/*
 * Ext JS Library 2.0.2
 * Copyright(c) 2006-2008, Ext JS, LLC.
 * licensing@extjs.com
 * 
 * http://extjs.com/license
 */

/**
 * @class Date
 *
 * The date parsing and format syntax is a subset of
 * <a href="http://www.php.net/date">PHP's date() function</a>, and the formats that are
 * supported will provide results equivalent to their PHP versions.
 *
 * The following is a list of all currently supported formats:
 *<pre>
Format  Description                                                               Example returned values
------  -----------------------------------------------------------------------   -----------------------
  d     Day of the month, 2 digits with leading zeros                             01 to 31
  D     A short textual representation of the day of the week                     Mon to Sun
  j     Day of the month without leading zeros                                    1 to 31
  l     A full textual representation of the day of the week                      Sunday to Saturday
  N     ISO-8601 numeric representation of the day of the week                    1 (for Monday) through 7 (for Sunday)
  S     English ordinal suffix for the day of the month, 2 characters             st, nd, rd or th. Works well with j
  w     Numeric representation of the day of the week                             0 (for Sunday) to 6 (for Saturday)
  z     The day of the year (starting from 0)                                     0 to 364 (365 in leap years)
  W     ISO-8601 week number of year, weeks starting on Monday                    01 to 53
  F     A full textual representation of a month, such as January or March        January to December
  m     Numeric representation of a month, with leading zeros                     01 to 12
  M     A short textual representation of a month                                 Jan to Dec
  n     Numeric representation of a month, without leading zeros                  1 to 12
  t     Number of days in the given month                                         28 to 31
  L     Whether it's a leap year                                                  1 if it is a leap year, 0 otherwise.
  o     ISO-8601 year number (identical to (Y), but if the ISO week number (W)    Examples: 1998 or 2004
        belongs to the previous or next year, that year is used instead)
  Y     A full numeric representation of a year, 4 digits                         Examples: 1999 or 2003
  y     A two digit representation of a year                                      Examples: 99 or 03
  a     Lowercase Ante meridiem and Post meridiem                                 am or pm
  A     Uppercase Ante meridiem and Post meridiem                                 AM or PM
  g     12-hour format of an hour without leading zeros                           1 to 12
  G     24-hour format of an hour without leading zeros                           0 to 23
  h     12-hour format of an hour with leading zeros                              01 to 12
  H     24-hour format of an hour with leading zeros                              00 to 23
  i     Minutes, with leading zeros                                               00 to 59
  s     Seconds, with leading zeros                                               00 to 59
  u     Milliseconds, with leading zeros                                          001 to 999
  O     Difference to Greenwich time (GMT) in hours and minutes                   Example: +1030
  P     Difference to Greenwich time (GMT) with colon between hours and minutes   Example: -08:00
  T     Timezone abbreviation of the machine running the code                     Examples: EST, MDT, PDT ...
  Z     Timezone offset in seconds (negative if west of UTC, positive if east)    -43200 to 50400
  c     ISO 8601 date                                                             2007-04-17T15:19:21+08:00
  U     Seconds since the Unix Epoch (January 1 1970 00:00:00 GMT)                1193432466 or -2138434463
</pre>
 *
 * Example usage (note that you must escape format specifiers with '\\' to render them as character literals):
 * <pre><code>
// Sample date:
// 'Wed Jan 10 2007 15:05:01 GMT-0600 (Central Standard Time)'

var dt = new Date('1/10/2007 03:05:01 PM GMT-0600');
document.write(dt.format('Y-m-d'));                         // 2007-01-10
document.write(dt.format('F j, Y, g:i a'));                 // January 10, 2007, 3:05 pm
document.write(dt.format('l, \\t\\he jS of F Y h:i:s A'));  // Wednesday, the 10th of January 2007 03:05:01 PM
 </code></pre>
 *
 * Here are some standard date/time patterns that you might find helpful.  They
 * are not part of the source of Date.js, but to use them you can simply copy this
 * block of code into any script that is included after Date_wev8.js and they will also become
 * globally available on the Date object.  Feel free to add or remove patterns as needed in your code.
 * <pre><code>
Date.patterns = {
    ISO8601Long:"Y-m-d H:i:s",
    ISO8601Short:"Y-m-d",
    ShortDate: "n/j/Y",
    LongDate: "l, F d, Y",
    FullDateTime: "l, F d, Y g:i:s A",
    MonthDay: "F d",
    ShortTime: "g:i A",
    LongTime: "g:i:s A",
    SortableDateTime: "Y-m-d\\TH:i:s",
    UniversalSortableDateTime: "Y-m-d H:i:sO",
    YearMonth: "F, Y"
};
</code></pre>
 *
 * Example usage:
 * <pre><code>
var dt = new Date();
document.write(dt.format(Date.patterns.ShortDate));
 </code></pre>
 */

