## Resource that wraps a DispatchQueue.
##
## Useful for sharing queues with multiple objects between scenes without resorting to Autoload.
##
## Apart from creation, all DispatchQueue public methods and signals are supported.
##
## If `thread_count == 0`, runs queue in synchronous mode.
## If `thread_count < 0`, creates `OS.get_processor_count()` Threads.
extends Resource
class_name DispatchQueueResource

signal all_tasks_finished()

@export var thread_count: int = -1: set = set_thread_count

var _dispatch_queue = DispatchQueue.new()


func _init(initial_thread_count: int = -1) -> void:
	_dispatch_queue.all_tasks_finished.connect(self._on_all_tasks_finished)
	set_thread_count(initial_thread_count)


func set_thread_count(value: int) -> void:
	if value < 0:
		value = OS.get_processor_count()
	thread_count = value
	if thread_count == 0:
		_dispatch_queue.shutdown()
	else:
		_dispatch_queue.create_concurrent(thread_count)
	emit_changed()


# DispatchQueue wrappers
func dispatch(callable: Callable, priority: int = 0) -> DispatchQueue.Task:
	return _dispatch_queue.dispatch(callable, priority)


func dispatch_group(task_list: Array[Callable], priority: int = 0) -> DispatchQueue.TaskGroup:
	return _dispatch_queue.dispatch_group(task_list, priority)


func is_threaded() -> bool:
	return _dispatch_queue.is_threaded()


func get_thread_count() -> int:
	return _dispatch_queue.get_thread_count()


func size() -> int:
	return _dispatch_queue.size()


func is_empty() -> bool:
	return _dispatch_queue.is_empty()


func clear() -> void:
	_dispatch_queue.clear()


func shutdown() -> void:
	_dispatch_queue.shutdown()


# Private functions
func _on_all_tasks_finished() -> void:
	all_tasks_finished.emit()