Hide custom menu items based on session variables

nmr-session-roles.php

<?php
/*
Plugin Name: Nav Menu Roles + Session Roles
Plugin URI: http://www.kathyisawesome.com/449/nav-menu-roles/
Description: Hide custom menu items based on session variables
Version: 1.0.0
Author: Kathy Darling
Author URI: http://www.kathyisawesome.com
License: GPL-3.0

Copyright 2015 Kathy Darling(email: kathy.darling@gmail.com)

*/

/*
 * Set session
 */
function kia_group_session(){

	// start session
	if( ! session_id() ){
		session_start();
	}

	// if your group form is submitted store as session variable
	if( isset( $_POST['frm1'] ) ){
		$_SESSION['kia-group'] = $_POST['frm1']; // maybe sanitize this
	}

}
add_action( 'init', 'kia_group_session' );




/*
 * Add custom roles to Nav Menu Roles menu list
 * param: $roles an array of all available roles, by default is global $wp_roles 
 * return: array
 */
function kia_new_roles( $roles ){
	$roles['no-group'] = 'No Group';
	$roles['group-1'] = 'Group 1';
	$roles['group-2'] = 'Group 1';
	return $roles;
}
add_filter( 'nav_menu_roles', 'kia_new_roles' );


/*
 * Change visibilty of each menu item
 * param: $visible boolean
 * param: $item object, the complete menu object. Nav Menu Roles adds its info to $item->roles
 * $item->roles can be "in" (all logged in), "out" (all logged out) or an array of specific roles
 * return boolean
 */
function kia_item_visibility( $visible, $item ){
	if( isset( $item->roles ) && is_array( $item->roles ) ){

		// get the group ID from session variable
		$group_id = ! empty( $_SESSION['kia-group'] ) ? $_SESSION['kia-group'] : 'no-group';

		foreach ( $item->roles as $role ) {
			// check all logged in, all logged out, or role
			switch( $role ) {
				case 'group-1' :
					$visible = 'group-1' == $group_id ? true : false;
					break;
				case 'group-2' :
					$visible = 'group-2' == $group_id ? true : false;
					break;
				case 'no-group' :
					$visible = 'no-group' == $group_id ? true : false;
					break;
			}

		}

	}
	return $visible;
}
add_filter( 'nav_menu_roles_item_visibility', 'kia_item_visibility', 10, 2 );