Position tracker for android media3 Player

PlayerPositionTracker.kt

private const val MIN_UPDATE_INTERVAL_MS: Long = 200
private const val MAX_UPDATE_INTERVAL_MS: Long = 1000

class PlayerPositionTracker {

	private val handlerUpdatePosition = Handler()
	private val runnableUpdatePosition = Runnable { updatePosition() }

	var player: Player? = null
		set(value) {
			field = value

			updatePlayerEventListenerRegistration()
			updatePosition()
		}

	var playerPositionListener: PlayerPositionListener? = null
		set(value) {
			field = value

			updatePlayerEventListenerRegistration()
			updatePosition()
		}

	private val playerEventListener = object : Player.Listener {
		override fun onEvents(player: Player, events: Player.Events) {
			if (events.containsAny(
					Player.EVENT_PLAYBACK_STATE_CHANGED,
					Player.EVENT_PLAY_WHEN_READY_CHANGED,
					Player.EVENT_IS_PLAYING_CHANGED,
					Player.EVENT_AVAILABLE_COMMANDS_CHANGED,
					Player.EVENT_POSITION_DISCONTINUITY,
					Player.EVENT_TIMELINE_CHANGED,
					Player.EVENT_AVAILABLE_COMMANDS_CHANGED
				)
			) updatePosition(player)
		}
	}

	private fun updatePlayerEventListenerRegistration() = player?.let {
		if (playerPositionListener != null) it.addListener(playerEventListener)
		else it.removeListener(playerEventListener)
	}

	private fun updatePosition(player: Player? = this.player) {
		handlerUpdatePosition.removeCallbacks(runnableUpdatePosition)
		if (player == null) return

		val position = player.currentPosition
		playerPositionListener?.onPlayerPositionChanged(position)
		val playbackState = player.playbackState
		if (player.isPlaying)
			handlerUpdatePosition.postDelayed(
				runnableUpdatePosition,
				player.playbackParameters.speed.let { playbackSpeed ->
					if (playbackSpeed > 0) ((1000 - position % 1000) / playbackSpeed).toLong()
					else MAX_UPDATE_INTERVAL_MS
				}.coerceIn(MIN_UPDATE_INTERVAL_MS, MAX_UPDATE_INTERVAL_MS)
			)
		else if (playbackState != Player.STATE_ENDED && playbackState != Player.STATE_IDLE)
			handlerUpdatePosition.postDelayed(runnableUpdatePosition, MAX_UPDATE_INTERVAL_MS)
	}

	fun release() {
		handlerUpdatePosition.removeCallbacks(runnableUpdatePosition)
		player?.removeListener(playerEventListener)
		player = null
		playerPositionListener = null
	}
}

fun interface PlayerPositionListener {
	fun onPlayerPositionChanged(position: Long)
}