function Session_Click(session_id)
{	
	var Break_Num = 0;
	if (session_id % 7 ==0)
	{
		Break_Num = parseInt(session_id/7);
	}
	else
	{
		Break_Num = parseInt(session_id/7) + 1;
	}	

	if (!document.getElementById("ckbSession_" + session_id).checked) return;
	
	if (Check_BreakCheckbox(Break_Num) )
	{
		var begin_id = (Break_Num - 1) * 7 + 1;
		var end_id = (Break_Num - 1) * 7 + 7;
		
		for (var i=begin_id; i<=end_id; i++)
		{
			if (i != session_id)
			{				
				document.getElementById("ckbSession_" + i).checked = false;
			}	 
		}
	} 
	else
	{
		alert("You have already selected the maximum of 3 sessions.");
		document.getElementById("ckbSession_" + session_id).checked = false;
	}
		
}

function Check_BreakCheckbox(index) 
{
	for (var i=1; i<=4; i++)
	{
		if (i != index)
		{
			var begin_id = (i - 1) * 7 + 1;
			var end_id = (i - 1) * 7 + 7;	
			var IsChecked = false;		
			for (var j=begin_id; j<=end_id; j++)
			{			
				if (document.getElementById("ckbSession_" + j).checked)
				{
					IsChecked = true;
					break;
				}	 
			} 
						
			if (!IsChecked)
			{
				return true;
			}						
		}				
	}
	
	return false;	
} 

function Add_AttendeeNames () { 
	var obj = document.getElementById("lbxAttenNames");
	
	var PeopleNum = parseInt(document.getElementById("txtPeopleNum").value);
	if (obj.options.length >= (PeopleNum-1)) 
	{
		alert("You only registered for " + PeopleNum + " people.");
		return;
	}
	
        var AttName = document.getElementById("txtAttName").value;
        if (AttName == "")
        {
        	alert("Attendee name is required");
        	document.getElementById("txtAttName").focus();
        	return false;
        }
        
	
	var customOptions = document.createElement("OPTION");
	
	customOptions.text = AttName;
	customOptions.value = AttName;
					
	if(navigator.appName == 'Microsoft Internet Explorer')
	{
		obj.add(customOptions);
	}
	else
	{
		obj.appendChild(customOptions);
	}
	
	document.getElementById("txtAttName").value = "";
	document.getElementById("txtAttName").focus();
	
	var tmp_AttNames = ""; 
	for(var i = 0; i<obj.options.length; i++)
	{
		tmp_AttNames += obj.options[i].value + "|" ;
	}
	tmp_AttNames = tmp_AttNames.substring(0,tmp_AttNames.length-1);
	document.getElementById("txtHidAttNames").value = tmp_AttNames;	
	
}

function Delete_AttendeeNames() { 
	var obj = document.getElementById("lbxAttenNames");
	var IsSelected = false;
	for(var i = obj.options.length - 1 ;i >= 0;i--)
	{
		if(obj.options[i].selected)
		{
			IsSelected = true;
			obj.remove(i);
			
			break;
		}
	}
	
	if (IsSelected == false)			
	{
		alert("please select");	
		document.getElementById("lbxAttenNames").focus();
	}
	
	var tmp_AttNames = ""; 
	for(var i = 0; i<obj.options.length; i++)
	{
		tmp_AttNames += obj.options[i].value + "|" ;
	}
	tmp_AttNames = tmp_AttNames.substring(0,tmp_AttNames.length-1);
	document.getElementById("txtHidAttNames").value = tmp_AttNames;		

}