content: /*
   * Copyright 2024-2025 the original author or authors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.cloud.scheduling.schedulerx.util;
  
  import java.text.ParseException;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Locale;
  import java.util.Map;
  import java.util.SortedSet;
  import java.util.StringTokenizer;
  import java.util.TimeZone;
  import java.util.TreeSet;
  
  import org.springframework.util.Assert;
  
  /**
   * @author yaohui
   */
  public final class CronExpression {
  
  	protected static final int SECOND = 0;
  	protected static final int MINUTE = 1;
  	protected static final int HOUR = 2;
  	protected static final int DAY_OF_MONTH = 3;
  	protected static final int MONTH = 4;
  	protected static final int DAY_OF_WEEK = 5;
  	protected static final int YEAR = 6;
  	protected static final int ALL_SPEC_INT = 99; // '*'
  	protected static final int NO_SPEC_INT = 98; // '?'
  	protected static final Integer ALL_SPEC = ALL_SPEC_INT;
  	protected static final Integer NO_SPEC = NO_SPEC_INT;
  
  	protected static final Map<String, Integer> monthMap = new HashMap<>(20);
  	protected static final Map<String, Integer> dayMap = new HashMap<>(60);
  
  	static {
  		monthMap.put("JAN", 0);
  		monthMap.put("FEB", 1);
  		monthMap.put("MAR", 2);
  		monthMap.put("APR", 3);
  		monthMap.put("MAY", 4);
  		monthMap.put("JUN", 5);
  		monthMap.put("JUL", 6);
  		monthMap.put("AUG", 7);
  		monthMap.put("SEP", 8);
  		monthMap.put("OCT", 9);
  		monthMap.put("NOV", 10);
  		monthMap.put("DEC", 11);
  
  		dayMap.put("SUN", 1);
  		dayMap.put("MON", 2);
  		dayMap.put("TUE", 3);
  		dayMap.put("WED", 4);
  		dayMap.put("THU", 5);
  		dayMap.put("FRI", 6);
  		dayMap.put("SAT", 7);
  	}
  
  	private final String cronExpression;
  	private TimeZone timeZone = null;
  	protected transient TreeSet<Integer> seconds;
  	protected transient TreeSet<Integer> minutes;
  	protected transient TreeSet<Integer> hours;
  	protected transient TreeSet<Integer> daysOfMonth;
  	protected transient TreeSet<Integer> months;
  	protected transient TreeSet<Integer> daysOfWeek;
  	protected transient TreeSet<Integer> years;
  
  	protected transient boolean lastdayOfWeek = false;
  	protected transient int nthdayOfWeek = 0;
  	protected transient boolean lastdayOfMonth = false;
  	protected transient boolean nearestWeekday = false;
  	protected transient int lastdayOffset = 0;
  	protected transient boolean expressionParsed = false;
  
  	/**
  	 * MAX_YEAR.
  	 */
  	public static final int MAX_YEAR = Calendar.getInstance().get(Calendar.YEAR) + 100;
  
  	/**
  	 * MIN_CAL.
  	 */
  	public static final Calendar MIN_CAL = Calendar.getInstance();
  
  	static {
  		MIN_CAL.set(1970, 0, 1);
  	}
  
  	/**
  	 * MIN_DATE.
  	 */
  	public static final Date MIN_DATE = MIN_CAL.getTime();
  
  	/**
  	 * Constructs a new <CODE>CronExpression</CODE> based on the specified
  	 * parameter.
  	 *
  	 * @param cronExpression String representation of the cron expression the
  	 *                       new object should represent
  	 * @throws ParseException if the string expression cannot be parsed into a valid
  	 *                        <CODE>CronExpression</CODE>
  	 */
  	public CronExpression(final String cronExpression) throws ParseException {
  		if (cronExpression == null) {
  			throw new IllegalArgumentException("cronExpression cannot be null");
  		}
  
  		this.cronExpression = cronExpression.toUpperCase(Locale.US);
  
  		buildExpression(this.cronExpression);
  	}
  
  	/**
  	 * Indicates whether the given date satisfies the cron expression. Note that
  	 * milliseconds are ignored, so two Dates falling on different milliseconds
  	 * of the same second will always have the same result here.
  	 *
  	 * @param date the date to evaluate
  	 * @return a boolean indicating whether the given date satisfies the cron
  	 * expression.
  	 */
  	public boolean isSatisfiedBy(final Date date) {
  		final Calendar testDateCal = Calendar.getInstance(getTimeZone());
  		testDateCal.setTime(date);
  		testDateCal.set(Calendar.MILLISECOND, 0);
  		final Date originalDate = testDateCal.getTime();
  
  		testDateCal.add(Calendar.SECOND, -1);
  
  		final Date timeAfter = getTimeAfter(testDateCal.getTime());
  
  		return ((timeAfter != null) && (timeAfter.equals(originalDate)));
  	}
  
  	/**
  	 * Returns the next date/time <I>after</I> the given date/time which
  	 * satisfies the cron expression.
  	 *
  	 * @param date the date/time at which to begin the search for the next valid
  	 *             date/time
  	 * @return the next valid date/time.
  	 */
  	public Date getNextValidTimeAfter(final Date date) {
  		return getTimeAfter(date);
  	}
  
  	/**
  	 * Returns the next date/time <I>after</I> the given date/time which does
  	 * <I>not</I> satisfy the expression.
  	 *
  	 * @param date the date/time at which to begin the search for the next
  	 *             invalid date/time
  	 * @return the next valid date/time.
  	 */
  	public Date getNextInvalidTimeAfter(final Date date) {
  		long difference = 1000;
  
  		//move back to the nearest second so differences will be accurate
  		final Calendar adjustCal = Calendar.getInstance(getTimeZone());
  		adjustCal.setTime(date);
  		adjustCal.set(Calendar.MILLISECOND, 0);
  		Date lastDate = adjustCal.getTime();
  
  		Date newDate;
  
  		//FUTURE_TODO: (QUARTZ-481) IMPROVE THIS! The following is a BAD solution to this problem. Performance will be very bad here, depending on the cron expression. It is, however A solution.
  
