Chris@0: <?php
Chris@0: namespace GuzzleHttp\Psr7;
Chris@0: 
Chris@0: use Psr\Http\Message\StreamInterface;
Chris@0: 
Chris@0: /**
Chris@0:  * Stream decorator that can cache previously read bytes from a sequentially
Chris@0:  * read stream.
Chris@0:  */
Chris@0: class CachingStream implements StreamInterface
Chris@0: {
Chris@0:     use StreamDecoratorTrait;
Chris@0: 
Chris@0:     /** @var StreamInterface Stream being wrapped */
Chris@0:     private $remoteStream;
Chris@0: 
Chris@0:     /** @var int Number of bytes to skip reading due to a write on the buffer */
Chris@0:     private $skipReadBytes = 0;
Chris@0: 
Chris@0:     /**
Chris@0:      * We will treat the buffer object as the body of the stream
Chris@0:      *
Chris@0:      * @param StreamInterface $stream Stream to cache
Chris@0:      * @param StreamInterface $target Optionally specify where data is cached
Chris@0:      */
Chris@0:     public function __construct(
Chris@0:         StreamInterface $stream,
Chris@0:         StreamInterface $target = null
Chris@0:     ) {
Chris@0:         $this->remoteStream = $stream;
Chris@0:         $this->stream = $target ?: new Stream(fopen('php://temp', 'r+'));
Chris@0:     }
Chris@0: 
Chris@0:     public function getSize()
Chris@0:     {
Chris@0:         return max($this->stream->getSize(), $this->remoteStream->getSize());
Chris@0:     }
Chris@0: 
Chris@0:     public function rewind()
Chris@0:     {
Chris@0:         $this->seek(0);
Chris@0:     }
Chris@0: 
Chris@0:     public function seek($offset, $whence = SEEK_SET)
Chris@0:     {
Chris@0:         if ($whence == SEEK_SET) {
Chris@0:             $byte = $offset;
Chris@0:         } elseif ($whence == SEEK_CUR) {
Chris@0:             $byte = $offset + $this->tell();
Chris@0:         } elseif ($whence == SEEK_END) {
Chris@0:             $size = $this->remoteStream->getSize();
Chris@0:             if ($size === null) {
Chris@0:                 $size = $this->cacheEntireStream();
Chris@0:             }
Chris@0:             $byte = $size + $offset;
Chris@0:         } else {
Chris@0:             throw new \InvalidArgumentException('Invalid whence');
Chris@0:         }
Chris@0: 
Chris@0:         $diff = $byte - $this->stream->getSize();
Chris@0: 
Chris@0:         if ($diff > 0) {
Chris@0:             // Read the remoteStream until we have read in at least the amount
Chris@0:             // of bytes requested, or we reach the end of the file.
Chris@0:             while ($diff > 0 && !$this->remoteStream->eof()) {
Chris@0:                 $this->read($diff);
Chris@0:                 $diff = $byte - $this->stream->getSize();
Chris@0:             }
Chris@0:         } else {
Chris@0:             // We can just do a normal seek since we've already seen this byte.
Chris@0:             $this->stream->seek($byte);
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     public function read($length)
Chris@0:     {
Chris@0:         // Perform a regular read on any previously read data from the buffer
Chris@0:         $data = $this->stream->read($length);
Chris@0:         $remaining = $length - strlen($data);
Chris@0: 
Chris@0:         // More data was requested so read from the remote stream
Chris@0:         if ($remaining) {
Chris@0:             // If data was written to the buffer in a position that would have
Chris@0:             // been filled from the remote stream, then we must skip bytes on
Chris@0:             // the remote stream to emulate overwriting bytes from that
Chris@0:             // position. This mimics the behavior of other PHP stream wrappers.
Chris@0:             $remoteData = $this->remoteStream->read(
Chris@0:                 $remaining + $this->skipReadBytes
Chris@0:             );
Chris@0: 
Chris@0:             if ($this->skipReadBytes) {
Chris@0:                 $len = strlen($remoteData);
Chris@0:                 $remoteData = substr($remoteData, $this->skipReadBytes);
Chris@0:                 $this->skipReadBytes = max(0, $this->skipReadBytes - $len);
Chris@0:             }
Chris@0: 
Chris@0:             $data .= $remoteData;
Chris@0:             $this->stream->write($remoteData);
Chris@0:         }
Chris@0: 
Chris@0:         return $data;
Chris@0:     }
Chris@0: 
Chris@0:     public function write($string)
Chris@0:     {
Chris@0:         // When appending to the end of the currently read stream, you'll want
Chris@0:         // to skip bytes from being read from the remote stream to emulate
Chris@0:         // other stream wrappers. Basically replacing bytes of data of a fixed
Chris@0:         // length.
Chris@0:         $overflow = (strlen($string) + $this->tell()) - $this->remoteStream->tell();
Chris@0:         if ($overflow > 0) {
Chris@0:             $this->skipReadBytes += $overflow;
Chris@0:         }
Chris@0: 
Chris@0:         return $this->stream->write($string);
Chris@0:     }
Chris@0: 
Chris@0:     public function eof()
Chris@0:     {
Chris@0:         return $this->stream->eof() && $this->remoteStream->eof();
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Close both the remote stream and buffer stream
Chris@0:      */
Chris@0:     public function close()
Chris@0:     {
Chris@0:         $this->remoteStream->close() && $this->stream->close();
Chris@0:     }
Chris@0: 
Chris@0:     private function cacheEntireStream()
Chris@0:     {
Chris@0:         $target = new FnStream(['write' => 'strlen']);
Chris@0:         copy_to_stream($this, $target);
Chris@0: 
Chris@0:         return $this->tell();
Chris@0:     }
Chris@0: }