function checkEmptyFields() {	
	var messages = '';
	var emailFilter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	firstName = document.getElementsByName('FirstName')[0].value;
	lastName = document.getElementsByName('LastName')[0].value;
	email = document.getElementsByName('EmailFrom')[0].value;
	message = document.getElementsByName('Message')[0].value;
	if (firstName=='')
		messages += "'first name' can't be empty !\n";
	if (lastName=='')
		messages += "'last name' can't be empty !\n";
	if (email=='')
		messages += "'email' can't be empty !\n";
	if (!emailFilter.test(email))
		messages += "'email' is incorrect !\n";
	if (message=='')
		messages += "'message' can't be empty !\n";
	if (messages=='') {
		return true;
	}
	else {
		alert(messages);
		return false;
	}
}




function N(element)
{
	if(document.getElementsByName(element))
	{
		return document.getElementsByName(element);
	}	
}


function Nvalue(element)
{
	if(document.getElementsByName(element))
	{
		return document.getElementsByName(element)[0].value;
	}	
}

function $(element)
{
	if(document.getElementsById(element)){
		return document.getElementsById(element);
	}
}


function checkEventForm()
{
	var mainF =  Array(
	"FirstName",
	"LastName",
	"EmailFrom",
	"Mobile");	
	
	var friend1  = new Array(
	"FirstName-Friend1",
	"LastName-Friend1",
	"EmailFrom-Friend1",
	"Mobile-Friend1"	);	
	
	var friend2  = new Array(
	"FirstName-Friend2",
	"LastName-Friend2",
	"EmailFrom-Friend2",
	"Mobile-Friend2");	
	
	var friend3  = new Array(
	"FirstName-Friend3",
	"LastName-Friend3",
	"EmailFrom-Friend3",
	"Mobile-Friend3");	
	
	var friendsArray = new Array(friend1, friend2,friend3)
	var emailFilter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	
	var radioChecked = false;
	var formValid = true;
	var ss = N('coming-at-the-meeting');

			
	// Checking empty field + email for main form
	for (var i = 0 ; i < mainF.length; i++)
	{
		if (Nvalue(mainF[i]) == "") 
		{
			showErrorFrom(N(mainF[i]));	
			formValid = false;
		} 
		else 
		{		
			// FOR EMAIL
			if ( mainF[i] == "EmailFrom" && !emailFilter.test(Nvalue(mainF[i])) )			
			{
				showErrorFrom(N(mainF[i]));	
				formValid = false;
			}
			else{removeError(N(mainF[i]))}			
		}				
	}
	
	// check if checked
	isChecked = false;
	
	for (var i = 0 ; i < ss.length; i++)		
	{
	 if(ss[i].checked){isChecked = true;}
	}		
	
	
	if(isChecked)
	{
		
		for (var i = 0 ; i < ss.length; i++)		
		{
		var tt = ss[i]			
		removeError(ss[i].nextSibling)
		
		
		if(N('coming-at-the-meeting')[i].checked)
			{
				if (N('coming-at-the-meeting')[i].value == "3")
				{

					for (var p = 0; p  < $('number-of-person').value; p++)
					{
						// checking friend form
						for (var t = 0 ; t < friendsArray[p].length; t++)
						{								
							
							if (Nvalue(friendsArray[p][t]) == "") 
							{
								showErrorFrom(N(friendsArray[p][t]));							
								formValid = false;
							} 
							else 
							{		
								// FOR EMAIL
								if ( friendsArray[p][t] == "EmailFrom-Friend"+(p+1).toString() && !emailFilter.test(Nvalue(friendsArray[p][t])) )			
								{																											
									showErrorFrom(N(friendsArray[p][t]));								
									formValid = false;
								}
								else{removeError(N(friendsArray[p][t]))}								
							}	
						}
						
					}
				}
			}		
		}		
	}	
	else
	{	
		
		for(var p = 0 ; p <ss.length; p++ )
		{
			var tt = ss[p]
			
			showErrorFrom(ss[p].nextSibling)
		}
		
		formValid = false;
	}

	return formValid;
}

function showErrorFrom(element)
{
	try{
		var errorToShow = element[0].nextSibling;
		errorToShow.style.display = "inline";
		
	}
	catch(e)
	{
		try{
		var errorToShow = element
		errorToShow.style.display = "inline";
		
		}
		catch(e){}
	}
	
}

function removeError(element)
{
	if (element[0])
	{
		var errorToShow = element[0].nextSibling;
		errorToShow.style.display = "none";
	}
	else
	{
		var errorToShow = element
		errorToShow.style.display = "none";
	}
	
}