class_name AbilityButtonLayout
extends Node

# Keeps the aimed fleet abilities close to the firing thumb. One ability sits
# directly above the fire stick; multiple abilities fan through its upper-left
# quadrant instead of becoming a detached horizontal toolbar.

@export var arc_radius: float = 280.0

@onready var fire_stick: Control = get_node("../UI/FireStick")
@onready var buttons: Array = [
	get_node("../UI/DashButton"),
	get_node("../UI/GasBombButton"),
	get_node("../UI/LaserButton"),
]

var visibility_signature: int = -1


func _ready() -> void:
	get_viewport().size_changed.connect(_layout_visible_buttons)
	_layout_visible_buttons.call_deferred()


func _process(_delta: float) -> void:
	var signature: int = 0
	for i in range(buttons.size()):
		if buttons[i].visible:
			signature |= 1 << i
	if signature == visibility_signature:
		return
	visibility_signature = signature
	_layout_visible_buttons()


func _layout_visible_buttons() -> void:
	var visible_buttons: Array = buttons.filter(func(button): return button.visible)
	if visible_buttons.is_empty():
		return
	var center: Vector2 = fire_stick.global_position + fire_stick.size * 0.5
	for i in range(visible_buttons.size()):
		# Screen coordinates grow downward: PI points left and 3*PI/2 points
		# upward, tracing exactly the useful quarter around a bottom-right stick.
		var weight: float = 1.0 if visible_buttons.size() == 1 \
			else float(i) / float(visible_buttons.size() - 1)
		var angle: float = lerpf(PI, PI * 1.5, weight)
		var button: Control = visible_buttons[i]
		button.global_position = center + Vector2.from_angle(angle) * arc_radius \
			- button.size * 0.5