content: /*
   * All content copyright Terracotta, Inc., unless otherwise indicated. All rights reserved.
   * 
   * 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 
   * 
   *   http://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.platform.admin.core.cron;
  
  import java.io.Serializable;
  import java.text.ParseException;
  import java.util.*;
  
  /**
   * Provides a parser and evaluator for unix-like cron expressions. Cron 
   * expressions provide the ability to specify complex time combinations such as
   * &quot;At 8:00am every Monday through Friday&quot; or &quot;At 1:30am every 
   * last Friday of the month&quot;. 
   * <P>
   * Cron expressions are comprised of 6 required fields and one optional field
   * separated by white space. The fields respectively are described as follows:
   * 
   * <table cellspacing="8">
   * <tr>
   * <th align="left">Field Name</th>
   * <th align="left">&nbsp;</th>
   * <th align="left">Allowed Values</th>
   * <th align="left">&nbsp;</th>
   * <th align="left">Allowed Special Characters</th>
   * </tr>
   * <tr>
   * <td align="left"><code>Seconds</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>0-59</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>, - * /</code></td>
   * </tr>
   * <tr>
   * <td align="left"><code>Minutes</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>0-59</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>, - * /</code></td>
   * </tr>
   * <tr>
   * <td align="left"><code>Hours</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>0-23</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>, - * /</code></td>
   * </tr>
   * <tr>
   * <td align="left"><code>Day-of-month</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>1-31</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>, - * ? / L W</code></td>
   * </tr>
   * <tr>
   * <td align="left"><code>Month</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>0-11 or JAN-DEC</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>, - * /</code></td>
   * </tr>
   * <tr>
   * <td align="left"><code>Day-of-Week</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>1-7 or SUN-SAT</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>, - * ? / L #</code></td>
   * </tr>
   * <tr>
   * <td align="left"><code>Year (Optional)</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>empty, 1970-2199</code></td>
   * <td align="left">&nbsp;</th>
   * <td align="left"><code>, - * /</code></td>
   * </tr>
   * </table>
   * <P>
   * The '*' character is used to specify all values. For example, &quot;*&quot; 
   * in the minute field means &quot;every minute&quot;.
   * <P>
   * The '?' character is allowed for the day-of-month and day-of-week fields. It
   * is used to specify 'no specific value'. This is useful when you need to
   * specify something in one of the two fields, but not the other.
   * <P>
   * The '-' character is used to specify ranges For example &quot;10-12&quot; in
   * the hour field means &quot;the hours 10, 11 and 12&quot;.
   * <P>
   * The ',' character is used to specify additional values. For example
   * &quot;MON,WED,FRI&quot; in the day-of-week field means &quot;the days Monday,
   * Wednesday, and Friday&quot;.
   * <P>
   * The '/' character is used to specify increments. For example &quot;0/15&quot;
   * in the seconds field means &quot;the seconds 0, 15, 30, and 45&quot;. And 
   * &quot;5/15&quot; in the seconds field means &quot;the seconds 5, 20, 35, and
   * 50&quot;.  Specifying '*' before the  '/' is equivalent to specifying 0 is
   * the value to start with. Essentially, for each field in the expression, there
   * is a set of numbers that can be turned on or off. For seconds and minutes, 
   * the numbers range from 0 to 59. For hours 0 to 23, for days of the month 0 to
   * 31, and for months 0 to 11 (JAN to DEC). The &quot;/&quot; character simply helps you turn
   * on every &quot;nth&quot; value in the given set. Thus &quot;7/6&quot; in the
   * month field only turns on month &quot;7&quot;, it does NOT mean every 6th 
   * month, please note that subtlety.  
   * <P>
   * The 'L' character is allowed for the day-of-month and day-of-week fields.
   * This character is short-hand for &quot;last&quot;, but it has different 
   * meaning in each of the two fields. For example, the value &quot;L&quot; in 
   * the day-of-month field means &quot;the last day of the month&quot; - day 31 
   * for January, day 28 for February on non-leap years. If used in the 
   * day-of-week field by itself, it simply means &quot;7&quot; or 
   * &quot;SAT&quot;. But if used in the day-of-week field after another value, it
   * means &quot;the last xxx day of the month&quot; - for example &quot;6L&quot;
   * means &quot;the last friday of the month&quot;. You can also specify an offset 
   * from the last day of the month, such as "L-3" which would mean the third-to-last 
   * day of the calendar month. <i>When using the 'L' option, it is important not to 
   * specify lists, or ranges of values, as you'll get confusing/unexpected results.</i>
   * <P>
   * The 'W' character is allowed for the day-of-month field.  This character 
   * is used to specify the weekday (Monday-Friday) nearest the given day.  As an 
   * example, if you were to specify &quot;15W&quot; as the value for the 
   * day-of-month field, the meaning is: &quot;the nearest weekday to the 15th of
   * the month&quot;. So if the 15th is a Saturday, the trigger will fire on 
   * Friday the 14th. If the 15th is a Sunday, the trigger will fire on Monday the
   * 16th. If the 15th is a Tuesday, then it will fire on Tuesday the 15th. 
   * However if you specify &quot;1W&quot; as the value for day-of-month, and the
   * 1st is a Saturday, the trigger will fire on Monday the 3rd, as it will not 
   * 'jump' over the boundary of a month's days.  The 'W' character can only be 
   * specified when the day-of-month is a single day, not a range or list of days.
   * <P>
   * The 'L' and 'W' characters can also be combined for the day-of-month 
   * expression to yield 'LW', which translates to &quot;last weekday of the 
   * month&quot;.
   * <P>
   * The '#' character is allowed for the day-of-week field. This character is
   * used to specify &quot;the nth&quot; XXX day of the month. For example, the 
   * value of &quot;6#3&quot; in the day-of-week field means the third Friday of 
   * the month (day 6 = Friday and &quot;#3&quot; = the 3rd one in the month). 
   * Other examples: &quot;2#1&quot; = the first Monday of the month and 
   * &quot;4#5&quot; = the fifth Wednesday of the month. Note that if you specify
   * &quot;#5&quot; and there is not 5 of the given day-of-week in the month, then
   * no firing will occur that month.  If the '#' character is used, there can
   * only be one expression in the day-of-week field (&quot;3#1,6#3&quot; is 
   * not valid, since there are two expressions).
   * <P>
   * <!--The 'C' character is allowed for the day-of-month and day-of-week fields.
   * This character is short-hand for "calendar". This means values are
   * calculated against the associated calendar, if any. If no calendar is
   * associated, then it is equivalent to having an all-inclusive calendar. A
   * value of "5C" in the day-of-month field means "the first day included by the
   * calendar on or after the 5th". A value of "1C" in the day-of-week field
   * means "the first day included by the calendar on or after Sunday".-->
   * <P>
   * The legal characters and the names of months and days of the week are not
   * case sensitive.
   * 
   * <p>
   * <b>NOTES:</b>
   * <ul>
   * <li>Support for specifying both a day-of-week and a day-of-month value is
   * not complete (you'll need to use the '?' character in one of these fields).
   * </li>
   * <li>Overflowing ranges is supported - that is, having a larger number on 
   * the left hand side than the right. You might do 22-2 to catch 10 o'clock 
   * at night until 2 o'clock in the morning, or you might have NOV-FEB. It is 
   * very important to note that overuse of overflowing ranges creates ranges 
   * that don't make sense and no effort has been made to determine which 
   * interpretation CronExpression chooses. An example would be 
   * "0 0 14-6 ? * FRI-MON". </li>
   * </ul>
   * </p>
   *
   * Borrowed from quartz v2.3.1
   *
   */
  public final class CronExpression implements Serializable, Cloneable {
  
