.tween_callback(layer.queue_free)


## Keeps [param container] glowing in [param colour], softly pulsing, until the returned
## layer is freed. With animations off the glow stays still.
static func pulse(container: Container, colour: Color) -> ColorRect:
	var layer: ColorRect = _layer(container, colour)
	layer.name = "Pulse"
	if enabled():
		var pulse_tween: Tween = layer.create_tween().set_loops()
		pulse_tween.tween_property(layer, "color:a", colour.a * 0.3, 0.6) \
				.set_trans(Tween.TRANS_SINE)
		pulse_tween.tween_property(layer, "color:a", colour.a, 0.6) \
				.set_trans(Tween.TRANS_SINE)
	return layer


# A layer of [param colour] over the whole of [param container] that lets clicks through
static func _layer(container: Container, colour: Color) -> ColorRect:
	var layer: ColorRect = ColorRect.new()
	layer.color = colour
	layer.mouse_filter = Control.MOUSE_FILTER_IGNORE
	container.add_child(layer)
	return layer