/**
* Global variables
*/
   dynCalendar_layers          = new Array();
   dynCalendar_mouseoverStatus = false;
   dynCalendar_mouseX          = 0;
   dynCalendar_mouseY          = 0;

/**
* The calendar constructor
*
* @access public
* @param string objName      Name of the object that you create
* @param string callbackFunc Name of the callback function
* @param string OPTIONAL     Optional layer name
* @param string OPTIONAL     Optional images path
*/
   function dynCalendar(objName, callbackFunc)
   {
      /**
        * Properties
        */
      // Todays date
      this.today          = new Date();
      this.date           = this.today.getDate();
      this.month          = this.today.getMonth();
      this.year           = this.today.getFullYear();

      this.objName        = objName;
      this.callbackFunc   = callbackFunc;
      this.imagesPath     = arguments[2] ? arguments[2] : 'images/';
      this.layerID        = arguments[3] ? arguments[3] : 'dynCalendar_layer_' + dynCalendar_layers.length;

      this.offsetX        = 5;
      this.offsetY        = 5;

      this.useMonthCombo  = true;
      this.useYearCombo   = true;
         //this.yearComboRange = 1;
      this.yearComboRange = 2;

      this.currentMonth   = this.month;
      this.currentYear    = this.year;

      /**
        * Public Methods
        */
      this.show              = dynCalendar_show;
      this.writeHTML         = dynCalendar_writeHTML;

      // Accessor methods
      this.setOffset         = dynCalendar_setOffset;
      this.setOffsetX        = dynCalendar_setOffsetX;
      this.setOffsetY        = dynCalendar_setOffsetY;
      this.setImagesPath     = dynCalendar_setImagesPath;
      this.setMonthCombo     = dynCalendar_setMonthCombo;
      this.setYearCombo      = dynCalendar_setYearCombo;
      this.setCurrentMonth   = dynCalendar_setCurrentMonth;
      this.setCurrentYear    = dynCalendar_setCurrentYear;
      this.setYearComboRange = dynCalendar_setYearComboRange;

      /**
        * Private methods
        */
      // Layer manipulation
      this._getLayer         = dynCalendar_getLayer;
      this._hideLayer        = dynCalendar_hideLayer;
      this._showLayer        = dynCalendar_showLayer;
      this._setLayerPosition = dynCalendar_setLayerPosition;
      this._setHTML          = dynCalendar_setHTML;

      // Miscellaneous
      this._getDaysInMonth   = dynCalendar_getDaysInMonth;
      this._mouseover        = dynCalendar_mouseover;

      /**
        * Constructor type code
        */
      dynCalendar_layers[dynCalendar_layers.length] = this;
      this.writeHTML();
   }

/**
* Shows the calendar, or updates the layer if
* already visible.
*
* @access public
* @param integer month Optional month number (0-11)
* @param integer year  Optional year (YYYY format)
*/
   function dynCalendar_show()
   {
      // Variable declarations to prevent globalisation
      var month, year, monthnames, numdays, thisMonth, firstOfMonth;
      var ret, row, i, cssClass, linkHTML, previousMonth, previousYear;
      var nextMonth, nextYear, prevImgHTML, prevLinkHTML, nextImgHTML, nextLinkHTML;
      var monthComboOptions, monthCombo, yearComboOptions, yearCombo, html;
      
      this.currentMonth = month = arguments[0] != null ? arguments[0] : this.currentMonth;
      this.currentYear  = year  = arguments[1] != null ? arguments[1] : this.currentYear;

      monthnames = new Array('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec');
      numdays    = this._getDaysInMonth(month, year);

      thisMonth    = new Date(year, month, 1);
      firstOfMonth = thisMonth.getDay();

      // First few blanks up to first day
      ret = new Array(new Array());
      for(i=0; i<firstOfMonth; i++){
         ret[0][ret[0].length] = '<td>&nbsp;</td>';
      }

      // Main body of calendar
      row = 0;
      i   = 1;
      while(i <= numdays){
         if(ret[row].length == 7){
            ret[++row] = new Array();
         }

         /**
            * Generate this cells' HTML
            */
         cssClass = (i == this.date && month == this.month && year == this.year) ? 'dynCalendar_today' : 'dynCalendar_day';
         linkHTML = '<a href="javascript: ' + this.callbackFunc + '(' + i + ', ' + (Number(month) + 1) + ', ' + year + '); ' + this.objName + '._hideLayer()"  class=dynCalendar_day>' + (i++) + '</a>';
         ret[row][ret[row].length] = '<td align="center" class="' + cssClass + '">' + linkHTML + '</td>';
      }