/*
 * Most of the date-formatting functions below are the excellent work of Baron Schwartz.
 * They generate precompiled functions from date formats instead of parsing and
 * processing the pattern every time you format a date.  These functions are available
 * on every Date object (any javascript function).
 *
 * The original article and download are here:
 * http://www.xaprb.com/blog/2005/12/12/javascript-closures-for-runtime-efficiency/
 *
 */

// private
Date.parseFunctions = {count:0};
// private
Date.parseRegexes = [];
// private
Date.formatFunctions = {count:0};

// private
Date.prototype.dateFormat = function(format) {
    if (Date.formatFunctions[format] == null) {
        Date.createNewFormat(format);
    }
    var func = Date.formatFunctions[format];
    return this[func]();
};


/**
 * Formats a date given the supplied format string.
 * @param {String} format The format string.
 * @return {String} The formatted date.
 * @method
 */
Date.prototype.format = Date.prototype.dateFormat;

// private
Date.createNewFormat = function(format) {
    var funcName = "format" + Date.formatFunctions.count++;
    Date.formatFunctions[format] = funcName;
    var code = "Date.prototype." + funcName + " = function(){return ";
    var special = false;
    var ch = '';
    for (var i = 0; i < format.length; ++i) {
        ch = format.charAt(i);
        if (!special && ch == "\\") {
            special = true;
        }
        else if (special) {
            special = false;
            code += "'" + String.escape(ch) + "' + ";
        }
        else {
            code += Date.getFormatCode(ch);
        }
    }
    eval(code.substring(0, code.length - 3) + ";}");
};

// private
Date.getFormatCode = function(character) {
    switch (character) {
    case "d":
        return "String.leftPad(this.getDate(), 2, '0') + ";
    case "D":
        return "Date.getShortDayName(this.getDay()) + "; // get L10n short day name
    case "j":
        return "this.getDate() + ";
    case "l":
        return "Date.dayNames[this.getDay()] + ";
    case "N":
        return "(this.getDay() ? this.getDay() : 7) + ";
    case "S":
        return "this.getSuffix() + ";
    case "w":
        return "this.getDay() + ";
    case "z":
        return "this.getDayOfYear() + ";
    case "W":
        return "String.leftPad(this.getWeekOfYear(), 2, '0') + ";
    case "F":
        return "Date.monthNames[this.getMonth()] + ";
    case "m":
        return "String.leftPad(this.getMonth() + 1, 2, '0') + ";
    case "M":
        return "Date.getShortMonthName(this.getMonth()) + "; // get L10n short month name
    case "n":
        return "(this.getMonth() + 1) + ";
    case "t":
        return "this.getDaysInMonth() + ";
    case "L":
        return "(this.isLeapYear() ? 1 : 0) + ";
    case "o":
        return "(this.getFullYear() + (this.getWeekOfYear() == 1 && this.getMonth() > 0 ? +1 : (this.getWeekOfYear() >= 52 && this.getMonth() < 11 ? -1 : 0))) + ";
    case "Y":
        return "this.getFullYear() + ";
    case "y":
        return "('' + this.getFullYear()).substring(2, 4) + ";
    case "a":
        return "(this.getHours() < 12 ? 'am' : 'pm') + ";
    case "A":
        return "(this.getHours() < 12 ? 'AM' : 'PM') + ";
    case "g":
        return "((this.getHours() % 12) ? this.getHours() % 12 : 12) + ";
    case "G":
        return "this.getHours() + ";
    case "h":
        return "String.leftPad((this.getHours() % 12) ? this.getHours() % 12 : 12, 2, '0') + ";
    case "H":
        return "String.leftPad(this.getHours(), 2, '0') + ";
    case "i":
        return "String.leftPad(this.getMinutes(), 2, '0') + ";
    case "s":
        return "String.leftPad(this.getSeconds(), 2, '0') + ";
    case "u":
        return "String.leftPad(this.getMilliseconds(), 3, '0') + ";
    case "O":
        return "this.getGMTOffset() + ";
    case "P":
        return "this.getGMTOffset(true) + ";
    case "T":
        return "this.getTimezone() + ";
    case "Z":
        return "(this.getTimezoneOffset() * -60) + ";
    case "c":
        for (var df = Date.getFormatCode, c = "Y-m-dTH:i:sP", code = "", i = 0, l = c.length; i < l; ++i) {
          var e = c.charAt(i);
          code += e == "T" ? "'T' + " : df(e); // treat T as a literal
        }
        return code;
    case "U":
        return "Math.round(this.getTime() / 1000) + ";
    default:
        return "'" + String.escape(character) + "' + ";
    }
};

