Partial hiding of files in Omeka

EmbargoAclAssertion.php

<?php

class EmbargoAclAssertion implements Zend_Acl_Assert_Interface
{
    public function assert(
        Zend_Acl $acl,
        Zend_Acl_Role_Interface $role = null,
        Zend_Acl_Resource_Interface $resource = null,
        $privilege = null)
    {
        if (is_object($role)) {
            if($role->getRoleId() == 'super') {
                return false;
            }
            if($role->getRoleId() == 'admin') {
                if(get_class($resource) == 'Item') {
                    return false;
                }
                if(get_class($resource) == 'File') {
                    return true;
                }
            }
            
        }
        return true;
    }
}

EmbargoPlugin.php

<?php

class EmbargoPlugin extends Omeka_Plugin_AbstractPlugin
{
    public $_hooks = array('define_acl');
    
    public function hookDefineAcl($args)
    {
        $acl = $args['acl'];
        require_once(__DIR__ . '/EmbargoAclAssertion.php');
        $acl = $args['acl'];
        $acl->addResource('viewEmbargoedItems');
        $acl->deny(null, 
                array('Items', 'Files'),
                array('show', 'showNotPublic'),
                new EmbargoAclAssertion);
    }
}