/*
*  $Id: dateextensions.js 43 2006-08-17 19:11:44Z wingedfox $
*  $HeadURL: https://svn.debugger.ru/repos/jslibs/BrowserExtensions/tags/BrowserExtensions.003/dateextensions.js $
*
*  Extension implements additional methods to operate with Date object
*  @author Ilya Lebedev <ilya@lebedev.net>
*  @modified $Date: 2006-08-17 23:11:44 +0400 (Чтв, 17 Авг 2006) $
*  @version $Rev: 43 $
*  @license LGPL 2.1 or later
*/
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');

/*
*  leap year check
*
*  @return bool check result
*  @access public
*/
Date.prototype.isLeapYear = function () {
  var y = this.getFullYear();
  return (y % 4 == 0  &&  y % 100 != 0) || y % 400 == 0;
}
/*
*  the day of year number
*
*  @return int day of year
*  @access public
*/
Date.prototype.getDayOfYear = function () {
   var md = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334],
       m = this.getMonth(),
       d = this.getDate()+md[m];
   return this.isLeapYear()&&m>2?d+1:d;
}
/*
*  return year according to Iso notation
*
*  @return int year number
*  @access public
*/
Date.prototype.getIsoYear = function () {
  var d = this.getDayOfYear(),
      j1 = (new Date(this.getFullYear(),0,1)).getIsoDay(),
      y = this.getFullYear();
  if (d <= (8 - j1) && j1 > 4) {
    return y-1;
  } else if (((this.isLeapYear()?366:365) - d) < (4 - this.getIsoDay())) {
    return y+1;
  } else {
    return y;
  }
}
/*
*  find day number in ISO notation (Mon = 1, Sun=7)
*
*  @return day number
*  @access public
*/
Date.prototype.getIsoDay = function () {
   var y = this.getFullYear(),
       yy = (y-1) % 100,
       c = (y-1) - yy,
       g = yy + Math.floor(yy/4),
       j1 = 1 + ((((Math.floor(c / 100) % 4) * 5) + g) % 7);
   return (1 + ((this.getDayOfYear() + (j1 - 1) - 1) % 7));
}
/*
*  return week number in ISO notation
*
*  @return int week number
*  @access public
*/
Date.prototype.getIsoWeek = function () {
  var y = this.getFullYear(),
      yi = this.getIsoYear(),
      j1 = (new Date(y,0,1)).getIsoDay();
  if ( yi < y ) {
    if (j1 == 5 || (j1 == 6 && (new Date(yi,0,1)).isLeapYear())) {
      w = 53;
    } else {
      w = 52;
    }
  } else if (yi > y) {
    w = 1;
  } else {
    var w = Math.floor((this.getDayOfYear() + (7-this.getIsoDay()) + (j1 - 1)) / 7);
    if (j1 > 4) w -= 1;
  }
  return w;
}
/*
*  Converts Date object to formatted string
*
*  @description
*  Possible formatting options
*    %a - abbreviated weekday name according to the current locale
*    %A - full weekday name according to the current locale
*    %b - abbreviated month name according to the current locale
*    %B - full month name according to the current locale
*    %c - preferred date and time representation for the current locale
*    %C - century number (the year divided by 100 and truncated to an integer, range 00 to 99)
*    %d - day of the month as a decimal number (range 01 to 31)
*    %D - same as %m/%d/%y
*    %e - day of the month as a decimal number, a single digit is preceded by a space (range ' 1' to '31')
*    %g - like %G, but without the century.
*    %G - The 4-digit year corresponding to the ISO week number (see %V). 
*         self has the same format and value as %Y, except that if the ISO week number belongs 
*         to the previous or next year, that year is used instead.
*    %h - same as %b
*    %H - hour as a decimal number using a 24-hour clock (range 00 to 23)
*    %I - hour as a decimal number using a 12-hour clock (range 01 to 12)
*    %j - day of the year as a decimal number (range 001 to 366)
*    %m - month as a decimal number (range 01 to 12)
*    %M - minute as a decimal number
*    %n - newline character
*    %p - either `am' or `pm' according to the given time value, or the corresponding strings for the current locale
*    %r - time in a.m. and p.m. notation
*    %R - time in 24 hour notation
*    %S - second as a decimal number
*    %t - tab character
*    %T - current time, equal to %H:%M:%S
*    %V - The ISO 8601:1988 week number of the current year as a decimal number, range 01 to 53, 
*         where week 1 is the first week that has at least 4 days in the current year, 
*         and with Monday as the first day of the week. 