      private static final long serialVersionUID = 12423409423L;
      
      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<String, Integer>(20);
      protected static final Map<String, Integer> dayMap = new HashMap<String, Integer>(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;
      
      public static final int MAX_YEAR = Calendar.getInstance().get(Calendar.YEAR) + 100;
  
      /**
       * 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 java.text.ParseException
       *         if the string expression cannot be parsed into a valid
       *         <CODE>CronExpression</CODE>
       */
      public CronExpression(String cronExpression) throws ParseException {
          if (cronExpression == null) {
              throw new IllegalArgumentException("cronExpression cannot be null");
          }
  
          this.cronExpression = cronExpression.toUpperCase(Locale.US);
  
          buildExpression(this.cronExpression);
      }
  
      /**
       * Constructs a new {@code CronExpression} as a copy of an existing
       * instance.
       *
       * @param expression
       *            The existing cron expression to be copied
       */
      public CronExpression(CronExpression expression) {
          /*
           * We don't call the other constructor here since we need to swallow the
           * ParseException. We also elide some of the sanity checking as it is
           * not logically trippable.
           */
          this.cronExpression = expression.getCronExpression();
          try {
              buildExpression(cronExpression);
          } catch (ParseException ex) {
              throw new AssertionError();
          }
          if (expression.getTimeZone() != null) {
              setTimeZone((TimeZone) expression.getTimeZone().clone());
          }
      }
  
