<?php

/*
 * This file is part of SwiftMailer.
 * (c) 2004-2009 Chris Corbyn
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */


/**
 * Allows reading and writing of bytes to and from an array.
 * @package Swift
 * @subpackage ByteStream
 * @author Chris Corbyn
 */
class Swift_ByteStream_ArrayByteStream
  implements Swift_InputByteStream, Swift_OutputByteStream
{

  /**
   * The internal stack of bytes.
   * @var string[]
   * @access private
   */
  private $_array = array();

  /**
   * The size of the stack
   * @var int
   * @access private
   */
  private $_arraySize = 0;

  /**
   * The internal pointer offset.
   * @var int
   * @access private
   */
  private $_offset = 0;
  
  /** Bound streams */
  private $_mirrors = array();
  
  /**
   * Create a new ArrayByteStream.
   * If $stack is given the stream will be populated with the bytes it contains.
   * @param mixed $stack of bytes in string or array form, optional
   */
  public function __construct($stack = null)
  {
    if (is_array($stack))
    {
      $this->_array = $stack;
      $this->_arraySize = count($stack);
    }
    elseif (is_string($stack))
    {
      $this->write($stack);
    }
    else
    {
      $this->_array = array();
    }
  }

  /**
   * Reads $length bytes from the stream into a string and moves the pointer
   * through the stream by $length. If less bytes exist than are requested the
   * remaining bytes are given instead. If no bytes are remaining at all, boolean
   * false is returned.
   * @param int $length
   * @return string
   */
  public function read($length)
  {
    if ($this->_offset == $this->_arraySize)
    {
      return false;
    }

    // Don't use array slice
    $end = $length + $this->_offset;
    $end = $this->_arraySize<$end
      ?$this->_arraySize
      :$end;
    $ret = '';
    for (; $this->_offset < $end; ++$this->_offset)
    {
      $ret .= $this->_array[$this->_offset];
    }
    return $ret;
  }

  /**
   * Writes $bytes to the end of the stream.
   * @param string $bytes
   */
  public function write($bytes)
  {
    $to_add = str_split($bytes);
    foreach ($to_add as $value)
    {
      $this->_array[] = $value;
    }
    $this->_arraySize = count($this->_array);
    
    foreach ($this->_mirrors as $stream)
    {
      $stream->write($bytes);
    }
  }
  
  /**
   * Not used.
   */
  public function commit()
  {
  }
  
  /**
   * Attach $is to this stream.
   * The stream acts as an observer, receiving all data that is written.
   * All {@link write()} and {@link flushBuffers()} operations will be mirrored.
   *
   * @param Swift_InputByteStream $is
   */
  public function bind(Swift_InputByteStream $is)
  {
    $this->_mirrors[] = $is;
  }
  
  /**
   * Remove an already bound stream.
   * If $is is not bound, no errors will be raised.
   * If the stream currently has any buffered data it will be written to $is
   * before unbinding occurs.
   *
   * @param Swift_InputByteStream $is
   */
  public function unbind(Swift_InputByteStream $is)
  {
    foreach ($this->_mirrors as $k => $stream)
    {
      if ($is === $stream)
      {
        unset($this->_mirrors[$k]);
      }
    }
  }

  /**
   * Move the internal read pointer to $byteOffset in the stream.
   * @param int $byteOffset
   * @return boolean
   */
  public function setReadPointer($byteOffset)
  {
    if ($byteOffset > $this->_arraySize)
    {
      $byteOffset = $this->_arraySize;
    }
    elseif ($byteOffset < 0)
    {
      $byteOffset = 0;
    }

    $this->_offset = $byteOffset;
  }

  /**
   * Flush the contents of the stream (empty it) and set the internal pointer
   * to the beginning.
   */
  public function flushBuffers()
  {
    $this->_offset = 0;
    $this->_array = array();
    $this->_arraySize = 0;
    
    foreach ($this->_mirrors as $stream)
    {
      $stream->flushBuffers();
    }
  }

}
