protected function setLanguage($prefix, $assetPath = null, $filePath = null, $suffix = '.js')
    {
        $pwd = Env::getCurrentDir($this);
        $s = DIRECTORY_SEPARATOR;
        if ($assetPath === null) {
            $assetPath = "{$pwd}{$s}assets{$s}";
        } elseif (substr($assetPath, -1) != $s) {
            $assetPath .= $s;
        }

        if ($filePath === null) {
            $filePath = "js{$s}locales{$s}";
        } elseif (substr($filePath, -1) != $s) {
            $filePath .= $s;
        }

        $full = $filePath . $prefix . $this->language . $suffix;
        $fullLower = $filePath . $prefix . strtolower($this->language) . $suffix;
        $short = $filePath . $prefix . $this->_lang . $suffix;
        if (Env::fileExists($assetPath . $full)) {
            $this->_langFile = $full;
            $this->pluginOptions['language'] = $this->language;
        } elseif (Env::fileExists($assetPath . $fullLower)) {
            $this->_langFile = $fullLower;
            $this->pluginOptions['language'] = strtolower($this->language);
        } elseif (Env::fileExists($assetPath . $short)) {
            $this->_langFile = $short;
            $this->pluginOptions['language'] = $this->_lang;
        } else {
            $this->_langFile = '';
        }

        $this->_langFile = str_replace($s, '/', $this->_langFile);
    }