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

var dayArrayShort = new Array('S', 'M', 'T', 'W', 'T', 'F', 'S');
var dayArrayMed = new Array('Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat');
var dayArrayLong = new Array('Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday');
var monthArrayShort = new Array('Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec');
var monthArrayMed = new Array('Jan', 'Feb', 'Mar', 'Apr', 'May', 'June', 'July', 'Aug', 'Sept', 'Oct', 'Nov', 'Dec');
var monthArrayLong = new Array('January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December');

var defaultDateSeparator = "-";
var defaultDateFormat = "ymd"
var dateSeparator = defaultDateSeparator;
var dateFormat = defaultDateFormat;

function drawDatePicker(targetDateField, x, y)
{
	var dt = getFieldDate(targetDateField.value );

	if (!$(datePickerDivID))
	{
		var newNode = document.createElement("div");
		newNode.setAttribute("id", datePickerDivID);
		newNode.setAttribute("class", "dpDiv");
		newNode.setAttribute("style", "position:absolute;left:-99999px;top:-99999px;visibility: hidden;");
		document.body.appendChild(newNode);
	}

	var pickerDiv = $(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;

	refreshDatePicker(targetDateField.name, dt.getFullYear(), dt.getMonth(), dt.getDate());
}

function refreshDatePicker(dateFieldName, year, month, day)
{
	var thisDay = new Date();

	if ((month >= 0) && (year > 0))
	{
		thisDay = new Date(year, month, 1);
	} 
	else 
	{
		day = thisDay.getDate();
		thisDay.setDate(1);
	}

	var crlf = "\r\n";
	var TABLE = "<table cols=7 class='dpTable'>" + crlf;
	var xTABLE = "</table>" + crlf;
	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\";' ";
	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\";' ";
	var xTD = "</td>" + crlf;
	var DIV_title = "<div class='dpTitleText'>";
	var DIV_selected = "<div class='dpDayHighlight'>";
	var xDIV = "</div>";

	var html = TABLE;

	html += TR_title;
	html += TD_buttons + getButtonCode(dateFieldName, thisDay, -1, "&laquo;") + xTD;
	html += TD_title + DIV_title + monthArrayLong[ thisDay.getMonth()] + " " + thisDay.getFullYear() + xDIV + xTD;
	html += TD_buttons + getButtonCode(dateFieldName, thisDay, 1, "&raquo;") + xTD;
	html += xTR;

	html += TR_days;
	var i;
	for(i = 0; i < dayArrayShort.length; i++) { html += TD_days + dayArrayShort[i] + xTD; }
	html += xTR;

	html += TR;

	for (i = 0; i < thisDay.getDay(); i++) { html += TD + "&nbsp;" + xTD; }

	do
	{
		var dayNum = thisDay.getDate();
		var TD_onclick = " onclick=\"updateDateField('" + dateFieldName + "', '" + getDateString(thisDay) + "');\">";

		if (dayNum == day) html += TD_selected + TD_onclick + DIV_selected + dayNum + xDIV + xTD;
		else html += TD + TD_onclick + dayNum + xTD;

		if (thisDay.getDay() == 6) html += xTR + TR;

		thisDay.setDate(thisDay.getDate() + 1);
	}
	while (thisDay.getDate() > 1)

	if (thisDay.getDay() > 0)
	{
		for (i = 6; i > thisDay.getDay(); i--) html += TD + "&nbsp;" + xTD;
	}
	html += xTR;

	var today = new Date();
	var todayString = "Today is " + dayArrayMed[today.getDay()] + ", " + monthArrayMed[ today.getMonth()] + " " + today.getDate();
	html += TR_todaybutton + TD_todaybutton;
	html += "<button class='dpTodayButton' onClick='refreshDatePicker(\"" + dateFieldName + "\");'>Today</button> ";
	html += "<button class='dpTodayButton' onClick='updateDateField(\"" + dateFieldName + "\");'>Close</button>";
	html += xTD + xTR;

	html += xTABLE;

