extends SceneTree

# Headless gameplay test: run with
#   godot --headless -s res://tests/test_asteroid_safe_spawn.gd
# Asteroid chunks are populated around wherever the fleet is - including the
# chunk it is standing in - and positions used to be uniform within a chunk.
# So an asteroid could be created directly on top of a ship and destroy it
# with no chance to react. Worst on the frame a scene loads: coming back from
# a planet's surface could cost a vessel instantly, which is also what made
# test_return_position_matches_planet fail intermittently.
#
# Verifies:
#   1. _safe_position never returns a point inside the bubble, for candidates
#      all around and including the exact centre. This is checked directly
#      rather than by looking at where asteroids happened to land: with ~54
#      asteroids spread over 25 chunks, any single run only rarely produces a
#      near miss, so an observational check passes just as happily with the
#      guard removed and proves nothing.
#   2. candidates already outside the bubble are left exactly where they are,
#      so the field is not distorted away from the fleet
#   3. the field still spawns a full complement, and a stationary fleet loses
#      no ships

var scene: Node
var fleet: Node
var field: Node
var stage: int = 0
var elapsed: float = 0.0
var ships_at_start: int = 0


func _initialize() -> void:
	root.get_node("GameState").reset_formation()
	scene = load("res://world/Main.tscn").instantiate()
	root.add_child(scene)
	fleet = scene.get_node("Fleet")
	field = scene.get_node("AsteroidField")


func _process(delta: float) -> bool:
	elapsed += delta
	match stage:
		0:
			scene.get_node("EnemySpawner").set_process(false)
			ships_at_start = fleet.ships.size()
			elapsed = 0.0
			stage = 1
			return false
		1:
			# Let the field populate around the fleet a few times over.
			if elapsed < 1.5:
				return false

			var centre: Vector2 = fleet.get_centroid()
			var safe: float = field.safe_spawn_radius

			# --- the guard itself, deterministically ----------------------
			var worst_inside: float = 1e9
			var moved_an_outside_one: bool = false
			for i in range(72):
				var a: float = (float(i) / 72.0) * TAU
				var dir: Vector2 = Vector2(cos(a), sin(a))
				# Candidates well inside, just inside, and exactly on centre.
				for d in [0.0, 1.0, safe * 0.25, safe * 0.99]:
					var got: Vector2 = field._safe_position(centre + dir * d, centre)
					worst_inside = minf(worst_inside, got.distance_to(centre))
				# Candidates already outside must be returned untouched.
				var outside: Vector2 = centre + dir * (safe * 1.5)
				if field._safe_position(outside, centre).distance_to(outside) > 0.001:
					moved_an_outside_one = true
			print("closest result for an inside candidate: %.1f (safe radius %.1f)" % [
				worst_inside, safe
			])
			if worst_inside < safe - 0.001:
				print("TEST_ASTEROID_SAFE_SPAWN: FAIL (guard let a spawn land inside the fleet's bubble)")
				quit(1)
				return true
			if moved_an_outside_one:
				print("TEST_ASTEROID_SAFE_SPAWN: FAIL (guard displaced an asteroid that was already clear)")
				quit(1)
				return true

			var asteroids: Array = get_nodes_in_group("asteroids")
			var closest: float = 1e9
			for a in asteroids:
				if is_instance_valid(a):
					closest = minf(closest, a.position.distance_to(centre))

			print("%d asteroids, closest is %.1f units from the fleet (safe radius %.1f)" % [
				asteroids.size(), closest, safe
			])
			if asteroids.is_empty():
				print("TEST_ASTEROID_SAFE_SPAWN: FAIL (field spawned nothing - test proves nothing)")
				quit(1)
				return true
			# Asteroids drift, so one may have travelled inward since it was
			# created. Allow for that, but nothing should be anywhere near
			# on top of the fleet.
			if closest < safe * 0.5:
				print("TEST_ASTEROID_SAFE_SPAWN: FAIL (asteroid created on top of the fleet)")
				quit(1)
				return true

			var kept_ships: bool = fleet.ships.size() == ships_at_start
			print("ships %d -> %d (kept=%s)" % [ships_at_start, fleet.ships.size(), kept_ships])
			if not kept_ships:
				print("TEST_ASTEROID_SAFE_SPAWN: FAIL (a stationary fleet lost a ship to a spawn)")
				quit(1)
				return true

			print("TEST_ASTEROID_SAFE_SPAWN: PASS")
			quit(0)
			return true
	return false