@tool
class_name TimedMusicAnimationPlayer
extends AnimPlayerEditorCalls

## A animation player that tries to sync the music with the animation as best as it can.
##
## This is a animation player, that tries to sync up the music and animation as best as it can,
## in case they get desynced.[br]
## This can happen due to a lag, stuff loading in,
## or other stuff that blocks the main thread.[br][br]
## It first tries to sync them back up again by adjusting
## the [member AnimationPlayer.speed_scale] or [member AudioStreamPlayer.pitch_scale] property
## [i](depending on [member catch_up_behaviour])[/i].[br]
## However, if the difference between them is too big,
## it will just snap audio playback back to the animation, because the audio continues to
## run, even if the main thread is blocked.[br][br]
## [b]Note:[/b] Catching up happens before the audio get's snapped,[br]
## so [member max_error] is only effective, if the difference between audio and animation
## is bigger than the [member max_catchup_threshold],
## or lower than the [method AudioServer.get_output_latency].

enum CatchupBehaviour {
	NONE, ## Don't catch up slowsly.
	SPEED_SCALE_ANIMATION, ## Adjusts the [member AnimationPlayer.speed_scale] property when desynced.
	PITCH_SCALE_MUSIC ## Adjusts the [member AudioStreamPlayer.pitch_scale] property when desynced.
}

## The [AudioStreamPlayer], [AudioStreamPlayer2D]
## or [AudioStreamPlayer3D] the music should be played on.[br]
## [b]Should be set to the same player as defined in your animation.[/b]
@export_node_path("AudioStreamPlayer", "AudioStreamPlayer2D", "AudioStreamPlayer3D")
var audio_player: NodePath = ^"": set = set_audio_player
## The track-index in the animation,
## where the music is played from [i](should be of type [constant Animation.TYPE_AUDIO])[/i].
@export var music_anim_track_index: int = 0
# The offset from 0.0 seconds when the music starts in the animation.
#@export var music_anim_offset: float = 0.0
## @deprecated: Actually reduntant, because this should always happen if above [member max_catchup_threshold].
## The max difference audio and animation can have to each other,
## until the audio is snapped back to the animation.[br]
## However, [member catch_up_behaviour] takes priority, if this is set to value lower than that.
@export var max_error: float = 0.375 # 0.02175
@export_group("Catching up")
## Defines in what way we want to sync the audio and animation back up.
@export var catch_up_behaviour := CatchupBehaviour.SPEED_SCALE_ANIMATION
#@export var min_catchup_threshold: float = 0.0015
## Should be set to a value above- or equal to [member max_error].
@export var max_catchup_threshold: float = 0.375
@export_subgroup("Pitch Scale")
## The maximum pitch scale change the audio can be set to, when they are desynced.
@export var max_pitch_scale_difference: float = 1.01
## Helper variable in case you want to modify the [member AudioStreamPlayer.pitch_scale] property.
@export var custom_pitch_scale: float = 1.0
@export_subgroup("Speed Scale")
## The maximum speed scale change the animation can be set to, when they are desynced.
@export var max_speed_scale_difference: float = 1.15
## Helper variable in case you want to modify the [member AnimationPlayer.speed_scale] property.
@export var custom_speed_scale: float = 1.0

var _audio_player: Node
var _timer := Timer.new()
var _track_time: float = 0.0


func _ready() -> void:
	super()

	if not Engine.is_editor_hint():
		add_child(_timer)
		_timer.one_shot = false

		set_audio_player(audio_player)
		animation_started.connect(_anim_started)
		animation_finished.connect(_anim_finished)


func _process(delta: float) -> void:
	if Engine.is_editor_hint():
		super(delta)
		return

	if not active or not is_playing() or not is_instance_valid(_audio_player):
		return

	var latency: float = AudioServer.get_output_latency()
	var audio_position: float = _audio_player.get_playback_position()
	var anim_position: float = current_animation_position + AudioServer.get_time_since_last_mix()
	var difference: float = anim_position - (audio_position + _track_time)
	var abs_difference: float = absf(difference)

