var Calendar = Class.create()

Calendar.VERSION = '1.2'

Calendar.DAY_NAMES = new Array(
  'Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday',
  'Sunday'
)

Calendar.SHORT_DAY_NAMES = new Array(
  'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'
)

Calendar.MONTH_NAMES = new Array('January', 'February', 'March', 'April', 'May', 'June', 'July', 
'August','September', 'October', 'November', 'December')

Calendar.SHORT_MONTH_NAMES = new Array('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov','Dec' )

Calendar.NAV_TODAY          =  0
Calendar.NAV_NEXT_MONTH     =  1

Calendar.handleMouseDownEvent = function(event)
{
  Event.observe(document, 'mouseup', Calendar.handleMouseUpEvent)
  Event.stop(event)
}

Calendar.handleMouseUpEvent = function(event)
{
  var el        = Event.element(event)
  var calendar  = el.calendar
  var isNewDate = false

  if (!calendar) return false

  // Clicked on a day
  if (typeof el.navAction == 'undefined')
  {
    if (calendar.currentDateElement) {
      Element.removeClassName(calendar.currentDateElement, 'selected')
      Element.addClassName(el, 'selected')
      calendar.shouldClose = (calendar.currentDateElement == el)
      if (!calendar.shouldClose) calendar.currentDateElement = el
    }
    calendar.date.setDateOnly(el.date)
    isNewDate = true
    
  }

  // Clicked on an action button
  else
  {
    var date = new Date(calendar.date)

    if (el.navAction == Calendar.NAV_TODAY)
      date.setDateOnly(new Date())

    var year = date.getFullYear()
    var mon = date.getMonth()
    function setMonth(m)
	{
      var day = date.getDate()
      var max = date.getMonthDays(m)
      if (day > max) date.setDate(max)
      date.setMonth(m)
    }
    
    if (!date.equalsTo(calendar.date)) 
	{
      calendar.setDate(date)
      isNewDate = true
    } 
  }

  if (isNewDate) event && calendar.callSelectHandler()
 
  return Event.stop(event)
}

Calendar.defaultSelectHandler = function(calendar)
{
  if (!calendar.dateField) return false

  // Update dateField value
  if (calendar.dateField.tagName == 'DIV')
    Element.update(calendar.dateField, calendar.date.print(calendar.dateFormat))
  else if (calendar.dateField.tagName == 'INPUT') {
    calendar.dateField.value = calendar.date.print(calendar.dateFormat) }

}

// Calendar Setup

Calendar.setup = function(params)
{

  function param_default(name, def) {
    if (!params[name]) params[name] = def
  }

  param_default('dateField', null)
  param_default('triggerElement', null)
  param_default('parentElement', null)
  param_default('selectHandler',  null)
  param_default('closeHandler', null)

  // In-Page Calendar
  if (params.parentElement)
  {
    var calendar = new Calendar(params.parentElement)
    calendar.setSelectHandler(params.selectHandler || Calendar.defaultSelectHandler)
    if (params.dateFormat)
      calendar.setDateFormat(params.dateFormat)
    if (params.dateField) {
      calendar.setDateField(params.dateField)
      calendar.parseDate(calendar.dateField.innerHTML || calendar.dateField.value)
    }
    //calendar.show()
    return calendar
  }
}

// Calendar Instance

Calendar.prototype = {

  // The HTML Container Element
  container: null,

  // Callbacks
  selectHandler: null,
  closeHandler: null,

  // Configuration
  minYear: 1900,
  maxYear: 2100,
  dateFormat: '%Y-%m-%d',

  // Dates
  date: new Date(),
  currentDateElement: null,

  dateField: null,

    // Initialize  

  initialize: function(parent)
  {
    if (parent)
      this.create($(parent))
    else
      this.create()
  },

  // Update / (Re)initialize Calendar
  
  update: function(date)
  {
    var calendar   = this
    var today      = new Date()
    var thisYear   = today.getFullYear()
    var thisMonth  = today.getMonth()
    var thisDay    = today.getDate()
    var month      = date.getMonth();
    var dayOfMonth = date.getDate();

    // Ensure date is within the defined range
     if (date.getFullYear() > this.maxYear)
      date.setFullYear(this.maxYear)

    this.date = new Date(date)

    // Calculate the first day to display (including the previous month)
    date.setDate(1)
   date.setDate(-(date.getDay()) + 1)

