extends SceneTree

# Headless test: run with
#   godot --headless -s res://tests/test_ship_death.gd
# Forgejo #130: "they would break away from the fleet by a few metres, and
# end up exploding a little further off, with a rather more explosive
# explosion than just a light animation."
#
# Three claims, and the first one is the one that could quietly break
# everything else: the wreck must be SCENERY. A dying ship kept alive to
# animate would still be an Area2D in the player_ships group with live
# weapon components - still shooting, still a target, still colliding - so
# the test checks that the fleet, the group and the node are all rid of it
# on the same frame they always were.
#
# Covers:
#   A. the ship itself dies immediately: out of the fleet, out of the group,
#      freed - exactly as before
#   B. a wreck is left behind, and it travels AWAY from the fleet
#   C. it explodes where it ended up, not where it was hit
#   D. the explosion is a real one - and no quieter than the one an enemy
#      gets, which is the comparison #130 is making
#   E. #135 - the prologue hands over an interceptor even when the belt has
#      taken every escort

var game_state: Node
var scene: Node
var fleet: Node2D
var stage: int = 0
var elapsed: float = 0.0
var wreck: Node2D
var wreck_start: Vector2 = Vector2.ZERO
var fleet_centre: Vector2 = Vector2.ZERO
var last_wreck_at: Vector2 = Vector2.ZERO
var ships_before: int = 0


func _initialize() -> void:
	# GameState is an autoload: a bare GameState.<instance member> does not
	# compile in a SceneTree script, so the node is fetched by name instead.
	game_state = root.get_node("GameState")
	game_state.reset_new_game()
	game_state.intro_active = false
	game_state.reset_quests()


func _fail(message: String) -> bool:
	print("TEST_SHIP_DEATH: FAIL (%s)" % message)
	quit(1)
	return true


func _wrecks() -> Array:
	var out: Array = []
	for node in root.get_children():
		if node is ShipWreckVFX:
			out.append(node)
	return out


func _explosions() -> Array:
	var out: Array = []
	for node in root.get_children():
		if node is ShipExplosionVFX:
			out.append(node)
	return out


func _process(delta: float) -> bool:
	elapsed += delta
	match stage:
		0:
			scene = load("res://world/Main.tscn").instantiate()
			root.add_child(scene)
			current_scene = scene
			fleet = scene.get_node("Fleet")
			elapsed = 0.0
			stage = 1
			return false
		1:
			if elapsed < 0.4:
				return false
			scene.get_node("AsteroidField").set_process(false)
			scene.get_node("EnemySpawner").set_process(false)
			# A wedge, so there is a formation to break away FROM.
			fleet.spawn_ships(3, Vector2.ZERO,
				PackedStringArray([GameState.VESSEL_INTERCEPTOR,
					GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_INTERCEPTOR]))
			elapsed = 0.0
			stage = 2
			return false
		2:
			if elapsed < 0.3:
				return false
			if fleet.ships.size() != 3:
				return _fail("wanted a fleet of 3 to kill one out of, got %d" % fleet.ships.size())
			fleet_centre = fleet.get_centroid()
			var doomed: Node2D = fleet.ships[0]
			wreck_start = doomed.position
			var before: int = get_nodes_in_group("player_ships").size()
			doomed.take_damage(1)

			# --- A. the ship is gone, on this frame ------------------
			if fleet.ships.size() != 2:
				return _fail("a killed ship is still in the fleet (%d ships)" % fleet.ships.size())
			if is_instance_valid(doomed) and not doomed.is_queued_for_deletion():
				return _fail("a killed ship was not freed")
			ships_before = before
			print("the ship leaves the fleet and is freed on the frame it dies")

