extends SceneTree

# Headless gameplay test: run with
#   godot --headless -s res://tests/test_enemy_bomber.gd
# Forgejo #114: the enemy bomber - the artillery enemy, the one that lobs an
# area shell.
#
# It was a siege piece that crept at 20px/s and threw a shell taking five
# seconds to cross the gap, which read as a thing that was stuck rather than
# a thing that was dangerous: by the time a shell landed the fleet had
# wandered off, and the tower was still approaching.
#
# Covers:
#   A. it closes on a target at a speed worth calling flying, and faces
#      where it is going
#   B. its bombs travel fast enough to arrive while the target is roughly
#      where they were aimed
#   C. the bomb damages a player vessel it lands on
#   D. and a BUILDING it lands on - it used to hit only player_ships, which
#      was already out of step with #101
#   E. it bombs a structure with no fleet in sight, through the shared
#      targeting rather than asking Fleet directly
#   F. its hull is its own, not a copy of another enemy's

const MIN_FLYING_SPEED: float = 90.0
const MIN_SHELL_SPEED: float = 350.0

var game_state: Node
var main: Node
var fleet: Node
var field: Node
var bomber: Node2D
var target_ship: Node2D
var stage: int = 0
var elapsed: float = 0.0
var start_distance: float = 0.0
var building_id: int = 0
var hp_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.buildings.clear()
	game_state.extractors.clear()
	game_state.transporters.clear()
	game_state.reset_progression()
	game_state.reset_waves()
	game_state.intro_active = false
	main = load("res://world/Main.tscn").instantiate()
	root.add_child(main)
	current_scene = main
	fleet = main.get_node("Fleet")
	field = main.get_node("BuildingField")


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


func _spawn_bomber(at: Vector2) -> Node2D:
	var enemy: Node2D = load("res://enemies/Enemy.tscn").instantiate()
	enemy.enemy_id = "artillery"
	enemy.position = at
	main.add_child(enemy)
	return enemy


func _shells() -> Array:
	var out: Array = []
	for shell in get_nodes_in_group("artillery_shells"):
		if is_instance_valid(shell) and not shell.is_queued_for_deletion():
			out.append(shell)
	return out


func _process(delta: float) -> bool:
	elapsed += delta
	match stage:
		0:
			if elapsed < 0.3:
				return false
			main.get_node("EnemySpawner").set_process(false)
			main.get_node("AsteroidField").set_process(false)
			for hazard in get_nodes_in_group("asteroids") + get_nodes_in_group("enemies"):
				if is_instance_valid(hazard):
					hazard.queue_free()

			# --- F. its own silhouette -------------------------------
			var definitions: Script = load("res://enemies/EnemyDefinitions.gd")
			var bomber_def: Resource = definitions.get_definition("artillery")
			for other in definitions.all():
				if other.enemy_id == "artillery":
					continue
				if other.hull_points == bomber_def.hull_points:
					return _fail("the bomber shares its hull with the %s" % other.enemy_id)
			if bomber_def.speed < MIN_FLYING_SPEED:
				return _fail("the bomber's top speed is %.0f - that is still creeping" \
					% bomber_def.speed)
			print("bomber: %d hull points of its own, %.0fpx/s top speed" \
				% [bomber_def.hull_points.size() / 2, bomber_def.speed])

			fleet.spawn_ships(1, Vector2.ZERO,
				PackedStringArray([GameState.VESSEL_INTERCEPTOR]))
			target_ship = fleet.ships[0]
			target_ship.move_target = target_ship.position
			bomber = _spawn_bomber(Vector2(700.0, 0.0))
			start_distance = bomber.global_position.distance_to(target_ship.global_position)
			elapsed = 0.0
			stage = 1
			return false
		1:
			# --- A. it flies, and faces where it is going ------------
			if elapsed < 1.0:
				return false
			if not is_instance_valid(bomber):
				return _fail("the bomber is gone before it could be measured")
			var closed: float = start_distance \
				- bomber.global_position.distance_to(target_ship.global_position)
			var speed: float = closed / elapsed
			if speed < MIN_FLYING_SPEED:
				return _fail("the bomber closed at %.0fpx/s - #114 asks for an aircraft" % speed)
			var heading: Vector2 = target_ship.global_position - bomber.global_position
			var drift: float = absf(angle_difference(bomber.rotation, heading.angle() + PI / 2.0))
			if drift > PI / 3.0:
				return _fail("it flew %.0f degrees away from where it was pointing" \
					% rad_to_deg(drift))
			print("closed %.0fpx in %.1fs (%.0fpx/s), nose within %.0f degrees" \
				% [closed, elapsed, speed, rad_to_deg(drift)])

			# --- B/C. the bomb arrives, and it hurts -----------------
			var component: Node = bomber.get_component("artillery")
			if component.shell_speed < MIN_SHELL_SPEED:
				return _fail("its bombs travel at %.0f - too slow to arrive" % component.shell_speed)
			component.cooldown_left = 0.0
			elapsed = 0.0
			stage = 2
			return false
		2:
			if _shells().is_empty():
				if elapsed > 6.0:
					return _fail("the bomber never dropped a bomb")
				return false
			print("bomb away, travelling at %.0fpx/s" % _shells()[0].shell_speed)
			elapsed = 0.0
			stage = 3
			return false
		3:
			if elapsed < 4.0:
				return false
			if is_instance_valid(target_ship) and not target_ship.is_queued_for_deletion():
				return _fail("a bomb landed on a stationary vessel and it survived")
			print("the vessel it was aimed at is gone")

			# --- D/E. and it bombs what the player has built ---------
			for hazard in get_nodes_in_group("enemies"):
				if is_instance_valid(hazard):
					hazard.queue_free()
			# The fleet is parked far away, so nothing here is about ships.
			fleet.spawn_ships(1, Vector2(-9000.0, 0.0),
				PackedStringArray([GameState.VESSEL_INTERCEPTOR]))
			fleet.ships[0].move_target = fleet.ships[0].position
			field.place(GameState.BUILDING_SHIP_CRAFTER, Vector2.ZERO)
			building_id = int(game_state.buildings[-1].id)
			elapsed = 0.0
			stage = 4
			return false
		4:
			if elapsed < 0.3:
				return false
			hp_before = game_state.building_hp(building_id)
			bomber = _spawn_bomber(Vector2(600.0, 0.0))
			bomber.speed = 0.0
			bomber.get_component("artillery").cooldown_left = 0.0
			elapsed = 0.0
			stage = 5
			return false
		5:
			if elapsed < 5.0:
				return false
			var now: int = game_state.building_hp(building_id)
			if now >= hp_before:
				return _fail("the bomber shelled a crafter with no fleet in sight and did nothing")
			print("with the fleet 9000px away it bombed the crafter: %d -> %d hp" % [hp_before, now])

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