  		//keep getting the next included time until it's farther than one second
  		// apart. At that point, lastDate is the last valid fire time. We return
  		// the second immediately following it.
  		while (difference == 1000) {
  			newDate = getTimeAfter(lastDate);
  			if (newDate == null) {
  				break;
  			}
  
  			difference = newDate.getTime() - lastDate.getTime();
  
  			if (difference == 1000) {
  				lastDate = newDate;
  			}
  		}
  
  		return new Date(lastDate.getTime() + 1000);
  	}
  
  	/**
  	 * Returns the time zone for which this <code>CronExpression</code>
  	 * will be resolved.
  	 *
  	 * @return the time zone.
  	 */
  	public TimeZone getTimeZone() {
  		if (timeZone == null) {
  			timeZone = TimeZone.getDefault();
  		}
  
  		return timeZone;
  	}
  
  	public void setTimeZone(final TimeZone timeZone) {
  		this.timeZone = timeZone;
  	}
  
  	@Override
  	public String toString() {
  		return cronExpression;
  	}
  
  	/**
  	 * check cron expression is valid or not.
  	 *
  	 * @param cronExpression cron expression
  	 * @return return{@code true}if Cron expression is valid，otherwise return{@code false}.
  	 */
  	public static boolean isValidExpression(final String cronExpression) {
  		try {
  			new CronExpression(cronExpression);
  		}
  		catch (final ParseException pe) {
  			return false;
  		}
  		return true;
  	}
  
  	public static void validateExpression(final String cronExpression) throws ParseException {
  		new CronExpression(cronExpression);
  	}
  
  	protected void buildExpression(final String expression) throws ParseException {
  		expressionParsed = true;
  		try {
  			if (seconds == null) {
  				seconds = new TreeSet<>();
  			}
  			if (minutes == null) {
  				minutes = new TreeSet<>();
  			}
  			if (hours == null) {
  				hours = new TreeSet<>();
  			}
  			if (daysOfMonth == null) {
  				daysOfMonth = new TreeSet<>();
  			}
  			if (months == null) {
  				months = new TreeSet<>();
  			}
  			if (daysOfWeek == null) {
  				daysOfWeek = new TreeSet<>();
  			}
  			if (years == null) {
  				years = new TreeSet<>();
  			}
  
  			int exprOn = SECOND;
  
  			final StringTokenizer exprsTok = new StringTokenizer(expression, " \t",
  					false);
  
  			while (exprsTok.hasMoreTokens() && exprOn <= YEAR) {
  				final String expr = exprsTok.nextToken().trim();
  
  				// throw an exception if L is used with other days of the month
  				if (exprOn == DAY_OF_MONTH && expr.indexOf('L') != -1 && expr.length() > 1 && expr.contains(",")) {
  					throw new ParseException("Support for specifying 'L' and 'LW' with other days of the month is not implemented", -1);
  				}
  				// throw an exception if L is used with other days of the week
  				if (exprOn == DAY_OF_WEEK && expr.indexOf('L') != -1 && expr.length() > 1 && expr.contains(",")) {
  					throw new ParseException("Support for specifying 'L' with other days of the week is not implemented", -1);
  				}
  				if (exprOn == DAY_OF_WEEK && expr.indexOf('#') != -1 && expr.indexOf('#', expr.indexOf('#') + 1) != -1) {
  					throw new ParseException("Support for specifying multiple \"nth\" days is not implemented.", -1);
  				}
  
  				final StringTokenizer vTok = new StringTokenizer(expr, ",");
  				while (vTok.hasMoreTokens()) {
  					final String v = vTok.nextToken();
  					storeExpressionVals(0, v, exprOn);
  				}
  
  				exprOn++;
  			}
  
  			if (exprOn <= DAY_OF_WEEK) {
  				throw new ParseException("Unexpected end of expression.",
  						expression.length());
  			}
  
  			if (exprOn <= YEAR) {
  				storeExpressionVals(0, "*", YEAR);
  			}
  
  			final TreeSet<Integer> dow = getSet(DAY_OF_WEEK);
  			final TreeSet<Integer> dom = getSet(DAY_OF_MONTH);
  
  			// Copying the logic from the UnsupportedOperationException below
  			final boolean dayOfMSpec = !dom.contains(NO_SPEC);
  			final boolean dayOfWSpec = !dow.contains(NO_SPEC);
  
  			if (!dayOfMSpec || dayOfWSpec) {
  				if (!dayOfWSpec || dayOfMSpec) {
  					throw new ParseException(
  							"Support for specifying both a day-of-week AND a day-of-month parameter is not implemented.", 0);
  				}
  			}
  		}
  		catch (final ParseException pe) {
  			throw pe;
  		}
  		catch (final Exception e) {
  			throw new ParseException("Illegal cron expression format ("
  					+ e.toString() + ")", 0);
  		}
  	}
  
  	protected int storeExpressionVals(final int pos, final String s, final int type)
  			throws ParseException {
  
  		int incr = 0;
  		int i = skipWhiteSpace(pos, s);
  		if (i >= s.length()) {
  			return i;
  		}
  		char c = s.charAt(i);
  		if ((c >= 'A') && (c <= 'Z') && (!s.equals("L")) && (!s.equals("LW")) && (!s.matches("^L-[0-9]*[W]?"))) {
  			String sub = s.substring(i, i + 3);
  			int sval = -1;
  			int eval = -1;
  			if (type == MONTH) {
  				sval = getMonthNumber(sub) + 1;
  				if (sval <= 0) {
  					throw new ParseException("Invalid Month value: '" + sub + "'", i);
  				}
  				if (s.length() > i + 3 && (s.charAt(i + 3) == '-')) {
  					i += 4;
  					sub = s.substring(i, i + 3);
  					eval = getMonthNumber(sub) + 1;
  					Assert.isTrue(eval > 0, "Invalid Month value: '" + sub + "'");
  				}
  			}
  			else if (type == DAY_OF_WEEK) {
  				sval = getDayOfWeekNumber(sub);
  				if (sval < 0) {
  					throw new ParseException("Invalid Day-of-Week value: '"
  							+ sub + "'", i);
  				}
  				if (s.length() > i + 3) {
  					c = s.charAt(i + 3);
  					if (c == '-') {
  						i += 4;
  						sub = s.substring(i, i + 3);
  						eval = getDayOfWeekNumber(sub);
  						Assert.isTrue(eval >= 0, "Invalid Day-of-Week value: '" + sub + "'");
  					}
  					else if (c == '#') {
  						i += 4;
  						nthdayOfWeek = Integer.parseInt(s.substring(i));
  						Assert.isTrue(nthdayOfWeek > 0 && nthdayOfWeek < 6, "A numeric value between 1 and 5 must follow the '#' option");
  					}
  					else if (c == 'L') {
  						lastdayOfWeek = true;
  						i++;
  					}
  				}
  			}
  			else {
  				throw new ParseException(
  						"Illegal characters for this position: '" + sub + "'",
  						i);
  			}
  			if (eval != -1) {
  				incr = 1;
  			}
  			addToSet(sval, eval, incr, type);
  			return (i + 3);
  		}
  
