<?php
/**
 * A Node DHT facade class
 *
 * @author		Roland Haeder <webmaster@ship-simu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2012 Hub Developer Team
 * @license		GNU GPL 3.0 or any newer version
 * @link		http://www.ship-simu.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
class NodeDhtFacade extends BaseDht implements Distributable, Registerable {
	/**
	 * Protected constructor
	 *
	 * @return	void
	 */
	protected function __construct () {
		// Call parent constructor
		parent::__construct(__CLASS__);
	}

	/**
	 * Creates an instance of this class
	 *
	 * @return	$dhtInstance	An instance of a Distributable class
	 */
	public final static function createNodeDhtFacade () {
		// Get new instance
		$dhtInstance = new NodeDhtFacade();

		// Get a database wrapper instance
		$wrapperInstance = DatabaseWrapperFactory::createWrapperByConfiguredName('node_dht_db_wrapper_class');

		// Set it in this class
		$dhtInstance->setWrapperInstance($wrapperInstance);

		// Return the prepared instance
		return $dhtInstance;
	}

	/**
	 * Initializes the distributed hash table (DHT)
	 *
	 * @return	void
	 * @todo	Please implement this method
	 */
	public function initDht () {
		// Is the local node registered?
		if ($this->getWrapperInstance()->isLocalNodeRegistered()) {
			// Then only update session id
			$this->getWrapperInstance()->updateLocalNode();
		} else {
			// No, so register it
			$this->getWrapperInstance()->registerLocalNode();
		}
	}

	/**
	 * Finds a node by given session id
	 *
	 * @param	$sessionId	Session id to lookup
	 * @return	$nodeData	Node data array
	 */
	public function findNodeBySessionId ($sessionId) {
		// Default is empty data array
		$nodeData = array();

		// Call the wrapper to do the job and get back a result instance
		$resultInstance = $this->getWrapperInstance()->findNodeBySessionId($sessionId);

		// Is the next entry valid?
		if ($resultInstance->next()) {
			// Then load the entry
			$nodeData = $resultInstance->current();
		} // END - if

		// Return node data
		return $nodeData;
	}

	/**
	 * Registers an other node with this node by given message data. The
	 * following data must always be present:
	 *
	 * - session-id  (for finding the node's record together with below data)
	 * - external-ip (hostname or IP number)
	 * - listen-port (TCP/UDP listen port for inbound connections)
	 *
	 * @param	$messageArray		An array with all minimum message data
	 * @param	$handlerInstance	An instance of a Handleable class
	 * @param	$forceUpdate		Optionally force update, don't register (default: register if not found)
	 * @return	void
	 * @throws	NodeSessionIdVerficationException	If the node was not found and update is forced
	 */
	public function registerNodeByMessageData (array $messageData, Handleable $handlerInstance, $forceUpdate = FALSE) {
		// Get a search criteria class
		$searchInstance = ObjectFactory::createObjectByConfiguredName('search_criteria_class');

		// Debug message
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('DHT-FACADE: messageData=' . print_r($messageData, true));

		// Search for the node's session id and external IP/hostname + TCP/UDP listen port
		foreach ($handlerInstance->getSearchData() as $key) {
			// Debug message
			/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('DHT-FACADE: messageData[' . $key . ']=' . $messageData[$key]);

			// Is it there?
			assert(isset($messageData[$key]));

			// Add criteria
			$searchInstance->addCriteria(str_replace('my-', '', $key), $messageData[$key]);
		} // END - foreach

		// Only one entry is fine
		$searchInstance->setLimit(1);

		// Run the query
		$resultInstance = $this->getWrapperInstance()->doSelectByCriteria($searchInstance);

		// Is there already an entry?
		if ($resultInstance->next()) {
			// Entry found, so update it
			$this->getWrapperInstance()->updateNodeByMessageData($messageData, $handlerInstance, $searchInstance);
		} elseif ($forceUpdate === FALSE) {
			// Nothing found, so register it
			$this->getWrapperInstance()->registerNodeByMessageData($messageData, $handlerInstance);
		} else {
			/*
			 * Do not register non-existent nodes here. This is maybe fatal,
			 * caused by "stolen" session id and/or not matching IP
			 * number/port combination.
			 */
			throw new NodeSessionIdVerficationException(array($this, $messageData), BaseHubSystem::EXCEPTION_NODE_SESSION_ID_NOT_VERIFYING);
		}

		// Save last exception
		$handlerInstance->setLastException($this->getWrapperInstance()->getLastException());
	}

	/**
	 * Queries the local DHT data(base) for a node list with all supported
	 * object types except the node by given session id.
	 *
	 * @param	$messageData	An array with message data from a node_list request
	 * @return	$nodeList		An array with all found nodes
	 * @todo	Implement exclusion/choise-inclusion criteria
	 */
	public function queryLocalNodeListExceptByMessageData (array $messageData) {
		// Get a search criteria class
		$searchInstance = ObjectFactory::createObjectByConfiguredName('search_criteria_class');

		// Debug message
		/* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('DHT-FACADE: messageData=' . print_r($messageData, true));

		// Only X entries are fine
		$searchInstance->setLimit($this->getConfigInstance()->getConfigEntry('node_dht_list_limit'));

		// Run the query
		$resultInstance = $this->getWrapperInstance()->doSelectByCriteria($searchInstance);

		// Get node list
		$nodeList = array();
		while ($resultInstance->next()) {
			// Add this entry
			array_push($nodeList, $resultInstance->current());
		} // END - while

		// Save last exception
		$handlerInstance->setLastException($this->getWrapperInstance()->getLastException());

		// Return node list (array)
		return $nodeList;
	}
}

// [EOF]
?>