gistfile1.php

<?php

        if (!empty($this->request->query['tr']))
        {
            $this->Cookie->write('tr', $this->request->query['tr'], true, '30 day');            
        }
        else
        {
            if ($this->Cookie->check('tr'))
            {
                $this->Cookie->write('tr', $this->Cookie->read('tr'), true, '30 day');
            }
        }