			# --- B. and leaves a wreck behind ------------------------
			var wrecks: Array = _wrecks()
			if wrecks.size() != 1:
				return _fail("%d wrecks left behind, expected 1" % wrecks.size())
			wreck = wrecks[0]
			if wreck.position.distance_to(wreck_start) > 1.0:
				return _fail("the wreck did not start where the ship died")
			last_wreck_at = wreck.position
			elapsed = 0.0
			stage = 3
			return false
		3:
			# Halfway through the drift: still there, and further out.
			if elapsed < ShipWreckVFX.DRIFT_SECONDS * 0.5:
				return false
			if not is_instance_valid(wreck):
				return _fail("the wreck was gone before it had finished drifting")
			# A frame has passed, so the deletion queue has been flushed: the
			# dead ship is out of the group the enemies pick targets from.
			if get_nodes_in_group("player_ships").size() != ships_before - 1:
				return _fail("a killed ship is still in the player_ships group a frame later")
			var travelled: float = wreck.position.distance_to(wreck_start)
			if travelled < 40.0:
				return _fail("the wreck drifted %.0fpx - it is meant to break away" % travelled)
			# Away from the fleet, not through it.
			if wreck.position.distance_to(fleet_centre) <= wreck_start.distance_to(fleet_centre):
				return _fail("the wreck drifted towards the fleet, not away from it")
			if wreck.rotation == 0.0:
				return _fail("the wreck is not tumbling")
			last_wreck_at = wreck.position
			print("wreck drifted %.0fpx clear of the fleet, tumbling" % travelled)
			elapsed = 0.0
			stage = 4
			return false
		4:
			if elapsed < ShipWreckVFX.DRIFT_SECONDS:
				return false
			# --- C. it went up where it ended up ---------------------
			if is_instance_valid(wreck) and not wreck.is_queued_for_deletion():
				return _fail("the wreck never exploded")
			var blasts: Array = _explosions()
			if blasts.is_empty():
				return _fail("the wreck vanished without an explosion")
			var at: Vector2 = blasts[0].position
			if at.distance_to(wreck_start) < 40.0:
				return _fail("the explosion happened at the kill (%.0fpx away), not out where the wreck drifted to" \
					% at.distance_to(wreck_start))
			print("it exploded %.0fpx from where the ship was hit" % at.distance_to(wreck_start))

			# --- D. and it is a real explosion -----------------------
			var ours: ShipExplosionVFX = ShipExplosionVFX.new()
			var theirs: EnemyExplosionVFX = EnemyExplosionVFX.new()
			if ours.shockwave_radius <= 0.0:
				return _fail("a lost vessel still goes up without a shockwave")
			if ours.particle_count < theirs.particle_count:
				return _fail("losing a vessel (%d particles) is quieter than killing an enemy (%d)" \
					% [ours.particle_count, theirs.particle_count])
			if ours.lifetime < theirs.lifetime:
				return _fail("a lost vessel's explosion is shorter than an enemy's")
			print("player explosion: %d particles over %.2fs, shockwave %.0f (enemy: %d over %.2fs)" \
				% [ours.particle_count, ours.lifetime, ours.shockwave_radius,
					theirs.particle_count, theirs.lifetime])
			ours.free()
			theirs.free()

			# --- E. #135: the prologue's survivor --------------------
			scene.free()
			game_state.reset_new_game()
			scene = load("res://world/Main.tscn").instantiate()
			root.add_child(scene)
			current_scene = scene
			fleet = scene.get_node("Fleet")
			elapsed = 0.0
			stage = 5
			return false
		5:
			if elapsed < 0.4:
				return false
			var director: Node2D = scene.get_node("IntroDirector")
			var narration: Control = scene.get_node("UI/NarrationBanner")
			narration.clear()
			# The belt takes every escort on the way through - the corners of
			# the convoy are the exposed part of it. This is the case #135
			# reported: what is left is all cargo.
			for i in range(fleet.ships.size() - 1, -1, -1):
				var ship: Node2D = fleet.ships[i]
				if String(ship.vessel_type) == GameState.VESSEL_INTERCEPTOR:
					fleet.ships.remove_at(i)
					fleet.formation_offsets.remove_at(i)
					ship.free()
			if fleet.ships.is_empty():
				return _fail("the test emptied the convoy instead of stripping its escorts")
			for ship in fleet.ships:
				if String(ship.vessel_type) == GameState.VESSEL_INTERCEPTOR:
					return _fail("an escort survived the test's own belt")
			print("convoy stripped to %d holds and no escorts" % fleet.ships.size())

			director._begin(director.Beat.VORTEX)
			if not fleet.has_vessel_type(GameState.VESSEL_INTERCEPTOR):
				return _fail("the vortex began with no basic vessel to leave behind")
			if String(director._survivor().vessel_type) != GameState.VESSEL_INTERCEPTOR:
				return _fail("the survivor is a %s" % director._survivor().vessel_type)
			director.finish()
			if fleet.ships.size() != GameState.STARTING_SHIP_COUNT:
				return _fail("the prologue handed over %d vessels" % fleet.ships.size())
			if String(fleet.ships[0].vessel_type) != GameState.VESSEL_INTERCEPTOR:
				return _fail("the prologue handed over a %s, not the basic vessel" \
					% fleet.ships[0].vessel_type)
			print("with every escort lost, the prologue still hands over an interceptor")

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