  		if (c == '?') {
  			i++;
  			if ((i + 1) < s.length()
  					&& (s.charAt(i) != ' ' && s.charAt(i + 1) != '\t')) {
  				throw new ParseException("Illegal character after '?': "
  						+ s.charAt(i), i);
  			}
  			if (type != DAY_OF_WEEK && type != DAY_OF_MONTH) {
  				throw new ParseException(
  						"'?' can only be specfied for Day-of-Month or Day-of-Week.",
  						i);
  			}
  			if (type == DAY_OF_WEEK && !lastdayOfMonth) {
  				final int val = daysOfMonth.last();
  				if (val == NO_SPEC_INT) {
  					throw new ParseException(
  							"'?' can only be specfied for Day-of-Month -OR- Day-of-Week.",
  							i);
  				}
  			}
  
  			addToSet(NO_SPEC_INT, -1, 0, type);
  			return i;
  		}
  
  		if (c == '*' || c == '/') {
  			if (c == '*' && (i + 1) >= s.length()) {
  				addToSet(ALL_SPEC_INT, -1, incr, type);
  				return i + 1;
  			}
  			else if (c == '/'
  					&& ((i + 1) >= s.length() || s.charAt(i + 1) == ' ' || s
  					.charAt(i + 1) == '\t')) {
  				throw new ParseException("'/' must be followed by an integer.", i);
  			}
  			else if (c == '*') {
  				i++;
  			}
  			c = s.charAt(i);
  			if (c == '/') { // is an increment specified?
  				i++;
  				if (i >= s.length()) {
  					throw new ParseException("Unexpected end of string.", i);
  				}
  
  				incr = getNumericValue(s, i);
  
  				i++;
  				if (incr > 10) {
  					i++;
  				}
  				if (incr > 59 && (type == SECOND || type == MINUTE)) {
  					throw new ParseException("Increment > 60 : " + incr, i);
  				}
  				else if (incr > 23 && (type == HOUR)) {
  					throw new ParseException("Increment > 24 : " + incr, i);
  				}
  				else if (incr > 31 && (type == DAY_OF_MONTH)) {
  					throw new ParseException("Increment > 31 : " + incr, i);
  				}
  				else if (incr > 7 && (type == DAY_OF_WEEK)) {
  					throw new ParseException("Increment > 7 : " + incr, i);
  				}
  				else if (incr > 12 && (type == MONTH)) {
  					throw new ParseException("Increment > 12 : " + incr, i);
  				}
  			}
  			else {
  				incr = 1;
  			}
  
  			addToSet(ALL_SPEC_INT, -1, incr, type);
  			return i;
  		}
  		else if (c == 'L') {
  			i++;
  			if (type == DAY_OF_MONTH) {
  				lastdayOfMonth = true;
  			}
  			if (type == DAY_OF_WEEK) {
  				addToSet(7, 7, 0, type);
  			}
  			if (type == DAY_OF_MONTH && s.length() > i) {
  				c = s.charAt(i);
  				if (c == '-') {
  					final ValueSet vs = getValue(0, s, i + 1);
  					lastdayOffset = vs.value;
  					if (lastdayOffset > 30) {
  						throw new ParseException("Offset from last day must be <= 30", i + 1);
  					}
  					i = vs.pos;
  				}
  				if (s.length() > i) {
  					c = s.charAt(i);
  					if (c == 'W') {
  						nearestWeekday = true;
  						i++;
  					}
  				}
  			}
  			return i;
  		}
  		else if (c >= '0' && c <= '9') {
  			int val = Integer.parseInt(String.valueOf(c));
  			i++;
  			if (i >= s.length()) {
  				addToSet(val, -1, -1, type);
  			}
  			else {
  				c = s.charAt(i);
  				if (c >= '0' && c <= '9') {
  					final ValueSet vs = getValue(val, s, i);
  					val = vs.value;
  					i = vs.pos;
  				}
  				i = checkNext(i, s, val, type);
  				return i;
  			}
  		}
  		else {
  			throw new ParseException("Unexpected character: " + c, i);
  		}
  
  		return i;
  	}
  
  	protected int checkNext(final int pos, final String s, final int val, final int type)
  			throws ParseException {
  
  		int end = -1;
  		int i = pos;
  
  		if (i >= s.length()) {
  			addToSet(val, end, -1, type);
  			return i;
  		}
  
  		char c = s.charAt(pos);
  
  		if (c == 'L') {
  			if (type == DAY_OF_WEEK) {
  				if (val < 1 || val > 7) {
  					throw new ParseException("Day-of-Week values must be between 1 and 7", -1);
  				}
  				lastdayOfWeek = true;
  			}
  			else {
  				throw new ParseException("'L' option is not valid here. (pos=" + i + ")", i);
  			}
  			final TreeSet<Integer> set = getSet(type);
  			set.add(val);
  			i++;
  			return i;
  		}
  
  		if (c == 'W') {
  			if (type == DAY_OF_MONTH) {
  				nearestWeekday = true;
  			}
  			else {
  				throw new ParseException("'W' option is not valid here. (pos=" + i + ")", i);
  			}
  			if (val > 31) {
  				throw new ParseException("The 'W' option does not make sense with values larger than 31 (max number of days in a month)", i);
  			}
  			final TreeSet<Integer> set = getSet(type);
  			set.add(val);
  			i++;
  			return i;
  		}
  
