// ===================================================================
// Author: Matt Kruse <matt@mattkruse.com>
// WWW: http://www.mattkruse.com/
//
// NOTICE: You may use this code for any purpose, commercial or
// private, without any further permission from the author. You may
// remove this notice from your final code if you wish, however it is
// appreciated by the author if at least my web site address is kept.
//
// You may *NOT* re-distribute this code in any way except through its
// use. That means, you can include it in your product, or your web
// site, or any other form where the code is actually being used. You
// may not put the plain javascript up on your site for download or
// include it in your javascript libraries for download. 
// If you wish to share this code with others, please just point them
// to the URL instead.
// Please DO NOT link directly to my .js files from your site. Copy
// the files to your server and use them there. Thank you.
// ===================================================================

// HISTORY
// ------------------------------------------------------------------
// May 17, 2003: Fixed bug in parseDate() for dates <1970
// March 11, 2003: Added parseDate() function
// March 11, 2003: Added "NNN" formatting option. Doesn't match up
//                 perfectly with SimpleDateFormat formats, but 
//                 backwards-compatability was required.

// ------------------------------------------------------------------
// These functions use the same 'format' strings as the 
// java.text.SimpleDateFormat class, with minor exceptions.
// The format string consists of the following abbreviations:
// 
// Field        | Full Form          | Short Form
// -------------+--------------------+-----------------------
// Year         | yyyy (4 digits)    | yy (2 digits), y (2 or 4 digits)
// Month        | MMM (name or abbr.)| MM (2 digits), M (1 or 2 digits)
//              | NNN (abbr.)        |
// Day of Month | dd (2 digits)      | d (1 or 2 digits)
// Day of Week  | EE (name)          | E (abbr)
// Hour (1-12)  | hh (2 digits)      | h (1 or 2 digits)
// Hour (0-23)  | HH (2 digits)      | H (1 or 2 digits)
// Hour (0-11)  | KK (2 digits)      | K (1 or 2 digits)
// Hour (1-24)  | kk (2 digits)      | k (1 or 2 digits)
// Minute       | mm (2 digits)      | m (1 or 2 digits)
// Second       | ss (2 digits)      | s (1 or 2 digits)
// AM/PM        | a                  |
//
// NOTE THE DIFFERENCE BETWEEN MM and mm! Month=MM, not mm!
// Examples:
//  "MMM d, y" matches: January 01, 2000
//                      Dec 1, 1900
//                      Nov 20, 00
//  "M/d/yy"   matches: 01/20/00
//                      9/2/00
//  "MMM dd, yyyy hh:mm:ssa" matches: "January 01, 2000 12:30:45AM"
// ------------------------------------------------------------------

var MONTH_NAMES = new Array('January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December', 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec');
var DAY_NAMES = new Array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat');
function LZ(x) { return (x < 0 || x > 9 ? "" : "0") + x }

// ------------------------------------------------------------------
// isDate ( date_string, format_string )
// Returns true if date string matches format of format string and
// is a valid date. Else returns false.
// It is recommended that you trim whitespace around the value before
// passing it to this function, as whitespace is NOT ignored!
// ------------------------------------------------------------------
function isDate(val, format) {
    var date = getDateFromFormat(val, format);
    if (date == 0) { return false; }
    return true;
}

// -------------------------------------------------------------------
// compareDates(date1,date1format,date2,date2format)
//   Compare two date strings to see which is greater.
//   Returns:
//   1 if date1 is greater than date2
//   0 if date2 is greater than date1 of if they are the same
//  -1 if either of the dates is in an invalid format
// -------------------------------------------------------------------
function compareDates(date1, dateformat1, date2, dateformat2) {
    var d1 = getDateFromFormat(date1, dateformat1);
    var d2 = getDateFromFormat(date2, dateformat2);
    if (d1 == 0 || d2 == 0) {
        return -1;
    }
    else if (d1 > d2) {
        return 1;
    }
    return 0;
}

