var datePickerDivID = "datepicker";
var iFrameDivID = "datepickeriframe";

var dayArrayShort = new Array('Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa');
var monthArrayLong = new Array('January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December');
 
var dateSeparator = "-";
var startDay;
var startMonth;
var startYear;
var restrictToTwoMonths;

var SEARCH_ALL_STRING = 'Search all possibilities...';

function displayCalendar(dateFieldName, givenRestrictToTwoMonths) {

	if(givenRestrictToTwoMonths == 1) {
		restrictToTwoMonths = true;
	} else {
		restrictToTwoMonths = false;
	}
	
	today = new Date();
	startDay = today.getDate(); // Day of month (1-31).
	startMonth = today.getMonth();
	startYear = today.getFullYear();

	var targetDateField = document.getElementsByName (dateFieldName).item(0);
	
	if( targetDateField.value == SEARCH_ALL_STRING ) {
		targetDateField.value = null;
	}

	var x = targetDateField.offsetLeft;
	var y = targetDateField.offsetTop + targetDateField.offsetHeight ;

	// deal with elements inside tables and such
	var parent = targetDateField;
	while ( parent.offsetParent ) {
		parent = parent.offsetParent;
		x += parent.offsetLeft;
		y += parent.offsetTop ;
	}
	
	drawDatePicker(targetDateField, x, y);
}


/**
 * Draw Calendar.
*/
function drawDatePicker(targetDateField, x, y) {

	var dt = getFieldDate(targetDateField.value);
	
	if (!document.getElementById(datePickerDivID)) {
		var newNode = document.createElement("div");
		newNode.setAttribute("id", datePickerDivID);
		newNode.setAttribute("class", "dpDiv");
		newNode.setAttribute("style", "visibility: hidden;");
		document.body.appendChild(newNode);
	}
	
	// move the datepicker div to the proper x,y coordinate and toggle the visiblity
	var pickerDiv = document.getElementById(datePickerDivID);
	pickerDiv.style.position = "absolute";
	pickerDiv.style.left = x + "px";
	pickerDiv.style.top = y + "px";
	pickerDiv.style.visibility = (pickerDiv.style.visibility == "visible" ? "hidden" : "visible");
	pickerDiv.style.display = (pickerDiv.style.display == "block" ? "none" : "block");
	pickerDiv.style.zIndex = 10000;
	
	// draw the datepicker table
	refreshDatePicker(targetDateField.name, dt.getFullYear(), dt.getMonth(), dt.getDate());
}


/**
This is the function that actually draws the datepicker calendar.
*/
function refreshDatePicker(dateFieldName, year, month, day) {
	// if no arguments are passed, use today's date; otherwise, month and year
	// are required (if a day is passed, it will be highlighted later)
	var thisDay = new Date();

	// Prevent the drawing of months less than this month:
	if(month < startMonth && year <= startYear) {
		return;
	}
	var startBlanks = false;
	// Restrict the dates, if necessary:
	if(restrictToTwoMonths == true ) {
		if(month > startMonth+2) {
			return;
		} else if(month > startMonth+1) {
			startBlanks = true;
		}
	} 

	if ((month >= 0) && (year > 0)) {
		thisDay = new Date(year, month, 1);
	} else {
		day = thisDay.getDate();
		thisDay.setDate(1);
	}
 
  // the calendar will be drawn as a table
  // you can customize the table elements with a global CSS style sheet,
  // or by hardcoding style and formatting elements below
  var crlf = "\r\n";
  var TR = "<tr class='dpTR'>";
  var TR_title = "<tr class='dpTitleTR'>";
  var TR_days = "<tr class='dpDayTR'>";
  var TR_todaybutton = "<tr class='dpTodayButtonTR'>";
  var xTR = "</tr>" + crlf;
  var TD = "<td class='dpTD' onMouseOut='this.className=\"dpTD\";' onMouseOver=' this.className=\"dpTDHover\";' ";    // leave this tag open, because we'll be adding an onClick event
  var TD_title = "<td colspan=5 class='dpTitleTD'>";
  var TD_buttons = "<td class='dpButtonTD'>";
  var TD_todaybutton = "<td colspan=7 class='dpTodayButtonTD'>";
  var TD_days = "<td class='dpDayTD'>";
  var TD_selected = "<td class='dpDayHighlightTD' onMouseOut='this.className=\"dpDayHighlightTD\";' onMouseOver='this.className=\"dpTDHover\";' ";    // leave this tag open, because we'll be adding an onClick event
  var xTD = "</td>" + crlf;
  var DIV_title = "<div class='dpTitleText'>";
  var DIV_selected = "<div class='dpDayHighlight'>";
  var xDIV = "</div>";
 
 
 
 	// Begin table:
  	var html = "<table width=\"200px\" cols=7 class='dpTable'>" + crlf;
 
	// Title bar:
	html += TR_title;
	html += TD_buttons + getButtonCode(dateFieldName, thisDay, -1, "&lt;") + xTD;
	html += TD_title + DIV_title + monthArrayLong[ thisDay.getMonth()] + " " + thisDay.getFullYear() + xDIV + xTD;
	html += TD_buttons + getButtonCode(dateFieldName, thisDay, 1, "&gt;") + xTD;
	html += xTR;
 
  	// this is the row that indicates which day of the week we're on
	html += TR_days;
	for(i = 0; i < dayArrayShort.length; i++) {
		html += TD_days + dayArrayShort[i] + xTD;
	}
	html += xTR;
 
  // now we'll start populating the table with days of the month
  html += TR;
 
