var CALENDAR_MONTHS           = [ 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec' ];
var CALENDAR_WEEKDAYS         = [ 'S', 'M', 'T', 'W', 'T', 'F', 'S' ];
var CALENDAR_DATEFORMAT       = 'M/d/y';
var CALENDAR_DATEPATTERN      = null;
var CALENDAR_DATEPART_INDICES = [ 1, 0, 2, '/', '/' ];
var CALENDAR_MONTHDAYS        = [ 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ];

//document.onclick = ve_hideCalendar;

function ve_showCalendar( sLink )
{
  if( ve_showCalendar.open )
  {
    ve_hideCalendar();
  }
  else
  {
    var oTextbox = getTag( sLink );
    var oButton = getTag( "btn" + sLink );
    var oCalendar = document.getElementById( "veCalendar" );

    var iLeft = oButton.offsetLeft;
    var iTop = oButton.offsetTop + oButton.parentNode.offsetTop + oButton.offsetHeight;

    oCalendar.style.marginLeft = iLeft;
    oCalendar.style.marginTop = iTop;
    ve_showCalendar.currentDate = ve_calcValidDate( null, getTag( sLink ).value );
    ve_showCalendar.months = CALENDAR_MONTHS;
    ve_showCalendar.weekdays = CALENDAR_WEEKDAYS;

    if( oCalendar.contentWindow ) {
      oCalendar.contentWindow.init( ve_showCalendar.currentDate, ve_showCalendar.months, ve_showCalendar.weekdays );
      }

    oCalendar.style.display = "block";
    ve_showCalendar.link = sLink;
    ve_showCalendar.open = true;
  }
}

function ve_hideCalendar()
{
  if( !ve_showCalendar.open )
    return;

  var oCalendar = getTag( "veCalendar" );

  if(oCalendar != null && oCalendar.style != null)
  {
    oCalendar.style.display = "none";
    ve_showCalendar.open = false;
  }
}

function ve_submitCalendar( oDate )
{
  ve_hideCalendar();
  var format = CALENDAR_DATEFORMAT;
  var month = "" + ( oDate.getMonth() + 1 );
  var day = "" + oDate.getDate();
  var year = oDate.getFullYear();
  var oLink = getTag( ve_showCalendar.link );

  if( month.length < 2 )
    month = "0" + month;

  if( day.length < 2 )
    day = "0" + day;

  var dateString = "";

  for( var i = 0; i < format.length; i++ )
    if( ( ch = format.charAt( i ) ) == 'd' )
      dateString += day;
    else if( ch == 'M' )
      dateString += month;
    else if( ch == 'y' )
      dateString += year;
    else
      dateString += ch;

  oLink.value = dateString;
  oLink.select();
  oLink.focus();

  if( oLink.onchange )
    oLink.onchange();
}

function ve_calcValidDate( pattern, strValue )
{
  var objRegExp = pattern == null || pattern == "" ? CALENDAR_DATEPATTERN : pattern;
  var arrayDate;

  if( objRegExp == null )
    objRegExp = ve_initDatePattern();

  //check to see if in correct format
  if( !( arrayDate = objRegExp.exec( strValue ) ) )
    return null; //doesn't match pattern, bad date
  else
  {
    var intDay = parseInt( arrayDate[ CALENDAR_DATEPART_INDICES[ 0 ] + 1 ], 10 );
    var intYear = parseInt( arrayDate[ CALENDAR_DATEPART_INDICES[ 2 ] + 1 ], 10 );
    var intMonth = parseInt( arrayDate[ CALENDAR_DATEPART_INDICES[ 1 ] + 1 ], 10 );

    if( intYear <	100 )
      intYear += intYear < 70 ? 2000 : 1900;

    //check for valid month
    if( intMonth > 12 || intMonth < 1 )
      return null;

    var maxMonthDays = CALENDAR_MONTHDAYS[ intMonth - 1 ];

    if( intDay > maxMonthDays || intDay < 1 )
      return null;
    else if( intMonth == 2 )
    {
      //check for February
      var booLeapYear = ( intYear % 4 == 0 && ( intYear % 100 != 0 || intYear % 400 == 0 ) );

      if( !booLeapYear && intDay > 28 )
        return null; //Feb. has invalid number of days
    }

    return new Date( intYear, intMonth - 1, intDay );
  }

  return null; //any other values, bad date
}

function ve_validateDateString( pattern, strValue )
{
  return ve_calcValidDate( pattern, strValue ) != null;
}

function ve_validateDate( element, pattern )
{
  if( element.value != "" && !ve_validateDateString( pattern, element.value ) )
  {
    alert( 'Invalid Date.' );
    setTimeout( function(){ element.select(); element.focus(); }, 10 );
    return false;
  }

  return true;
}

function getDateFilter( name, id )
{
  var dateVal = document.getElementById( id ).value;
  return name + ' >= "' + dateVal + '" && ' + name + ' <= "' + dateVal + '"';
}

function ve_initDatePattern()
{
  var format = CALENDAR_DATEFORMAT;
  var pattern = "^";
  var partIndex = 0;
  var ch;

  for( var i = 0; i < format.length; i++ )
    if( ( ch = format.charAt( i ) ) == 'd' )
    {
      CALENDAR_DATEPART_INDICES[ 0 ] = partIndex++;
      pattern += "(\\d{1,2})";
    }
    else if( ch == 'M' )
    {
      CALENDAR_DATEPART_INDICES[ 1 ] = partIndex++;
      pattern += "(\\d{1,2})";
    }
    else if( ch == 'y' )
    {
      CALENDAR_DATEPART_INDICES[ 2 ] = partIndex++;
      pattern += "(\\d{2,4})";
    }
    else
      pattern += "\\" + ch;

  return CALENDAR_DATEPATTERN = new RegExp( pattern + "$" );
}