// ------------------------------------------------------------------
// formatDate (date_object, format)
// Returns a date in the output format specified.
// The format string uses the same abbreviations as in getDateFromFormat()
// ------------------------------------------------------------------
function formatDate(date, format) {
    format = format + "";
    var result = "";
    var i_format = 0;
    var c = "";
    var token = "";
    var y = date.getYear() + "";
    var M = date.getMonth() + 1;
    var d = date.getDate();
    var E = date.getDay();
    var H = date.getHours();
    var m = date.getMinutes();
    var s = date.getSeconds();
    var yyyy, yy, MMM, MM, dd, hh, h, mm, ss, ampm, HH, H, KK, K, kk, k;
    // Convert real date parts into formatted versions
    var value = new Object();
    if (y.length < 4) { y = "" + (y - 0 + 1900); }
    value["y"] = "" + y;
    value["yyyy"] = y;
    value["yy"] = y.substring(2, 4);
    value["M"] = M;
    value["MM"] = LZ(M);
    value["MMM"] = MONTH_NAMES[M - 1];
    value["NNN"] = MONTH_NAMES[M + 11];
    value["d"] = d;
    value["dd"] = LZ(d);
    value["E"] = DAY_NAMES[E + 7];
    value["EE"] = DAY_NAMES[E];
    value["H"] = H;
    value["HH"] = LZ(H);
    if (H == 0) { value["h"] = 12; }
    else if (H > 12) { value["h"] = H - 12; }
    else { value["h"] = H; }
    value["hh"] = LZ(value["h"]);
    if (H > 11) { value["K"] = H - 12; } else { value["K"] = H; }
    value["k"] = H + 1;
    value["KK"] = LZ(value["K"]);
    value["kk"] = LZ(value["k"]);
    if (H > 11) { value["a"] = "PM"; }
    else { value["a"] = "AM"; }
    value["m"] = m;
    value["mm"] = LZ(m);
    value["s"] = s;
    value["ss"] = LZ(s);
    while (i_format < format.length) {
        c = format.charAt(i_format);
        token = "";
        while ((format.charAt(i_format) == c) && (i_format < format.length)) {
            token += format.charAt(i_format++);
        }
        if (value[token] != null) { result = result + value[token]; }
        else { result = result + token; }
    }
    return result;
}

// ------------------------------------------------------------------
// Utility functions for parsing in getDateFromFormat()
// ------------------------------------------------------------------
function _isInteger(val) {
    var digits = "1234567890";
    for (var i = 0; i < val.length; i++) {
        if (digits.indexOf(val.charAt(i)) == -1) { return false; }
    }
    return true;
}
function _getInt(str, i, minlength, maxlength) {
    for (var x = maxlength; x >= minlength; x--) {
        var token = str.substring(i, i + x);
        if (token.length < minlength) { return null; }
        if (_isInteger(token)) { return token; }
    }
    return null;
}

// ------------------------------------------------------------------
// getDateFromFormat( date_string , format_string )
//
// This function takes a date string and a format string. It matches
// If the date string matches the format string, it returns the 
// getTime() of the date. If it does not match, it returns 0.
// ------------------------------------------------------------------
function getDateFromFormat(val, format) {
    val = val + "";
    format = format + "";
    var i_val = 0;
    var i_format = 0;
    var c = "";
    var token = "";
    var token2 = "";
    var x, y;
    var now = new Date();
    var year = now.getYear();
    var month = now.getMonth() + 1;
    var date = 1;
    var hh = now.getHours();
    var mm = now.getMinutes();
    var ss = now.getSeconds();
    var ampm = "";

