How to shortcode ai1ec step 3

// Replace shortcode with page content
            If  (stripos($content, '[ai1ec'))
            {
                $shortcode_pos= stripos($content, '[ai1ec');
                $content_pre = substr($content,0, $shortcode_pos);
                $content_post = substr($content,$shortcode_pos);
                $shortcode = substr($content, $shortcode_pos+1, (stripos($content_post, ']')-1));
                $content_post = substr($content_post,(stripos($content_post, ']')+1));

                $atts=shortcode_parse_atts($shortcode);
                //do shortcode
                $this->route_request_shortcode($atts);

                $content = $content_pre .
                    '<div id="ai1ec-container" class="ai1ec-container">' .
                    $this->page_content .
                    '</div>'.$content_post;

                // used for adding support to have multiple calender in one post
                // If functionality is needed: reactivate next line
                //$content= $this->append_content( $content );
            }
        }