private fun Duration.truncatedTo(unit: Duration): Duration = unit.multipliedBy(this.dividedBy(unit))

@Composable
fun CountDownTimer(
    goal: Instant = Instant.ofEpochSecond(Int.MAX_VALUE.toLong()),
    tick: Duration = Duration.ofSeconds(1L),
    clock: Clock = Clock.systemUTC(),
) {
    val remaining by flow {
        do {
            val remaining = Duration.between(clock.instant(), goal)
            var next = remaining.truncatedTo(tick)
            if (next >= remaining) next -= tick
            next = next.coerceAtLeast(Duration.ZERO)
            delay((remaining - next).toMillis())
            emit(next)
        } while (next > Duration.ZERO)
    }.collectAsState(Duration.between(clock.instant(), goal).coerceAtLeast(Duration.ZERO).truncatedTo(tick))
    Text(text = remaining.toString())
}

@IgnoredOnParcel
  val millisLeft = flow {
    while (true) {
      emit(calculateMillisLeft())
      delay(3)
    }
  }

calculateMillisLeft