PMPro show content before expiration shortcode [pmpro_before_expiration]

functions.php

/*-- Show Content Before Expiration Shortcode -----------------*/
function pmpro_before_expiration_shortcode( $atts, $content=null, $code="" ) {
	//make sure PMPro is active
	if(!function_exists('pmpro_getMembershipLevelForUser'))
		return;
	
	//get attributes
	$a = shortcode_atts( array(
	    'user' => '',
		'days' => '15',
	), $atts );
	
	$days_before = $a['days'];
	
	//find user
	if(!empty($a['user']) && is_numeric($a['user'])) {
		$user_id = $a['user'];
	} elseif(!empty($a['user']) && strpos($a['user'], '@') !== false) {
		$user = get_user_by('email', $a['user']);
		$user_id = $user->ID;
	} elseif(!empty($a['user'])) {
		$user = get_user_by('login', $a['user']);
		$user_id = $user->ID;
	} else {
		$user_id = false;
	}
	
	//no user ID? bail
	if(!isset($user_id))
		return "";

	//get the user's level
	$level = pmpro_getMembershipLevelForUser($user_id);

	if(!empty($level) && !empty($level->enddate)) {
		$enddate = date("Y-m-d", $level->enddate);
	    $beforetime = strtotime($enddate.' -'.$days_before.' days');
	    $beforedate = date("Y-m-d", $beforetime);
	    $todaydate = date("Y-m-d");
	    if(($todaydate >= $beforedate) && ($todaydate <= $enddate)){
	    	return do_shortcode($content);
		} else {
			return "";
		}
	} else {
		return "";
	}

	//return $content;
}
add_shortcode('pmpro_before_expiration', 'pmpro_before_expiration_shortcode');