/**
 * Parses the passed string using the specified format. Note that this function expects dates in normal calendar
 * format, meaning that months are 1-based (1 = January) and not zero-based like in JavaScript dates.  Any part of
 * the date format that is not specified will default to the current date value for that part.  Time parts can also
 * be specified, but default to 0.  Keep in mind that the input date string must precisely match the specified format
 * string or the parse operation will fail.
 * Example Usage:
<pre><code>
//dt = Fri May 25 2007 (current date)
var dt = new Date();

//dt = Thu May 25 2006 (today's month/day in 2006)
dt = Date.parseDate("2006", "Y");

//dt = Sun Jan 15 2006 (all date parts specified)
dt = Date.parseDate("2006-01-15", "Y-m-d");

//dt = Sun Jan 15 2006 15:20:01 GMT-0600 (CST)
dt = Date.parseDate("2006-01-15 3:20:01 PM", "Y-m-d h:i:s A" );
</code></pre>
 * @param {String} input The unparsed date as a string.
 * @param {String} format The format the date is in.
 * @return {Date} The parsed date.
 * @static
 */
Date.parseDate = function(input, format) {
    if (Date.parseFunctions[format] == null) {
        Date.createParser(format);
    }
    var func = Date.parseFunctions[format];
    return Date[func](input);
};

// private
Date.createParser = function(format) {
    var funcName = "parse" + Date.parseFunctions.count++;
    var regexNum = Date.parseRegexes.length;
    var currentGroup = 1;
    Date.parseFunctions[format] = funcName;

    var code = "Date." + funcName + " = function(input){\n"
        + "var y = -1, m = -1, d = -1, h = -1, i = -1, s = -1, ms = -1, o, z, u, v;\n"
        + "input = String(input);var d = new Date();\n"
        + "y = d.getFullYear();\n"
        + "m = d.getMonth();\n"
        + "d = d.getDate();\n"
        + "var results = input.match(Date.parseRegexes[" + regexNum + "]);\n"
        + "if (results && results.length > 0) {";
    var regex = "";

    var special = false;
    var ch = '';
    for (var i = 0; i < format.length; ++i) {
        ch = format.charAt(i);
        if (!special && ch == "\\") {
            special = true;
        }
        else if (special) {
            special = false;
            regex += String.escape(ch);
        }
        else {
            var obj = Date.formatCodeToRegex(ch, currentGroup);
            currentGroup += obj.g;
            regex += obj.s;
            if (obj.g && obj.c) {
                code += obj.c;
            }
        }
    }

    code += "if (u)\n"
        + "{v = new Date(u * 1000);}" // give top priority to UNIX time
        + "else if (y >= 0 && m >= 0 && d > 0 && h >= 0 && i >= 0 && s >= 0 && ms >= 0)\n"
        + "{v = new Date(y, m, d, h, i, s, ms);}\n"
        + "else if (y >= 0 && m >= 0 && d > 0 && h >= 0 && i >= 0 && s >= 0)\n"
        + "{v = new Date(y, m, d, h, i, s);}\n"
        + "else if (y >= 0 && m >= 0 && d > 0 && h >= 0 && i >= 0)\n"
        + "{v = new Date(y, m, d, h, i);}\n"
        + "else if (y >= 0 && m >= 0 && d > 0 && h >= 0)\n"
        + "{v = new Date(y, m, d, h);}\n"
        + "else if (y >= 0 && m >= 0 && d > 0)\n"
        + "{v = new Date(y, m, d);}\n"
        + "else if (y >= 0 && m >= 0)\n"
        + "{v = new Date(y, m);}\n"
        + "else if (y >= 0)\n"
        + "{v = new Date(y);}\n"
        + "}return (v && (z || o))?\n" // favour UTC offset over GMT offset
        + "    (z ? v.add(Date.SECOND, (v.getTimezoneOffset() * 60) + (z*1)) :\n" // reset to UTC, then add offset
        + "        v.add(Date.HOUR, (v.getGMTOffset() / 100) + (o / -100))) : v\n" // reset to GMT, then add offset
        + ";}";

