private function findHashOf(FileIDHelper $helper, ParsedFileID $parsedFileID, Filesystem $filesystem)
    {
        // Re build the file ID but without the variant
        $fileID = $helper->buildFileID(
            $parsedFileID->getFilename(),
            $parsedFileID->getHash()
        );

        // Couldn't find the original file, let's bail.
        if (!$filesystem->has($fileID)) {
            return false;
        }

        // Get hash from stream
        $stream = $filesystem->readStream($fileID);
        $hc = hash_init('sha1');
        hash_update_stream($hc, $stream);
        $fullHash = hash_final($hc);

        return $fullHash;
    }