  		if (c == '#') {
  			if (type != DAY_OF_WEEK) {
  				throw new ParseException("'#' option is not valid here. (pos=" + i + ")", i);
  			}
  			i++;
  			try {
  				nthdayOfWeek = Integer.parseInt(s.substring(i));
  				if (nthdayOfWeek < 1 || nthdayOfWeek > 5) {
  					throw new Exception();
  				}
  			}
  			catch (final Exception e) {
  				throw new ParseException(
  						"A numeric value between 1 and 5 must follow the '#' option",
  						i);
  			}
  
  			final TreeSet<Integer> set = getSet(type);
  			set.add(val);
  			i++;
  			return i;
  		}
  
  		if (c == '-') {
  			i++;
  			c = s.charAt(i);
  			final int v = Integer.parseInt(String.valueOf(c));
  			end = v;
  			i++;
  			if (i >= s.length()) {
  				addToSet(val, end, 1, type);
  				return i;
  			}
  			c = s.charAt(i);
  			if (c >= '0' && c <= '9') {
  				final ValueSet vs = getValue(v, s, i);
  				end = vs.value;
  				i = vs.pos;
  			}
  			if (i < s.length() && (s.charAt(i) == '/')) {
  				i++;
  				c = s.charAt(i);
  				final int v2 = Integer.parseInt(String.valueOf(c));
  				i++;
  				if (i >= s.length()) {
  					addToSet(val, end, v2, type);
  					return i;
  				}
  				c = s.charAt(i);
  				if (c >= '0' && c <= '9') {
  					final ValueSet vs = getValue(v2, s, i);
  					final int v3 = vs.value;
  					addToSet(val, end, v3, type);
  					i = vs.pos;
  					return i;
  				}
  				else {
  					addToSet(val, end, v2, type);
  					return i;
  				}
  			}
  			else {
  				addToSet(val, end, 1, type);
  				return i;
  			}
  		}
  
  		if (c == '/') {
  			i++;
  			c = s.charAt(i);
  			final int v2 = Integer.parseInt(String.valueOf(c));
  			i++;
  			if (i >= s.length()) {
  				addToSet(val, end, v2, type);
  				return i;
  			}
  			c = s.charAt(i);
  			if (c >= '0' && c <= '9') {
  				final ValueSet vs = getValue(v2, s, i);
  				final int v3 = vs.value;
  				addToSet(val, end, v3, type);
  				i = vs.pos;
  				return i;
  			}
  			else {
  				throw new ParseException("Unexpected character '" + c + "' after '/'", i);
  			}
  		}
  
  		addToSet(val, end, 0, type);
  		i++;
  		return i;
  	}
  
  	public String getCronExpression() {
  		return cronExpression;
  	}
  
  	public String getExpressionSummary() {
  		final StringBuilder buf = new StringBuilder();
  
  		buf.append("seconds: ");
  		buf.append(getExpressionSetSummary(seconds));
  		buf.append("\n");
  		buf.append("minutes: ");
  		buf.append(getExpressionSetSummary(minutes));
  		buf.append("\n");
  		buf.append("hours: ");
  		buf.append(getExpressionSetSummary(hours));
  		buf.append("\n");
  		buf.append("daysOfMonth: ");
  		buf.append(getExpressionSetSummary(daysOfMonth));
  		buf.append("\n");
  		buf.append("months: ");
  		buf.append(getExpressionSetSummary(months));
  		buf.append("\n");
  		buf.append("daysOfWeek: ");
  		buf.append(getExpressionSetSummary(daysOfWeek));
  		buf.append("\n");
  		buf.append("lastdayOfWeek: ");
  		buf.append(lastdayOfWeek);
  		buf.append("\n");
  		buf.append("nearestWeekday: ");
  		buf.append(nearestWeekday);
  		buf.append("\n");
  		buf.append("NthDayOfWeek: ");
  		buf.append(nthdayOfWeek);
  		buf.append("\n");
  		buf.append("lastdayOfMonth: ");
  		buf.append(lastdayOfMonth);
  		buf.append("\n");
  		buf.append("years: ");
  		buf.append(getExpressionSetSummary(years));
  		buf.append("\n");
  
  		return buf.toString();
  	}
  
  	protected String getExpressionSetSummary(final java.util.Set<Integer> set) {
  
  		if (set.contains(NO_SPEC)) {
  			return "?";
  		}
  		if (set.contains(ALL_SPEC)) {
  			return "*";
  		}
  
  		final StringBuilder buf = new StringBuilder();
  
  		final Iterator<Integer> itr = set.iterator();
  		boolean first = true;
  		while (itr.hasNext()) {
  			final Integer iVal = itr.next();
  			final String val = iVal.toString();
  			if (!first) {
  				buf.append(",");
  			}
  			buf.append(val);
  			first = false;
  		}
  
  		return buf.toString();
  	}
  
  	protected String getExpressionSetSummary(final java.util.ArrayList<Integer> list) {
  
  		if (list.contains(NO_SPEC)) {
  			return "?";
  		}
  		if (list.contains(ALL_SPEC)) {
  			return "*";
  		}
  
  		final StringBuilder buf = new StringBuilder();
  
  		final Iterator<Integer> itr = list.iterator();
  		boolean first = true;
  		while (itr.hasNext()) {
  			final Integer iVal = itr.next();
  			final String val = iVal.toString();
  			if (!first) {
  				buf.append(",");
  			}
  			buf.append(val);
  			first = false;
  		}
  
  		return buf.toString();
  	}
  
  	protected int skipWhiteSpace(int i, final String s) {
  		for (; i < s.length() && (s.charAt(i) == ' ' || s.charAt(i) == '\t'); i++) {
  			// empty
  		}
  
  		return i;
  	}
  
  	protected int findNextWhiteSpace(int i, final String s) {
  		for (; i < s.length() && (s.charAt(i) != ' ' || s.charAt(i) != '\t'); i++) {
  			// empty
  		}
  
  		return i;
  	}
  
  	protected void addToSet(final int val, final int end, int incr, final int type)
  			throws ParseException {
  
  		final TreeSet<Integer> set = getSet(type);
  
