<?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.
 */


/**
 * A MIME entity, such as an attachment.
 * @package Swift
 * @subpackage Mime
 * @author Chris Corbyn
 */
interface Swift_Mime_MimeEntity
  extends Swift_Mime_CharsetObserver, Swift_Mime_EncodingObserver
{
  
  /** Main message document; there can only be one of these */
  const LEVEL_TOP = 16;
  
  /** An entity which nests with the same precedence as an attachment */
  const LEVEL_MIXED = 256;
  
  /** An entity which nests with the same precedence as a mime part */
  const LEVEL_ALTERNATIVE = 4096;
  
  /** An entity which nests with the same precedence as embedded content */
  const LEVEL_RELATED = 65536;
  
  /**
   * Get the level at which this entity shall be nested in final document.
   * The lower the value, the more outermost the entity will be nested.
   * @return int
   * @see LEVEL_TOP, LEVEL_MIXED, LEVEL_RELATED, LEVEL_ALTERNATIVE
   */
  public function getNestingLevel();
  
  /**
   * Get the qualified content-type of this mime entity.
   * @return string
   */
  public function getContentType();
  
  /**
   * Returns a unique ID for this entity.
   * For most entities this will likely be the Content-ID, though it has
   * no explicit semantic meaning and can be considered an identifier for
   * programming logic purposes.
   * If a Content-ID header is present, this value SHOULD match the value of
   * the header.
   * @return string
   */
  public function getId();
  
  /**
   * Get all children nested inside this entity.
   * These are not just the immediate children, but all children.
   * @return Swift_Mime_MimeEntity[]
   */
  public function getChildren();
  
  /**
   * Set all children nested inside this entity.
   * This includes grandchildren.
   * @param Swift_Mime_MimeEntity[] $children
   */
  public function setChildren(array $children);
  
  /**
   * Get the collection of Headers in this Mime entity.
   * @return Swift_Mime_Header[]
   */
  public function getHeaders();
  
  /**
   * Get the body content of this entity as a string.
   * Returns NULL if no body has been set.
   * @return string
   */
  public function getBody();
  
  /**
   * Set the body content of this entity as a string.
   * @param string $body
   * @param string $contentType optional
   */
  public function setBody($body, $contentType = null);
  
  /**
   * Get this entire entity in its string form.
   * @return string
   */
  public function toString();
  
  /**
   * Get this entire entity as a ByteStream.
   * @param Swift_InputByteStream $is to write to
   */
  public function toByteStream(Swift_InputByteStream $is);
  
}
