extends SceneTree

# Headless gameplay test: run with
#   godot --headless -s res://tests/test_lancer_enemy.gd
# Forgejo #96, the lancer: a ramming enemy that announces itself.
#
#   "A new enemy vessel tries to suicide itself like the default vessel.
#    Though this new enemy starts a bit far from the target, lock it and
#    wait a bit. A small back and forth announce its departure to its
#    target, in a straight line, quickly. 300ms before it actually starts
#    going, a small line goes from it to its target to announce its
#    trajectory."
#
# Covers:
#   A. it is in the catalog, composes a lunge component and nothing that
#      would fight it over position, and rams like the chaser does
#   B. from beyond lock_range it does NOT charge - it closes slowly, so the
#      player sees it coming
#   C. once locked it holds station for the wind-up and rocks back and forth
#      along the charge axis instead of drifting toward the target
#   D. the trajectory line comes up during the wind-up and lasts about
#      300ms - not the whole wind-up, and not nothing
#   E. the charge is straight, fast, and aimed at where the target WAS: a
#      ship that moves after the lock is missed, which is what makes the
#      telegraph worth reading
#   F. it dies on contact, taking the vessel with it
#   G. the roaming spawner can actually produce one, and still produces
#      chasers - a new enemy nobody meets is not a new enemy

var game_state: Node
var main: Node
var fleet: Node
var lancer: Node2D
var target_ship: Node2D
var victim: Node2D
var stage: int = 0
var elapsed: float = 0.0
var lunge: Node

var approach_start: float = 0.0
var windup_seen: bool = false
var windup_anchor: Vector2 = Vector2.ZERO
var max_sway: float = 0.0
var max_lateral: float = 0.0
var telegraph_time_seen: float = 0.0
var charge_start: Vector2 = Vector2.ZERO
var dodged_to: Vector2 = Vector2.ZERO
var charge_locked: Vector2 = Vector2.ZERO
var max_off_axis: float = 0.0
var charge_seen: bool = false
var destroyed_fired: bool = false


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.reset_progression()
	main = load("res://world/Main.tscn").instantiate()
	root.add_child(main)
	current_scene = main
	fleet = main.get_node("Fleet")


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


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()

			# --- A. catalogued, composed, and a rammer -------------------
			var definitions: Script = load("res://enemies/EnemyDefinitions.gd")
			var definition: Resource = definitions.get_definition("lancer")
			if definition.enemy_id != "lancer":
				return _fail("EnemyDefinitions has no \"lancer\" - get_definition fell back")
			if not bool(definition.dies_on_contact):
				return _fail("the lancer is not marked dies_on_contact, so it is not a rammer")

			fleet.spawn_ships(1, Vector2.ZERO, PackedStringArray([GameState.VESSEL_INTERCEPTOR]))
			target_ship = fleet.ships[0]
			# Ship steers toward move_target every frame; pinning it there is
			# how a vessel is held still (see test_sniper_enemy.gd).
			target_ship.move_target = target_ship.position

			lancer = _spawn_lancer(target_ship.global_position + Vector2(1300.0, 0.0))
			lunge = lancer.get_component("lunge")
			if lunge == null:
				return _fail("the lancer composed no lunge component")
			if lancer.has_capability("pursuit") or lancer.has_capability("standoff"):
				return _fail("the lancer also carries a mover that would fight the lunge for position")
			if 1300.0 <= lunge.lock_range:
				return _fail("the test spawns inside lock_range, so case B proves nothing")
			print("lancer: hp %d, lock_range %.0f, windup %.2fs, telegraph %.2fs" % [
				lancer.max_hp, lunge.lock_range, lunge.windup_time, lunge.telegraph_time])
			approach_start = lancer.global_position.distance_to(target_ship.global_position)
			elapsed = 0.0
			stage = 1
			return false
		1:
			# --- B. it approaches rather than charging from out there ----
			if elapsed < 0.6:
				if lunge.phase == lunge.Phase.CHARGE:
					return _fail("the lancer charged from beyond its lock_range")
				return false
			var closed: float = approach_start - lancer.global_position.distance_to(
				target_ship.global_position)
			if closed <= 1.0:
				return _fail("the lancer never closed on the fleet from %.0f away" % approach_start)
			# The stalk must be slower than the charge, or the "starts a bit
			# far, waits" reading is lost.
			var approach_speed: float = closed / elapsed
			if approach_speed >= lunge.charge_speed * 0.5:
				return _fail("it approached at %.0fpx/s, barely short of its %.0fpx/s charge" % [
					approach_speed, lunge.charge_speed])
			print("closed %.0fpx in %.1fs (%.0fpx/s) without charging" % [
				closed, elapsed, approach_speed])
			elapsed = 0.0
			stage = 2
			return false
		2:
			# --- C/D. wind-up: rocks in place, and puts the line up late --
			if lunge.phase == lunge.Phase.WINDUP:
				if not windup_seen:
					windup_seen = true
					windup_anchor = lunge.charge_anchor
					charge_locked = lunge.locked_point
				var offset: Vector2 = lancer.global_position - windup_anchor
				max_sway = maxf(max_sway, absf(offset.dot(lunge.charge_direction)))
				var across: Vector2 = Vector2(-lunge.charge_direction.y, lunge.charge_direction.x)
				max_lateral = maxf(max_lateral, absf(offset.dot(across)))
				if lunge.is_telegraphing():
					telegraph_time_seen += delta
					if dodged_to == Vector2.ZERO:
						# What the warning is FOR: the moment the line shows,
						# the ship steps off it. The lock is already frozen,
						# so this must not drag the charge along with it.
						var sidestep: Vector2 = Vector2(-lunge.charge_direction.y,
							lunge.charge_direction.x) * 400.0
						target_ship.position += sidestep
						target_ship.move_target = target_ship.position
						dodged_to = target_ship.position
				return false
			if not windup_seen:
				if elapsed > 6.0:
					return _fail("the lancer never entered a wind-up within 6s of locking range")
				return false
			if lunge.phase != lunge.Phase.CHARGE:
				return _fail("the wind-up ended in phase %d rather than a charge" % lunge.phase)