  		if (type == SECOND || type == MINUTE) {
  			if ((val < 0 || val > 59 || end > 59) && (val != ALL_SPEC_INT)) {
  				throw new ParseException(
  						"Minute and Second values must be between 0 and 59",
  						-1);
  			}
  		}
  		else if (type == HOUR) {
  			if ((val < 0 || val > 23 || end > 23) && (val != ALL_SPEC_INT)) {
  				throw new ParseException(
  						"Hour values must be between 0 and 23", -1);
  			}
  		}
  		else if (type == DAY_OF_MONTH) {
  			if ((val < 1 || val > 31 || end > 31) && (val != ALL_SPEC_INT)
  					&& (val != NO_SPEC_INT)) {
  				throw new ParseException(
  						"Day of month values must be between 1 and 31", -1);
  			}
  		}
  		else if (type == MONTH) {
  			if ((val < 1 || val > 12 || end > 12) && (val != ALL_SPEC_INT)) {
  				throw new ParseException(
  						"Month values must be between 1 and 12", -1);
  			}
  		}
  		else if (type == DAY_OF_WEEK) {
  			if ((val == 0 || val > 7 || end > 7) && (val != ALL_SPEC_INT)
  					&& (val != NO_SPEC_INT)) {
  				throw new ParseException(
  						"Day-of-Week values must be between 1 and 7", -1);
  			}
  		}
  
  		if ((incr == 0 || incr == -1) && val != ALL_SPEC_INT) {
  			if (val != -1) {
  				set.add(val);
  			}
  			else {
  				set.add(NO_SPEC);
  			}
  
  			return;
  		}
  
  		int startAt = val;
  		int stopAt = end;
  
  		if (val == ALL_SPEC_INT && incr <= 0) {
  			incr = 1;
  			set.add(ALL_SPEC); // put in a marker, but also fill values
  		}
  
  		if (type == SECOND || type == MINUTE) {
  			if (stopAt == -1) {
  				stopAt = 59;
  			}
  			if (startAt == -1 || startAt == ALL_SPEC_INT) {
  				startAt = 0;
  			}
  		}
  		else if (type == HOUR) {
  			if (stopAt == -1) {
  				stopAt = 23;
  			}
  			if (startAt == -1 || startAt == ALL_SPEC_INT) {
  				startAt = 0;
  			}
  		}
  		else if (type == DAY_OF_MONTH) {
  			if (stopAt == -1) {
  				stopAt = 31;
  			}
  			if (startAt == -1 || startAt == ALL_SPEC_INT) {
  				startAt = 1;
  			}
  		}
  		else if (type == MONTH) {
  			if (stopAt == -1) {
  				stopAt = 12;
  			}
  			if (startAt == -1 || startAt == ALL_SPEC_INT) {
  				startAt = 1;
  			}
  		}
  		else if (type == DAY_OF_WEEK) {
  			if (stopAt == -1) {
  				stopAt = 7;
  			}
  			if (startAt == -1 || startAt == ALL_SPEC_INT) {
  				startAt = 1;
  			}
  		}
  		else if (type == YEAR) {
  			if (stopAt == -1) {
  				stopAt = MAX_YEAR;
  			}
  			if (startAt == -1 || startAt == ALL_SPEC_INT) {
  				startAt = 1970;
  			}
  		}
  
  		// if the end of the range is before the start, then we need to overflow into
  		// the next day, month etc. This is done by adding the maximum amount for that
  		// type, and using modulus max to determine the value being added.
  		int max = -1;
  		if (stopAt < startAt) {
  			switch (type) {
  				case SECOND:
  					max = 60;
  					break;
  				case MINUTE:
  					max = 60;
  					break;
  				case HOUR:
  					max = 24;
  					break;
  				case MONTH:
  					max = 12;
  					break;
  				case DAY_OF_WEEK:
  					max = 7;
  					break;
  				case DAY_OF_MONTH:
  					max = 31;
  					break;
  				case YEAR:
  					throw new IllegalArgumentException("Start year must be less than stop year");
  				default:
  					throw new IllegalArgumentException("Unexpected type encountered");
  			}
  			stopAt += max;
  		}
  
  		for (int i = startAt; i <= stopAt; i += incr) {
  			if (max == -1) {
  				// ie: there's no max to overflow over
  				set.add(i);
  			}
  			else {
  				// take the modulus to get the real value
  				int i2 = i % max;
  
  				// 1-indexed ranges should not include 0, and should include their max
  				if (i2 == 0 && (type == MONTH || type == DAY_OF_WEEK || type == DAY_OF_MONTH)) {
  					i2 = max;
  				}
  
  				set.add(i2);
  			}
  		}
  	}
  
  	TreeSet<Integer> getSet(final int type) throws ParseException {
  		switch (type) {
  			case SECOND:
  				return seconds;
  			case MINUTE:
  				return minutes;
  			case HOUR:
  				return hours;
  			case DAY_OF_MONTH:
  				return daysOfMonth;
  			case MONTH:
  				return months;
  			case DAY_OF_WEEK:
  				return daysOfWeek;
  			case YEAR:
  				return years;
  			default:
  				throw new ParseException("Invalid type value: '" + type + "'", -1);
  		}
  	}
  
  	protected ValueSet getValue(final int v, final String s, int i) {
  		char c = s.charAt(i);
  		final StringBuilder s1 = new StringBuilder(String.valueOf(v));
  		while (c >= '0' && c <= '9') {
  			s1.append(c);
  			i++;
  			if (i >= s.length()) {
  				break;
  			}
  			c = s.charAt(i);
  		}
  		final ValueSet val = new ValueSet();
  
  		val.pos = (i < s.length()) ? i : i + 1;
  		val.value = Integer.parseInt(s1.toString());
  		return val;
  	}
  
  	protected int getNumericValue(final String s, final int i) {
  		final int endOfVal = findNextWhiteSpace(i, s);
  		final String val = s.substring(i, endOfVal);
  		return Integer.parseInt(val);
  	}
  
  	protected int getMonthNumber(final String s) {
  		final Integer integer = monthMap.get(s);
  
  		if (integer == null) {
  			return -1;
  		}
  
  		return integer;
  	}
  
  	protected int getDayOfWeekNumber(final String s) {
  		final Integer integer = dayMap.get(s);
  
  		if (integer == null) {
  			return -1;
  		}
  
  		return integer;
  	}
  
  	public Date getTimeAfter(Date afterTime) {
  
  		// Computation is based on Gregorian year only.
  		final Calendar cl = new java.util.GregorianCalendar(getTimeZone());
  
