extends Node
##
## TimelineModule - keyframe timeline for objects and bones (Features 81-100).
##
## Backed by a real Godot Animation resource + AnimationPlayer, so playback,
## interpolation and looping use engine-native code (fast, cached). The module
## exposes a touch-friendly API: scrub(), add_keyframe(), play(), pause().
##

@export var duration: float = 5.0
@export var fps: int = 30

var _host: Node = null
var _player: AnimationPlayer = null
var _anim: Animation = null
var _playhead: float = 0.0
var _playing := false
var _key_count := 0


func _activate(host: Node) -> void:
	_host = host
	_ensure_player()
	print("[Timeline] activated (%.1fs @ %d fps)" % [duration, fps])


func _deactivate() -> void:
	_playing = false
	_player = null
	_anim = null
	_host = null


func _ensure_player() -> void:
	if _player != null and is_instance_valid(_player):
		return
	_anim = Animation.new()
	_anim.length = duration
	_anim.step = 1.0 / float(fps)
	_player = AnimationPlayer.new()
	_player.name = "TimelinePlayer"
	if _host != null:
		_host.add_child(_player)
	var lib := AnimationLibrary.new()
	lib.add_animation("main", _anim)
	_player.add_animation_library("", lib)
	_player.animation_finished.connect(_on_finished)


func _process(delta: float) -> void:
	if not _playing or _player == null:
		return
	_playhead = _player.current_animation_position
	StudioBus.timeline_playhead.emit(_playhead)


## --- Playback ---------------------------------------------------------------

func play(from: float = -1.0) -> void:
	_ensure_player()
	if from >= 0.0:
		_player.seek(from, true)
	_player.play("main")
	_playing = true
	StudioBus.playback_state_changed.emit(true)


func pause() -> void:
	if _player != null:
		_player.pause()
	_playing = false
	StudioBus.playback_state_changed.emit(false)


func stop() -> void:
	if _player != null:
		_player.stop()
	_playhead = 0.0
	_playing = false
	StudioBus.playback_state_changed.emit(false)


## Jump the playhead to `time` seconds (scrubbing).
func scrub(time: float) -> void:
	_ensure_player()
	time = clampf(time, 0.0, duration)
	_playhead = time
	_player.seek(time, true)
	StudioBus.timeline_playhead.emit(time)


func is_playing() -> bool:
	return _playing


func playhead() -> float:
	return _playhead


## --- Keyframes --------------------------------------------------------------

## Add a keyframe for a `property` (NodePath-style) on an object at `time`.
## For bones use property like "bones/Head:position" (Skeleton3D pose tracks).
func add_keyframe(target_node: Node3D, property: String, time: float, value: Variant) -> void:
	_ensure_player()
	time = clampf(time, 0.0, duration)
	var path := _player.get_path_to(target_node)
	if path == NodePath():
		push_warning("Timeline: target is not under the player root")
		return
	var track := _find_or_create_track(String(path), property, value)
	var key_idx := _anim.track_insert_key(track, time, value, 0.0)
	if key_idx >= 0:
		_key_count += 1
		StudioBus.keyframe_added.emit(String(path), property, time)
		StudioBus.scene_modified.emit()


func _find_or_create_track(node_path: String, property: String, value: Variant) -> int:
	var full := NodePath(node_path + ":" + property)
	for i in range(_anim.get_track_count()):
		if _anim.track_get_path(i) == full:
			return i
	var type := Animation.TYPE_VALUE
	if value is Transform3D:
		type = Animation.TYPE_VALUE
	_anim.add_track(type)
	var idx := _anim.get_track_count() - 1
	_anim.track_set_path(idx, full)
	if value is Vector3:
		_anim.track_set_interpolation_type(idx, Animation.INTERPOLATION_CUBIC)
	return idx


## Convenience: key every transform channel of a bone of a Skeleton3D.
## Godot stores bone poses as 3D transforms, so we key position/rotation/scale.
func add_bone_keyframe(skeleton: Skeleton3D, bone_name: String, time: float) -> void:
	if skeleton == null:
		return
	var bone_idx := skeleton.find_bone(bone_name)
	if bone_idx < 0:
		push_warning("Timeline: bone '%s' not found" % bone_name)
		return
	var skin_path := "%s:%s" % [_player.get_path_to(skeleton), bone_name]
	var pose := skeleton.get_bone_pose(bone_idx)
	add_keyframe(skeleton, "bones/" + bone_name + "/position", time, pose.origin)
	# Store rotation as quaternion for clean interpolation.
	add_keyframe(skeleton, "bones/" + bone_name + "/rotation", time, pose.basis.get_rotation_quaternion())
	add_keyframe(skeleton, "bones/" + bone_name + "/scale", time, pose.basis.get_scale())


func delete_keyframe(track: int, key: int) -> void:
	if track >= 0 and track < _anim.get_track_count():
		_anim.track_remove_key(track, key)
		_key_count = maxi(0, _key_count - 1)


func track_count() -> int:
	return _anim.get_track_count() if _anim != null else 0


func key_count() -> int:
	return _key_count


func set_duration(seconds: float) -> void:
	duration = maxf(0.1, seconds)
	_ensure_player()
	_anim.length = duration


func _on_finished() -> void:
	_playing = false
	StudioBus.playback_state_changed.emit(false)