/*
 * Date prototype extensions. Doesn't depend on any
 * other code. Doens't overwrit#E6F1FAe existing methods.
  * Copyright (c) 2006 Jörn Zaefferer and Brandon Aaron (brandon.aaron@gmail.com || http://brandonaaron.net)
 * Dual licensed under the MIT and GPL licenses:
 *   http://www.opensource.org/licenses/mit-license.php
 *   http://www.gnu.org/licenses/gpl.html
 */

Date.dayNames = ['Sonntag', 'Montag', 'Dienstag', 'Mittwoch', 'Donnerstag', 'Freitag', 'Samstag'];
Date.abbrDayNames = ['So', 'Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa'];
Date.monthNames = ['Januar', 'Februar', 'März', 'April', 'Mai', 'Juni', 'Juli', 'August', 'September', 'Oktober', 'November', 'Dezember'];
Date.abbrMonthNames = ['Jan', 'Feb', 'Mrz', 'Apr', 'Mai', 'Jun', 'Jul', 'Aug', 'Sep', 'Okt', 'Nov', 'Dez'];
Date.firstDayOfWeek = 1;

Date.format = 'dd.mm.yyyy';
Date.fullYearStart = '20';

(function() {
function add(name, method) {
  if( !Date.prototype[name] ) {
    Date.prototype[name] = method;
  }
};
add("isLeapYear", function() {
  var y = this.getFullYear();
  return (y%4==0 && y%100!=0) || y%400==0;
});
add("isWeekend", function() {
  return this.getDay()==0 || this.getDay()==6;
});
add("isWeekDay", function() {
  return !this.isWeekend();
});

add("getDaysInMonth", function() {
  return [31,(this.isLeapYear() ? 29:28),31,30,31,30,31,31,30,31,30,31][this.getMonth()];
});

add("getDayName", function(abbreviated) {
  return abbreviated ? Date.abbrDayNames[this.getDay()] : Date.dayNames[this.getDay()];
});

add("getMonthName", function(abbreviated) {
  return abbreviated ? Date.abbrMonthNames[this.getMonth()] : Date.monthNames[this.getMonth()];
});

add("getDayOfYear", function() {
  var tmpdtm = new Date("1/1/" + this.getFullYear());
  return Math.floor((this.getTime() - tmpdtm.getTime()) / 86400000);
});

add("getWeekOfYear", function() {
  return Math.ceil(this.getDayOfYear() / 7);
});

add("setDayOfYear", function(day) {
  this.setMonth(0);
  this.setDate(day);
  return this;
});

add("addYears", function(num) {
  this.setFullYear(this.getFullYear() + num);
  return this;
});

add("addMonths", function(num) {
  var tmpdtm = this.getDate();

  this.setMonth(this.getMonth() + num);

  if (tmpdtm > this.getDate())
    this.addDays(-this.getDate());

  return this;
});

add("addDays", function(num) {
  this.setDate(this.getDate() + num);
  return this;
});

add("addHours", function(num) {
  this.setHours(this.getHours() + num);
  return this;
});

add("addMinutes", function(num) {
  this.setMinutes(this.getMinutes() + num);
  return this;
});

add("addSeconds", function(num) {
  this.setSeconds(this.getSeconds() + num);
  return this;
});

add("zeroTime", function() {
  this.setMilliseconds(0);
  this.setSeconds(0);
  this.setMinutes(0);
  this.setHours(0);
  return this;
});

add("asString", function() {
  var r = Date.format;
  return r
    .split('yyyy').join(this.getFullYear())
    .split('yy').join((this.getFullYear() + '').substring(2))
    .split('mmm').join(this.getMonthName(true))
    .split('mm').join(_zeroPad(this.getMonth()+1))
    .split('dd').join(_zeroPad(this.getDate()));
});

Date.fromString = function(s)
{
  var f = Date.format;
  var d = new Date('01/01/1977');
  var iY = f.indexOf('yyyy');
  if (iY > -1) {
    d.setFullYear(Number(s.substr(iY, 4)));
  } else {
    // T ODO - this doesn't work very well - are there any rules for what is meant by a two digit year?
    d.setFullYear(Number(Date.fullYearStart + s.substr(f.indexOf('yy'), 2)));
  }
  var iM = f.indexOf('mmm');
  if (iM > -1) {
    var mStr = s.substr(iM, 3);
    for (var i=0; i<Date.abbrMonthNames.length; i++) {
      if (Date.abbrMonthNames[i] == mStr) break;
    }
    d.setMonth(i);
  } else {
    d.setMonth(Number(s.substr(f.indexOf('mm'), 2)) - 1);
  }
  d.setDate(Number(s.substr(f.indexOf('dd'), 2)));
  if (isNaN(d.getTime())) {
    return false;
  }
  return d;
};

// utility method
var _zeroPad = function(num) {
  var s = '0'+num;
  return s.substring(s.length-2)
  //return ('0'+num).substring(-2); // doesn't work on IE :(
};
  
})();