class_name BubbleGradientBackground
extends Control

const CORNER_SEGMENTS: int = 8

var host_button: BaseButton
var profile: BubbleMenuProfile


func configure(
	button: BaseButton,
	menu_profile: BubbleMenuProfile,
) -> void:
	host_button = button
	profile = menu_profile
	mouse_filter = Control.MOUSE_FILTER_IGNORE
	show_behind_parent = true
	set_anchors_and_offsets_preset(Control.PRESET_FULL_RECT)
	queue_redraw()


func _draw() -> void:
	if host_button == null or profile == null or size.x <= 0.0 or size.y <= 0.0:
		return
	var fill_color: Color = _get_fill_color()
	var top_color: Color = fill_color.lightened(profile.gradient_top_lift)
	var points := PackedVector2Array()
	_append_arc(points, Vector2(profile.corner_radius, profile.corner_radius), PI, PI * 1.5)
	_append_arc(
		points,
		Vector2(size.x - profile.corner_radius, profile.corner_radius),
		PI * 1.5,
		TAU,
	)
	_append_arc(
		points,
		Vector2(size.x - profile.corner_radius, size.y - profile.corner_radius),
		0.0,
		PI * 0.5,
	)
	_append_arc(
		points,
		Vector2(profile.corner_radius, size.y - profile.corner_radius),
		PI * 0.5,
		PI,
	)
	var colors := PackedColorArray()
	for point: Vector2 in points:
		colors.append(top_color.lerp(fill_color, clampf(point.y / size.y, 0.0, 1.0)))
	draw_polygon(points, colors)


func _append_arc(
	points: PackedVector2Array,
	center: Vector2,
	start_angle: float,
	end_angle: float,
) -> void:
	var radius: float = minf(
		float(profile.corner_radius),
		minf(size.x, size.y) * 0.5,
	)
	for index: int in range(CORNER_SEGMENTS + 1):
		var weight: float = float(index) / float(CORNER_SEGMENTS)
		var angle: float = lerpf(start_angle, end_angle, weight)
		points.append(center + Vector2(cos(angle), sin(angle)) * radius)


func _get_fill_color() -> Color:
	if host_button.disabled:
		return profile.disabled_fill
	match host_button.get_draw_mode():
		BaseButton.DRAW_PRESSED, BaseButton.DRAW_HOVER_PRESSED:
			return profile.pressed_fill
		BaseButton.DRAW_HOVER:
			return profile.hover_fill
	if host_button.has_focus():
		return profile.hover_fill
	return profile.normal_fill