class_name StudioSimulationManager
extends Node
## Manages Play / Run / Stop simulation harness for ModBison Studio.
## Takes full state snapshot before play and restores on stop.

signal simulation_started(mode: String)
signal simulation_stopped

enum SimulationState { EDIT, PLAYING, PAUSED }

var state: SimulationState = SimulationState.EDIT
var _snapshot: Array[Dictionary] = []
var _spawned_avatar: Node = null
var _core: EditorCore = null
var _world_container: Node3D = null


func setup(core: EditorCore, world_container: Node3D = null) -> void:
	_core = core
	_world_container = world_container


func start_play(spawn_player: bool = true) -> void:
	if state == SimulationState.PLAYING:
		return

	# 1. Capture snapshot of all objects
	_capture_snapshot()

	state = SimulationState.PLAYING

	# 2. Spawn test avatar if requested
	if spawn_player and _world_container != null:
		_spawn_test_avatar()

	# 3. Activate moving objects
	for m in _get_moving_nodes():
		if m.has_method("start_motion"):
			m.start_motion()

	simulation_started.emit("play" if spawn_player else "run")


func pause_simulation() -> void:
	if state != SimulationState.PLAYING:
		return
	state = SimulationState.PAUSED
	for m in _get_moving_nodes():
		if m.has_method("stop_motion"):
			m.stop_motion()


func resume_simulation() -> void:
	if state != SimulationState.PAUSED:
		return
	state = SimulationState.PLAYING
	for m in _get_moving_nodes():
		if m.has_method("start_motion"):
			m.start_motion()


func stop_simulation() -> void:
	if state == SimulationState.EDIT:
		return

	# 1. Stop all moving objects
	for m in _get_moving_nodes():
		if m.has_method("stop_motion"):
			m.stop_motion()

	# 2. Despawn test avatar
	if _spawned_avatar != null and is_instance_valid(_spawned_avatar):
		_spawned_avatar.queue_free()
		_spawned_avatar = null

	# 3. Restore state snapshot
	_restore_snapshot()

	state = SimulationState.EDIT
	simulation_stopped.emit()


func _get_moving_nodes() -> Array:
	if is_inside_tree() and get_tree() != null:
		return get_tree().get_nodes_in_group("moving_objects")
	var main_loop = Engine.get_main_loop()
	if main_loop is SceneTree:
		return (main_loop as SceneTree).get_nodes_in_group("moving_objects")
	return []


func _capture_snapshot() -> void:
	_snapshot.clear()
	if _core == null or _core.model == null:
		return
	for obj in _core.model.payload.objects:
		_snapshot.append({
			"id": obj.id,
			"position": obj.position,
			"rotation": obj.rotation,
			"scale": obj.scale,
			"properties": obj.properties.duplicate(true)
		})


func _restore_snapshot() -> void:
	if _core == null or _core.model == null:
		return
	for snap in _snapshot:
		var obj = _core.model.find_object(snap["id"])
		if obj != null:
			obj.position = snap["position"]
			obj.rotation = snap["rotation"]
			obj.scale = snap["scale"]
			obj.properties = snap["properties"].duplicate(true)
	_snapshot.clear()


func _spawn_test_avatar() -> void:
	var player_scene = load("res://scenes/player.tscn")
	if player_scene != null:
		var p = player_scene.instantiate()
		p.name = "TestStudioPlayer"
		p.position = Vector3(0, 2, 0)
		_world_container.add_child(p)
		_spawned_avatar = p
	else:
		var p: CharacterBody3D = CharacterBody3D.new()
		p.name = "TestStudioPlayer"
		p.position = Vector3(0, 2, 0)
		_world_container.add_child(p)
		_spawned_avatar = p


func is_playing() -> bool:
	return state == SimulationState.PLAYING


func is_editing() -> bool:
	return state == SimulationState.EDIT