<?php
/**
 * A database wrapper for distributed hash tables
 *
 * @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 NodeDistributedHashTableDatabaseWrapper extends BaseDatabaseWrapper implements NodeDhtWrapper, Registerable {
	// Constants for database table names
	const DB_TABLE_NODE_DHT = 'node_dht';

	// Constants for database column names
	const DB_COLUMN_NODE_ID          = 'node_id';
	const DB_COLUMN_SESSION_ID       = 'session_id';
	const DB_COLUMN_IP_PORT          = 'ip_port';
	const DB_COLUMN_PRIVATE_KEY      = 'private_key';
	const DB_COLUMN_PRIVATE_KEY_HASH = 'private_key_hash';
	const DB_COLUMN_NODE_TYPE        = 'node_type';

	/**
	 * Protected constructor
	 *
	 * @return	void
	 */
	protected function __construct () {
		// Call parent constructor
		parent::__construct(__CLASS__);
	}

	/**
	 * Creates an instance of this database wrapper by a provided user class
	 *
	 * @return	$wrapperInstance	An instance of the created wrapper class
	 */
	public static final function createNodeDistributedHashTableDatabaseWrapper () {
		// Get a new instance
		$wrapperInstance = new NodeDistributedHashTableDatabaseWrapper();

		// Set (primary!) table name
		$wrapperInstance->setTableName(self::DB_TABLE_NODE_DHT);

		// Return the instance
		return $wrapperInstance;
	}

	/**
	 * Prepares an instance of a StoreableCriteria class with all node data for
	 * insert/update queries.
	 *
	 * @return	$dataSetInstance	An instance of a StoreableCriteria class
	 */
	private function prepareDataSetInstance () {
		// Get node/request instances
		$nodeInstance = Registry::getRegistry()->getInstance('node');
		$requestInstance = ApplicationHelper::getSelfInstance()->getRequestInstance();

		// Get a dataset instance
		$dataSetInstance = ObjectFactory::createObjectByConfiguredName('dataset_criteria_class', array(self::DB_TABLE_NODE_DHT));

		// Set the primary key
		$dataSetInstance->setUniqueKey(self::DB_COLUMN_NODE_ID);

		// Add public node data
		$dataSetInstance->addCriteria(self::DB_COLUMN_NODE_TYPE       , $requestInstance->getRequestElement('mode'));
		$dataSetInstance->addCriteria(self::DB_COLUMN_IP_PORT         , $nodeInstance->getAddressPort());
		$dataSetInstance->addCriteria(self::DB_COLUMN_NODE_ID         , $nodeInstance->getNodeId());
		$dataSetInstance->addCriteria(self::DB_COLUMN_SESSION_ID      , $nodeInstance->getSessionId());
		$dataSetInstance->addCriteria(self::DB_COLUMN_PRIVATE_KEY_HASH, $nodeInstance->getPrivateKeyHash());

		// Return it
		return $dataSetInstance;
	}

	/**
	 * Checks whether the local (*this*) node is registered in the DHT by
	 * checking if the external ip/port is found.
	 *
	 * @return	$isRegistered	Whether *this* node is registered in the DHT
	 */
	public function isLocalNodeRegistered () {
		// Is there cache?
		if (!isset($GLOBALS[__METHOD__])) {
			// Get a search criteria instance
			$searchInstance = ObjectFactory::createObjectByConfiguredName('search_criteria_class');

			// Get node instance
			$nodeInstance = Registry::getRegistry()->getInstance('node');

			// Add ip:port as criteria
			$searchInstance->addCriteria(self::DB_COLUMN_IP_PORT, $nodeInstance->getAddressPort());
			$searchInstance->setLimit(1);

			// Query database and get a result instance back
			$resultInstance = $this->doSelectByCriteria($searchInstance);

			// Cache result of if there is an entry, next() will tell us if the next entry is valid
			$GLOBALS[__METHOD__] = $resultInstance->next();
		} // END - if

		// Return result
		return $GLOBALS[__METHOD__];
	}

	/**
	 * Registeres the local (*this*) node with its data in the DHT.
	 *
	 * @return	void
	 */
	public function registerLocalNode () {
		// Assert to make sure this method is called with no record in DB (the actual backend of the DHT)
		assert(!$this->isLocalNodeRegistered());

		// Get prepared data set instance
		$dataSetInstance = $this->prepareDataSetInstance();

		// "Insert" this dataset instance completely into the database
		$this->queryInsertDataSet($dataSetInstance);
	}

	/**
	 * Updates local (*this*) node data in DHT, this is but not limited to the
	 * session id, ip number (and/or hostname) and port number.
	 *
	 * @return	void
	 */
	public function updateLocalNode () {
		// Assert to make sure this method is called with one record in DB (the actual backend of the DHT)
		assert($this->isLocalNodeRegistered());

		// Get node instance
		$nodeInstance = Registry::getRegistry()->getInstance('node');

		// Get search criteria
		$searchInstance = ObjectFactory::createObjectByConfiguredName('search_criteria_class');

		// Search for node id and limit it to one entry
		$searchInstance->addCriteria(self::DB_COLUMN_NODE_ID, $nodeInstance->getNodeId());
		$searchInstance->setLimit(1);

		// Get a prepared dataset instance
		$dataSetInstance = $this->prepareDataSetInstance();

		// Set search instance
		$dataSetInstance->setSearchInstance($searchInstance);

		// Update DHT database record
		$this->queryUpdateDataSet($dataSetInstance);
	}
}

// [EOF]
?>