/**
 * @author koen
 */

 function showTarget(targetID)
 {
 	el = document.getElementById(targetID);
	el.style.display = ''; 		
 }
 
 function hideTarget(targetID)
 {
 	el = document.getElementById(targetID);
	el.style.display = 'none';	
 }
 
 function showNewsletterForm(type)
 {
	 switch(type)
	 {
	 	case 'in':
	 		showTarget('zone_newsletter_in');
	 		hideTarget('zone_newsletter_out');
	 		document.newsletter_in.emailaddress.value = document.newsletter_out.emailaddress.value;
	 		break;
	 	case 'out':
	 		showTarget('zone_newsletter_out');
	 		hideTarget('zone_newsletter_in');
	 		document.newsletter_out.emailaddress.value = document.newsletter_in.emailaddress.value;
	 		break;
	 }
 }
 
 
 /* checking of the forms */
 
 function checkSubscribeForm()
 {
 	var email = document.newsletter_in.emailaddress.value;
	if(email=='')
	{
		alert('Please provide an email address!');
		return false;
	}
	else if(!emailCheck(email))
	{
		return false;
	}
	else 
	{
		return true;
	}	
 }
 
 function checkUnsubscribeForm()
 {
 	var email = document.newsletter_out.emailaddress.value;
	if(email=='')
	{
		alert('Please provide an email address!');
		return false;
	}
	else if(!emailCheck(email))
	{
		return false;
	}
	else 
	{
		return true;
	}
}

function emailCheck(str) 
{
	var at="@"
	var dot="."
	var lat=str.indexOf(at)
	var lstr=str.length
	var ldot=str.indexOf(dot)
	if (str.indexOf(at)==-1){
	   alert("Invalid E-mail ID")
	   return false
	}

	if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
	   alert("Invalid E-mail ID")
	   return false
	}

	if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
	    alert("Invalid E-mail ID")
	    return false
	}

	 if (str.indexOf(at,(lat+1))!=-1){
	    alert("Invalid E-mail ID")
	    return false
	 }

	 if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
	    alert("Invalid E-mail ID")
	    return false
	 }

	 if (str.indexOf(dot,(lat+2))==-1){
	    alert("Invalid E-mail ID")
	    return false
	 }
	
	 if (str.indexOf(" ")!=-1){
	    alert("Invalid E-mail ID")
	    return false
	 }

	 return true					
}