extends Control
class_name BoltRule

## A lightning bolt struck through a horizontal rule.
##
## The motif the whole UI is built around, in one reusable widget: menus use it
## as a section divider, the HUD uses it to underline a heading. It is drawn
## rather than shipped as an image so it takes the theme's colours and scales to
## any width without a second asset.
##
## The zigzag is deliberately not centred. A bolt centred in its rule reads as an
## ornament; struck a third of the way along, it reads as something that HIT the
## line — which is the difference between decorative and energetic.

@export var line_color: Color = Color(1.0, 0.47, 0.10)
@export var bolt_color: Color = Color(1.0, 0.93, 0.22)
@export var ink: Color = Color(0.045, 0.040, 0.075)
## Where along the rule the bolt strikes, 0..1.
@export var strike_at: float = 0.34
@export var thickness: float = 3.0


func _init() -> void:
	custom_minimum_size = Vector2(0, 22)
	mouse_filter = Control.MOUSE_FILTER_IGNORE


func _draw() -> void:
	var w := size.x
	var h := size.y
	if w <= 1.0:
		return
	var mid := h * 0.5
	var strike := w * clampf(strike_at, 0.05, 0.95)
	var half := h * 0.42

	# The rule, broken where the bolt lands so the bolt reads as passing
	# THROUGH it rather than sitting on top.
	var gap := h * 0.55
	draw_line(Vector2(0, mid), Vector2(maxf(0.0, strike - gap), mid),
		line_color, thickness)
	draw_line(Vector2(minf(w, strike + gap), mid), Vector2(w, mid),
		line_color, thickness)

	# Bolt: down-right, kick back left, down-right again.
	var pts := PackedVector2Array([
		Vector2(strike + half * 0.55, mid - half),
		Vector2(strike - half * 0.10, mid + half * 0.12),
		Vector2(strike + half * 0.30, mid + half * 0.12),
		Vector2(strike - half * 0.55, mid + half),
		Vector2(strike + half * 0.12, mid - half * 0.10),
		Vector2(strike - half * 0.28, mid - half * 0.10),
	])
	# Ink first, one step out, so the bolt keeps a drawn edge against any
	# background it is placed on.
	draw_colored_polygon(_grown(pts, 2.0), ink)
	draw_colored_polygon(pts, bolt_color)


## The same polygon pushed out from its own centre — a cheap outline that needs
## no second point list to maintain.
func _grown(pts: PackedVector2Array, by: float) -> PackedVector2Array:
	var centre := Vector2.ZERO
	for p in pts:
		centre += p
	centre /= float(pts.size())
	var out := PackedVector2Array()
	for p in pts:
		var dir := (p - centre)
		out.append(p + (dir.normalized() * by if dir.length() > 0.001 else Vector2.ZERO))
	return out