extends SceneTree

# Headless gameplay test: run with
#   godot --headless -s res://tests/test_aim_assist.gd
# Forgejo #89: a shot fired roughly toward an enemy bends onto it, so aiming
# with a thumb on a stick does not have to be exact.
#
# Covers:
#   A. an enemy just off the aimed heading is picked up, and the bolt flies at
#      IT rather than where the stick pointed
#   B. an enemy far off the heading is not - past the cone the shot goes where
#      the player pointed, or the gun would be choosing its own targets again,
#      which is exactly what #80 took away
#   C. cursor proximity can select a target outside the directional cone
#   D. with several candidates, the one nearest the cursor wins rather than
#      blindly choosing the one nearest the shooter
#   E. asteroids participate through the same aimable-target contract
#   F. the guide snaps to the target position and reachable guns bend to the
#      same target, so the on-screen reticle tells the truth

var game_state: Node
var main: Node
var fleet: Node
var controller: Node
var weapon: Node
var shooter: Node2D
var stage: int = 0
var elapsed: float = 0.0

const AIM := Vector2(1.0, 0.0)


func _initialize() -> void:
	game_state = root.get_node("GameState")
	game_state.buildings.clear()
	game_state.extractors.clear()
	game_state.reset_progression()
	main = load("res://world/Main.tscn").instantiate()
	root.add_child(main)
	current_scene = main
	fleet = main.get_node("Fleet")
	controller = main.get_node("FireStickController")


func _clear() -> void:
	for node in get_nodes_in_group("enemies") + get_nodes_in_group("asteroids") \
			+ get_nodes_in_group("player_projectiles"):
		if is_instance_valid(node):
			node.free()


func _enemy_at(offset: Vector2) -> Node2D:
	var enemy: Node2D = load("res://enemies/Enemy.tscn").instantiate()
	enemy.position = shooter.global_position + offset
	main.add_child(enemy)
	enemy.speed = 0.0
	return enemy


func _heading(direction: Vector2) -> Vector2:
	var script: Script = load("res://vessels/VesselWeaponComponent.gd")
	return script.assisted_heading(self, shooter.global_position, direction,
		weapon.fire_range)


func _point(at: Vector2) -> Vector2:
	var script: Script = load("res://vessels/VesselWeaponComponent.gd")
	return script.assisted_point(self, shooter.global_position, at,
		weapon.fire_range)


func _process(delta: float) -> bool:
	elapsed += delta
	if stage != 0:
		return false
	if elapsed < 0.3:
		return false
	stage = 1

	main.get_node("EnemySpawner").set_process(false)
	main.get_node("AsteroidField").set_process(false)
	_clear()
	fleet.spawn_ships(1, Vector2.ZERO, PackedStringArray([GameState.VESSEL_INTERCEPTOR]))
	shooter = fleet.ships[0]
	weapon = shooter.get_component("weapon")

	# --- A. just off the heading is picked up -----------------------------
	var near_angle: float = deg_to_rad(18.0)
	var target: Node2D = _enemy_at(Vector2(600.0, 0.0).rotated(near_angle))
	var assisted: Vector2 = _heading(AIM)
	var wanted: Vector2 = (target.global_position - shooter.global_position).normalized()
	if assisted.distance_to(wanted) > 0.01:
		return _fail("an enemy 18 degrees off the heading was not picked up (heading %s)" % assisted)
	print("an enemy 18 degrees off the aim is picked up")

	# --- B. far off the heading is not ------------------------------------
	_clear()
	_enemy_at(Vector2(600.0, 0.0).rotated(deg_to_rad(55.0)))
	assisted = _heading(AIM)
	if assisted.distance_to(AIM) > 0.01:
		return _fail("an enemy 55 degrees off the heading was still picked up (heading %s)" % assisted)
	print("an enemy 55 degrees off the aim is ignored - the shot goes where it was aimed")

	# --- C. a nearby cursor is magnetic too -------------------------------
	_clear()
	var raw_cursor: Vector2 = shooter.global_position + Vector2(250.0, 0.0)
	var cursor_target: Node2D = _enemy_at(Vector2(150.0, 0.0).rotated(deg_to_rad(45.0)))
	var snapped: Vector2 = _point(raw_cursor)
	if snapped.distance_to(cursor_target.global_position) > 0.01:
		return _fail("a cursor %.0f units from a target outside the cone did not stick to it" \
			% raw_cursor.distance_to(cursor_target.global_position))
	print("a cursor near a target sticks to its position even outside the directional cone")

	# --- D. cursor proximity chooses between cone candidates --------------
	_clear()
	var far_distance: float = weapon.fire_range - 100.0
	var far_target: Node2D = _enemy_at(Vector2(far_distance, 0.0).rotated(deg_to_rad(5.0)))
	var close_target: Node2D = _enemy_at(Vector2(300.0, 0.0).rotated(deg_to_rad(20.0)))
	assisted = _heading(AIM)
	var to_close: Vector2 = (close_target.global_position - shooter.global_position).normalized()
	var to_far: Vector2 = (far_target.global_position - shooter.global_position).normalized()
	if assisted.distance_to(to_far) > 0.01:
		return _fail("the assist ignored the cursor-near enemy at %.0f for the shooter-near one at 300 (heading %s, close %s, far %s)" \
			% [far_distance, assisted, to_close, to_far])
	print("with two in the cone, the target nearest the cursor wins")

	# --- E. asteroids use the same assist contract -------------------------
	_clear()
	var rock: Node2D = load("res://world/Asteroid.tscn").instantiate()
	rock.position = shooter.global_position + Vector2(400.0, 0.0).rotated(deg_to_rad(15.0))
	main.add_child(rock)
	assisted = _heading(AIM)
	var to_rock: Vector2 = (rock.global_position - shooter.global_position).normalized()
	if assisted.distance_to(to_rock) > 0.01:
		return _fail("the assist did not snap onto an asteroid (heading %s, asteroid %s)" \
			% [assisted, to_rock])
	print("asteroids opt into the same aim-assist target group as enemies")

	# --- F. the guide and reachable guns share the snapped target ----------
	_clear()
	var guide_target: Node2D = _enemy_at(Vector2(500.0, 0.0).rotated(deg_to_rad(20.0)))
	controller.aim(AIM)
	if controller.aim_point.distance_to(guide_target.global_position) > 0.02:
		return _fail("the reticle stayed at %s instead of sticking to %s" \
			% [controller.aim_point, guide_target.global_position])
	var gun_heading: Vector2 = weapon.firing_heading()
	var target_heading: Vector2 = (guide_target.global_position - shooter.global_position).normalized()
	if gun_heading.distance_to(target_heading) > 0.02:
		return _fail("the reachable gun headed %s instead of toward snapped target %s" \
			% [gun_heading, target_heading])
	# And the guide must be drawn from that same helper, not a copy of the maths.
	var source: FileAccess = FileAccess.open("res://controllers/FireStickController.gd", FileAccess.READ)
	var text: String = source.get_as_text()
	source.close()
	if "assisted_point" not in text:
		return _fail("FireStickController draws its guide without the assist, so the line and the shot would diverge")
	print("the reticle snaps to the target and reachable guns bend toward it")

	print("TEST_AIM_ASSIST: PASS")
	quit(0)
	return true


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