Fatal error: ... helix3 ...

<?php
/**
* @package Helix3 Framework
* @author JoomShaper http://www.joomshaper.com
* @copyright Copyright (c) 2010 - 2015 JoomShaper
* @license http://www.gnu.org/licenses/gpl-2.0.html GNU/GPLv2 or Later
*/  

//no direct accees
defined ('_JEXEC') or die ('resticted aceess');

jimport('joomla.plugin.plugin');
jimport('joomla.filesystem.folder');
jimport('joomla.filesystem.file');

class plgAjaxHelix3 extends JPlugin
{
    function onAjaxHelix3()
    {
        if ($_POST['data']) {
            $data = json_decode(json_encode($_POST['data']),true);;
            $action = $data['action'];
            $layoutName = '';

            if (isset($data['layoutName'])) {
                $layoutName = $data['layoutName'];
            }

            $template  = self::getTemplate();
            $layoutPath = JPATH_SITE.'/templates/'.$template.'/layout/';

            $filepath = $layoutPath.$layoutName;

            $report = array();
            $report['action'] = 'none';
            $report['status'] = 'false';

            switch ($action) {
                case 'remove':
                        if (file_exists($filepath)) {
                            unlink($filepath);
                            $report['action'] = 'remove';
                            $report['status'] = 'true';
                        }
                        $report['layout'] = JFolder::files($layoutPath, '.json');
                    break;

                case 'save':
                        if ($layoutName) {
                            $layoutName = strtolower(str_replace(' ','-',$layoutName));
                        }
                        $content = $data['content'];

                        if ($content && $layoutName) {
                            $file = fopen($layoutPath.$layoutName.'.json', 'wb');
                            fwrite($file, $content);
                            fclose($file);