Chris@0: <?php
Chris@0: namespace GuzzleHttp\Psr7;
Chris@0: 
Chris@0: use Psr\Http\Message\StreamInterface;
Chris@0: 
Chris@0: 
Chris@0: /**
Chris@0:  * Decorator used to return only a subset of a stream
Chris@0:  */
Chris@0: class LimitStream implements StreamInterface
Chris@0: {
Chris@0:     use StreamDecoratorTrait;
Chris@0: 
Chris@0:     /** @var int Offset to start reading from */
Chris@0:     private $offset;
Chris@0: 
Chris@0:     /** @var int Limit the number of bytes that can be read */
Chris@0:     private $limit;
Chris@0: 
Chris@0:     /**
Chris@0:      * @param StreamInterface $stream Stream to wrap
Chris@0:      * @param int             $limit  Total number of bytes to allow to be read
Chris@0:      *                                from the stream. Pass -1 for no limit.
Chris@0:      * @param int             $offset Position to seek to before reading (only
Chris@0:      *                                works on seekable streams).
Chris@0:      */
Chris@0:     public function __construct(
Chris@0:         StreamInterface $stream,
Chris@0:         $limit = -1,
Chris@0:         $offset = 0
Chris@0:     ) {
Chris@0:         $this->stream = $stream;
Chris@0:         $this->setLimit($limit);
Chris@0:         $this->setOffset($offset);
Chris@0:     }
Chris@0: 
Chris@0:     public function eof()
Chris@0:     {
Chris@0:         // Always return true if the underlying stream is EOF
Chris@0:         if ($this->stream->eof()) {
Chris@0:             return true;
Chris@0:         }
Chris@0: 
Chris@0:         // No limit and the underlying stream is not at EOF
Chris@0:         if ($this->limit == -1) {
Chris@0:             return false;
Chris@0:         }
Chris@0: 
Chris@0:         return $this->stream->tell() >= $this->offset + $this->limit;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Returns the size of the limited subset of data
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function getSize()
Chris@0:     {
Chris@0:         if (null === ($length = $this->stream->getSize())) {
Chris@0:             return null;
Chris@0:         } elseif ($this->limit == -1) {
Chris@0:             return $length - $this->offset;
Chris@0:         } else {
Chris@0:             return min($this->limit, $length - $this->offset);
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Allow for a bounded seek on the read limited stream
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function seek($offset, $whence = SEEK_SET)
Chris@0:     {
Chris@0:         if ($whence !== SEEK_SET || $offset < 0) {
Chris@0:             throw new \RuntimeException(sprintf(
Chris@0:                 'Cannot seek to offset % with whence %s',
Chris@0:                 $offset,
Chris@0:                 $whence
Chris@0:             ));
Chris@0:         }
Chris@0: 
Chris@0:         $offset += $this->offset;
Chris@0: 
Chris@0:         if ($this->limit !== -1) {
Chris@0:             if ($offset > $this->offset + $this->limit) {
Chris@0:                 $offset = $this->offset + $this->limit;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         $this->stream->seek($offset);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Give a relative tell()
Chris@0:      * {@inheritdoc}
Chris@0:      */
Chris@0:     public function tell()
Chris@0:     {
Chris@0:         return $this->stream->tell() - $this->offset;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Set the offset to start limiting from
Chris@0:      *
Chris@0:      * @param int $offset Offset to seek to and begin byte limiting from
Chris@0:      *
Chris@0:      * @throws \RuntimeException if the stream cannot be seeked.
Chris@0:      */
Chris@0:     public function setOffset($offset)
Chris@0:     {
Chris@0:         $current = $this->stream->tell();
Chris@0: 
Chris@0:         if ($current !== $offset) {
Chris@0:             // If the stream cannot seek to the offset position, then read to it
Chris@0:             if ($this->stream->isSeekable()) {
Chris@0:                 $this->stream->seek($offset);
Chris@0:             } elseif ($current > $offset) {
Chris@0:                 throw new \RuntimeException("Could not seek to stream offset $offset");
Chris@0:             } else {
Chris@0:                 $this->stream->read($offset - $current);
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         $this->offset = $offset;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Set the limit of bytes that the decorator allows to be read from the
Chris@0:      * stream.
Chris@0:      *
Chris@0:      * @param int $limit Number of bytes to allow to be read from the stream.
Chris@0:      *                   Use -1 for no limit.
Chris@0:      */
Chris@0:     public function setLimit($limit)
Chris@0:     {
Chris@0:         $this->limit = $limit;
Chris@0:     }
Chris@0: 
Chris@0:     public function read($length)
Chris@0:     {
Chris@0:         if ($this->limit == -1) {
Chris@0:             return $this->stream->read($length);
Chris@0:         }
Chris@0: 
Chris@0:         // Check if the current position is less than the total allowed
Chris@0:         // bytes + original offset
Chris@0:         $remaining = ($this->offset + $this->limit) - $this->stream->tell();
Chris@0:         if ($remaining > 0) {
Chris@0:             // Only return the amount of requested data, ensuring that the byte
Chris@0:             // limit is not exceeded
Chris@0:             return $this->stream->read(min($remaining, $length));
Chris@0:         }
Chris@0: 
Chris@0:         return '';
Chris@0:     }
Chris@0: }