			if max_sway < 1.0:
				return _fail("the lancer sat perfectly still through the wind-up - no back and forth")
			if max_sway > lunge.windup_sway + 1.0:
				return _fail("it moved %.0fpx along the charge axis, more than the %.0fpx sway - that is departing early" % [
					max_sway, lunge.windup_sway])
			if max_lateral > 1.0:
				return _fail("it wandered %.0fpx sideways during the wind-up instead of holding station" % max_lateral)
			print("wind-up: rocked %.0fpx back and forth, %.0fpx sideways" % [max_sway, max_lateral])

			# 300ms of line, give or take the frames either side of the
			# threshold. Both bounds matter: a line up for the whole wind-up
			# is not a 300ms warning either.
			if absf(telegraph_time_seen - lunge.telegraph_time) > 0.1:
				return _fail("the trajectory line showed for %.2fs, not the %.2fs it promises" % [
					telegraph_time_seen, lunge.telegraph_time])
			if lunge.telegraph_time >= lunge.windup_time:
				return _fail("the line covers the whole wind-up, so it announces nothing")
			print("trajectory line up for %.2fs of the %.2fs wind-up" % [
				telegraph_time_seen, lunge.windup_time])

			charge_start = lancer.global_position
			elapsed = 0.0
			stage = 3
			return false
		3:
			# --- E. straight, fast, and at the locked point --------------
			if lunge.phase == lunge.Phase.CHARGE:
				charge_seen = true
				var travel: Vector2 = lancer.global_position - charge_start
				var across: Vector2 = Vector2(-lunge.charge_direction.y, lunge.charge_direction.x)
				max_off_axis = maxf(max_off_axis, absf(travel.dot(across)))
				return false
			if not charge_seen:
				return _fail("the charge was over before a single frame of it was observed")
			if dodged_to == Vector2.ZERO:
				return _fail("the trajectory line never showed, so nothing was dodged")
			if not is_instance_valid(target_ship) or target_ship.is_queued_for_deletion():
				return _fail("the ship stepped off the telegraphed line and was hit anyway")
			if max_off_axis > 1.0:
				return _fail("the charge bent %.0fpx off its locked axis - it homed instead of flying straight" % max_off_axis)
			var covered: float = charge_start.distance_to(lancer.global_position)
			var speed: float = covered / maxf(elapsed, 0.001)
			if speed < lunge.charge_speed * 0.8:
				return _fail("the charge averaged %.0fpx/s against a stated %.0fpx/s" % [
					speed, lunge.charge_speed])
			# It aimed at the locked point, not at wherever the ship is now.
			var passed_by: float = (charge_locked - target_ship.global_position).length()
			if passed_by < 200.0:
				return _fail("the charge followed the ship as it dodged - the lock is not frozen")
			print("charged %.0fpx at %.0fpx/s, %.0fpx off axis, locked point %.0fpx from the ship" % [
				covered, speed, max_off_axis, passed_by])
			lancer.queue_free()

			# --- F. contact kills both ----------------------------------
			fleet.spawn_ships(1, Vector2(4000.0, 0.0), PackedStringArray([GameState.VESSEL_INTERCEPTOR]))
			victim = fleet.ships[0]
			elapsed = 0.0
			stage = 4
			return false
		4:
			if elapsed < 0.2:
				return false
			lancer = _spawn_lancer(victim.global_position)
			lancer.destroyed.connect(func(): destroyed_fired = true)
			elapsed = 0.0
			stage = 5
			return false
		5:
			if elapsed < 0.5:
				return false
			if is_instance_valid(lancer) and not lancer.is_queued_for_deletion():
				return _fail("the lancer survived ramming a vessel")
			if not destroyed_fired:
				return _fail("the lancer vanished without firing `destroyed` - not routed through take_damage")
			if is_instance_valid(victim) and not victim.is_queued_for_deletion():
				return _fail("the rammed vessel survived, so the lancer cost nothing to stop")
			print("lancer and vessel destroyed each other")

			# --- G. the roaming spawner puts it in the game --------------
			var spawner: Node2D = main.get_node("EnemySpawner")
			if spawner.lancer_chance <= 0.0 or spawner.lancer_chance >= 1.0:
				return _fail("the spawner's lancer_chance is %.2f - it makes one enemy or the other, never a mix" \
					% spawner.lancer_chance)
			# The spawner refuses to spawn against an empty fleet, and the
			# ram just emptied it - the wipe safety net normally refills it,
			# but this must not depend on that having happened yet.
			if fleet.ships.is_empty():
				fleet.spawn_ships(1, Vector2(8000.0, 0.0))
			var made: Dictionary = {}
			for i in range(40):
				spawner.lancer_chance = 1.0 if i % 2 == 0 else 0.0
				spawner._spawn_enemy()
			for enemy in get_nodes_in_group("enemies"):
				if is_instance_valid(enemy):
					made[enemy.enemy_id] = true
					enemy.queue_free()
			if not made.has("lancer"):
				return _fail("40 spawns at lancer_chance 1.0 produced no lancer")
			if not made.has("chaser"):
				return _fail("40 spawns at lancer_chance 0.0 produced no chaser")
			print("the roaming spawner makes both %s" % str(made.keys()))

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


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