extends SceneTree

# Headless gameplay test: run with
#   godot --headless -s res://tests/test_sniper_enemy.gd
# Verifies:
#   1. against a stationary fleet, a sniper closes to roughly its standoff
#      component's preferred_range and never reaches contact range
#   2. its ranged weapon only fires within fire_range, and respects cooldown
#   3. the projectile is slow enough that a ship moving away right after the
#      shot clears the impact point unharmed
#   4. a hit (ship held in place) destroys an unshielded ship and is
#      absorbed by a shielded one, losing exactly one charge
#
# Movement (1) and combat (2-4) use SEPARATE sniper instances: a stationary
# ship left in weapon range for many seconds would otherwise take stray
# hits during the movement check and die before the later stages run, which
# is a test-harness artifact, not anything about the sniper's own design.

var game_state: Node
var main: Node
var fleet: Node
var mover: Node          # movement-only: its ranged_weapon is removed
var sniper: Node         # combat-only: pinned in place via speed = 0
var target_ship: Node
var interceptor: Node
var shield_ship: Node
var min_distance: float = INF
var cooldown_watermark: float = 0.0
var projectiles_before: int = 0
var stage: int = 0
var elapsed: float = 0.0
var settle_elapsed: float = 0.0


func _initialize() -> void:
	game_state = root.get_node("GameState")
	game_state.buildings.clear()
	game_state.extractors.clear()
	game_state.transporters.clear()
	game_state.stored_vessels.clear()
	game_state.build_time_scale = 0.02
	game_state.reset_progression()
	game_state.rocks = 2000
	main = load("res://Main.tscn").instantiate()
	root.add_child(main)
	fleet = main.get_node("Fleet")


func _projectile_count() -> int:
	return get_nodes_in_group("enemy_projectiles").size()


func _process(delta: float) -> bool:
	elapsed += delta
	match stage:
		0:
			if elapsed < 0.1:
				return false
			main.get_node("EnemySpawner").set_process(false)
			main.get_node("AsteroidField").set_process(false)
			for a in get_nodes_in_group("asteroids"):
				a.queue_free()

			fleet.spawn_ships(1, Vector2.ZERO)
			target_ship = fleet.ships[0]

			mover = load("res://Enemy.tscn").instantiate()
			mover.enemy_id = "sniper"
			mover.position = target_ship.position + Vector2(1000, 0)
			main.add_child(mover)
			mover.get_component("ranged_weapon").queue_free()

			elapsed = 0.0
			settle_elapsed = 0.0
			stage = 1
			return false
		1:
			# --- standoff: close in, never reach contact, settle near
			# preferred_range -----------------------------------------
			settle_elapsed += delta
			min_distance = minf(min_distance, mover.position.distance_to(target_ship.position))
			if min_distance < 100.0:
				return _fail("sniper reached near-contact range (%.1f) against a stationary fleet" % min_distance)
			if settle_elapsed < 8.0:
				return false
			var standoff: Node = mover.get_component("standoff")
			var final_distance: float = mover.position.distance_to(target_ship.position)
			var preferred: float = standoff.preferred_range
			print("min_distance=%.1f final_distance=%.1f preferred=%.1f" % [min_distance, final_distance, preferred])
			if final_distance < preferred * 0.6 or final_distance > preferred * 1.4:
				return _fail("sniper did not settle near its preferred_range (final=%.1f preferred=%.1f)" % [
					final_distance, preferred
				])
			mover.queue_free()

			# --- fire range gating: a fresh, pinned sniper out of range ---
			fleet.spawn_ships(1, target_ship.position + Vector2(-2000, 0))
			interceptor = fleet.ships[0]
			sniper = load("res://Enemy.tscn").instantiate()
			sniper.enemy_id = "sniper"
			main.add_child(sniper)
			sniper.speed = 0.0
			sniper.position = interceptor.position + Vector2(2000, 0)   # beyond fire_range
			projectiles_before = _projectile_count()
			elapsed = 0.0
			stage = 2
			return false
		2:
			var ranged: Node = sniper.get_component("ranged_weapon")
			if elapsed < ranged.fire_cooldown + 0.5:
				return false
			if _projectile_count() != projectiles_before:
				return _fail("sniper fired while beyond fire_range")

