spaceship/enemies/EnemySpawnerComponent.gd

class_name EnemySpawnerComponent
extends Node

# Continuously spawns another enemy type beside its host, at a fixed
# interval, capped at max_alive concurrently. The spawned enemies are
# added as children of the spawner's OWN PARENT - not the spawner itself -
# so killing the spawner never frees its already-spawned children (they
# are siblings, not descendants) and so a surface-hosted spawner keeps its
# spawns under the same host a `../Fleet`-style path assumption would miss
# (see #44's note on why that hazard exists for anything parented under a
# planet surface's PlanetSetupHost rather than directly under Main.tscn).

var capability_id: String = "spawner"

@export var spawn_interval: float = 4.0
@export var spawned_enemy_id: String = "chaser"
@export var max_alive: int = 6
@export var spawn_radius: float = 90.0

var spawn_timer: float = 0.0
var spawned: Array = []
# Resolved lazily via load() on first use rather than preload()d as a
# compile-time constant: when a definition's component_scenes chain leads
# BACK to Enemy.tscn while it is still mid-load (e.g. two different preset
# scenes of this same script both live on one definition, as the
# mothership's chaser/artillery spawners are), the preloaded constant can
# get permanently baked in as a broken, empty PackedScene - confirmed by
# ResourceLoader.has_cached() being true (a good copy exists) while the
# preloaded reference's own resource_path was empty. load() at first real
# use instead always resolves against whatever is actually in the cache
# by then.
var enemy_scene: PackedScene = null


func _ready() -> void:
	# Start counting down from a full interval rather than firing on the
	# very first tick: besides reading more naturally (a freshly-placed
	# spawner doesn't insta-spawn), this keeps two sibling spawners with
	# different intervals (e.g. the mothership's chaser/artillery presets)
	# from both landing their first attempt on the exact same physics
	# frame - which hit a transient PackedScene.instantiate() failure on
	# this engine build when it happened.
	spawn_timer = spawn_interval


func tick(delta: float) -> void:
	spawned = spawned.filter(func(node): return is_instance_valid(node))
	if spawned.size() >= max_alive:
		return

	spawn_timer -= delta
	if spawn_timer > 0.0:
		return
	spawn_timer = spawn_interval

	var fleet: Node2D = get_tree().get_first_node_in_group("player_fleet")
	if fleet == null or fleet.ships.is_empty():
		return

	var spawner: Node2D = get_parent()
	var host: Node = spawner.get_parent()
	if host == null:
		return

	var angle: float = randf() * TAU
	var offset: Vector2 = Vector2(cos(angle), sin(angle)) * spawn_radius

	if enemy_scene == null:
		enemy_scene = load("res://enemies/Enemy.tscn")
	var new_enemy: Node2D = enemy_scene.instantiate()
	new_enemy.enemy_id = spawned_enemy_id
	# spawner.position is already expressed in `host`'s local space, and
	# new_enemy is about to be added to that same `host` - unlike
	# EnemyRangedWeaponComponent's projectile, which reparents to root and
	# needs global_position, there is no space conversion needed here.
	new_enemy.position = spawner.position + offset
	host.add_child(new_enemy)
	spawned.append(new_enemy)