recyclerView.layoutManager = TimetableLayoutManager(columnWidth, heightPerMin) { position ->
  val period = periods[position]
  TimetableLayoutManager.PeriodInfo(period.startAt, period.endAt, period.stageNumber)
}

recyclerView.addItemDecoration(ProgramTimeLabelDecoration(context, periods, heightPerMin))
recyclerView.addItemDecoration(StageNameDecoration(context, periods, columnCount))

class ProgramTimeLabelDecoration(private val periods: List<Period>, ...) : TimeLabelDecoration(...) {

  private val formatter = DateTimeFormatter.ofPattern("HH:mm")

  override fun canDecorate(position: Int): Boolean = periods.getOrNull(position) is Program

  override fun getStartUnixMillis(position: Int): Long = periods.getOrNull(position)?.startAt ?: 0

  override fun formatUnixMillis(unixMillis: Long): String =
    LocalDateTime.ofEpochSecond(unixMillis / 1000, 0, ZoneOffset.UTC).format(formatter)
}

class StageNameDecoration(private val periods: List<Period>, ...) : ColumnNameDecoration(...) {

  override fun getColumnNumber(position: Int): Int {
    return periods.getOrNull(position)?.stageNumber ?: 0
  }

  override fun getColumnName(columnNumber: Int): String {
    return when (columnNumber) {
      0 -> "Melodic Hardcore"
      1 -> "Metalcore"
      2 -> "Hardcore"
      3 -> "Deathcore"
      else -> "Djent"
    }
  }
}