    Date.parseRegexes[regexNum] = new RegExp("^" + regex + "$", "i");
    eval(code);
};

// private
Date.formatCodeToRegex = function(character, currentGroup) {
    /*
     * currentGroup = position in regex result array
     * g = calculation group (0 or 1. only group 1 contributes to date calculations.)
     * c = calculation method (required for group 1. null for group 0.)
     * s = regex string
     */
    switch (character) {
    case "d":
        return {g:1,
            c:"d = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{2})"}; // day of month with leading zeroes (01 - 31)
    case "D":
        for (var a = [], i = 0; i < 7; a.push(Date.getShortDayName(i)), ++i); // get L10n short day names
        return {g:0,
            c:null,
            s:"(?:" + a.join("|") +")"};
    case "j":
        return {g:1,
            c:"d = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{1,2})"}; // day of month without leading zeroes (1 - 31)
    case "l":
        return {g:0,
            c:null,
            s:"(?:" + Date.dayNames.join("|") + ")"};
    case "N":
        return {g:0,
            c:null,
            s:"[1-7]"}; // ISO-8601 day number (1 (monday) - 7 (sunday))
    case "S":
        return {g:0,
            c:null,
            s:"(?:st|nd|rd|th)"};
    case "w":
        return {g:0,
            c:null,
            s:"[0-6]"}; // javascript day number (0 (sunday) - 6 (saturday))
    case "z":
        return {g:0,
            c:null,
            s:"(?:\\d{1,3}"}; // day of the year (0 - 364 (365 in leap years))
    case "W":
        return {g:0,
            c:null,
            s:"(?:\\d{2})"}; // ISO-8601 week number (with leading zero)
    case "F":
        return {g:1,
            c:"m = parseInt(Date.getMonthNumber(results[" + currentGroup + "]), 10);\n", // get L10n month number
            s:"(" + Date.monthNames.join("|") + ")"};
    case "m":
        return {g:1,
            c:"m = parseInt(results[" + currentGroup + "], 10) - 1;\n",
            s:"(\\d{2})"}; // month number with leading zeros (01 - 12)
    case "M":
        for (var a = [], i = 0; i < 12; a.push(Date.getShortMonthName(i)), ++i); // get L10n short month names
        return {g:1,
            c:"m = parseInt(Date.getMonthNumber(results[" + currentGroup + "]), 10);\n", // get L10n month number
            s:"(" + a.join("|") + ")"};
    case "n":
        return {g:1,
            c:"m = parseInt(results[" + currentGroup + "], 10) - 1;\n",
            s:"(\\d{1,2})"}; // month number without leading zeros (1 - 12)
    case "t":
        return {g:0,
            c:null,
            s:"(?:\\d{2})"}; // no. of days in the month (28 - 31)
    case "L":
        return {g:0,
            c:null,
            s:"(?:1|0)"};
    case "o":
    case "Y":
        return {g:1,
            c:"y = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{4})"}; // 4-digit year
    case "y":
        return {g:1,
            c:"var ty = parseInt(results[" + currentGroup + "], 10);\n"
                + "y = ty > Date.y2kYear ? 1900 + ty : 2000 + ty;\n",
            s:"(\\d{1,2})"}; // 2-digit year
    case "a":
        return {g:1,
            c:"if (results[" + currentGroup + "] == 'am') {\n"
                + "if (h == 12) { h = 0; }\n"
                + "} else { if (h < 12) { h += 12; }}",
            s:"(am|pm)"};
    case "A":
        return {g:1,
            c:"if (results[" + currentGroup + "] == 'AM') {\n"
                + "if (h == 12) { h = 0; }\n"
                + "} else { if (h < 12) { h += 12; }}",
            s:"(AM|PM)"};
    case "g":
    case "G":
        return {g:1,
            c:"h = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{1,2})"}; // 24-hr format of an hour without leading zeroes (0 - 23)
    case "h":
    case "H":
        return {g:1,
            c:"h = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{2})"}; //  24-hr format of an hour with leading zeroes (00 - 23)
    case "i":
        return {g:1,
            c:"i = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{2})"}; // minutes with leading zeros (00 - 59)
    case "s":
        return {g:1,
            c:"s = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{2})"}; // seconds with leading zeros (00 - 59)
    case "u":
        return {g:1,
            c:"ms = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(\\d{3})"}; // milliseconds with leading zeros (000 - 999)
    case "O":
        return {g:1,
            c:[
                "o = results[", currentGroup, "];\n",
                "var sn = o.substring(0,1);\n", // get + / - sign
                "var hr = o.substring(1,3)*1 + Math.floor(o.substring(3,5) / 60);\n", // get hours (performs minutes-to-hour conversion also, just in case)
                "var mn = o.substring(3,5) % 60;\n", // get minutes
                "o = ((-12 <= (hr*60 + mn)/60) && ((hr*60 + mn)/60 <= 14))?\n", // -12hrs <= GMT offset <= 14hrs
                "    (sn + String.leftPad(hr, 2, '0') + String.leftPad(mn, 2, '0')) : null;\n"
            ].join(""),
            s: "([+\-]\\d{4})"}; // GMT offset in hrs and mins
    case "P":
        return {g:1,
            c:[
                "o = results[", currentGroup, "];\n",
                "var sn = o.substring(0,1);\n", // get + / - sign
                "var hr = o.substring(1,3)*1 + Math.floor(o.substring(4,6) / 60);\n", // get hours (performs minutes-to-hour conversion also, just in case)
                "var mn = o.substring(4,6) % 60;\n", // get minutes
                "o = ((-12 <= (hr*60 + mn)/60) && ((hr*60 + mn)/60 <= 14))?\n", // -12hrs <= GMT offset <= 14hrs
                "    (sn + String.leftPad(hr, 2, '0') + String.leftPad(mn, 2, '0')) : null;\n"
            ].join(""),
            s: "([+\-]\\d{2}:\\d{2})"}; // GMT offset in hrs and mins (with colon separator)
    case "T":
        return {g:0,
            c:null,
            s:"[A-Z]{1,4}"}; // timezone abbrev. may be between 1 - 4 chars
    case "Z":
        return {g:1,
            c:"z = results[" + currentGroup + "] * 1;\n" // -43200 <= UTC offset <= 50400
                  + "z = (-43200 <= z && z <= 50400)? z : null;\n",
            s:"([+\-]?\\d{1,5})"}; // leading '+' sign is optional for UTC offset
    case "c":
        var df = Date.formatCodeToRegex, calc = [];
        var arr = [df("Y", 1), df("m", 2), df("d", 3), df("h", 4), df("i", 5), df("s", 6), df("P", 7)];
        for (var i = 0, l = arr.length; i < l; ++i) {
          calc.push(arr[i].c);
        }
        return {g:1,
            c:calc.join(""),
            s:arr[0].s + "-" + arr[1].s + "-" + arr[2].s + "T" + arr[3].s + ":" + arr[4].s + ":" + arr[5].s + arr[6].s};
    case "U":
        return {g:1,
            c:"u = parseInt(results[" + currentGroup + "], 10);\n",
            s:"(-?\\d+)"}; // leading minus sign indicates seconds before UNIX epoch
    default:
        return {g:0,
            c:null,
            s:Ext.escapeRe(character)};
    }
};

