class DroppingStream

final class DroppingStream implements StreamInterface {
    use StreamDecoratorTrait;
    
    /** @var int */
    private $maxLength;
    
    /** @var StreamInterface */
    private $stream;
    
    /**
     * @param StreamInterface $stream    Underlying stream to decorate.
     * @param int             $maxLength Maximum size before dropping data.
     */
    public function __construct(StreamInterface $stream, int $maxLength) {
        $this->stream = $stream;
        $this->maxLength = $maxLength;
    }
    public function write($string) : int {
        $diff = $this->maxLength - $this->stream
            ->getSize();
        // Begin returning 0 when the underlying stream is too large.
        if ($diff <= 0) {
            return 0;
        }
        // Write the stream or a subset of the stream if needed.
        if (strlen($string) < $diff) {
            return $this->stream
                ->write($string);
        }
        return $this->stream
            ->write(substr($string, 0, $diff));
    }

}