extends Node2D

# A landable world-object - unlike regular Asteroid.gd, planets are
# stationary ("Big Stable Asteroid" - stable means it doesn't drift or
# destroy ships on touch). Whether the fleet counts as "landed" is decided
# by PlanetField comparing the fleet's CENTROID distance to landing_radius,
# not per-ship Area2D collision - a single stable number, immune to the
# constant minor jostling of individual ships holding formation, which
# used to make the "enter atmosphere" prompt flicker on/off as ships
# drifted in and out of the boundary independently of each other even
# while the fleet as a whole was clearly sitting on the planet.

@export var planet_name: String = ""
@export var planet_type: String = "big_stable_asteroid"
@export var landing_radius: float = 140.0
# Set by whoever spawns this planet (PlanetField, seeded from the chunk's
# own coordinates) so the outline shape is stable across respawns of the
# same chunk, instead of reading as a "different" planet every time.
@export var shape_seed: int = 0

var shape_points: PackedVector2Array = PackedVector2Array()

# An extractor is built down on this planet's SURFACE, in a different scene
# the player is no longer looking at, so from space nothing distinguished a
# planet already being mined from an untouched one - you had to land to find
# out. This is a derrick planted on the rim: the same amber the world map
# uses for its extractor badge, so the two read as the same fact.
const EXTRACTOR_MARKER_COLOR: Color = Color(1.0, 0.85, 0.3)
const DERRICK_HEIGHT: float = 44.0
const DERRICK_HALF_WIDTH: float = 16.0

# Kept in step with GameState.extractor_added rather than polled per frame.
# An extractor is built from SPACE (BuildController._planet_under_fleet(),
# with the fleet parked on the planet), so this node is already in the tree
# with its _ready() long since run when the answer changes - resolving it
# only at _ready() left the planet looking untouched until it happened to
# despawn and respawn.
var shows_extractor: bool = false


func _ready() -> void:
	add_to_group("planets")
	z_index = -1

	var rng: RandomNumberGenerator = RandomNumberGenerator.new()
	rng.seed = shape_seed
	var point_count: int = 10
	for i in range(point_count):
		var angle: float = (float(i) / point_count) * TAU
		var radius: float = rng.randf_range(70.0, 100.0)
		shape_points.append(Vector2(cos(angle), sin(angle)) * radius)
	shows_extractor = GameState.has_extractor_at(planet_name)
	GameState.extractor_added.connect(_on_extractor_added)
	queue_redraw()


func _on_extractor_added(built_on: String) -> void:
	# Only the planet it was actually built on, and only a redraw when the
	# answer really changed - every other planet in range gets this too.
	if built_on != planet_name or shows_extractor:
		return
	shows_extractor = true
	queue_redraw()


func extractor_derrick_anchor() -> Vector2:
	# The rim vertex the derrick stands on: the shape's own topmost point,
	# rather than a fixed radius, so it sits ON the outline whatever lumpy
	# shape the seed drew instead of floating off it or sinking inside it.
	var base: Vector2 = Vector2(0.0, -100.0)
	for p in shape_points:
		if p.y < base.y:
			base = p
	return base


func extractor_derrick_tip() -> Vector2:
	# Exposed separately from the polygon because "does the derrick clear the
	# planet's outline" is a question about the TIP alone. The base corners
	# sit a half-width off to either side, so they are sqrt(|base|^2 + w^2)
	# from the centre and can clear the rim on their own even when the tower
	# points straight into the ground.
	var base: Vector2 = extractor_derrick_anchor()
	var out: Vector2 = base.normalized()
	if out == Vector2.ZERO:
		out = Vector2.UP
	return base + out * DERRICK_HEIGHT


func extractor_derrick_points() -> PackedVector2Array:
	var base: Vector2 = extractor_derrick_anchor()
	var out: Vector2 = base.normalized()
	if out == Vector2.ZERO:
		out = Vector2.UP
	var side: Vector2 = Vector2(-out.y, out.x)
	var tip: Vector2 = extractor_derrick_tip()
	return PackedVector2Array([
		base - side * DERRICK_HALF_WIDTH,
		tip - side * (DERRICK_HALF_WIDTH * 0.35),
		tip + side * (DERRICK_HALF_WIDTH * 0.35),
		base + side * DERRICK_HALF_WIDTH,
	])


func _draw() -> void:
	NeonDraw.draw_glowing_polygon(self, shape_points, Color(0.6, 0.55, 0.5), 1.0)
	if shows_extractor:
		NeonDraw.draw_glowing_polygon(self, extractor_derrick_points(), EXTRACTOR_MARKER_COLOR, 1.0)