			# --- move into range: it should fire ---
			sniper.position = interceptor.position + Vector2(400, 0)
			projectiles_before = _projectile_count()
			elapsed = 0.0
			stage = 3
			return false
		3:
			if elapsed < 0.4:
				return false
			if _projectile_count() <= projectiles_before:
				return _fail("sniper did not fire once in range")

			# The already-fired shot is still travelling toward interceptor's
			# stationary position and would otherwise connect and vanish -
			# sidestep it (staying within fire_range, so the next stage's
			# wait for a fresh shot still has a target). Also re-pin
			# move_target to match - otherwise Ship's own steering
			# immediately drives it back toward the stale target.
			interceptor.position += Vector2(0, 150)
			interceptor.move_target = interceptor.position

			# --- cooldown: fire_timer must not jump back up before it's
			# counted all the way down, which is what a second shot would
			# do. Read from the component's own state rather than inferring
			# it from projectile counts against a wall-clock wait: physics
			# ticks can run in catch-up bursts relative to this SceneTree's
			# own _process() under device load, so an EnemyProjectile's age
			# and this script's `elapsed` are not guaranteed to stay in
			# lockstep even with --fixed-fps.
			cooldown_watermark = sniper.get_component("ranged_weapon").fire_timer
			elapsed = 0.0
			stage = 4
			return false
		4:
			# fire_timer can never be caught externally at exactly <= 0: the
			# component decrements-checks-refires atomically in one tick, so
			# by the time this poll runs it has either not reached zero yet
			# or has already fired and jumped back up to fire_cooldown. A
			# RISE from the last observed value is therefore the reliable
			# externally-visible signal for "it just fired again" - within
			# the first 0.6s that is a bug (still cooling down from the
			# first shot), afterward it is the legitimate next shot to dodge.
			var current: float = sniper.get_component("ranged_weapon").fire_timer
			if current > cooldown_watermark:
				if elapsed < 0.6:
					return _fail("sniper's cooldown timer jumped back up (a second shot fired) before it finished counting down")
				interceptor.position += Vector2(0, 900)   # perpendicular, well clear
				interceptor.move_target = interceptor.position
				elapsed = 0.0
				stage = 6
				return false
			cooldown_watermark = current
			if elapsed > 6.0:
				return _fail("sniper never fired its next shot")
			return false
		6:
			# Give the projectile its full lifetime to have resolved either way.
			if elapsed < 3.5:
				return false
			if not is_instance_valid(interceptor):
				return _fail("a slow sniper shot still hit a ship that moved away immediately")
			print("dodge held: interceptor survived after moving off the impact point")

			# --- direct hit: ship held in place, unshielded then shielded ---
			interceptor.position = sniper.position + Vector2(300, 0)
			interceptor.move_target = interceptor.position
			fleet.add_ship(GameState.VESSEL_SHIELD)
			shield_ship = fleet.ships[fleet.ships.size() - 1]
			shield_ship.position = Vector2(20000, 0)   # far from the line of fire
			shield_ship.move_target = shield_ship.position
			elapsed = 0.0
			stage = 7
			return false
		7:
			if elapsed < 0.3:
				return false
			if not shield_ship.has_shield():
				return _fail("a fresh shield vessel has no shield")
			elapsed = 0.0
			stage = 8
			return false
		8:
			if is_instance_valid(interceptor):
				if elapsed > 4.0:
					return _fail("held interceptor was never hit by the sniper")
				return false
			print("stationary unshielded interceptor destroyed by sniper fire")

			shield_ship.position = sniper.position + Vector2(300, 0)
			shield_ship.move_target = shield_ship.position
			elapsed = 0.0
			stage = 9
			return false
		9:
			if elapsed < 4.0:
				return false
			if not is_instance_valid(shield_ship):
				return _fail("a shielded ship was destroyed by sniper fire")
			if shield_ship.shield_charges != 0:
				return _fail("shield charges did not drop to 0 after absorbing one hit (charges=%d)" %
					shield_ship.shield_charges)
			print("shielded ship absorbed a sniper hit and lost exactly one charge")
			print("TEST_SNIPER_ENEMY: PASS")
			quit(0)
			return true
	return false


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