    // Fill in the days of the month
    Element.getElementsBySelector(this.container, 'tbody tr').each(
      function(row, i) {
        var rowHasDays = false
        row.immediateDescendants().each(
          function(cell, j) {
            var day            = date.getDate()
            var dayOfWeek      = date.getDay()
            var isCurrentMonth = (date.getMonth() == month)
			var isCurrentDay = (date.getDay() == day)
			

            // Reset classes on the cell
            cell.className = ''
            cell.date = new Date(date)
            cell.update(day)

            // Account for days of the month other than the current month
        		
			if (!isCurrentMonth)
		  		cell.addClassName('otherDay')
				
              rowHasDays = true

            // Ensure the current day is selected
            if (isCurrentMonth && day == dayOfMonth)
			{
              cell.addClassName('selected')
              calendar.currentDateElement = cell
            }
            // Today
            if (date.getFullYear() == thisYear && date.getMonth() == thisMonth && day == thisDay)
              cell.addClassName('today')

            // Weekend
            if ([0, 6].indexOf(dayOfWeek) != -1)
              cell.addClassName('weekend')

            // Set the date to tommorrow
            date.setDate(day + 1)
          }
        )
        // Hide the extra row if it contains only days from another month
        !rowHasDays ? row.hide() : row.show()
      }
    )

    this.container.getElementsBySelector('td.title')[0].update(
      Calendar.MONTH_NAMES[month] + ' ' + this.date.getFullYear()
    )
  },

  //----------------------------------------------------------------------------
  // Create/Draw the Calendar HTML Elements
  //----------------------------------------------------------------------------

  create: function(parent)
  {
    // Calendar Table
    var table = new Element('table')

    // Calendar Header
    var thead = new Element('thead')
    table.appendChild(thead)

    // Title Placeholder
    var row  = new Element('tr')
    var cell = new Element('td', { colSpan: 7 } )
    cell.addClassName('title')
    row.appendChild(cell)
    thead.appendChild(row)

    // Calendar Navigation
    //row = new Element('tr')
    //this._drawButtonCell(row, 'Today',    6, Calendar.NAV_TODAY)
    //this._drawButtonCell(row, '›', 1, Calendar.NAV_NEXT_MONTH)
   // thead.appendChild(row)

    // Day Names
    row = new Element('tr')
    for (var i = 0; i < 7; ++i)
	{
      cell = new Element('th').update(Calendar.SHORT_DAY_NAMES[i])
      if (i == 0 || i == 6)
        cell.addClassName('weekend')
		row.appendChild(cell)
    }
    thead.appendChild(row)

    // Calendar Days
    var tbody = table.appendChild(new Element('tbody'))
    for (i = 6; i > 0; --i)
	{
      row = tbody.appendChild(new Element('tr'))
      row.addClassName('days')
      for (var j = 7; j > 0; --j)
	  {
        cell = row.appendChild(new Element('td'))
        cell.calendar = this
      }
    }

    // Calendar Container (div)
	this.container = new Element('div')
	this.container.addClassName('calendar')
   
    this.container.appendChild(table)

    // Initialize Calendar
    this.update(this.date)

    // Observe the container for mousedown events
    Event.observe(this.container, 'mousedown', Calendar.handleMouseDownEvent)

    // Append to parent element
    parent.appendChild(this.container)

  },

  _drawButtonCell: function(parent, text, colSpan, navAction)
  {
    var cell          = new Element('td')
    if (colSpan > 1) cell.colSpan = colSpan
    cell.className    = 'button'
    cell.calendar     = this
    cell.navAction    = navAction
    cell.innerHTML    = text
    cell.unselectable = 'on' // IE
    parent.appendChild(cell)
    return cell
  },

   /* ***Callbacks*** */
 
  // Calls the Select Handler (if defined)
  callSelectHandler: function()
  {
    if (this.selectHandler)
      this.selectHandler(this, this.date.print(this.dateFormat))
  },
  
  /* ****Calendar Display Functions**** */
 
  // Shows the calendar at the given absolute position
  showAt: function (x, y)
  {
    this.container.setStyle({ left: x + 'px', top: y + 'px' })
    this.show()
  },

  
  // Miscellaneous
  
  parseDate: function(str, format)
  {
    if (!format)
      format = this.dateFormat
    this.setDate(Date.parseDate(str, format))
  },

  // Getters/Setters
 
  setSelectHandler: function(selectHandler)
  {
    this.selectHandler = selectHandler
  },

  setDate: function(date)
  {
    if (!date.equalsTo(this.date))
      this.update(date)
  },

  setDateFormat: function(format)
  {
    this.dateFormat = format
  },

 setDateField: function(field)
  {
    this.dateField = $(field)
  },

  setRange: function(minYear, maxYear)
  {
    this.minYear = minYear
    this.maxYear = maxYear
  }

