if $current_user->first_name is null how to show $current_user->user_login ???

Hey guys, how would you write this in a function..

Basically I want to echo the first name but if field is empty to show user name or user id instead..

This is what I have..

// Callback function for displaying admin messages @return calls jraba_show_msg()
function jraba_admin_msgs() {  global 

$jraba_settings_pg = strpos($_GET['page'], JRABA_PAGE_BASENAME);
$jraba_errors = get_settings_errors();
$current_user; get_currentuserinfo();

//display admin message only for the admin to see, only on our settings page and only when setting errors/notices are returned!
if(current_user_can ('manage_options') && $jraba_settings_pg !== FALSE && !empty($jraba_errors)){  

// have our settings succesfully been updated?
if($jraba_errors[0]['code'] == 'settings_updated' && isset($_GET['settings-updated'])){
jraba_show_msg("<p>" . $update_message = 'Hey ' . $current_user->first_name . ', your settings have been successfully updated. Why don\'t you hover over the menu to ensure that your options are either ON or OFF.' . "</p>", 'updated');
// have errors been found?
}else{ foreach($jraba_errors as $jraba_error){  

// set the title attribute to match the error "setting title" - need this in js file
jraba_show_msg("<p class='setting-error-message' title='" . $jraba_error['setting'] . "'>" . $jraba_error['message'] . "</p>", 'error'); } } } }

function jraba_show_msg($message, $msgclass = 'info') { echo "<div id='message' class='$msgclass'>$message</div>"; } 

if ' . $current_user->first_name . ' empty show ' $current_user->user_login . '

Now if you look under $update_message you will see my update message “Hey ‘ . $current_user->first_name . ‘, your settings have been successfully updated. Why don\’t you hover over the menu to ensure that your options are either ON or OFF.”

The $current_user->first_name will echo out the first name, which works good, but what if the user does not have the first name field filled out, I would like it to echo out if $current_user->user_login if the first name is not available..

How would you do this?