  		// move ahead one second, since we're computing the time *after* the
  		// given time
  		if (afterTime == null) {
  			return null;
  		}
  		afterTime = new Date(afterTime.getTime() + 1000);
  		// CronTrigger does not deal with milliseconds
  		cl.setTime(afterTime);
  		cl.set(Calendar.MILLISECOND, 0);
  
  		boolean gotOne = false;
  		// loop until we've computed the next time, or we've past the endTime
  		while (!gotOne) {
  			//if (endTime != null && cl.getTime().after(endTime)) return null;
  			if (cl.get(Calendar.YEAR) > 2999) { // prevent endless loop...
  				return null;
  			}
  
  			SortedSet<Integer> st = null;
  			int t = 0;
  
  			int sec = cl.get(Calendar.SECOND);
  			int min = cl.get(Calendar.MINUTE);
  
  			// get second.................................................
  			st = seconds.tailSet(sec);
  			if (st != null && st.size() != 0) {
  				sec = st.first();
  			}
  			else {
  				sec = seconds.first();
  				min++;
  				cl.set(Calendar.MINUTE, min);
  			}
  			cl.set(Calendar.SECOND, sec);
  
  			min = cl.get(Calendar.MINUTE);
  			int hr = cl.get(Calendar.HOUR_OF_DAY);
  			t = -1;
  
  			// get minute.................................................
  			st = minutes.tailSet(min);
  			if (st != null && st.size() != 0) {
  				t = min;
  				min = st.first();
  			}
  			else {
  				min = minutes.first();
  				hr++;
  			}
  			if (min != t) {
  				cl.set(Calendar.SECOND, 0);
  				cl.set(Calendar.MINUTE, min);
  				setCalendarHour(cl, hr);
  				continue;
  			}
  			cl.set(Calendar.MINUTE, min);
  
  			hr = cl.get(Calendar.HOUR_OF_DAY);
  			int day = cl.get(Calendar.DAY_OF_MONTH);
  			t = -1;
  
  			// get hour...................................................
  			st = hours.tailSet(hr);
  			if (st != null && st.size() != 0) {
  				t = hr;
  				hr = st.first();
  			}
  			else {
  				hr = hours.first();
  				day++;
  			}
  			if (hr != t) {
  				cl.set(Calendar.SECOND, 0);
  				cl.set(Calendar.MINUTE, 0);
  				cl.set(Calendar.DAY_OF_MONTH, day);
  				setCalendarHour(cl, hr);
  				continue;
  			}
  			cl.set(Calendar.HOUR_OF_DAY, hr);
  
  			day = cl.get(Calendar.DAY_OF_MONTH);
  			int mon = cl.get(Calendar.MONTH) + 1;
  			// '+ 1' because calendar is 0-based for this field, and we are
  			// 1-based
  			t = -1;
  			int tmon = mon;
  
  			// get day...................................................
  			final boolean dayOfMSpec = !daysOfMonth.contains(NO_SPEC);
  			final boolean dayOfWSpec = !daysOfWeek.contains(NO_SPEC);
  			if (dayOfMSpec && !dayOfWSpec) { // get day by day of month rule
  				st = daysOfMonth.tailSet(day);
  				if (lastdayOfMonth) {
  					if (!nearestWeekday) {
  						t = day;
  						day = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
  						day -= lastdayOffset;
  						day = t > day ? 1 : day;
  						if (t > day && ++mon > 12) {
  							mon = 1;
  							tmon = 3333; // ensure test of mon != tmon further below fails
  							cl.add(Calendar.YEAR, 1);
  						}
  					}
  					else {
  						t = day;
  						day = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
  						day -= lastdayOffset;
  
  						final Calendar tcal = Calendar.getInstance(getTimeZone());
  						tcal.set(Calendar.SECOND, 0);
  						tcal.set(Calendar.MINUTE, 0);
  						tcal.set(Calendar.HOUR_OF_DAY, 0);
  						tcal.set(Calendar.DAY_OF_MONTH, day);
  						tcal.set(Calendar.MONTH, mon - 1);
  						tcal.set(Calendar.YEAR, cl.get(Calendar.YEAR));
  
  						final int ldom = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
  						final int dow = tcal.get(Calendar.DAY_OF_WEEK);
  
  						if (dow == Calendar.SATURDAY && day == 1) {
  							day += 2;
  						}
  						else if (dow == Calendar.SATURDAY) {
  							day -= 1;
  						}
  						else if (dow == Calendar.SUNDAY && day == ldom) {
  							day -= 2;
  						}
  						else if (dow == Calendar.SUNDAY) {
  							day += 1;
  						}
  
  						tcal.set(Calendar.SECOND, sec);
  						tcal.set(Calendar.MINUTE, min);
  						tcal.set(Calendar.HOUR_OF_DAY, hr);
  						tcal.set(Calendar.DAY_OF_MONTH, day);
  						tcal.set(Calendar.MONTH, mon - 1);
  						final Date nTime = tcal.getTime();
  						if (nTime.before(afterTime)) {
  							day = 1;
  							mon++;
  						}
  					}
  				}
  				else if (nearestWeekday) {
  					t = day;
  					day = daysOfMonth.first();
  
  					final Calendar tcal = Calendar.getInstance(getTimeZone());
  					tcal.set(Calendar.SECOND, 0);
  					tcal.set(Calendar.MINUTE, 0);
  					tcal.set(Calendar.HOUR_OF_DAY, 0);
  					tcal.set(Calendar.DAY_OF_MONTH, day);
  					tcal.set(Calendar.MONTH, mon - 1);
  					tcal.set(Calendar.YEAR, cl.get(Calendar.YEAR));
  
  					final int ldom = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
  					final int dow = tcal.get(Calendar.DAY_OF_WEEK);
  
  					if (dow == Calendar.SATURDAY && day == 1) {
  						day += 2;
  					}
  					else if (dow == Calendar.SATURDAY) {
  						day -= 1;
  					}
  					else if (dow == Calendar.SUNDAY && day == ldom) {
  						day -= 2;
  					}
  					else if (dow == Calendar.SUNDAY) {
  						day += 1;
  					}
  
