protected function execute(InputInterface $input, OutputInterface $output)
    {
        $io = new SymfonyStyle($input, $output);
        $io->title('Start ke_search indexer process');
        $indexerRunner = GeneralUtility::makeInstance(IndexerRunner::class);
        $indexerRunner->logger->log('notice', 'Indexer process started by command controller.');
        $indexerResponse = $indexerRunner->startIndexing(
            true, [], 'CLI'
        );

        if (strstr($indexerResponse, 'You can\'t start the indexer twice')) {
            $io->warning(
                'Indexing lock is set. You can\'t start the indexer process twice.' . chr(10) . chr(10)
                . 'If lock was not reset because of indexer errors you can use ke_search:removelock command.'
            );
        } else {

            // set custom style
            $titleStyle = new OutputFormatterStyle('blue', 'black', array('bold'));
            $output->getFormatter()->setStyle('title', $titleStyle);
            $warning = false;

            foreach (explode(chr(10), $indexerResponse) as $line) {

                // skip empty lines
                if (empty(strip_tags($line))) {
                    continue;
                }

                // format lines and catch warnings
                if (strstr($line, 'There were errors')) {
                    $warning = strip_tags(str_replace('[DANGER] ', '', $line));
                } else if (strstr($line, 'Index contains')) {
                    $io->writeln('<info>' . strip_tags($line) . '</info>');
                } else if (strstr($line, '<p><b>')) {
                    $io->writeln(chr(10) . '<title>' . strip_tags($line) . '</>');
                } else {
                    $io->writeln(strip_tags($line));
                }
            }

            if ($warning !== false) {
                $io->warning($warning);
            }

            $io->success('Indexer process completed.');
        }
    }