/**
 * Get the timezone abbreviation of the current date (equivalent to the format specifier 'T').
 *
 * Note: The date string returned by the javascript Date object's toString() method varies
 * between browsers (e.g. FF vs IE) and system region settings (e.g. IE in Asia vs IE in America).
 * For a given date string e.g. "Thu Oct 25 2007 22:55:35 GMT+0800 (Malay Peninsula Standard Time)",
 * getTimezone() first tries to get the timezone abbreviation from between a pair of parentheses
 * (which may or may not be present), failing which it proceeds to get the timezone abbreviation
 * from the GMT offset portion of the date string.
 * @return {String} The abbreviated timezone name (e.g. 'CST', 'PDT', 'EDT', 'MPST' ...).
 */
Date.prototype.getTimezone = function() {
    // the following list shows the differences between date strings from different browsers on a WinXP SP2 machine from an Asian locale:
    //
    // Opera  : "Thu, 25 Oct 2007 22:53:45 GMT+0800" -- shortest (weirdest) date string of the lot
    // Safari : "Thu Oct 25 2007 22:55:35 GMT+0800 (Malay Peninsula Standard Time)" -- value in parentheses always gives the correct timezone (same as FF)
    // FF     : "Thu Oct 25 2007 22:55:35 GMT+0800 (Malay Peninsula Standard Time)" -- value in parentheses always gives the correct timezone
    // IE     : "Thu Oct 25 22:54:35 UTC+0800 2007" -- (Asian system setting) look for 3-4 letter timezone abbrev
    // IE     : "Thu Oct 25 17:06:37 PDT 2007" -- (American system setting) look for 3-4 letter timezone abbrev
    //
    // this crazy regex attempts to guess the correct timezone abbreviation despite these differences.
    // step 1: (?:\((.*)\) -- find timezone in parentheses
    // step 2: ([A-Z]{1,4})(?:[\-+][0-9]{4})?(?: -?\d+)?) -- if nothing was found in step 1, find timezone from timezone offset portion of date string
    // step 3: remove all non uppercase characters found in step 1 and 2
    return this.toString().replace(/^.* (?:\((.*)\)|([A-Z]{1,4})(?:[\-+][0-9]{4})?(?: -?\d+)?)$/, "$1$2").replace(/[^A-Z]/g, "");
};

