public static List generateTimePrefixes()

in src/main/java/com/google/gcs/sdrs/util/PrefixGeneratorUtility.java [42:80]

• 26 lines of code
• 9 McCabe index (conditional complexity)

  public static List<String> generateTimePrefixes(
      String pattern, ZonedDateTime startTime, ZonedDateTime endTime) {

    if (endTime.isBefore(startTime)) {
      throw new IllegalArgumentException("endTime occurs before startTime; try swapping them.");
    }

    endTime = endTime.truncatedTo(ChronoUnit.HOURS);

    List<String> result = new ArrayList<>();

    // The general approach here is to work backwards from the endTime to the start time at the
    // largest interval granularity possible. This means that first prefixes on the same day as the
    // endTime will be generated, then month, then year.
    ZonedDateTime currentTime = ZonedDateTime.from(endTime);
    // Generate all prefixes on the current day
    while (currentTime.getHour() > 0 && currentTime.isAfter(startTime)) {
      currentTime = currentTime.minus(1, ChronoUnit.HOURS);
      result.add(formatPrefix(currentTime, pattern, DateTimeFormatter.ofPattern("yyyy/MM/dd/HH")));
    }
    // Generate all prefixes in the current month
    while (currentTime.getDayOfMonth() > 1 && currentTime.isAfter(startTime)) {
      currentTime = currentTime.minus(1, ChronoUnit.DAYS);
      result.add(formatPrefix(currentTime, pattern, DateTimeFormatter.ofPattern("yyyy/MM/dd")));
    }
    // Generate all prefixes in the current year
    while (currentTime.getMonthValue() > 1 && currentTime.isAfter(startTime)) {
      currentTime = currentTime.minus(1, ChronoUnit.MONTHS);
      result.add(formatPrefix(currentTime, pattern, DateTimeFormatter.ofPattern("yyyy/MM")));
    }
    // From here on only year prefixes will be added. This might include values older than the
    // provided startTime
    while (currentTime.isAfter(startTime)) {
      currentTime = currentTime.minus(1, ChronoUnit.YEARS);
      result.add(formatPrefix(currentTime, pattern, DateTimeFormatter.ofPattern("yyyy")));
    }

    return result;
  }