public function getHelperPath($helper)
    {
        if ($this->finder) {
            if (file_exists($file = $this->finder->find($helper))) {
                return $file;
            }
        }

        if (file_exists($helper)) {
            return $helper;
        } elseif (file_exists($helper . '.helper.php')) {
            return $helper . '.helper.php';
        }

        foreach ($this->viewPaths as $viewPath) {
            if (file_exists($viewPath . '/helpers/' . $helper . '.helper.php')) {
                return $viewPath . '/helpers/' . $helper . '.helper.php';
            }
        }

        return null;
    }