public static function diffUndo(array $args, array $named)
{
if (count($args) !== 1) {
throw new WrongNumberArgumentsException($args, 'one');
}
list($diffContent) = $args;
$differenceEngine = new \DifferenceEngine();
$multi = $differenceEngine->getMultiNotice();
$notice = '';
if ($diffContent === '') {
$notice = '<div class="mw-diff-empty">' . wfMessage('diff-empty')->parse() . "</div>\n";
}
$differenceEngine->showDiffStyle();
return self::html($differenceEngine->addHeader($diffContent, wfMessage('flow-undo-latest-revision'), wfMessage('flow-undo-your-text'), $multi, $notice));
}