<?php

/**

 * Magento

 *

 * NOTICE OF LICENSE

 *

 * This source file is subject to the Open Software License (OSL 3.0)

 * that is bundled with this package in the file LICENSE.txt.

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

 * http://opensource.org/licenses/osl-3.0.php

 * 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@magentocommerce.com so we can send you a copy immediately.

 *

 * DISCLAIMER

 *

 * Do not edit or add to this file if you wish to upgrade Magento to newer

 * versions in the future. If you wish to customize Magento for your

 * needs please refer to http://www.magentocommerce.com for more information.

 *

 * @category    Mage

 * @package     Mage_Connect

 * @copyright   Copyright (c) 2011 Magento Inc. (http://www.magentocommerce.com)

 * @license     http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)

 */



class Mage_Connect_Structures_Node

{

    

    protected $_data = null;    

    protected $_metadata = array();    

    protected $_arcs = array();    

    protected $_graph = null;

    

    /**

     * Node graph getter

     *

     * @return Mage_Connect_Structures_Graph

     */

    public function &getGraph() 

    {

        return $this->_graph;

    }



    /**

     *

     * Node graph setter. 

     * This method should not be called directly. 

     * Use Graph::addNode instead.

     *

     * @param $graph

     */

    public function setGraph(&$graph) 

    {

        $this->_graph =& $graph;

    }



    /**

     *

     * Node data getter.

     *

     * Each graph node can contain a reference to one variable. This is the getter for that reference.

     *

     * @return   mixed   Data stored in node

     * @access   public

     */

    public function &getData() 

    {

        return $this->_data;

    }



    /**

     * Node data setter

     * 

     * Each graph node can contain a reference to one variable. This is the setter for that reference.

     *   

     * @return   mixed   Data to store in node

     */

    public function setData($data) 

    {

        $this->_data =& $data;

    }



    /**

     *

     * Test for existence of metadata under a given key.

     *

     * @param    string    Key to test

     * @return   boolean

     * @access   public

     */

    public function metadataKeyExists($key) 

    {

        return array_key_exists($key, $this->_metadata);

    }



    /**

     *

     * Get node metadata

     *

     * @param    string  $key 

     * @param    boolean $nullIfNonexistent (defaults to false).

     * @return   mixed   

     */

    public function & getMetadata($key, $nullIfNonexistent = false) 

    {

        if (array_key_exists($key, $this->_metadata)) {

            return $this->_metadata[$key];

        } elseif ($nullIfNonexistent) {

                $a = null;

                return $a;

        } else {

            throw new Exception(__METHOD__." : requested key doesn't exist: {$key}");            

        }

    }



    /**

     *

     * Delete metadata by key

     *

     * @param    string  Key

     */

    public function unsetMetadata($key) 

    {

        if (array_key_exists($key, $this->_metadata)) {

            unset($this->_metadata[$key]);

        }    

        

    }

        

    /**

     *

     * Node metadata setter

     *

     * Each graph node can contain multiple 'metadata' entries, each stored under a different key, as in an

     * associative array or in a dictionary. This method stores data under the given key. If the key already exists,

     * previously stored data is discarded.

     *

     * @param    string  $key

     * @param    mixed   $data

     */

    public function setMetadata($key, $data) 

    {

        $this->_metadata[$key] =& $data;

    }



    protected function _connectTo(&$destinationNode) 

    {

        $this->_arcs[] =& $destinationNode;

    }



    /**

     * Connect this node to another one.

     * If the graph is not directed, the reverse arc, connecting $destinationNode to $this is also created.

     * @param    Structures_Graph Node to connect to

     */

    public function connectTo(&$destinationNode)

    {

        $class = get_class($this);

        if(!$destinationNode instanceof $class) {

            throw new Exception(__METHOD__." : argument should be instance of {$class}");

        }

         

        // Nodes must already be in graphs to be connected

        if ($this->_graph == null) {

            throw new Exception(__METHOD__." : tried to connect to null graph");

        }



        if ($destinationNode->getGraph() == null) {

            throw new Exception(__METHOD__." : tried to connect to node that is not connected to any graph");

        }



        // Connect here

        $this->_connectTo($destinationNode);

        // If graph is undirected, connect back

        if (!$this->_graph->isDirected()) {

            $destinationNode->_connectTo($this);

        }

    }





    /**

     * Return nodes connected to this one.

     * @return array 

     */

    public function getNeighbours()

    {

        return $this->_arcs;

    }



    /**

     * Test wether this node has an arc to the target node

     * Returns true if the two nodes are connected

     * @return boolean   

     */

    public function connectsTo(&$target)

    {

        $arcKeys = array_keys($this->_arcs);

        foreach($arcKeys as $key) {

            $arc =& $this->_arcs[$key];

            if ($target === $arc) { 

                return true;

            }

        }

        return false;

    }



    /**

     * Calculate the in degree of the node.

     *

     * The indegree for a node is the number of arcs 

     * entering the node. 

     * 

     * For non directed graphs:

     *  always outdegree = indegree.

     *  

     * @return int

     */

    public function inDegree() 

    {

        $result = 0;



        if ($this->_graph == null) {

            return $result;

        }

        if (!$this->_graph->isDirected()) {

            return $this->outDegree();

        }



        $graphNodes =& $this->_graph->getNodes();

        foreach (array_keys($graphNodes) as $key) {

            if ($graphNodes[$key]->connectsTo($this)) {

                $result++;

            }

        }

        return $result;



    }



    /**

     * Calculate the out degree of the node.

     *

     * The outdegree for a node is the number of arcs exiting the node. 

     * For non directed graphs:

     *  always outdegree = indegree.

     *

     * @return int

     */

    public function outDegree()

    {

        if ($this->_graph == null) {

            return 0;

        }

        return count($this->_arcs);

    }



}