extends Node2D

# Same informal interface as GasGiantVisual/RockyPlanetVisual - configure(),
# extractor_anchor(), animates via its own _process(). Deliberately angular
# and armoured rather than a natural silhouette (#63: this is an ENEMY
# installation, not a celestial body), with a rotating dish and blinking
# warning lights to read as occupied/hostile at a glance.
#
# Built out of NeonPiece children rather than redrawn each frame. Issues #6
# and #10 established that rule for the buildings: every NeonDraw call
# expands into four antialiased polylines, so re-running _draw() to advance
# an animation re-tessellates the whole thing. This visual was doing exactly
# that - nine draw calls a frame, of which eight were fixed geometry - to
# rotate one dish and fade six lights. Both are node properties: the dish is
# a child that spins, the lights are a child whose modulate breathes, and the
# hull is rasterised once and never touched again.

var phase: float = 0.0

const RADIUS: float = 108.0
const HULL_COLOR: Color = Color(0.55, 0.1, 0.08)
const CORE_COLOR: Color = Color(0.9, 0.25, 0.18)
const WARNING_COLOR: Color = Color(1.0, 0.2, 0.15)
const DARK_CORE: Color = Color(0.14, 0.02, 0.02)

var _dish: NeonPiece
var _lights: NeonPiece


func _ready() -> void:
	_build()


func configure(_shape_seed: int) -> void:
	if _dish == null:
		_build()


func extractor_anchor() -> Vector2:
	return Vector2(0.0, -(RADIUS + 40.0))


func _build() -> void:
	for child in get_children():
		child.queue_free()

	# The armoured hull and its core: fixed, so drawn once.
	var shell: NeonPiece = NeonPiece.create(self, Vector2.ZERO, HULL_COLOR)
	shell.core_color = DARK_CORE
	shell.add_polygon(_ring(RADIUS, 0.0), 0.85)
	var core: NeonPiece = NeonPiece.create(self, Vector2.ZERO, CORE_COLOR)
	core.core_color = DARK_CORE
	core.add_polygon(_ring(RADIUS * 0.55, PI / 6.0), 0.9)

	# The dish, drawn along +X and then SPUN by rotating this node - the
	# rotation is what used to cost a full re-tessellation every frame.
	_dish = NeonPiece.create(self, Vector2.ZERO, CORE_COLOR)
	_dish.core_color = DARK_CORE
	var tip: Vector2 = Vector2(RADIUS * 1.35, 0.0)
	_dish.add_line(Vector2.ZERO, tip, 0.55, 0.8)
	_dish.add_polygon(_circle(tip, 11.0), 1.0)

	# The warning lights blink by fading the whole piece, not by redrawing
	# six circles at a new alpha.
	_lights = NeonPiece.create(self, Vector2.ZERO, WARNING_COLOR)
	_lights.core_color = DARK_CORE
	for i in range(6):
		var angle: float = TAU * float(i) / 6.0
		_lights.add_polygon(_circle(Vector2(cos(angle), sin(angle)) * RADIUS, 5.0), 1.0)


func _ring(radius: float, offset: float) -> PackedVector2Array:
	var points: PackedVector2Array = PackedVector2Array()
	for i in range(6):
		var angle: float = TAU * float(i) / 6.0 + offset
		points.append(Vector2(cos(angle), sin(angle)) * radius)
	return points


func _circle(centre: Vector2, radius: float) -> PackedVector2Array:
	var points: PackedVector2Array = PackedVector2Array()
	for i in range(12):
		var angle: float = TAU * float(i) / 12.0
		points.append(centre + Vector2(cos(angle), sin(angle)) * radius)
	return points


func _process(delta: float) -> void:
	phase += delta
	# Two node properties. Nothing is rasterised again.
	if _dish != null:
		_dish.rotation = phase * 0.6
	if _lights != null:
		_lights.modulate.a = 0.4 + 0.6 * absf(sin(phase * 4.0))