	SPrint.print_msgf("Audio-Position: %s\nAnim-Position: %s" % [audio_position, anim_position])
	SPrint.print_msgf("Audio-Anim Diff: %s" % difference)#[audio_position - anim_position])
	SPrint.print_msgf("ABS-Difference: %s" % abs_difference)
	SPrint.print_msgf("Anim-Speed-Scale: %s" % [speed_scale])
	SPrint.print_msgf("Audio-Pitch: %s\nLatency: %s" % [_audio_player.pitch_scale, latency])

	if (
		not catch_up_behaviour == CatchupBehaviour.NONE
		and abs_difference < max_catchup_threshold
		#and abs_difference > latency #min_catchup_threshold:
	):
		match catch_up_behaviour:
			CatchupBehaviour.SPEED_SCALE_ANIMATION:
				_sync_anim_speed_scale(difference, delta)
			CatchupBehaviour.PITCH_SCALE_MUSIC:
				_sync_music_pitch_scale(latency, difference, delta)
	elif abs_difference > max_error:
		#_audio_player.seek(difference)
		_audio_player.play(anim_position + _track_time + latency)
		SPrint.print_msg("Snapped Audio to: %s" % [_audio_player.get_playback_position()])
	else:
		_audio_player.pitch_scale = custom_pitch_scale
		speed_scale = custom_speed_scale


func set_audio_player(path: NodePath) -> void:
	audio_player = path

	var node: Node = get_node_or_null(path)
	_audio_player = node if Utils.is_node_audioplayer(node) else null


#func play_timed(
	#anim_name: StringName,
	#from_marker: StringName = &"",
	#end_marker: StringName = &"",
	#custom_blend: float = -1.0,
	#custom_speed: float = 1.0,
	#from_end: bool = false
#) -> void:
	#_anim_started(anim_name)
	#play_section_with_markers(anim_name, from_marker, end_marker, custom_blend, custom_speed, from_end)


func _sync_anim_speed_scale(difference: float, delta: float) -> void:
	var max_speed_scale: float = max_speed_scale_difference
	var min_speed_scale: float = custom_speed_scale + (custom_speed_scale - max_speed_scale)
	var speed: float = custom_speed_scale - difference

	speed = clampf(speed, min_speed_scale, max_speed_scale)

	if absf(difference) >= 0.05:
		speed = move_toward(speed_scale, speed, delta * 0.01)
	#else:
		#speed = lerp(speed_scale, speed, 1.0 - pow(0.5, delta)) #0.001

	speed_scale = speed#clampf(speed, min_speed_scale, max_speed_scale)


func _sync_music_pitch_scale(latency: float, difference: float, delta: float) -> void:
	var max_pitch_scale: float = max_pitch_scale_difference
	var min_pitch_scale: float = custom_pitch_scale + (custom_pitch_scale - max_pitch_scale)

	var pitch: float = custom_pitch_scale + difference + latency
	pitch = clampf(pitch, min_pitch_scale, max_pitch_scale)
	pitch = lerp(_audio_player.pitch_scale, pitch, 1.0 - pow(0.5, delta))

	_audio_player.pitch_scale = clampf(pitch, min_pitch_scale, max_pitch_scale)


func _anim_started(anim_name: StringName) -> void:
	if Engine.is_editor_hint():
		return

	var animation: Animation = get_animation(anim_name)
	animation.track_set_enabled(music_anim_track_index, false)
	_audio_player.stream = null

	_track_time = animation.track_get_key_time(music_anim_track_index, 0)
	var duration: float = _track_time - current_animation_position

	if duration > 0.0:
		_timer.start(duration)

		var _signals: Array[Signal] = await SignalGroup.await_signals(
			[_timer.timeout, animation_finished, animation_changed], 1
		)

		if not _signals.front() == _timer.timeout:
			return

	#var latency: float = AudioServer.get_output_latency() - AudioServer.get_time_to_next_mix()
	_audio_player.stream = animation.audio_track_get_key_stream(music_anim_track_index, 0)
	_audio_player.play(current_animation_position - _track_time)# - latency)


func _anim_finished(_anim_name: StringName) -> void:
	if Engine.is_editor_hint():
		return

	if is_instance_valid(_audio_player):
		_audio_player.stop()
		_audio_player.stream = null