<?php
// Own namespace
namespace Org\Mxchange\CoreFramework\Cache\Memory;

// Import framework stuff
use Org\Mxchange\CoreFramework\Cache\Cacheable;
use Org\Mxchange\CoreFramework\Object\BaseFrameworkSystem;
use Org\Mxchange\CoreFramework\ObjectArray\FrameworkArrayObject;

/**
 * A simple memory cache (similar to a registry)
 *
 * @author		Roland Haeder <webmaster@shipsimu.org>
 * @version		0.0.0
 * @copyright	Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2023 Core Developer Team
 * @license		GNU GPL 3.0 or any newer version
 * @link		http://www.shipsimu.org
 * @todo		Rename to InProgressCache
 *
 * 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 MemoryCache extends BaseFrameworkSystem implements Cacheable {
	/**
	 * The "memory cache" is simply a wrapped object array
	 */
	private $dataCache = NULL;

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

	/**
	 * Creates an instance of this class
	 *
	 * @return	$cacheInstance	An instance of this cache class
	 */
	public static final function createMemoryCache () {
		// Get a new instance
		$cacheInstance = new MemoryCache();

		// Initialize the cache
		$cacheInstance->initCache();

		// Return the prepared instance
		return $cacheInstance;
	}

	/**
	 * Initialize this cache by creating an object array
	 *
	 * @return	void
	 */
	protected function initCache () {
		// Now create the "data cache"
		$this->dataCache = new FrameworkArrayObject('FakedDataCache');
	}

	/**
	 * Does the specified offset exist in cache?
	 *
	 * @param	$offset			The offset we are looking for
	 * @param	$arrayElement	If type is array, then this element must be found
	 * @param	$minimumCount	If array element is found then this count must at least match
	 * @return	$exists			Whether the offset exists
	 */
	public function offsetExists ($offset, $arrayElement = NULL, $minimumCount = 0) {
		// Is it there?
		$exists = $this->dataCache->offsetExists($offset);

		// So look for array element?
		if (($exists === true) && (!is_null($arrayElement))) {
			// Get it
			$array = $this->offsetGet($offset);

			// Is it an array and element is found?
			if ((is_array($array)) && (isset($array[$arrayElement]))) {
				// Is an array and element is found, so check count
				$exists = (count($array[$arrayElement]) >= $minimumCount);
			} else {
				// Not found
				$exists = false;
			}
		}

		// Return status
		return $exists;
	}

	/**
	 * Setter for cache offset
	 *
	 * @param	$offset		The offset we shall set
	 * @param	$data		Data to store in cache
	 * @return	void
	 */
	public function offsetSet ($offset, $data) {
		$this->dataCache->offsetSet($offset, $data);
	}

	/**
	 * Getter for cache offset or "null" if not found
	 *
	 * @param	$offset		The offset we shall set
	 * @return	$data		Data to store in cache
	 */
	public function offsetGet ($offset) {
		// Default is offset not found
		$data = NULL;

		// Is the offset there?
		if ($this->offsetExists($offset)) {
			// Then get the data from it
			$data = $this->dataCache->offsetGet($offset);
		}

		// Return data
		return $data;
	}

	/**
	 * Purges the given cache entry
	 *
	 * @param	$offset		The offset we shall set
	 * @return	void
	 */
	public function purgeOffset ($offset) {
		// Is the offset there?
		if ($this->offsetExists($offset)) {
			// Purge only existing keys
			//* DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('CACHE: Unsetting cache ' . $offset);
			$this->dataCache->offsetUnset($offset);
		}
	}

}