  					tcal.set(Calendar.SECOND, sec);
  					tcal.set(Calendar.MINUTE, min);
  					tcal.set(Calendar.HOUR_OF_DAY, hr);
  					tcal.set(Calendar.DAY_OF_MONTH, day);
  					tcal.set(Calendar.MONTH, mon - 1);
  					final Date nTime = tcal.getTime();
  					if (nTime.before(afterTime)) {
  						day = daysOfMonth.first();
  						mon++;
  					}
  				}
  				else if (st != null && st.size() != 0) {
  					t = day;
  					day = st.first();
  					// make sure we don't over-run a short month, such as february
  					final int lastDay = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
  					if (day > lastDay) {
  						day = daysOfMonth.first();
  						mon++;
  					}
  				}
  				else {
  					day = daysOfMonth.first();
  					mon++;
  				}
  
  				if (day != t || mon != tmon) {
  					cl.set(Calendar.SECOND, 0);
  					cl.set(Calendar.MINUTE, 0);
  					cl.set(Calendar.HOUR_OF_DAY, 0);
  					cl.set(Calendar.DAY_OF_MONTH, day);
  					cl.set(Calendar.MONTH, mon - 1);
  					// '- 1' because calendar is 0-based for this field, and we
  					// are 1-based
  					continue;
  				}
  			}
  			else if (dayOfWSpec && !dayOfMSpec) { // get day by day of week rule
  				if (lastdayOfWeek) { // are we looking for the last XXX day of
  					// the month?
  					final int dow = daysOfWeek.first(); // desired
  					// d-o-w
  					final int cDow = cl.get(Calendar.DAY_OF_WEEK); // current d-o-w
  					int daysToAdd = 0;
  					if (cDow < dow) {
  						daysToAdd = dow - cDow;
  					}
  					if (cDow > dow) {
  						daysToAdd = dow + (7 - cDow);
  					}
  
  					final int lDay = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
  
  					if (day + daysToAdd > lDay) { // did we already miss the
  						// last one?
  						cl.set(Calendar.SECOND, 0);
  						cl.set(Calendar.MINUTE, 0);
  						cl.set(Calendar.HOUR_OF_DAY, 0);
  						cl.set(Calendar.DAY_OF_MONTH, 1);
  						cl.set(Calendar.MONTH, mon);
  						// no '- 1' here because we are promoting the month
  						continue;
  					}
  
  					// find date of last occurrence of this day in this month...
  					while ((day + daysToAdd + 7) <= lDay) {
  						daysToAdd += 7;
  					}
  					day += daysToAdd;
  					if (daysToAdd > 0) {
  						cl.set(Calendar.SECOND, 0);
  						cl.set(Calendar.MINUTE, 0);
  						cl.set(Calendar.HOUR_OF_DAY, 0);
  						cl.set(Calendar.DAY_OF_MONTH, day);
  						cl.set(Calendar.MONTH, mon - 1);
  						// '- 1' here because we are not promoting the month
  						continue;
  					}
  				}
  				else if (nthdayOfWeek != 0) {
  					// are we looking for the Nth XXX day in the month?
  					final int dow = daysOfWeek.first(); // desired
  					// d-o-w
  					final int cDow = cl.get(Calendar.DAY_OF_WEEK); // current d-o-w
  					int daysToAdd = 0;
  					if (cDow < dow) {
  						daysToAdd = dow - cDow;
  					}
  					else if (cDow > dow) {
  						daysToAdd = dow + (7 - cDow);
  					}
  
  					boolean dayShifted = false;
  					if (daysToAdd > 0) {
  						dayShifted = true;
  					}
  
  					day += daysToAdd;
  					int weekOfMonth = day / 7;
  					if (day % 7 > 0) {
  						weekOfMonth++;
  					}
  
  					daysToAdd = (nthdayOfWeek - weekOfMonth) * 7;
  					day += daysToAdd;
  					if (daysToAdd < 0
  							|| day > getLastDayOfMonth(mon, cl
  							.get(Calendar.YEAR))) {
  						cl.set(Calendar.SECOND, 0);
  						cl.set(Calendar.MINUTE, 0);
  						cl.set(Calendar.HOUR_OF_DAY, 0);
  						cl.set(Calendar.DAY_OF_MONTH, 1);
  						cl.set(Calendar.MONTH, mon);
  						// no '- 1' here because we are promoting the month
  						continue;
  					}
  					else if (daysToAdd > 0 || dayShifted) {
  						cl.set(Calendar.SECOND, 0);
  						cl.set(Calendar.MINUTE, 0);
  						cl.set(Calendar.HOUR_OF_DAY, 0);
  						cl.set(Calendar.DAY_OF_MONTH, day);
  						cl.set(Calendar.MONTH, mon - 1);
  						// '- 1' here because we are NOT promoting the month
  						continue;
  					}
  				}
  				else {
  					final int cDow = cl.get(Calendar.DAY_OF_WEEK); // current d-o-w
  					int dow = daysOfWeek.first(); // desired
  					// d-o-w
  					st = daysOfWeek.tailSet(cDow);
  					if (st != null && st.size() > 0) {
  						dow = st.first();
  					}
  
  					int daysToAdd = 0;
  					if (cDow < dow) {
  						daysToAdd = dow - cDow;
  					}
  					if (cDow > dow) {
  						daysToAdd = dow + (7 - cDow);
  					}
  
  					final int lDay = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
  
  					if (day + daysToAdd > lDay) { // will we pass the end of
  						// the month?
  						cl.set(Calendar.SECOND, 0);
  						cl.set(Calendar.MINUTE, 0);
  						cl.set(Calendar.HOUR_OF_DAY, 0);
  						cl.set(Calendar.DAY_OF_MONTH, 1);
  						cl.set(Calendar.MONTH, mon);
  						// no '- 1' here because we are promoting the month
  						continue;
  					}
  					else if (daysToAdd > 0) { // are we switching days?
  						cl.set(Calendar.SECOND, 0);
  						cl.set(Calendar.MINUTE, 0);
  						cl.set(Calendar.HOUR_OF_DAY, 0);
  						cl.set(Calendar.DAY_OF_MONTH, day + daysToAdd);
  						cl.set(Calendar.MONTH, mon - 1);
  						// '- 1' because calendar is 0-based for this field,
  						// and we are 1-based
  						continue;
  					}
  				}
  			}
  			else { // dayOfWSpec && !dayOfMSpec
  				throw new UnsupportedOperationException(
  						"Support for specifying both a day-of-week AND a day-of-month parameter is not implemented.");
  			}
  			cl.set(Calendar.DAY_OF_MONTH, day);
  
  			mon = cl.get(Calendar.MONTH) + 1;
  			// '+ 1' because calendar is 0-based for this field, and we are
  			// 1-based
  			int year = cl.get(Calendar.YEAR);
  			t = -1;
  