      /**
       * 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(Date date) {
          Calendar testDateCal = Calendar.getInstance(getTimeZone());
          testDateCal.setTime(date);
          testDateCal.set(Calendar.MILLISECOND, 0);
          Date originalDate = testDateCal.getTime();
  
          testDateCal.add(Calendar.SECOND, -1);
  
          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(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(Date date) {
          long difference = 1000;
  
          //move back to the nearest second so differences will be accurate
          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.
       */
      public TimeZone getTimeZone() {
          if (timeZone == null) {
              timeZone = TimeZone.getDefault();
          }
  
          return timeZone;
      }
  
      /**
       * Sets the time zone for which  this <code>CronExpression</code>
       * will be resolved.
       */
      public void setTimeZone(TimeZone timeZone) {
          this.timeZone = timeZone;
      }
  
      /**
       * Returns the string representation of the <CODE>CronExpression</CODE>
       *
       * @return a string representation of the <CODE>CronExpression</CODE>
       */
      @Override
      public String toString() {
          return cronExpression;
      }
  
      /**
       * Indicates whether the specified cron expression can be parsed into a
       * valid cron expression
       *
       * @param cronExpression the expression to evaluate
       * @return a boolean indicating whether the given expression is a valid cron
       *         expression
       */
      public static boolean isValidExpression(String cronExpression) {
  
          try {
              new CronExpression(cronExpression);
          } catch (ParseException pe) {
              return false;
          }
  
          return true;
      }
  
      public static void validateExpression(String cronExpression) throws ParseException {
  
          new CronExpression(cronExpression);
      }
  
  
      ////////////////////////////////////////////////////////////////////////////
      //
      // Expression Parsing Functions
      //
      ////////////////////////////////////////////////////////////////////////////
  
      protected void buildExpression(String expression) throws ParseException {
          expressionParsed = true;
  
          try {
  
              if (seconds == null) {
                  seconds = new TreeSet<Integer>();
              }
              if (minutes == null) {
                  minutes = new TreeSet<Integer>();
              }
              if (hours == null) {
                  hours = new TreeSet<Integer>();
              }
              if (daysOfMonth == null) {
                  daysOfMonth = new TreeSet<Integer>();
              }
              if (months == null) {
                  months = new TreeSet<Integer>();
              }
              if (daysOfWeek == null) {
                  daysOfWeek = new TreeSet<Integer>();
              }
              if (years == null) {
                  years = new TreeSet<Integer>();
              }
  
              int exprOn = SECOND;
  
              StringTokenizer exprsTok = new StringTokenizer(expression, " \t",
                      false);
  
              while (exprsTok.hasMoreTokens() && exprOn <= YEAR) {
                  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);
                  }
  
                  StringTokenizer vTok = new StringTokenizer(expr, ",");
                  while (vTok.hasMoreTokens()) {
                      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);
              }
  
              TreeSet<Integer> dow = getSet(DAY_OF_WEEK);
              TreeSet<Integer> dom = getSet(DAY_OF_MONTH);
  
              // Copying the logic from the UnsupportedOperationException below
              boolean dayOfMSpec = !dom.contains(NO_SPEC);
              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 (ParseException pe) {
              throw pe;
          } catch (Exception e) {
              throw new ParseException("Illegal cron expression format ("
                      + e.toString() + ")", 0);
          }
      }
  
