<?php

/**

 * Zend Framework

 *

 * LICENSE

 *

 * This source file is subject to the new BSD license that is bundled

 * with this package in the file LICENSE.txt.

 * It is also available through the world-wide-web at this URL:

 * http://framework.zend.com/license/new-bsd

 * If you did not receive a copy of the license and are unable to

 * obtain it through the world-wide-web, please send an email

 * to license@zend.com so we can send you a copy immediately.

 *

 * @category   Zend

 * @package    Zend_Amf

 * @subpackage Util

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

/**

 * Utility class to walk through a data stream byte by byte with conventional names

 *

 * @package    Zend_Amf

 * @subpackage Util

 * @license    http://framework.zend.com/license/new-bsd     New BSD License

 */

class Zend_Amf_Util_BinaryStream

{

    /**

     * @var string Byte stream

     */

    protected $_stream;

    /**

     * @var int Length of stream

     */

    protected $_streamLength;

    /**

     * @var bool BigEndian encoding?

     */

    protected $_bigEndian;

    /**

     * @var int Current position in stream

     */

    protected $_needle;

    /**

     * Constructor

     *

     * Create a reference to a byte stream that is going to be parsed or created

     * by the methods in the class. Detect if the class should use big or

     * little Endian encoding.

     *

     * @param  string $stream use '' if creating a new stream or pass a string if reading.

     * @return void

     */

    public function __construct($stream)

    {

        if (!is_string($stream)) {

            require_once 'Zend/Amf/Exception.php';

            throw new Zend_Amf_Exception('Inputdata is not of type String');

        }

        $this->_stream       = $stream;

        $this->_needle       = 0;

        $this->_bigEndian    = (pack('l', 1) === "\x00\x00\x00\x01");

    }

    /**

     * Returns the current stream

     *

     * @return string

     */

    public function getStream()

    {

        return $this->_stream;

    }

    /**

     * Read the number of bytes in a row for the length supplied.

     *

     * @todo   Should check that there are enough bytes left in the stream we are about to read.

     * @param  int $length

     * @return string

     * @throws Zend_Amf_Exception for buffer underrun

     */

    public function readBytes($length)

    {

        if (($length + $this->_needle) > $this->_streamLength) {

            require_once 'Zend/Amf/Exception.php';

            throw new Zend_Amf_Exception('Buffer underrun at needle position: ' . $this->_needle . ' while requesting length: ' . $length);

        }

        $this->_needle+= $length;

        return $bytes;

    }

    /**

     * Write any length of bytes to the stream

     *

     * Usually a string.

     *

     * @param  string $bytes

     * @return Zend_Amf_Util_BinaryStream

     */

    public function writeBytes($bytes)

    {

        $this->_stream.= $bytes;

        return $this;

    }

    /**

     * Reads a signed byte

     *

     * @return int Value is in the range of -128 to 127.

     */

    public function readByte()

    {

        if (($this->_needle + 1) > $this->_streamLength) {

            require_once 'Zend/Amf/Exception.php';

        }

        return ord($this->_stream{$this->_needle++});

    }

    /**

     * Writes the passed string into a signed byte on the stream.

     *

     * @param  string $stream

     * @return Zend_Amf_Util_BinaryStream

     */

    public function writeByte($stream)

    {

        $this->_stream.= pack('c', $stream);

        return $this;

    }

    /**

     * Reads a signed 32-bit integer from the data stream.

     *

     * @return int Value is in the range of -2147483648 to 2147483647

     */

    public function readInt()

    {

        return ($this->readByte() << 8) + $this->readByte();

    }

    /**

     * Write an the integer to the output stream as a 32 bit signed integer

     *

     * @param  int $stream

     * @return Zend_Amf_Util_BinaryStream

     */

    public function writeInt($stream)

    {

        $this->_stream.= pack('n', $stream);

        return $this;

    }

    /**

     * Reads a UTF-8 string from the data stream

     *

     * @return string A UTF-8 string produced by the byte representation of characters

     */

    public function readUtf()

    {

        $length = $this->readInt();

        return $this->readBytes($length);

    }

    /**

     * Wite a UTF-8 string to the outputstream

     *

     * @param  string $stream

     * @return Zend_Amf_Util_BinaryStream

     */

    public function writeUtf($stream)

    {

        $this->_stream.= $stream;

        return $this;

    }

    /**

     * Read a long UTF string

     *

     * @return string

     */

    public function readLongUtf()

    {

        $length = $this->readLong();

        return $this->readBytes($length);

    }

    /**

     * Write a long UTF string to the buffer

     *

     * @param  string $stream

     * @return Zend_Amf_Util_BinaryStream

     */

    public function writeLongUtf($stream)

    {

        $this->_stream.= $stream;

    }

    /**

     * Read a long numeric value

     *

     * @return double

     */

    public function readLong()

    {

        return ($this->readByte() << 24) + ($this->readByte() << 16) + ($this->readByte() << 8) + $this->readByte();

    }

    /**

     * Write long numeric value to output stream

     *

     * @param  int|string $stream

     * @return Zend_Amf_Util_BinaryStream

     */

    public function writeLong($stream)

    {

        $this->_stream.= pack('N', $stream);

        return $this;

    }

    /**

     * Read a 16 bit unsigned short.

     *

     * @todo   This could use the unpack() w/ S,n, or v

     * @return double

     */

    public function readUnsignedShort()

    {

        $byte1 = $this->readByte();

        $byte2 = $this->readByte();

        return (($byte1 << 8) | $byte2);

    }

    /**

     * Reads an IEEE 754 double-precision floating point number from the data stream.

     *

     * @return double Floating point number

     */

    public function readDouble()

    {

        $this->_needle+= 8;

        if (!$this->_bigEndian) {

            $bytes = strrev($bytes);

        }

        $double = unpack('dflt', $bytes);

        return $double['flt'];

    }

    /**

     * Writes an IEEE 754 double-precision floating point number from the data stream.

     *

     * @param  string|double $stream

     * @return Zend_Amf_Util_BinaryStream

     */

    public function writeDouble($stream)

    {

        $stream = pack('d', $stream);

        if (!$this->_bigEndian) {

            $stream = strrev($stream);

        }

        $this->_stream.= $stream;

        return $this;

    }

}