<?php
/**
 * A generic database wrapper
 *
 * @author		Roland Haeder <webmaster@ship-simu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2011 Core 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 BaseDatabaseWrapper extends BaseFrameworkSystem {
	/**
	 * Cache instance
	 */
	private $cacheInstance = NULL;

	/**
	 * Current table name to use
	 */
	private $tableName = 'unknown';

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

		// Initialize the cache instance
		$this->initCacheInstance();
	}

	/**
	 * Initializes the cache instance with a new object
	 *
	 * @return	void
	 */
	private final function initCacheInstance () {
		// Set the new instance
		$this->cacheInstance = CacheFactory::getFactory()->createConfiguredCache();
	}

	/**
	 * Setter for table name
	 *
	 * @param	$tableName	Name of table name to set
	 * @return	void
	 */
	protected final function setTableName ($tableName) {
		$this->tableName = (string) $tableName;
	}

	/**
	 * Getter for table name
	 *
	 * @return	$tableName	Name of table name to set
	 */
	protected final function getTableName () {
		return $this->tableName;
	}

	/**
	 * 'Inserts' a data set instance into a local file database folder
	 *
	 * @param	$dataSetInstance	A storeable data set
	 * @param	$onlyKeys			Only use these keys for a cache key
	 * @return	void
	 */
	protected function queryInsertDataSet (StoreableCriteria $dataSetInstance, array $onlyKeys = array()) {
		// First get a key suitable for our cache and extend it with this class name
		$cacheKey = $this->getCacheKeyByCriteria($dataSetInstance, $onlyKeys);
		//* DEBUG: */ $this->debugOutput('BASE-WRAPPER: Using cache key ' . $cacheKey . ' for purging ...');

		// Does this key exists in cache?
		if ($this->cacheInstance->offsetExists($cacheKey)) {
			// Purge the cache
			$this->cacheInstance->purgeOffset($cacheKey);
		} // END - if

		// Handle it over to the middleware
		$this->getDatabaseInstance()->queryInsertDataSet($dataSetInstance);
	}

	/**
	 * 'Updates' a data set instance with a database layer
	 *
	 * @param	$dataSetInstance	A storeable data set
	 * @param	$onlyKeys			Only use these keys for a cache key
	 * @return	void
	 */
	protected function queryUpdateDataSet (StoreableCriteria $dataSetInstance, array $onlyKeys = array()) {
		// First get a key suitable for our cache and extend it with this class name
		$cacheKey = $this->getCacheKeyByCriteria($dataSetInstance, $onlyKeys);
		//* DEBUG: */ $this->debugOutput('BASE-WRAPPER: Using cache key ' . $cacheKey . ' for purging ...');

		// Does this key exists in cache?
		if ($this->cacheInstance->offsetExists($cacheKey)) {
			// Purge the cache
			$this->cacheInstance->purgeOffset($cacheKey);
		} // END - if

		// Handle it over to the middleware
		$this->getDatabaseInstance()->queryUpdateDataSet($dataSetInstance);
	}

	/**
	 * Getter for index key
	 *
	 * @return	$indexKey	Index key
	 */
	public final function getIndexKey () {
		return $this->getDatabaseInstance()->getIndexKey();
	}

	/**
	 * Do a "select" query on the current table with the given search criteria and
	 * store it in cache for later usage
	 *
	 * @param	$criteriaInstance	An instance of a Criteria class
	 * @param	$onlyKeys			Only use these keys for a cache key
	 * @return	$resultInstance		An instance of a database result class
	 */
	public function doSelectByCriteria (Criteria $criteriaInstance, array $onlyKeys = array()) {
		// First get a key suitable for our cache and extend it with this class name
		$cacheKey = $this->getCacheKeyByCriteria($criteriaInstance, $onlyKeys);

		// Does this key exists in cache?
		if ($this->cacheInstance->offsetExists($cacheKey)) {
			// Debug message
			//* DEBUG: */ $this->debugOutput('BASE-WRAPPER: Cache used for cacheKey=' . $cacheKey);

			// Then use this result
			$result = $this->cacheInstance->offsetGet($cacheKey);
		} else {
			// Debug message
			//* DEBUG: */ $this->debugOutput('BASE-WRAPPER: Quering database, cacheKey=' . $cacheKey);

			// Now it's time to ask the database layer for this select statement
			$result = $this->getDatabaseInstance()->doSelectByTableCriteria($this->getTableName(), $criteriaInstance);

			// Cache the result if not null
			if (!is_null($result)) {
				// A valid result has returned from the database layer
				$this->cacheInstance->offsetSet($cacheKey, $result);
			} else {
				// This invalid result must be wrapped
				$result = array(
					BaseDatabaseFrontend::RESULT_INDEX_STATUS    => 'invalid',
					BaseDatabaseFrontend::RESULT_INDEX_EXCEPTION => $this->getDatabaseInstance()->getLastException()
				);
			}
		}

		// Create an instance of a DatabaseResult class with the given result
		$resultInstance = DatabaseResult::createDatabaseResult($result);

		// And return the instance
		return $resultInstance;
	}

	/**
	 * Count the numbers of rows we shall receive
	 *
	 * @param	$criteriaInstance	An instance of a Criteria class
	 * @param	$onlyKeys			Only use these keys for a cache key
	 * @return	$numRows			Numbers of rows of database entries
	 */
	public function doSelectCountByCriteria (Criteria $criteriaInstance, $onlyKeys =  array()) {
		// Total numbers is -1 so we can distinglish between failed and valid queries
		$numRows = 0;

		// Get the result from above method
		$resultInstance = $this->doSelectByCriteria($criteriaInstance, $onlyKeys);

		// Was that query fine?
		if ($resultInstance->ifStatusIsOkay()) {
			// Then get the number of rows
			$numRows = $resultInstance->getAffectedRows();

			// Debug message
			//* DEBUG: */ $this->debugOutput('BASE-WRAPPER: numRows=' . $numRows);
		} // END - if

		// Return the result
		return $numRows;
	}

	/**
	 * Getter for primary key used in wrapped table
	 *
	 * @return	$primaryKey		Primary key used in wrapped table
	 */
	public final function getPrimaryKeyValue () {
		// Get the table name and a database instance and ask for it
		$primaryKey = $this->getDatabaseInstance()->getPrimaryKeyOfTable($this->getTableName());

		// Return value
		return $primaryKey;
	}
}

// [EOF]
?>