*         (Use %G or %g for the year component that corresponds to the week number for the specified timestamp.)
*    %u - weekday as a decimal number [1,7], with 1 representing Monday
*    %U - week number of the current year as a decimal number, starting with the first Sunday as the first day of the first week
*    %w - day of the week as a decimal, Sunday being 0
*    %W - week number of the current year as a decimal number, starting with the first Monday as the first day of the first week
*    %x - preferred date representation for the current locale without the time
*    %X - preferred time representation for the current locale without the date
*    %y - year as a decimal number without a century (range 00 to 99)
*    %Y - year as a decimal number including the century
*    %Z or %z - time zone or name or abbreviation
*
*  @link http://php.net/strftime
*
*  @param string optional date format
*  @param string optional single char spacer, used to pad short values
*  @return string formatted Date
*  @access public
*/
Date.prototype.toFormatString = function (fmt, spacer) {
  var self = this;
  if (!fmt) return this.toString();
  if (typeof spacer != 'string') spacer = "0";
  if (spacer.length > 1) spacer.length = 1;

  return fmt.replace(/%\w+/g,function(a) {
      a = a.replace(/[%\s]/,"");
      switch (a) {
        case "a" : return DAY_NAMES[self.getDay()];
        case "A" : return DAY_NAMES[self.getDay()+7];
        case "b" : 
        case "h" : return MONTH_NAMES[self.getMonth()];
        case "B" : return MONTH_NAMES[self.getMonth()+12];
        case "c" : return; //???
        case "C" : return Math.round(self.getFullYear()/100);
        case "d" : return String(self.getDate()).padLeft(2,spacer);
        case "D" : return self.toFormatString("%m/%d/%y", spacer);//String(self.getMonth()+1).padLeft(2,"0")+"/"+String(self.getDate()+1).padLeft(2,"0")+"/"+String(self.getFullYear()).slice(-2);
        case "e" : return String(self.getDate()+1).padLeft(2);
        case "g" : return self.getIsoYear().slice(-2);
        case "G" : return self.getIsoYear();
        case "H" : return String(self.getHours()).padLeft(2,spacer);
        case "I" : return (self.getHours()>12?self.getHours()-12:self.getHours()).padLeft(2,spacer);
        case "j" : return String(self.getDayOfYear()).padLeft(3,spacer);
        case "m" : return String(self.getMonth()+1).padLeft(2,spacer);
        case "M" : return String(self.getMinutes()).padLeft(2,spacer);
        case "n" : return "\n";
        case "p" : return (self.getHours()>12?"PM":"AM");
        case "r" : return self.toFormatString("%I", spacer)+":"+self.toFormatString("%M", spacer)+":"+self.toFormatString("%S", spacer)+" "+self.toFormatString("%p", spacer);
        case "R" : return self.toFormatString("%H", spacer)+":"+self.toFormatString("%M", spacer);
        case "S" : return String(self.getSeconds()).padLeft(2,spacer);
        case "t" : return "\t";
        case "T" : return self.toFormatString("%H", spacer)+":"+self.toFormatString("%M", spacer)+":"+self.toFormatString("%S", spacer);
        case "u" : return self.getIsoDay();
        case "U" : return String(parseInt((self.getDayOfYear() - 1 - self.getIsoDay() + 13) / 7 - 1)).padLeft(2,"0");
        case "V" : return String(self.getIsoWeek()).padLeft(2,spacer);
        case "w" : return self.getDay();
        case "W" : return String(parseInt((self.getDayOfYear() - 1 - self.getDay() + 13) / 7 - 1)).padLeft(2,"0");
        case "x" : return; // ???
        case "X" : return; // ???
        case "y" : return String(self.getFullYear()).slice(-2);
        case "Y" : return self.getFullYear();
        case "z" : return; // ???
        case "Z" : return self.getTimezoneOffset() / 60;
      }
      return a;
    }
  )
}