}

Date.DAYS_IN_MONTH = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
Date.SECOND        = 1000 /* milliseconds */
Date.MINUTE        = 60 * Date.SECOND
Date.HOUR          = 60 * Date.MINUTE
Date.DAY           = 24 * Date.HOUR
Date.WEEK          =  7 * Date.DAY

// Parses Date
Date.parseDate = function(str, fmt) {
  var today = new Date();
  var y     = 0;
  var m     = -1;
  var d     = 0;
  var a     = str.split(/\W+/);
  var b     = fmt.match(/%./g);
  var i     = 0, j = 0;
  var hr    = 0;
  var min   = 0;

  for (i = 0; i < a.length; ++i) {
    if (!a[i]) continue;
    switch (b[i]) {
      case "%d":
      case "%e":
        d = parseInt(a[i], 10);
        break;
      case "%m":
        m = parseInt(a[i], 10) - 1;
        break;
      case "%Y":
      case "%y":
        y = parseInt(a[i], 10);
        (y < 100) && (y += (y > 29) ? 1900 : 2000);
        break;
      case "%b":
      case "%B":
        for (j = 0; j < 12; ++j) {
          if (Calendar.MONTH_NAMES[j].substr(0, a[i].length).toLowerCase() == a[i].toLowerCase()) {
            m = j;
            break;
          }
        }
        break;
      case "%H":
      case "%I":
      case "%k":
      case "%l":
        hr = parseInt(a[i], 10);
        break;
      case "%P":
      case "%p":
        if (/pm/i.test(a[i]) && hr < 12)
          hr += 12;
        else if (/am/i.test(a[i]) && hr >= 12)
          hr -= 12;
        break;
      case "%M":
        min = parseInt(a[i], 10);
        break;
    }
  }
  if (isNaN(y)) y = today.getFullYear();
  if (isNaN(m)) m = today.getMonth();
  if (isNaN(d)) d = today.getDate();
  if (isNaN(hr)) hr = today.getHours();
  if (isNaN(min)) min = today.getMinutes();
  if (y != 0 && m != -1 && d != 0)
    return new Date(y, m, d, hr, min, 0);
  y = 0; m = -1; d = 0;
  for (i = 0; i < a.length; ++i) {
    if (a[i].search(/[a-zA-Z]+/) != -1) {
      var t = -1;
      for (j = 0; j < 12; ++j) {
        if (Calendar.MONTH_NAMES[j].substr(0, a[i].length).toLowerCase() == a[i].toLowerCase()) { t = j; break; }
      }
      if (t != -1) {
        if (m != -1) {
          d = m+1;
        }
        m = t;
      }
    } else if (parseInt(a[i], 10) <= 12 && m == -1) {
      m = a[i]-1;
    } else if (parseInt(a[i], 10) > 31 && y == 0) {
      y = parseInt(a[i], 10);
      (y < 100) && (y += (y > 29) ? 1900 : 2000);
    } else if (d == 0) {
      d = a[i];
    }
  }
  if (y == 0)
    y = today.getFullYear();
  if (m != -1 && d != 0)
    return new Date(y, m, d, hr, min, 0);
  return today;
};

// Returns the number of days in the current month
Date.prototype.getMonthDays = function(month) 
{
  var year = this.getFullYear()
  if (typeof month == "undefined")
    month = this.getMonth()
  if (((0 == (year % 4)) && ( (0 != (year % 100)) || (0 == (year % 400)))) && month == 1)
    return 29
  else
    return Date.DAYS_IN_MONTH[month]
};

// Returns the number of day in the year
Date.prototype.getDayOfYear = function()
 {
  var now = new Date(this.getFullYear(), this.getMonth(), this.getDate(), 0, 0, 0);
  var then = new Date(this.getFullYear(), 0, 0, 0, 0, 0);
  var time = now - then;
  return Math.floor(time / Date.DAY);
};

/** Returns the number of the week in year, as defined in ISO 8601. */
Date.prototype.getWeekNumber = function() {
  var d = new Date(this.getFullYear(), this.getMonth(), this.getDate(), 0, 0, 0);
  var DoW = d.getDay();
  d.setDate(d.getDate() - (DoW + 6) % 7 + 3); // Nearest Thu
  var ms = d.valueOf(); // GMT
  d.setMonth(0);
  d.setDate(4); // Thu in Week 1
  return Math.round((ms - d.valueOf()) / (7 * 864e5)) + 1;
};