      // Format the HTML
      for(i=0; i<ret.length; i++){
         ret[i] = ret[i].join('\n') + '\n';
      }

      previousYear  = thisMonth.getFullYear();
      previousMonth = thisMonth.getMonth() - 1;
      if(previousMonth < 0){
         previousMonth = 11;
         previousYear--;
      }
      
      nextYear  = thisMonth.getFullYear();
      nextMonth = thisMonth.getMonth() + 1;
      if(nextMonth > 11){
         nextMonth = 0;
         nextYear++;
      }

      prevImgHTML  = '<img src="' + this.imagesPath + 'prev.gif" alt="<<" border="0" />';
      prevLinkHTML = '<a href="javascript: ' + this.objName + '.show(' + previousMonth + ', ' + previousYear + ')">' + prevImgHTML + '</a>';
      nextImgHTML  = '<img src="' + this.imagesPath + 'next.gif" alt="<<" border="0" />';
      nextLinkHTML = '<a href="javascript: ' + this.objName + '.show(' + nextMonth + ', ' + nextYear + ')">' + nextImgHTML + '</a>';

      /**
        * Build month combo
        */
      if (this.useMonthCombo) {
         monthComboOptions = '';
         for (i=0; i<12; i++) {
            selected = (i == thisMonth.getMonth() ? 'selected="selected"' : '');
            monthComboOptions += '<option value="' + i + '" ' + selected + '>' + monthnames[i] + '</option>';
         }
         monthCombo = '<select name="months" onchange="' + this.objName + '.show(this.options[this.selectedIndex].value, ' + this.objName + '.currentYear)">' + monthComboOptions + '</select>';
      } else {
         monthCombo = monthnames[thisMonth.getMonth()];
      }
      
      /**
        * Build year combo
        */
      if (this.useYearCombo) {
         yearComboOptions = '';
            for (i = thisMonth.getFullYear() - this.yearComboRange; i <= (thisMonth.getFullYear() + this.yearComboRange); i++) {
   
            selected = (i == thisMonth.getFullYear() ? 'selected="selected"' : '');
            yearComboOptions += '<option value="' + i + '" ' + selected + '>' + i + '</option>';
         }
         yearCombo = '<select style="border: 1px groove" name="years" onchange="' + this.objName + '.show(' + this.objName + '.currentMonth, this.options[this.selectedIndex].value)">' + yearComboOptions + '</select>';
      } else {
         yearCombo = thisMonth.getFullYear();
      }

      html = '<table border="0" bgcolor="#FFFFFF" cellspacing="0" cellpadding=0>';
      html += '<tr><td class="dynCalendar_header">' + prevLinkHTML + '</td><td colspan="5" align="center" class="dynCalendar_header">' + monthCombo + ' ' + yearCombo + '</td><td align="right" class="dynCalendar_header">' + nextLinkHTML + '</td></tr>';
      html += '<tr>';
      html += '<td class="dynCalendar_dayname">S</td>';
      html += '<td class="dynCalendar_dayname">M</td>';
      html += '<td class="dynCalendar_dayname">T</td>';
      html += '<td class="dynCalendar_dayname">W</td>';
      html += '<td class="dynCalendar_dayname">T</td>';
      html += '<td class="dynCalendar_dayname">F</td>';
      html += '<td class="dynCalendar_dayname">S</td></tr>';
            html += '<tr><td height=1 colspan=7 bgcolor=#666666></td></tr>';
      html += '<tr>' + ret.join('</tr>\n<tr>') + '</tr>';
         html += '</table>';

      this._setHTML(html);
      if (!arguments[0] && !arguments[1]) {
         this._showLayer();
         this._setLayerPosition();
      }
   }

/**
* Writes HTML to document for layer
*
* @access public
*/
   function dynCalendar_writeHTML()
   {
      if (is_ie5up || is_nav6up || is_gecko) {
         document.write('<a href="javascript: ' + this.objName + '.show()"><img src="' + this.imagesPath + 'dynCalendar.gif" border="0" width="20" height="18" /></a>');
         document.write('<div class="dynCalendar" id="' + this.layerID + '" onmouseover="' + this.objName + '._mouseover(true)" onmouseout="' + this.objName + '._mouseover(false)"></div>');
      }
   }

/**
* Sets the offset to the mouse position
* that the calendar appears at.
*
* @access public
* @param integer Xoffset Number of pixels for vertical
*                        offset from mouse position
* @param integer Yoffset Number of pixels for horizontal
*                        offset from mouse position
*/
   function dynCalendar_setOffset(Xoffset, Yoffset)
   {
      this.setOffsetX(Xoffset);
      this.setOffsetY(Yoffset);
   }