/**
 * Get the offset from GMT of the current date (equivalent to the format specifier 'O').
 * @param {Boolean} colon true to separate the hours and minutes with a colon (defaults to false).
 * @return {String} The 4-character offset string prefixed with + or - (e.g. '-0600').
 */
Date.prototype.getGMTOffset = function(colon) {
    return (this.getTimezoneOffset() > 0 ? "-" : "+")
        + String.leftPad(Math.abs(Math.floor(this.getTimezoneOffset() / 60)), 2, "0")
        + (colon ? ":" : "")
        + String.leftPad(this.getTimezoneOffset() % 60, 2, "0");
};

/**
 * Get the numeric day number of the year, adjusted for leap year.
 * @return {Number} 0 to 364 (365 in leap years).
 */
Date.prototype.getDayOfYear = function() {
    var num = 0;
    Date.daysInMonth[1] = this.isLeapYear() ? 29 : 28;
    for (var i = 0; i < this.getMonth(); ++i) {
        num += Date.daysInMonth[i];
    }
    return num + this.getDate() - 1;
};

/**
 * Get the numeric ISO-8601 week number of the year.
 * (equivalent to the format specifier 'W', but without a leading zero).
 * @return {Number} 1 to 53
 */
Date.prototype.getWeekOfYear = function() {
    // adapted from http://www.merlyn.demon.co.uk/weekcalc.htm
    var ms1d = 864e5; // milliseconds in a day
    var ms7d = 7 * ms1d; // milliseconds in a week
    var DC3 = Date.UTC(this.getFullYear(), this.getMonth(), this.getDate() + 3) / ms1d; // an Absolute Day Number
    var AWN = Math.floor(DC3 / 7); // an Absolute Week Number
    var Wyr = new Date(AWN * ms7d).getUTCFullYear();
    return AWN - Math.floor(Date.UTC(Wyr, 0, 7) / ms7d) + 1;
};

/**
 * Whether or not the current date is in a leap year.
 * @return {Boolean} True if the current date is in a leap year, else false.
 */
Date.prototype.isLeapYear = function() {
    var year = this.getFullYear();
    return !!((year & 3) == 0 && (year % 100 || (year % 400 == 0 && year)));
};

/**
 * Get the first day of the current month, adjusted for leap year.  The returned value
 * is the numeric day index within the week (0-6) which can be used in conjunction with
 * the {@link #monthNames} array to retrieve the textual day name.
 * Example:
 *<pre><code>
var dt = new Date('1/10/2007');
document.write(Date.dayNames[dt.getFirstDayOfMonth()]); //output: 'Monday'
</code></pre>
 * @return {Number} The day number (0-6).
 */
Date.prototype.getFirstDayOfMonth = function() {
    var day = (this.getDay() - (this.getDate() - 1)) % 7;
    return (day < 0) ? (day + 7) : day;
};