  	// Leading blanks
	for (i = 0; i < thisDay.getDay(); i++) {
		html += TD + "&nbsp;" + xTD;
	}
 
  // now, the days of the month
  do {
    dayNum = thisDay.getDate();
    TD_onclick = " onclick=\"updateDateField('" + dateFieldName + "', '" + getDateString(thisDay) + "');\">";
    
	if (dayNum == day) {
		html += TD_selected + TD_onclick + DIV_selected + dayNum + xDIV + xTD;
	} else if(startBlanks && dayNum > startDay) {
      	html += TD + "&nbsp;" + xTD;
	} else {
		html += TD + TD_onclick + dayNum + xTD;
	}
    
    // Start a new row if day is Saturday
    if (thisDay.getDay() == 6) {
		html += xTR + TR;
	}
    
    // Increment the day
    thisDay.setDate(thisDay.getDate() + 1);
	
  } while (thisDay.getDate() > 1)
 
  // fill in any trailing blanks
  if (thisDay.getDay() > 0) {
    for (i = 6; i > thisDay.getDay(); i--)
      html += TD + "&nbsp;" + xTD;
  }
  html += xTR;
 
  // add a button to allow the user to easily return to today, or close the calendar
  var today = new Date();
  
  html += TR_todaybutton + TD_todaybutton;
  html += "<button class='dpTodayButton' onClick='clearDateField(\"" + dateFieldName + "\");'>clear</button> ";
  html += "<button class='dpTodayButton' onClick='refreshDatePicker(\"" + dateFieldName + "\");'>this month</button> ";
  html += "<button class='dpTodayButton' onClick='updateDateField(\"" + dateFieldName + "\");'>close</button>";
  html += xTD + xTR;
 
  // and finally, close the table
  html += "</table>" + crlf;
 
  document.getElementById(datePickerDivID).innerHTML = html;
  // "iFrame shim":
  adjustiFrame();
}


/**
 *	Create forward/backward a month buttons:	
 */
function getButtonCode(dateFieldName, dateVal, adjust, label) {
  var newMonth = (dateVal.getMonth () + adjust) % 12;
  var newYear = dateVal.getFullYear() + parseInt((dateVal.getMonth() + adjust) / 12);
  if (newMonth < 0) {
    newMonth += 12;
    newYear += -1;
  }
  return "<button class='dpButton' onClick='refreshDatePicker(\"" + dateFieldName + "\", " + newYear + ", " + newMonth + ");'>" + label + "</button>";
}


/**
Convert a JavaScript Date object to a string, based on the dateFormat and dateSeparator
variables at the beginning of this script library.
*/
function getDateString(dateVal) {
	var dayString = "00" + dateVal.getDate();
	var monthString = "00" + (dateVal.getMonth()+1);
	dayString = dayString.substring(dayString.length - 2);
	monthString = monthString.substring(monthString.length - 2);
	return  dayString + dateSeparator + monthString + dateSeparator + dateVal.getFullYear();
}


/**
Convert a string to a JavaScript Date object.
*/
function getFieldDate( dateString ) {
	var dateVal;
	try {
		if (dateString) {
			// Date in format: dd-mm-yy:
			var dateArray = dateString.split('-');
			// Method as: yy, mm (zero based), dd:
			dateVal = new Date(dateArray[2],dateArray[1]-1,dateArray[0])
		} else {
			dateVal = new Date();
		}
	} catch(e) {
		dateVal = new Date();
	}
	
	return dateVal;
}

function clearDateField(dateFieldName) {

	var targetDateField = document.getElementsByName (dateFieldName).item(0);
	targetDateField.value = '';
 
	var pickerDiv = document.getElementById(datePickerDivID);
	pickerDiv.style.visibility = "hidden";
	pickerDiv.style.display = "none";
	
	adjustiFrame();
	targetDateField.focus();
}

function updateDateField(dateFieldName, dateString) {

  var targetDateField = document.getElementsByName (dateFieldName).item(0);
  if (dateString)
    targetDateField.value = dateString;
 
  var pickerDiv = document.getElementById(datePickerDivID);
  pickerDiv.style.visibility = "hidden";
  pickerDiv.style.display = "none";
 
  adjustiFrame();
  targetDateField.focus();
}


/**
 *	iFrame shim:
 */
function adjustiFrame(pickerDiv, iFrameDiv) {
  // If it's opera, return
  if (navigator.userAgent.toLowerCase().indexOf("opera") != -1)
    return;

  try {
    if (!document.getElementById(iFrameDivID)) {
      var newNode = document.createElement("iFrame");
      newNode.setAttribute("id", iFrameDivID);
      newNode.setAttribute("src", "javascript:false;");
      newNode.setAttribute("scrolling", "no");
      newNode.setAttribute ("frameborder", "0");
      document.body.appendChild(newNode);
    }
    
    if (!pickerDiv)
      pickerDiv = document.getElementById(datePickerDivID);
    if (!iFrameDiv)
      iFrameDiv = document.getElementById(iFrameDivID);
    
    try {
      iFrameDiv.style.position = "absolute";
      iFrameDiv.style.width = pickerDiv.offsetWidth;
      iFrameDiv.style.height = pickerDiv.offsetHeight ;
      iFrameDiv.style.top = pickerDiv.style.top;
      iFrameDiv.style.left = pickerDiv.style.left;
      iFrameDiv.style.zIndex = pickerDiv.style.zIndex - 1;
      iFrameDiv.style.visibility = pickerDiv.style.visibility ;
      iFrameDiv.style.display = pickerDiv.style.display;
    } catch(e) {
    }
 
  } catch (ee) {
  }
 }