      protected int storeExpressionVals(int pos, String s, 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) {
                      c = s.charAt(i + 3);
                      if (c == '-') {
                          i += 4;
                          sub = s.substring(i, i + 3);
                          eval = getMonthNumber(sub) + 1;
                          if (eval <= 0) {
                              throw new ParseException("Invalid Month value: '" + sub + "'", i);
                          }
                      }
                  }
              } 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);
                          if (eval < 0) {
                              throw new ParseException(
                                      "Invalid Day-of-Week value: '" + sub
                                          + "'", i);
                          }
                      } else if (c == '#') {
                          try {
                              i += 4;
                              nthdayOfWeek = Integer.parseInt(s.substring(i));
                              if (nthdayOfWeek < 1 || nthdayOfWeek > 5) {
                                  throw new Exception();
                              }
                          } catch (Exception e) {
                              throw new ParseException(
                                      "A numeric value between 1 and 5 must follow the '#' option",
                                      i);
                          }
                      } 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 specified for Day-of-Month or Day-of-Week.",
                              i);
              }
              if (type == DAY_OF_WEEK && !lastdayOfMonth) {
                  int val = daysOfMonth.last();
                  if (val == NO_SPEC_INT) {
                      throw new ParseException(
                                  "'?' can only be specified 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++;
                  }
                  checkIncrementRange(incr, type, 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 == '-') {
                      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') {
                      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;
      }
  
      private void checkIncrementRange(int incr, int type, int idxPos) throws ParseException {
          if (incr > 59 && (type == SECOND || type == MINUTE)) {
              throw new ParseException("Increment > 60 : " + incr, idxPos);
          } else if (incr > 23 && (type == HOUR)) {
              throw new ParseException("Increment > 24 : " + incr, idxPos);
          } else if (incr > 31 && (type == DAY_OF_MONTH)) {
              throw new ParseException("Increment > 31 : " + incr, idxPos);
          } else if (incr > 7 && (type == DAY_OF_WEEK)) {
              throw new ParseException("Increment > 7 : " + incr, idxPos);
          } else if (incr > 12 && (type == MONTH)) {
              throw new ParseException("Increment > 12 : " + incr, idxPos);
          }
      }
  
      protected int checkNext(int pos, String s, int val, 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);
              }
              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);
              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 (Exception e) {
                  throw new ParseException(
                          "A numeric value between 1 and 5 must follow the '#' option",
                          i);
              }
  
              TreeSet<Integer> set = getSet(type);
              set.add(val);
              i++;
              return i;
          }
  
          if (c == '-') {
              i++;
              c = s.charAt(i);
              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') {
                  ValueSet vs = getValue(v, s, i);
                  end = vs.value;
                  i = vs.pos;
              }
              if (i < s.length() && ((c = s.charAt(i)) == '/')) {
                  i++;
                  c = s.charAt(i);
                  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') {
                      ValueSet vs = getValue(v2, s, i);
                      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 == '/') {
              if ((i + 1) >= s.length() || s.charAt(i + 1) == ' ' || s.charAt(i + 1) == '\t') {
                  throw new ParseException("'/' must be followed by an integer.", i);
              }
  
              i++;
              c = s.charAt(i);
              int v2 = Integer.parseInt(String.valueOf(c));
              i++;
              if (i >= s.length()) {
                  checkIncrementRange(v2, type, i);
                  addToSet(val, end, v2, type);
                  return i;
              }
              c = s.charAt(i);
              if (c >= '0' && c <= '9') {
                  ValueSet vs = getValue(v2, s, i);
                  int v3 = vs.value;
                  checkIncrementRange(v3, type, i);
                  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() {
          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(java.util.Set<Integer> set) {
  
          if (set.contains(NO_SPEC)) {
              return "?";
          }
          if (set.contains(ALL_SPEC)) {
              return "*";
          }
  
          StringBuilder buf = new StringBuilder();
  
          Iterator<Integer> itr = set.iterator();
          boolean first = true;
          while (itr.hasNext()) {
              Integer iVal = itr.next();
              String val = iVal.toString();
              if (!first) {
                  buf.append(",");
              }
              buf.append(val);
              first = false;
          }
  
          return buf.toString();
      }
  
      protected String getExpressionSetSummary(java.util.ArrayList<Integer> list) {
  
          if (list.contains(NO_SPEC)) {
              return "?";
          }
          if (list.contains(ALL_SPEC)) {
              return "*";
          }
  
          StringBuilder buf = new StringBuilder();
  
          Iterator<Integer> itr = list.iterator();
          boolean first = true;
          while (itr.hasNext()) {
              Integer iVal = itr.next();
              String val = iVal.toString();
              if (!first) {
                  buf.append(",");
              }
              buf.append(val);
              first = false;
          }
  
          return buf.toString();
      }
  
      protected int skipWhiteSpace(int i, String s) {
          for (; i < s.length() && (s.charAt(i) == ' ' || s.charAt(i) == '\t'); i++) {
          }
  
          return i;
      }
  
      protected int findNextWhiteSpace(int i, String s) {
          for (; i < s.length() && (s.charAt(i) != ' ' || s.charAt(i) != '\t'); i++) {
          }
  
          return i;
      }
  
      protected void addToSet(int val, int end, int incr, int type)
          throws ParseException {
  
