<?php
namespace wcf\data;

/**
 * Every node of a database object tree has to implement this interface.
 * 
 * @author	Matthias Schmidt
 * @copyright	2001-2019 WoltLab GmbH
 * @license	GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
 * @package	WoltLabSuite\Core\Data
 * @since	5.2
 */
interface IObjectTreeNode extends \Countable, IIDObject, \RecursiveIterator {
	/**
	 * Adds the given node as child node and sets the child node's parent node to this node.
	 *
	 * @param	IObjectTreeNode		$child		added child node
	 * @throws	\InvalidArgumentException		if given object is no (deocrated) instance of this class
	 */
	public function addChild(IObjectTreeNode $child);
	
	/**
	 * Returns the depth of the node within the tree.
	 * 
	 * The minimum depth is `1`.
	 * 
	 * @return	integer
	 */
	public function getDepth();
	
	/**
	 * Returns the number of open parent nodes.
	 * 
	 * @return	integer
	 */
	public function getOpenParentNodes();
	
	/**
	 * Retruns the parent node of this node.
	 * 
	 * @return	static		parent node
	 */
	public function getParentNode();
	
	/**
	 * Returns `true` if this node is the last sibling and `false` otherwise.
	 * 
	 * @return	boolean
	 */
	public function isLastSibling();
	
	/**
	 * Sets the parent node of this node.
	 *
	 * @param	IObjectTreeNode		$parentNode	parent node
	 * @throws	\InvalidArgumentException		if given object is no (deocrated) instance of this class
	 */
	public function setParentNode(IObjectTreeNode $parentNode);
}