extends SceneTree

# Headless gameplay test: run with
#   godot --headless -s res://tests/test_distorder_stacking.gd
# Each space-time distorder vessel PAST THE FIRST raises the fleet's speed
# ceiling by 1.0, so a second one is worth crewing rather than dead weight.
#
# Covers:
#   A. one vessel gives the original ceiling, so nothing changed for a fleet
#      that carries a single distorder
#   B. each additional vessel adds exactly 1.0
#   C. the fader's full travel reaches the WIDENED ceiling, not the old one
#   D. losing a vessel mid-boost pulls the fleet back down to the new
#      ceiling rather than leaving it faster than its crew can sustain
#   E. full boost still costs the same energy per second however wide the
#      ceiling is - more vessels buy more speed, not cheaper speed

var game_state: Node
var main: Node
var fleet: Node
var fader: Node
var stage: int = 0
var elapsed: float = 0.0


func _initialize() -> void:
	game_state = root.get_node("GameState")
	game_state.reset_progression()
	game_state.vessel_levels["unlock_distorder"] = 1
	game_state.deposit_fleet_resource(GameState.RESOURCE_ENERGY, 500)
	main = load("res://Main.tscn").instantiate()
	root.add_child(main)
	fleet = main.get_node("Fleet")
	fader = main.get_node("UI/SpeedFader")


func _process(delta: float) -> bool:
	elapsed += delta
	match stage:
		0:
			if elapsed < 0.2:
				return false
			main.get_node("EnemySpawner").set_process(false)
			main.get_node("AsteroidField").set_process(false)
			# Room for a fleet of distorders.
			game_state.unlocked.append_array(["wing", "squadron", "armada"])

			# --- A. one vessel is unchanged ------------------------------
			fleet.spawn_ships(2, Vector2.ZERO, PackedStringArray([
				GameState.VESSEL_INTERCEPTOR, GameState.VESSEL_DISTORDER]))
			if not is_equal_approx(game_state.max_fleet_speed_multiplier, GameState.MAX_FLEET_SPEED_MULTIPLIER):
				return _fail("one distorder gives a ceiling of %.1f, expected the unchanged %.1f" \
					% [game_state.max_fleet_speed_multiplier, GameState.MAX_FLEET_SPEED_MULTIPLIER])
			print("1 distorder -> ceiling %.1fx" % game_state.max_fleet_speed_multiplier)

			# --- B. each additional vessel adds 1.0 ----------------------
			for extra in range(1, 4):
				fleet.add_ship(GameState.VESSEL_DISTORDER)
				var expected: float = GameState.MAX_FLEET_SPEED_MULTIPLIER + float(extra)
				if not is_equal_approx(game_state.max_fleet_speed_multiplier, expected):
					return _fail("%d distorders give a ceiling of %.1f, expected %.1f" \
						% [extra + 1, game_state.max_fleet_speed_multiplier, expected])
				print("%d distorders -> ceiling %.1fx" % [extra + 1, game_state.max_fleet_speed_multiplier])

			# --- C. the fader reaches the widened ceiling ----------------
			# Dragging the track to its top must mean the CURRENT ceiling, or
			# the extra vessels would be unreachable through the only control
			# that exists for them.
			fader._process(0.0)
			if not fader.visible:
				return _fail("the fader is hidden with four distorder vessels crewed")
			var press := InputEventScreenTouch.new()
			press.index = 3
			press.position = fader.global_position + Vector2(fader.size.x * 0.5, fader.size.y - 4.0)
			press.pressed = true
			main._handle_touch(press)
			var drag := InputEventScreenDrag.new()
			drag.index = 3
			drag.position = fader.global_position + Vector2(fader.size.x * 0.5, 0.0)
			main._handle_drag(drag)
			if not is_equal_approx(game_state.fleet_speed_multiplier, game_state.max_fleet_speed_multiplier):
				return _fail("dragging the fader to the top reached %.2fx, not the ceiling %.2fx" \
					% [game_state.fleet_speed_multiplier, game_state.max_fleet_speed_multiplier])
			print("fader top reaches %.1fx" % game_state.fleet_speed_multiplier)

			# --- E. full boost costs the same per second -----------------
			# The drain is normalized against the current ceiling, so sitting
			# at full boost is the same price whatever the ceiling is.
			var wide_energy: int = _energy_spent_over(1.0)

			# --- D. losing vessels pulls the boost back down -------------
			var boosted_before: float = game_state.fleet_speed_multiplier
			for i in range(fleet.ships.size() - 1, -1, -1):
				if is_instance_valid(fleet.ships[i]) and fleet.ships[i].vessel_type == GameState.VESSEL_DISTORDER:
					fleet.store_ship(i)
					break
			if game_state.max_fleet_speed_multiplier >= boosted_before:
				return _fail("losing a distorder left the ceiling at %.1f, no lower than the %.1f the fleet was already doing" \
					% [game_state.max_fleet_speed_multiplier, boosted_before])
			if game_state.fleet_speed_multiplier > game_state.max_fleet_speed_multiplier + 0.001:
				return _fail("the fleet is still doing %.2fx after its ceiling dropped to %.2fx" \
					% [game_state.fleet_speed_multiplier, game_state.max_fleet_speed_multiplier])
			print("losing one pulled %.1fx down to the new %.1fx ceiling" \
				% [boosted_before, game_state.fleet_speed_multiplier])

			# Same measurement at the narrower ceiling, also at full boost.
			game_state.set_fleet_speed_multiplier(game_state.max_fleet_speed_multiplier)
			var narrow_energy: int = _energy_spent_over(1.0)
			if absi(wide_energy - narrow_energy) > 1:
				return _fail("full boost cost %d energy with a wide ceiling and %d with a narrow one - extra vessels changed the PRICE, not just the speed" \
					% [wide_energy, narrow_energy])
			print("full boost costs %d/%d energy per second at either ceiling" % [wide_energy, narrow_energy])

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


# Energy actually consumed by holding the current multiplier for `seconds`,
# driven directly so the measurement does not depend on frame pacing.
func _energy_spent_over(seconds: float) -> int:
	var before: int = game_state.fleet_resource(GameState.RESOURCE_ENERGY)
	var step: float = 0.05
	var t: float = 0.0
	while t < seconds:
		game_state._advance_distorder_drain(step)
		t += step
	return before - game_state.fleet_resource(GameState.RESOURCE_ENERGY)


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