code: public static int parseDuration(String duration) {
          if (duration == null) {
              return 60 * 60 * 24 * 30;
          }
          Integer toAdd = null;
          if (days.matcher(duration).matches()) {
              Matcher matcher = days.matcher(duration);
              matcher.matches();
              toAdd = Integer.parseInt(matcher.group(1)) * (60 * 60) * 24;
          } else if (hours.matcher(duration).matches()) {
              Matcher matcher = hours.matcher(duration);
              matcher.matches();
              toAdd = Integer.parseInt(matcher.group(1)) * (60 * 60);
          } else if (minutes.matcher(duration).matches()) {
              Matcher matcher = minutes.matcher(duration);
              matcher.matches();
              toAdd = Integer.parseInt(matcher.group(1)) * (60);
          } else if (seconds.matcher(duration).matches()) {
              Matcher matcher = seconds.matcher(duration);
              matcher.matches();
              toAdd = Integer.parseInt(matcher.group(1));
          } else if ("forever".equals(duration)) {
              toAdd = -1;
          }
          if (toAdd == null) {
              throw new IllegalArgumentException("Invalid duration pattern : " + duration);
          }
          return toAdd;
      }
docs: Parse a duration
  
  @param duration 3h, 2mn, 7s
  @return The number of seconds