/**
         * Guestbook main functions
         */
        public static function main() {
            // Get guestbook table
            Guestbook::$guestbook = new Table('guestbook');
            // Select all records
            $records = Guestbook::$guestbook->select(null, 'all');
            // Get post data
            $username   = Request::post('guestbook_username'); 
            $email      = Request::post('guestbook_email');                    
            $message    = Request::post('guestbook_message');
            $actionlink = Option::get('siteurl').'/guestbook';
            $errors = array();
            // Add new record
            if (Request::post('guestbook_submit')) {
                if (Security::check(Request::post('csrf'))) {
                    if (Request::post('guestbook_username') == '' || Request::post('guestbook_email') == '' || Request::post('guestbook_message') == '') {
                        $errors['guestbook_empty_fields'] = __('Empty required fields!', 'guestbook');
                    }
                    if ( ! Valid::email(Request::post('guestbook_email'))) {
                        $errors['guestbook_email_not_valid'] = __('Email address is not valid!', 'guestbook');
                    }
                    if (Option::get('captcha_installed') == 'true' && ! CryptCaptcha::check(Request::post('answer'))) { 
                        $errors['users_captcha_wrong'] = __('Captcha code is wrong', 'users');
                    }
                    if (count($errors) == 0) {
                        Guestbook::$guestbook->insert(array('username' => $username, 'email' => $email, 'message' => $message, 'date' => time()));
                        Request::redirect($actionlink);
                    }
                } else { die('csrf detected!'); }
            }
            // Get index view
            Guestbook::$guestbook_records = View::factory('guestbook/views/frontend/index')
                        ->assign('records', $records)
                        ->render();
            // Get form view
            Guestbook::$guestbook_form = View::factory('guestbook/views/frontend/form')
                        ->assign('token', Security::token())
                        ->assign('actionlink', $actionlink)
                        ->assign('username', $username)
                        ->assign('email', $email)
                        ->assign('message', $message)
                        ->assign('errors', $errors)
                        ->render();
        }