    while (i_format < format.length) {
        // Get next token from format string
        c = format.charAt(i_format);
        token = "";
        while ((format.charAt(i_format) == c) && (i_format < format.length)) {
            token += format.charAt(i_format++);
        }
        // Extract contents of value based on format token
        if (token == "yyyy" || token == "yy" || token == "y") {
            if (token == "yyyy") { x = 4; y = 4; }
            if (token == "yy") { x = 2; y = 2; }
            if (token == "y") { x = 2; y = 4; }
            year = _getInt(val, i_val, x, y);
            if (year == null) { return 0; }
            i_val += year.length;
            if (year.length == 2) {
                if (year > 70) { year = 1900 + (year - 0); }
                else { year = 2000 + (year - 0); }
            }
        }
        else if (token == "MMM" || token == "NNN") {
            month = 0;
            for (var i = 0; i < MONTH_NAMES.length; i++) {
                var month_name = MONTH_NAMES[i];
                if (val.substring(i_val, i_val + month_name.length).toLowerCase() == month_name.toLowerCase()) {
                    if (token == "MMM" || (token == "NNN" && i > 11)) {
                        month = i + 1;
                        if (month > 12) { month -= 12; }
                        i_val += month_name.length;
                        break;
                    }
                }
            }
            if ((month < 1) || (month > 12)) { return 0; }
        }
        else if (token == "EE" || token == "E") {
            for (var i = 0; i < DAY_NAMES.length; i++) {
                var day_name = DAY_NAMES[i];
                if (val.substring(i_val, i_val + day_name.length).toLowerCase() == day_name.toLowerCase()) {
                    i_val += day_name.length;
                    break;
                }
            }
        }
        else if (token == "MM" || token == "M") {
            month = _getInt(val, i_val, token.length, 2);
            if (month == null || (month < 1) || (month > 12)) { return 0; }
            i_val += month.length;
        }
        else if (token == "dd" || token == "d") {
            date = _getInt(val, i_val, token.length, 2);
            if (date == null || (date < 1) || (date > 31)) { return 0; }
            i_val += date.length;
        }
        else if (token == "hh" || token == "h") {
            hh = _getInt(val, i_val, token.length, 2);
            if (hh == null || (hh < 1) || (hh > 12)) { return 0; }
            i_val += hh.length;
        }
        else if (token == "HH" || token == "H") {
            hh = _getInt(val, i_val, token.length, 2);
            if (hh == null || (hh < 0) || (hh > 23)) { return 0; }
            i_val += hh.length;
        }
        else if (token == "KK" || token == "K") {
            hh = _getInt(val, i_val, token.length, 2);
            if (hh == null || (hh < 0) || (hh > 11)) { return 0; }
            i_val += hh.length;
        }
        else if (token == "kk" || token == "k") {
            hh = _getInt(val, i_val, token.length, 2);
            if (hh == null || (hh < 1) || (hh > 24)) { return 0; }
            i_val += hh.length; hh--;
        }
        else if (token == "mm" || token == "m") {
            mm = _getInt(val, i_val, token.length, 2);
            if (mm == null || (mm < 0) || (mm > 59)) { return 0; }
            i_val += mm.length;
        }
        else if (token == "ss" || token == "s") {
            ss = _getInt(val, i_val, token.length, 2);
            if (ss == null || (ss < 0) || (ss > 59)) { return 0; }
            i_val += ss.length;
        }
        else if (token == "a") {
            if (val.substring(i_val, i_val + 2).toLowerCase() == "am") { ampm = "AM"; }
            else if (val.substring(i_val, i_val + 2).toLowerCase() == "pm") { ampm = "PM"; }
            else { return 0; }
            i_val += 2;
        }
        else {
            if (val.substring(i_val, i_val + token.length) != token) { return 0; }
            else { i_val += token.length; }
        }
    }
    // If there are any trailing characters left in the value, it doesn't match
    if (i_val != val.length) { return 0; }
    // Is date valid for month?
    if (month == 2) {
        // Check for leap year
        if (((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0)) { // leap year
            if (date > 29) { return 0; }
        }
        else { if (date > 28) { return 0; } }
    }
    if ((month == 4) || (month == 6) || (month == 9) || (month == 11)) {
        if (date > 30) { return 0; }
    }
    // Correct hours value
    if (hh < 12 && ampm == "PM") { hh = hh - 0 + 12; }
    else if (hh > 11 && ampm == "AM") { hh -= 12; }
    var newdate = new Date(year, month - 1, date, hh, mm, ss);
    return newdate.getTime();
}

// ------------------------------------------------------------------
// parseDate( date_string [, prefer_euro_format] )
//
// This function takes a date string and tries to match it to a
// number of possible date formats to get the value. It will try to
// match against the following international formats, in this order:
// y-M-d   MMM d, y   MMM d,y   y-MMM-d   d-MMM-y  MMM d
// M/d/y   M-d-y      M.d.y     MMM-d     M/d      M-d
// d/M/y   d-M-y      d.M.y     d-MMM     d/M      d-M
// A second argument may be passed to instruct the method to search
// for formats like d/M/y (european format) before M/d/y (American).
// Returns a Date object or null if no patterns match.
// ------------------------------------------------------------------
function parseDate(val) {
    var preferEuro = (arguments.length == 2) ? arguments[1] : false;
    generalFormats = new Array('y-M-d', 'MMM d, y', 'MMM d,y', 'y-MMM-d', 'd-MMM-y', 'MMM d');
    monthFirst = new Array('M/d/y', 'M-d-y', 'M.d.y', 'MMM-d', 'M/d', 'M-d');
    dateFirst = new Array('d/M/y', 'd-M-y', 'd.M.y', 'd-MMM', 'd/M', 'd-M');
    var checkList = new Array('generalFormats', preferEuro ? 'dateFirst' : 'monthFirst', preferEuro ? 'monthFirst' : 'dateFirst');
    var d = null;
    for (var i = 0; i < checkList.length; i++) {
        var l = window[checkList[i]];
        for (var j = 0; j < l.length; j++) {
            d = getDateFromFormat(val, l[j]);
            if (d != 0) { return new Date(d); }
        }
    }
    return null;
}