/**
* Sets the X offset to the mouse position
* that the calendar appears at.
*
* @access public
* @param integer Xoffset Number of pixels for horizontal
*                        offset from mouse position
*/
   function dynCalendar_setOffsetX(Xoffset)
   {
      this.offsetX = Xoffset;
   }

/**
* Sets the Y offset to the mouse position
* that the calendar appears at.
*
* @access public
* @param integer Yoffset Number of pixels for vertical
*                        offset from mouse position
*/
   function dynCalendar_setOffsetY(Yoffset)
   {
      this.offsetY = Yoffset;
   }
   
/**
* Sets the images path
*
* @access public
* @param string path Path to use for images
*/
   function dynCalendar_setImagesPath(path)
   {
      this.imagesPath = path;
   }

/**
* Turns on/off the month dropdown
*
* @access public
* @param boolean useMonthCombo Whether to use month dropdown or not
*/
   function dynCalendar_setMonthCombo(useMonthCombo)
   {
      this.useMonthCombo = useMonthCombo;
   }

/**
* Turns on/off the year dropdown
*
* @access public
* @param boolean useYearCombo Whether to use year dropdown or not
*/
   function dynCalendar_setYearCombo(useYearCombo)
   {
      this.useYearCombo = useYearCombo;
   }

/**
* Sets the current month being displayed
*
* @access public
* @param boolean month The month to set the current month to
*/
   function dynCalendar_setCurrentMonth(month)
   {
      this.currentMonth = month;
   }

/**
* Sets the current month being displayed
*
* @access public
* @param boolean year The year to set the current year to
*/
   function dynCalendar_setCurrentYear(year)
   {
      this.currentYear = year;
   }

/**
* Sets the range of the year combo. Displays this number of
* years either side of the year being displayed.
*
* @access public
* @param integer range The range to set
*/
   function dynCalendar_setYearComboRange(range)
   {
      this.yearComboRange = range;
   }

/**
* Returns the layer object
*
* @access private
*/
   function dynCalendar_getLayer()
   {
      var layerID = this.layerID;

      if (document.getElementById(layerID)) {

         return document.getElementById(layerID);

      } else if (document.all(layerID)) {
         return document.all(layerID);
      }
   }

/**
* Hides the calendar layer
*
* @access private
*/
   function dynCalendar_hideLayer()
   {
      this._getLayer().style.visibility = 'hidden';
   }

/**
* Shows the calendar layer
*
* @access private
*/
   function dynCalendar_showLayer()
   {
      this._getLayer().style.visibility = 'visible';
   }

/**
* Sets the layers position
*
* @access private
*/
   function dynCalendar_setLayerPosition()
   {
      this._getLayer().style.top  = '0px';
      this._getLayer().style.left = '0px';
   }

/**
* Sets the innerHTML attribute of the layer
*
* @access private
*/
   function dynCalendar_setHTML(html)
   {
      this._getLayer().innerHTML = html;
   }

/**
* Returns number of days in the supplied month
*
* @access private
* @param integer month The month to get number of days in
* @param integer year  The year of the month in question
*/
   function dynCalendar_getDaysInMonth(month, year)
   {
      monthdays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
      if (month != 1) {
         return monthdays[month];
      } else {
         return ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0 ? 29 : 28);
      }
   }

/**
* onMouse(Over|Out) event handler
*
* @access private
* @param boolean status Whether the mouse is over the
*                       calendar or not
*/
   function dynCalendar_mouseover(status)
   {
      dynCalendar_mouseoverStatus = status;
      return true;
   }

/**
* onMouseMove event handler
*/
   dynCalendar_oldOnmousemove = document.onmousemove ? document.onmousemove : new Function;

   document.onmousemove = function ()
   {
      if (is_ie5up || is_nav6up || is_gecko) {
         if (arguments[0]) {
            dynCalendar_mouseX = arguments[0].pageX;
            dynCalendar_mouseY = arguments[0].pageY;
         } else {
            dynCalendar_mouseX = event.clientX + document.body.scrollLeft;
            dynCalendar_mouseY = event.clientY + document.body.scrollTop;
            arguments[0] = null;
         }
   
         dynCalendar_oldOnmousemove();
      }
   }

/**
* Callbacks for document.onclick
*/
   dynCalendar_oldOnclick = document.onclick ? document.onclick : new Function;

   document.onclick = function ()
   {
      if (is_ie5up || is_nav6up || is_gecko) {
         if(!dynCalendar_mouseoverStatus){
            for(i=0; i<dynCalendar_layers.length; ++i){
               dynCalendar_layers[i]._hideLayer();
            }
         }
   
         dynCalendar_oldOnclick(arguments[0] ? arguments[0] : null);
      }
   }