	$(datePickerDivID).innerHTML = html;
	adjustiFrame();
}

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>";
}

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);
 
	switch (dateFormat)
	{
		case "dmy" :
			return dayString + dateSeparator + monthString + dateSeparator + dateVal.getFullYear();
		case "ymd" :
			return dateVal.getFullYear() + dateSeparator + monthString + dateSeparator + dayString;
		case "mdy" :
		default :
			return monthString + dateSeparator + dayString + dateSeparator + dateVal.getFullYear();
	}
}

function getFieldDate(dateString)
{
	var dateVal;
	var dArray;
	var d, m, y;
 
	try
	{
		dArray = splitDateString(dateString);
		if (dArray)
		{
			switch (dateFormat)
			{
				case "dmy" :
					d = parseInt(dArray[0], 10);
					m = parseInt(dArray[1], 10) - 1;
					y = parseInt(dArray[2], 10);
					break;
				case "ymd" :
					d = parseInt(dArray[2], 10);
					m = parseInt(dArray[1], 10) - 1;
					y = parseInt(dArray[0], 10);
					break;
				case "mdy" :
				default :
					d = parseInt(dArray[1], 10);
					m = parseInt(dArray[0], 10) - 1;
					y = parseInt(dArray[2], 10);
					break;
			}
			dateVal = new Date(y, m, d);
		}
		else if (dateString)
		{
			dateVal = new Date(dateString);
		}
		else
		{
			dateVal = new Date();
		}
	}
	catch(e)
	{
		dateVal = new Date();
	}
 
	return dateVal;
}

function splitDateString(dateString)
{
	var dArray;
	if (dateString.indexOf("/") >= 0) dArray = dateString.split("/");
	else if (dateString.indexOf(".") >= 0) dArray = dateString.split(".");
	else if (dateString.indexOf("-") >= 0) dArray = dateString.split("-");
	else if (dateString.indexOf("\\") >= 0) dArray = dateString.split("\\");
	else dArray = false;

	return dArray;
}

function updateDateField(dateFieldName, dateString)
{
	var targetDateField = document.getElementsByName (dateFieldName).item(0);
	if (dateString) targetDateField.value = dateString;

	var pickerDiv = $(datePickerDivID);
	pickerDiv.style.visibility = "hidden";
	pickerDiv.style.display = "none";

	adjustiFrame();
	targetDateField.focus();

	if ((dateString) && (typeof(datePickerClosed) == "function")) datePickerClosed(targetDateField);
}

function adjustiFrame(pickerDiv, iFrameDiv)
{
	var is_opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
	if (is_opera) return;

	try
	{
		if (!$(iFrameDivID))
		{
			var newNode = document.createElement("iFrame");
			newNode.setAttribute("id", iFrameDivID);
			newNode.setAttribute("src", "javascript:false;");
			newNode.setAttribute("scrolling", "no");
			newNode.setAttribute ("frameborder", "0");
			newNode.setAttribute("style", "position:absolute;left:-99999px;top:-99999px;");
			document.body.appendChild(newNode);
		}
	    
		if (!pickerDiv) pickerDiv = $(datePickerDivID);
		if (!iFrameDiv) iFrameDiv = $(iFrameDivID);
	    
		try
		{
			iFrameDiv.style.position = "absolute";
			iFrameDiv.style.width = pickerDiv.offsetWidth+'px';
			iFrameDiv.style.height = pickerDiv.offsetHeight+'px';
			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) { }
}

function displayDatePicker(dateFieldName, displayBelowThisObject, dtFormat, dtSep)
{
	var targetDateField = document.getElementsByName (dateFieldName).item(0);

	if (!displayBelowThisObject) displayBelowThisObject = targetDateField;

	if (dtSep) dateSeparator = dtSep;
	else dateSeparator = defaultDateSeparator;

	if (dtFormat) dateFormat = dtFormat;
	else dateFormat = defaultDateFormat;

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

	var parent = displayBelowThisObject;
	while (parent.offsetParent)
	{
		parent = parent.offsetParent;
		x += parent.offsetLeft;
		y += parent.offsetTop ;
	}
	 
	drawDatePicker(targetDateField, x, y);
}