  			// test for expressions that never generate a valid fire date,
  			// but keep looping...
  			if (year > MAX_YEAR) {
  				return null;
  			}
  
  			// get month...................................................
  			st = months.tailSet(mon);
  			if (st != null && st.size() != 0) {
  				t = mon;
  				mon = st.first();
  			}
  			else {
  				mon = months.first();
  				year++;
  			}
  			if (mon != t) {
  				cl.set(Calendar.SECOND, 0);
  				cl.set(Calendar.MINUTE, 0);
  				cl.set(Calendar.HOUR_OF_DAY, 0);
  				cl.set(Calendar.DAY_OF_MONTH, 1);
  				cl.set(Calendar.MONTH, mon - 1);
  				// '- 1' because calendar is 0-based for this field, and we are
  				// 1-based
  				cl.set(Calendar.YEAR, year);
  				continue;
  			}
  			cl.set(Calendar.MONTH, mon - 1);
  			// '- 1' because calendar is 0-based for this field, and we are
  			// 1-based
  
  			year = cl.get(Calendar.YEAR);
  			t = -1;
  
  			// get year...................................................
  			st = years.tailSet(year);
  			if (st != null && st.size() != 0) {
  				t = year;
  				year = st.first();
  			}
  			else {
  				return null; // ran out of years...
  			}
  
  			if (year != t) {
  				cl.set(Calendar.SECOND, 0);
  				cl.set(Calendar.MINUTE, 0);
  				cl.set(Calendar.HOUR_OF_DAY, 0);
  				cl.set(Calendar.DAY_OF_MONTH, 1);
  				cl.set(Calendar.MONTH, 0);
  				// '- 1' because calendar is 0-based for this field, and we are
  				// 1-based
  				cl.set(Calendar.YEAR, year);
  				continue;
  			}
  			cl.set(Calendar.YEAR, year);
  
  			gotOne = true;
  		} // while( !done )
  
  		return cl.getTime();
  	}
  
  	/**
  	 * Advance the calendar to the particular hour paying particular attention
  	 * to daylight saving problems.
  	 *
  	 * @param cal  the calendar to operate on
  	 * @param hour the hour to set
  	 */
  	protected void setCalendarHour(final Calendar cal, final int hour) {
  		cal.set(Calendar.HOUR_OF_DAY, hour);
  		if (cal.get(Calendar.HOUR_OF_DAY) != hour && hour != 24) {
  			cal.set(Calendar.HOUR_OF_DAY, hour + 1);
  		}
  	}
  
  	protected Date getTimeBefore(final Date targetDate) {
  		final Calendar cl = Calendar.getInstance(getTimeZone());
  
  		// CronTrigger does not deal with milliseconds, so truncate target
  		cl.setTime(targetDate);
  		cl.set(Calendar.MILLISECOND, 0);
  		final Date targetDateNoMs = cl.getTime();
  
  		// to match this
  		Date start = targetDateNoMs;
  		final long minIncrement = findMinIncrement();
  		Date prevFireTime;
  		do {
  			final Date prevCheckDate = new Date(start.getTime() - minIncrement);
  			prevFireTime = getTimeAfter(prevCheckDate);
  			if (prevFireTime == null || prevFireTime.before(MIN_DATE)) {
  				return null;
  			}
  			start = prevCheckDate;
  		} while (prevFireTime.compareTo(targetDateNoMs) >= 0);
  		return prevFireTime;
  	}
  
  	public Date getPrevFireTime(final Date targetDate) {
  		return getTimeBefore(targetDate);
  	}
  
  	private long findMinIncrement() {
  		if (seconds.size() != 1) {
  			return minInSet(seconds) * 1000;
  		}
  		else if (seconds.first() == ALL_SPEC_INT) {
  			return 1000;
  		}
  		if (minutes.size() != 1) {
  			return minInSet(minutes) * 60000;
  		}
  		else if (minutes.first() == ALL_SPEC_INT) {
  			return 60000;
  		}
  		if (hours.size() != 1) {
  			return minInSet(hours) * 3600000;
  		}
  		else if (hours.first() == ALL_SPEC_INT) {
  			return 3600000;
  		}
  		return 86400000;
  	}
  
  	private int minInSet(final TreeSet<Integer> set) {
  		int previous = 0;
  		int min = Integer.MAX_VALUE;
  		boolean first = true;
  		for (final int value : set) {
  			if (first) {
  				previous = value;
  				first = false;
  				continue;
  			}
  			else {
  				final int diff = value - previous;
  				if (diff < min) {
  					min = diff;
  				}
  			}
  		}
  		return min;
  	}
  
  	protected boolean isLeapYear(final int year) {
  		return ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0));
  	}
  
  	protected int getLastDayOfMonth(final int monthNum, final int year) {
  		switch (monthNum) {
  			case 1:
  				return 31;
  			case 2:
  				return (isLeapYear(year)) ? 29 : 28;
  			case 3:
  				return 31;
  			case 4:
  				return 30;
  			case 5:
  				return 31;
  			case 6:
  				return 30;
  			case 7:
  				return 31;
  			case 8:
  				return 31;
  			case 9:
  				return 30;
  			case 10:
  				return 31;
  			case 11:
  				return 30;
  			case 12:
  				return 31;
  			default:
  				throw new IllegalArgumentException("Illegal month number: "
  						+ monthNum);
  		}
  	}
  
  	private class ValueSet {
  		public int value;
  		public int pos;
  	}
  }
  