Java port of the "ms" npm library (on github: zeit/ms)

DateUtils.java

package com.swiss.pegma.middleware.core.utils;

import org.apache.commons.lang3.StringUtils;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class DateUtils {
    private static final Pattern READABLE_DURATION_PATTERN = Pattern.compile("([0-9]+)[\\s]*([a-zA-Z]+)");
    
    /**
     * Parses a human readable duration string in format {amount}{unit}.
     * This is adapted from the NPM "MS" library.
     *
     * @param durationString {amount}{unit}, eg. 20min
     * @return the duration in milliseconds
     * @params defaultDurationString fallback duration, if the durationString is empty or null
     * @see <a href="https://github.com/zeit/ms/">GitHub</a>
     */
    public static long parseHumanReadableDuration(String durationString, String defaultDurationString) {

        if (StringUtils.isBlank(durationString) && StringUtils.isBlank(defaultDurationString)) {
            throw new RuntimeException("Unable to parse empty duration, fallback string was also empty");
        }

        Matcher matcher = READABLE_DURATION_PATTERN.matcher(
            StringUtils.isBlank(durationString) ? defaultDurationString : durationString);

        if (!matcher.matches() || matcher.groupCount() < 2) {
            throw new RuntimeException("Unable to parse duration " + durationString);
        }
        final long time = Long.parseLong(matcher.group(1));
        String unit = matcher.group(2);

        long multiSec = 1000;
        long multiMin = multiSec * 60;
        long multiHour = multiMin * 60;
        long multiDay = multiHour * 24;
        long multiWeek = multiDay * 7;
        long multiYear = multiDay * 365;

        switch (unit) {
            case "years":
            case "year":
            case "yrs":
            case "yr":
            case "y":
                return time * multiYear;
            case "weeks":
            case "week":
            case "w":
                return time * multiWeek;
            case "days":
            case "day":
            case "d":
                return time * multiDay;
            case "hours":
            case "hour":
            case "hrs":
            case "hr":
            case "h":
                return time * multiHour;
            case "minutes":
            case "minute":
            case "mins":
            case "min":
            case "m":
                return time * multiMin;
            case "seconds":
            case "second":
            case "secs":
            case "sec":
            case "s":
                return time * multiSec;
            case "milliseconds":
            case "millisecond":
            case "msecs":
            case "msec":
            case "ms":
                return time;
            default:
                throw new RuntimeException("Unknown duration format of" +
                    (StringUtils.isBlank(durationString) ? defaultDurationString : durationString));
        }
    }
}