extends SceneTree

# Headless gameplay test: run with
#   godot --headless -s res://tests/test_laser_animation.gd
# Forgejo #90: the laser shot was one flat line that blinked on at full
# length and faded out. Nothing happened at the ship, nothing moved, and the
# only thing separating a hit from a miss was how long the line lingered.
#
# It now ignites: the blade runs out of the hull over the first slice of the
# flash, holds white-hot, and falls away, with sparks thrown off the hull
# that fired it.
#
# An animation cannot be eyeballed from a headless test, so this asserts the
# things that MAKE it one, and - more importantly - that none of it reached
# the gameplay underneath:
#   A. the beam extends: early in the flash it is drawn well short of its
#      full length, and by the end of the ignition it has arrived
#   B. the extension only ever moves outward, never back down the blade
#   C. the flash outlives the frame it was fired on, and clears itself
#   D. the DAMAGE is still instant, at full range, on the frame of the shot -
#      the picture extends, the weapon does not. A target at the far end
#      must be hit before the drawn beam has visibly got there
#   E. the hull throws sparks, in the beam's own colour rather than the
#      ordinary gun's gold

var game_state: Node
var main: Node
var fleet: Node
var laser: Node
var far_enemy: Node
var far_health: int = 0
var extensions: Array = []
var stage: int = 0
var elapsed: float = 0.0


func _initialize() -> void:
	game_state = root.get_node("GameState")
	game_state.buildings.clear()
	game_state.extractors.clear()
	game_state.stored_vessels.clear()
	game_state.reset_progression()
	game_state.vessel_levels["unlock_laser"] = 1
	game_state.deposit_fleet_resource(GameState.RESOURCE_ENERGY, 500)
	main = load("res://world/Main.tscn").instantiate()
	root.add_child(main)
	current_scene = main
	fleet = main.get_node("Fleet")
	laser = main.get_node("LaserController")


func _sparks() -> Array:
	var found: Array = []
	for node in root.get_children():
		if node.get_script() != null \
				and String(node.get_script().resource_path).ends_with("MuzzleSparkVFX.gd"):
			found.append(node)
	return found


func _spawn_enemy(at: Vector2) -> Node:
	var enemy: Node = load("res://enemies/Enemy.tscn").instantiate()
	enemy.position = at
	main.add_child(enemy)
	# Still, so where it was hit is where it was put.
	enemy.speed = 0.0
	return enemy


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)
			for hazard in get_nodes_in_group("asteroids") + get_nodes_in_group("enemies"):
				if is_instance_valid(hazard):
					hazard.queue_free()
			for spark in _sparks():
				spark.queue_free()
			fleet.spawn_ships(1, Vector2.ZERO, PackedStringArray([GameState.VESSEL_LASER]))
			laser._process(0.0)
			stage = 1
			elapsed = 0.0
			return false
		1:
			if elapsed < 0.1:
				return false
			var shooter: Node2D = laser._next_ready_laser_ship()
			if shooter == null:
				return _fail("no laser ship was ready to fire")

			# D. The target sits at the very end of the beam's reach, in the
			# direction it will be fired. If the shot only damaged what the
			# drawn blade had swept, this would survive the frame.
			var reach: float = shooter.get_component("laser").beam_range
			far_enemy = _spawn_enemy(shooter.global_position + Vector2(reach - 40.0, 0.0))
			far_health = far_enemy.hp
			laser.fire_at(shooter.global_position + Vector2(reach, 0.0))

			if laser.beams.is_empty():
				return _fail("firing produced no beam at all")
			if laser.last_hit_count < 1:
				return _fail("the target at the far end of the beam was not hit on the frame of the shot")
			# It may have died outright, which is still a hit; if it lived it
			# must have lost hit points.
			if is_instance_valid(far_enemy) and far_enemy.hp >= far_health:
				return _fail("the far target survived the shot untouched")
			print("full-range target hit on the firing frame: %d hp -> %s" % [
				far_health,
				str(far_enemy.hp) if is_instance_valid(far_enemy) else "destroyed",
			])

			# A. and the picture has NOT got there yet on that same frame.
			var first: float = laser.beam_extension(laser.beams[0])
			if first >= 0.5:
				return _fail("the beam was already %.0f%% extended on the frame it was fired" \
					% [first * 100.0])
			extensions.append(first)

			# E. sparks off the hull, in the beam's colour.
			var sparks: Array = _sparks()
			if sparks.is_empty():
				return _fail("firing threw no sparks off the hull")
			if sparks[0].color != laser.BEAM_COLOR:
				return _fail("the muzzle sparks are %s, not the beam's own %s" \
					% [sparks[0].color, laser.BEAM_COLOR])
			print("hull sparks in the beam's colour: %s" % sparks[0].color)

			stage = 2
			elapsed = 0.0
			return false
		2:
			# B/C. Sample the extension across the ignition.
			if laser.beams.is_empty():
				if extensions.size() < 3:
					return _fail("the flash was over after only %d frames - nothing to animate" \
						% extensions.size())
				if extensions[extensions.size() - 1] < 0.999:
					return _fail("the beam never reached its full length (stopped at %.2f)" \
						% extensions[extensions.size() - 1])
				print("beam extended over %d frames: %.2f -> %.2f, monotonically" % [
					extensions.size(), extensions[0], extensions[extensions.size() - 1]])
				print("TEST_LASER_ANIMATION: PASS")
				quit(0)
				return true
			var now: float = laser.beam_extension(laser.beams[0])
			if now < extensions[extensions.size() - 1] - 0.001:
				return _fail("the beam retracted: %.3f after %.3f" \
					% [now, extensions[extensions.size() - 1]])
			extensions.append(now)
			if elapsed > 3.0:
				return _fail("the beam flash never cleared")
			return false
	return false


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