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

var dayArrayShort = new Array('Su', 'Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa');
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 = "mdy"
var dateSeparator = defaultDateSeparator;
var dateFormat = defaultDateFormat;
var returnType; // null:fill form field - 'var':set dateTemp=date, call dateProcess();

function displayDatePicker(dateFieldName, displayBelowThisObject, retType) {
  	var targetDateField = document.getElementsByName(dateFieldName).item(0);
  	returnType=retType;
    
  	if (!displayBelowThisObject)
    	displayBelowThisObject = targetDateField;
  	var x = displayBelowThisObject.offsetLeft;
  	var y = displayBelowThisObject.offsetTop + displayBelowThisObject.offsetHeight;
  
  	// deal with elements inside tables and such
  	var parent = displayBelowThisObject;
  	while (parent.offsetParent) {
    	parent = parent.offsetParent;
    	x += parent.offsetLeft;
    	y += parent.offsetTop;
  	}
  	drawDatePicker(targetDateField, x, y);
}

function drawDatePicker(targetDateField, x, y) {
  	var dt = getFieldDate(targetDateField.value);
  
  	// the datepicker table will be drawn inside of a <div> with an ID defined by the
  	// global datePickerDivID variable. If such a div doesn't yet exist on the HTML
  	// document we're working with, add one.
  	if (!document.getElementById(datePickerDivID)) {
    	// don't use innerHTML to update the body, because it can cause global variables
    	// that are currently pointing to objects on the page to have bad references
    	//document.body.innerHTML += "<div id='" + datePickerDivID + "' class='dpDiv'></div>";
    	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.zIndex = 10000;
  
  	// draw the datepicker table
  	refreshDatePicker(targetDateField.name, dt.getFullYear(), dt.getMonth(), dt.getDate());
}

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();
  
  	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 TABLE = "<table cols=7 class='dpTable'>";
  var xTABLE = "</table>";
  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>";
  var TD = "<td class='dpTD'";	// 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'";	// leave this tag open, because we'll be adding an onClick event
  var xTD = "</td>";
  var DIV_title = "<div class='dpTitleText'>";
  var DIV_selected = "<div class='dpDayHighlight'>";
  var xDIV = "</div>";
  
  // start generating the code for the calendar table
  var html = TABLE;
  
  // this is the title bar, which displays the month and the buttons to
  // go back to a previous month or forward to the next month
  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;
  
  // first, the 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
      html += TD + TD_onclick + dayNum + xTD;
    
    // if this is a Saturday, start a new row
    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();
  var todayString = "Today is " + dayArrayMed[today.getDay()] + ", " + monthArrayMed[today.getMonth()] + " " + today.getDate();
  html += TR_todaybutton + TD_todaybutton;
  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 += xTABLE;
  
  document.getElementById(datePickerDivID).innerHTML = html;
  // add an "iFrame shim" to allow the datepicker to display above selection lists
  adjustiFrame();
}


/**
Convenience function for writing the code for the buttons that bring us back or forward
a month.
*/
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);
  
  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();
  }
}


/**
Convert a string to a JavaScript Date object.
*/
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;
      }
      if(y<100){y+=2000;}
      dateVal = new Date(y, m, d);
    } else {
      dateVal = new Date(dateString);
    }
  } catch(e) {
    dateVal = new Date();
  }
  return dateVal;
}


/**
Try to split a date string into an array of elements, using common date separators.
If the date is split, an array is returned; otherwise, we just return false.
*/
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){
	if(returnType=='var'){
		dateTmp=dateString;
		document.getElementById(datePickerDivID).style.visibility = "hidden";
		adjustiFrame();
		dateProcess();
	}else{
		var targetDateField = document.getElementsByName(dateFieldName).item(0);
		if (dateString)
			targetDateField.value = dateString;
		document.getElementById(datePickerDivID).style.visibility = "hidden";
		adjustiFrame();
		targetDateField.focus();
	}
	if(window.dateFieldChanged){
		dateFieldChanged();
	}
}

/*
    Is this a valid date?
    Do we need to calc the age and set it?
*/
function validDate(dateFieldName, age) {
    dateString = document.getElementById(dateFieldName).value;
	
	if (dateString && dateString != '00/00/0000') {
		// make sure / are used to seperate
		dateString = dateString.replace(/\D/g, '/');
		//alert(dateString);
		
		// check field lengths are right mm/dd/yyyy
		results = dateString.split('/');
		for (var i=0; i<2; i++) {
			if (results[i].length < 2) {
				results[i] = '0' + results[i];
			}
		}
		if (results[2].length < 4) {
			results[2] = '20' + results[2];
		}
		
		dateString = results[0] + '/' + results[1] + '/' + results[2];
		document.getElementById(dateFieldName).value = dateString;
		//alert(dateString);
		
		if (dateString) {
			var dt = getFieldDate(dateString);
			
			year = dt.getFullYear();
			month = dt.getMonth() + 1;
			day = dt.getDate();
			
			if (month < 10)
				month = '0' + month;
			
			if (day < 10)
				day = '0' + day;
			
			testDate = month + defaultDateSeparator + day + defaultDateSeparator + year;
			if (testDate == dateString) {
				if (age) {
					var years = parseInt(round((new Date() - dt) / 24 / 60 / 60 / 1000 / 365.25));
					
					if (years > 0 ) {
						document.getElementById(age).innerHTML = years + ' years';
					} else {
						var months = parseInt(round((new Date() - dt) / 24 / 60 / 60 / 1000 / 30));                
						document.getElementById(age).innerHTML = months + ' months';
					}
				}
			} else {
				alert('The date you just entered is invalid.\nPlease make sure it follows this format mm/dd/yyyy');
				//document.getElementById(dateFieldName).focus();
			}
		}
	}
}

function round(x) {
    return Math.round (x * 100) / 100;
}


/**
Use an "iFrame shim" to deal with problems where the datepicker shows up behind
selection list elements, if they're below the datepicker. The problem and solution are
described at:

http://dotnetjunkies.com/WebLog/jking/archive/2003/07/21/488.aspx
http://dotnetjunkies.com/WebLog/jking/archive/2003/10/30/2975.aspx
*/
function adjustiFrame(pickerDiv, iFrameDiv){
  if (!document.getElementById(iFrameDivID)) {
    // don't use innerHTML to update the body, because it can cause global variables
    // that are currently pointing to objects on the page to have bad references
    //document.body.innerHTML += "<iframe id='" + iFrameDivID + "' src='javascript:false;' scrolling='no' frameborder='0'>";
    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;
  } catch(e) {
  }
}