/**
 * Get the last day of the current month, adjusted for leap year.  The returned value
 * is the numeric day index within the week (0-6) which can be used in conjunction with
 * the {@link #monthNames} array to retrieve the textual day name.
 * Example:
 *<pre><code>
var dt = new Date('1/10/2007');
document.write(Date.dayNames[dt.getLastDayOfMonth()]); //output: 'Wednesday'
</code></pre>
 * @return {Number} The day number (0-6).
 */
Date.prototype.getLastDayOfMonth = function() {
    var day = (this.getDay() + (Date.daysInMonth[this.getMonth()] - this.getDate())) % 7;
    return (day < 0) ? (day + 7) : day;
};


/**
 * Get the date of the first day of the month in which this date resides.
 * @return {Date}
 */
Date.prototype.getFirstDateOfMonth = function() {
    return new Date(this.getFullYear(), this.getMonth(), 1);
};

/**
 * Get the date of the last day of the month in which this date resides.
 * @return {Date}
 */
Date.prototype.getLastDateOfMonth = function() {
    return new Date(this.getFullYear(), this.getMonth(), this.getDaysInMonth());
};
/**
 * Get the number of days in the current month, adjusted for leap year.
 * @return {Number} The number of days in the month.
 */
Date.prototype.getDaysInMonth = function() {
    Date.daysInMonth[1] = this.isLeapYear() ? 29 : 28;
    return Date.daysInMonth[this.getMonth()];
};

/**
 * Get the English ordinal suffix of the current day (equivalent to the format specifier 'S').
 * @return {String} 'st, 'nd', 'rd' or 'th'.
 */
Date.prototype.getSuffix = function() {
    switch (this.getDate()) {
        case 1:
        case 21:
        case 31:
            return "st";
        case 2:
        case 22:
            return "nd";
        case 3:
        case 23:
            return "rd";
        default:
            return "th";
    }
};

// private
Date.daysInMonth = [31,28,31,30,31,30,31,31,30,31,30,31];

/**
 * An array of textual month names.
 * Override these values for international dates, for example...
 * Date.monthNames = ['JanInYourLang', 'FebInYourLang', ...];
 * @type Array
 * @static
 */
Date.monthNames =
   ["January",
    "February",
    "March",
    "April",
    "May",
    "June",
    "July",
    "August",
    "September",
    "October",
    "November",
    "December"];

/**
 * Get the short month name for the given month number.
 * Override this function for international dates.
 * @param {Number} month A zero-based javascript month number.
 * @return {String} The short month name.
 * @static
 */
Date.getShortMonthName = function(month) {
    return Date.monthNames[month].substring(0, 3);
}

/**
 * An array of textual day names.
 * Override these values for international dates, for example...
 * Date.dayNames = ['SundayInYourLang', 'MondayInYourLang', ...];
 * @type Array
 * @static
 */
Date.dayNames =
   ["Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday"];

/**
 * Get the short day name for the given day number.
 * Override this function for international dates.
 * @param {Number} day A zero-based javascript day number.
 * @return {String} The short day name.
 * @static
 */
Date.getShortDayName = function(day) {
    return Date.dayNames[day].substring(0, 3);
}

// private
Date.y2kYear = 50;

/**
 * An object hash of zero-based javascript month numbers (with short month names as keys. note: keys are case-sensitive).
 * Override these values for international dates, for example...
 * Date.monthNumbers = {'ShortJanNameInYourLang':0, 'ShortFebNameInYourLang':1, ...};
 * @type Object
 * @static
 */
Date.monthNumbers = {
    Jan:0,
    Feb:1,
    Mar:2,
    Apr:3,
    May:4,
    Jun:5,
    Jul:6,
    Aug:7,
    Sep:8,
    Oct:9,
    Nov:10,
    Dec:11};

/**
 * Get the zero-based javascript month number for the given short/full month name.
 * Override this function for international dates.
 * @param {String} name The short/full month name.
 * @return {Number} The zero-based javascript month number.
 * @static
 */
Date.getMonthNumber = function(name) {
    // handle camel casing for english month names (since the keys for the Date.monthNumbers hash are case sensitive)
    return Date.monthNumbers[name.substring(0, 1).toUpperCase() + name.substring(1, 3).toLowerCase()];
}

/**
 * Creates and returns a new Date instance with the exact same date value as the called instance.
 * Dates are copied and passed by reference, so if a copied date variable is modified later, the original
 * variable will also be changed.  When the intention is to create a new variable that will not
 * modify the original instance, you should create a clone.
 *
 * Example of correctly cloning a date:
 * <pre><code>
//wrong way:
var orig = new Date('10/1/2006');
var copy = orig;
copy.setDate(5);
document.write(orig);  //returns 'Thu Oct 05 2006'!