          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(int type) {
          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:
                  return null;
          }
      }
  
      protected ValueSet getValue(int v, String s, int i) {
          char c = s.charAt(i);
          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);
          }
          ValueSet val = new ValueSet();
  
          val.pos = (i < s.length()) ? i : i + 1;
          val.value = Integer.parseInt(s1.toString());
          return val;
      }
  
      protected int getNumericValue(String s, int i) {
          int endOfVal = findNextWhiteSpace(i, s);
          String val = s.substring(i, endOfVal);
          return Integer.parseInt(val);
      }
  
      protected int getMonthNumber(String s) {
          Integer integer = monthMap.get(s);
  
          if (integer == null) {
              return -1;
          }
  
          return integer;
      }
  
      protected int getDayOfWeekNumber(String s) {
          Integer integer = dayMap.get(s);
  
          if (integer == null) {
              return -1;
          }
  
          return integer;
      }
  
      ////////////////////////////////////////////////////////////////////////////
      //
      // Computation Functions
      //
      ////////////////////////////////////////////////////////////////////////////
  
      public Date getTimeAfter(Date afterTime) {
  
          // Computation is based on Gregorian year only.
          Calendar cl = new java.util.GregorianCalendar(getTimeZone());
  
          // move ahead one second, since we're computing the time *after* the
          // given time
          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...................................................
              boolean dayOfMSpec = !daysOfMonth.contains(NO_SPEC);
              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;
                          if(t > day) {
                              mon++;
                              if(mon > 12) {
                                  mon = 1;
                                  tmon = 3333; // ensure test of mon != tmon further below fails
                                  cl.add(Calendar.YEAR, 1);
                              }
                              day = 1;
                          }
                      } else {
                          t = day;
                          day = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
                          day -= lastdayOffset;
  
                          java.util.Calendar tcal = java.util.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));
  
                          int ldom = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
                          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);
                          Date nTime = tcal.getTime();
                          if(nTime.before(afterTime)) {
                              day = 1;
                              mon++;
                          }
                      }
                  } else if(nearestWeekday) {
                      t = day;
                      day = daysOfMonth.first();
  
                      java.util.Calendar tcal = java.util.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));
  
                      int ldom = getLastDayOfMonth(mon, cl.get(Calendar.YEAR));
                      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);
                      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
                      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?
                      int dow = daysOfWeek.first(); // desired
                      // d-o-w
                      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);
                      }
  
                      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?
                      int dow = daysOfWeek.first(); // desired
                      // d-o-w
                      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 {
                      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);
                      }
  
                      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 swithing 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(Calendar cal, int hour) {
          cal.set(java.util.Calendar.HOUR_OF_DAY, hour);
          if (cal.get(java.util.Calendar.HOUR_OF_DAY) != hour && hour != 24) {
              cal.set(java.util.Calendar.HOUR_OF_DAY, hour + 1);
          }
      }
  
      /**
       * NOT YET IMPLEMENTED: Returns the time before the given time
       * that the <code>CronExpression</code> matches.
       */ 
      public Date getTimeBefore(Date endTime) {
          // FUTURE_TODO: implement QUARTZ-423
          return null;
      }
  
      /**
       * NOT YET IMPLEMENTED: Returns the final time that the 
       * <code>CronExpression</code> will match.
       */
      public Date getFinalFireTime() {
          // FUTURE_TODO: implement QUARTZ-423
          return null;
      }
      
      protected boolean isLeapYear(int year) {
          return ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0));
      }
  
      protected int getLastDayOfMonth(int monthNum, 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 void readObject(java.io.ObjectInputStream stream)
          throws java.io.IOException, ClassNotFoundException {
          
          stream.defaultReadObject();
          try {
              buildExpression(cronExpression);
          } catch (Exception ignore) {
          } // never happens
      }    
      
      @Override
      @Deprecated
      public Object clone() {
          return new CronExpression(this);
      }
  }
  
  class ValueSet {
      public int value;
  
      public int pos;
  }
  