/** Checks date and time equality */
Date.prototype.equalsTo = function(date) {
  return ((this.getFullYear() == date.getFullYear()) &&
   (this.getMonth() == date.getMonth()) &&
   (this.getDate() == date.getDate()) &&
   (this.getHours() == date.getHours()) &&
   (this.getMinutes() == date.getMinutes()));
};

/** Set only the year, month, date parts (keep existing time) */
Date.prototype.setDateOnly = function(date){
  var tmp = new Date(date);
  this.setDate(1);
  this.setFullYear(tmp.getFullYear());
  this.setMonth(tmp.getMonth());
  this.setDate(tmp.getDate());
};

/** Prints the date in a string according to the given format. */
Date.prototype.print = function (str) {
  var m = this.getMonth();
  var d = this.getDate();
  var y = this.getFullYear();
  var wn = this.getWeekNumber();
  var w = this.getDay();
  var s = {};
  var hr = this.getHours();
  var pm = (hr >= 12);
  var ir = (pm) ? (hr - 12) : hr;
  var dy = this.getDayOfYear();
  if (ir == 0)
    ir = 12;
  var min = this.getMinutes();
  var sec = this.getSeconds();
  s["%a"] = Calendar.SHORT_DAY_NAMES[w]; // abbreviated weekday name [FIXME: I18N]
  s["%A"] = Calendar.DAY_NAMES[w]; // full weekday name
  s["%b"] = Calendar.SHORT_MONTH_NAMES[m]; // abbreviated month name [FIXME: I18N]
  s["%B"] = Calendar.MONTH_NAMES[m]; // full month name
  // FIXME: %c : preferred date and time representation for the current locale
  s["%C"] = 1 + Math.floor(y / 100); // the century number
  s["%d"] = (d < 10) ? ("0" + d) : d; // the day of the month (range 01 to 31)
  s["%e"] = d; // the day of the month (range 1 to 31)
  // FIXME: %D : american date style: %m/%d/%y
  // FIXME: %E, %F, %G, %g, %h (man strftime)
  s["%H"] = (hr < 10) ? ("0" + hr) : hr; // hour, range 00 to 23 (24h format)
  s["%I"] = (ir < 10) ? ("0" + ir) : ir; // hour, range 01 to 12 (12h format)
  s["%j"] = (dy < 100) ? ((dy < 10) ? ("00" + dy) : ("0" + dy)) : dy; // day of the year (range 001 to 366)
  s["%k"] = hr;   // hour, range 0 to 23 (24h format)
  s["%l"] = ir;   // hour, range 1 to 12 (12h format)
  s["%m"] = (m < 9) ? ("0" + (1+m)) : (1+m); // month, range 01 to 12
  s["%M"] = (min < 10) ? ("0" + min) : min; // minute, range 00 to 59
  s["%n"] = "\n";   // a newline character
  s["%p"] = pm ? "PM" : "AM";
  s["%P"] = pm ? "pm" : "am";
  // FIXME: %r : the time in am/pm notation %I:%M:%S %p
  // FIXME: %R : the time in 24-hour notation %H:%M
  s["%s"] = Math.floor(this.getTime() / 1000);
  s["%S"] = (sec < 10) ? ("0" + sec) : sec; // seconds, range 00 to 59
  s["%t"] = "\t";   // a tab character
  // FIXME: %T : the time in 24-hour notation (%H:%M:%S)
  s["%U"] = s["%W"] = s["%V"] = (wn < 10) ? ("0" + wn) : wn;
  s["%u"] = w + 1;  // the day of the week (range 1 to 7, 1 = MON)
  s["%w"] = w;    // the day of the week (range 0 to 6, 0 = SUN)
  // FIXME: %x : preferred date representation for the current locale without the time
  // FIXME: %X : preferred time representation for the current locale without the date
  s["%y"] = ('' + y).substr(2, 2); // year without the century (range 00 to 99)
  s["%Y"] = y;    // year with the century
  s["%%"] = "%";    // a literal '%' character

  return str.gsub(/%./, function(match) { return s[match] || match });
};

Date.prototype.__msh_oldSetFullYear = Date.prototype.setFullYear;
Date.prototype.setFullYear = function(y)
 {
  var d = new Date(this);
  d.__msh_oldSetFullYear(y);
  if (d.getMonth() != this.getMonth())
    this.setDate(28);
  this.__msh_oldSetFullYear(y);
}