getCurrentPitchState.kt

fun getCurrentPitchState(pitchHz: Double): TunerState {
    val closestFrequency = getClosestFrequencyInAllNotes(pitchHz)
    val note = getNoteByFrequency(closestFrequency)

    val diff = if (closestFrequency > pitchHz) {
        abs(closestFrequency - pitchHz).unaryMinus()
    } else {
        abs(pitchHz - closestFrequency)
    }

    return when {
        diff.isInPermittedTolerance() -> TunerState.Tuned(note)
        diff < -0.5 -> TunerState.Down(note)
        else -> TunerState.Up(note)
    }
}