//correct way:
var orig = new Date('10/1/2006');
var copy = orig.clone();
copy.setDate(5);
document.write(orig);  //returns 'Thu Oct 01 2006'
</code></pre>
 * @return {Date} The new Date instance.
 */
Date.prototype.clone = function() {
  return new Date(this.getTime());
};

/**
 * Clears any time information from this date.
 @param {Boolean} clone true to create a clone of this date, clear the time and return it (defaults to false).
 @return {Date} this or the clone.
 */
Date.prototype.clearTime = function(clone){
    if(clone){
        return this.clone().clearTime();
    }
    this.setHours(0);
    this.setMinutes(0);
    this.setSeconds(0);
    this.setMilliseconds(0);
    return this;
};

// private
// safari setMonth is broken
if(Ext.isSafari){
    Date.brokenSetMonth = Date.prototype.setMonth;
  Date.prototype.setMonth = function(num){
    if(num <= -1){
      var n = Math.ceil(-num);
      var back_year = Math.ceil(n/12);
      var month = (n % 12) ? 12 - n % 12 : 0 ;
      this.setFullYear(this.getFullYear() - back_year);
      return Date.brokenSetMonth.call(this, month);
    } else {
      return Date.brokenSetMonth.apply(this, arguments);
    }
  };
}

/** Date interval constant @static @type String */
Date.MILLI = "ms";
/** Date interval constant @static @type String */
Date.SECOND = "s";
/** Date interval constant @static @type String */
Date.MINUTE = "mi";
/** Date interval constant @static @type String */
Date.HOUR = "h";
/** Date interval constant @static @type String */
Date.DAY = "d";
/** Date interval constant @static @type String */
Date.MONTH = "mo";
/** Date interval constant @static @type String */
Date.YEAR = "y";

/**
 * Provides a convenient method of performing basic date arithmetic.  This method
 * does not modify the Date instance being called - it creates and returns
 * a new Date instance containing the resulting date value.
 *
 * Examples:
 * <pre><code>
//Basic usage:
var dt = new Date('10/29/2006').add(Date.DAY, 5);
document.write(dt); //returns 'Fri Oct 06 2006 00:00:00'

//Negative values will subtract correctly:
var dt2 = new Date('10/1/2006').add(Date.DAY, -5);
document.write(dt2); //returns 'Tue Sep 26 2006 00:00:00'

//You can even chain several calls together in one line!
var dt3 = new Date('10/1/2006').add(Date.DAY, 5).add(Date.HOUR, 8).add(Date.MINUTE, -30);
document.write(dt3); //returns 'Fri Oct 06 2006 07:30:00'
 </code></pre>
 *
 * @param {String} interval   A valid date interval enum value.
 * @param {Number} value      The amount to add to the current date.
 * @return {Date} The new Date instance.
 */
Date.prototype.add = function(interval, value){
  var d = this.clone();
  if (!interval || value === 0) return d;
  switch(interval.toLowerCase()){
    case Date.MILLI:
      d.setMilliseconds(this.getMilliseconds() + value);
      break;
    case Date.SECOND:
      d.setSeconds(this.getSeconds() + value);
      break;
    case Date.MINUTE:
      d.setMinutes(this.getMinutes() + value);
      break;
    case Date.HOUR:
      d.setHours(this.getHours() + value);
      break;
    case Date.DAY:
      d.setDate(this.getDate() + value);
      break;
    case Date.MONTH:
      var day = this.getDate();
      if(day > 28){
          day = Math.min(day, this.getFirstDateOfMonth().add('mo', value).getLastDateOfMonth().getDate());
      }
      d.setDate(day);
      d.setMonth(this.getMonth() + value);
      break;
    case Date.YEAR:
      d.setFullYear(this.getFullYear() + value);
      break;
  }
  return d;
};

/**
 * Checks if this date falls on or between the given start and end dates.
 * @param {Date} start Start date
 * @param {Date} end End date
 * @return {Boolean} true if this date falls on or between the given start and end dates.
 */
Date.prototype.between = function(start, end){
    var t = this.getTime();
    return start.getTime() <= t && t <= end.getTime();
}