<?php
/* Copyright (C) NAVER <http://www.navercorp.com> */

/**
 * CacheHandler
 *
 * @author NAVER (developer@xpressengine.com)
 */
class CacheHandler extends Handler
{
	/**
	 * Instances are stored here.
	 */
	protected static $_instances = array();
	
	/**
	 * instance of cache handler
	 * @var CacheBase
	 */
	protected $handler = null;

	/**
	 * Version of key group
	 * @var int
	 */
	protected $keyGroupVersions = null;

	/**
	 * Get a instance of CacheHandler(for singleton)
	 *
	 * @param string $target type of cache (object|template)
	 * @param object $info info. of DB
	 * @param boolean $always_use_file If set true, use a file cache always
	 * @return CacheHandler
	 */
	public static function getInstance($target = 'object', $info = null, $always_use_file = false)
	{
		$key = 'object' . ($always_use_file ? '_file' : '');
		if (!isset(self::$_instances[$key]))
		{
			self::$_instances[$key] = new self($target, $info, $always_use_file);
		}
		return self::$_instances[$key];
	}

	/**
	 * Constructor.
	 *
	 * Do not use this directly. You can use getInstance() instead.
	 *
	 * @see CacheHandler::getInstance
	 * @param string $target type of cache (object)
	 * @param object $info info. of DB
	 * @param boolean $always_use_file If set true, use a file cache always
	 * @return CacheHandler
	 */
	protected function __construct($target, $info = null, $always_use_file = false)
	{
		// Allow using custom cache info for backward compatibility.
		if (is_object($info) && $info->use_object_cache)
		{
			$cache_config = $cache_config_array = $info->use_object_cache;
		}
		else
		{
			$cache_config = $cache_config_array = config('cache');
			if (is_array($cache_config) && count($cache_config))
			{
				$cache_config = array_first($cache_config);
			}
		}
		
		// Handle various types of cache backend.
		if (preg_match('/^(apc|memcache|redis|wincache|file)/', strval($cache_config), $matches))
		{
			$type = $matches[1];
		}
		elseif ($always_use_file)
		{
			$type = 'file';
		}
		else
		{
			return;
		}
		
		// Create an instance of cache backend.
		$class = 'Cache' . ucfirst($type);
		include_once sprintf('%sclasses/cache/%s.class.php', _XE_PATH_, $class);
		$this->handler = $class::getInstance($cache_config_array);
		
		// Initialize key group versions.
		$this->keyGroupVersions = $this->handler->get('key_group_versions', 0);
		if(!$this->keyGroupVersions)
		{
			$this->keyGroupVersions = array();
			$this->handler->put('key_group_versions', $this->keyGroupVersions, 0);
		}
	}

	/**
	 * Return whether support or not support cache
	 *
	 * @return boolean
	 */
	public function isSupport($type = null, $cache_config = null)
	{
		if ($type === null)
		{
			return ($this->handler && $this->handler->isSupport());
		}
		else
		{
			$class = 'Cache' . ucfirst(str_replace('memcached', 'memcache', $type));
			include_once sprintf('%sclasses/cache/%s.class.php', _XE_PATH_, $class);
			$handler = $class::getInstance($cache_config, true);
			return $handler->isSupport();
		}
	}

	/**
	 * Get cache name by key
	 *
	 * @param string $key The key that will be associated with the item.
	 * @return string Returns cache name
	 */
	public function getCacheKey($key)
	{
		return RX_VERSION . ':' . str_replace('/', ':', $key);
	}

	/**
	 * Get cached data
	 *
	 * @param string $key Cache key
	 * @param int $modified_time 	Unix time of data modified.
	 * 								If stored time is older then modified time, return false.
	 * @return false|mixed Return false on failure or older then modified time. Return the string associated with the $key on success.
	 */
	public function get($key, $modified_time = 0)
	{
		if (!$key) return false;
		return $this->handler ? $this->handler->get($this->getCacheKey($key), $modified_time) : false;
	}

	/**
	 * Put data into cache
	 *
	 * @param string $key Cache key
	 * @param mixed $obj	Value of a variable to store. $value supports all data types except resources, such as file handlers.
	 * @param int $valid_time	Time for the variable to live in the cache in seconds.
	 * 							After the value specified in ttl has passed the stored variable will be deleted from the cache.
	 * 							If no ttl is supplied, use the default valid time.
	 * @return bool|void Returns true on success or false on failure. If use CacheFile, returns void.
	 */
	public function put($key, $obj, $valid_time = 0)
	{
		if (!$key) return false;
		return $this->handler ? $this->handler->put($this->getCacheKey($key), $obj, $valid_time) : false;
	}

	/**
	 * Delete Cache
	 *
	 * @param string $key Cache key
	 * @return void
	 */
	public function delete($key)
	{
		if (!$key) return false;
		return $this->handler ? $this->handler->delete($this->getCacheKey($key)) : false;
	}

	/**
	 * Return whether cache is valid or invalid
	 *
	 * @param string $key Cache key
	 * @param int $modified_time 	Unix time of data modified.
	 * 								If stored time is older then modified time, the data is invalid.
	 * @return bool Return true on valid or false on invalid.
	 */
	public function isValid($key, $modified_time = 0)
	{
		if (!$key) return false;
		return $this->handler ? $this->handler->isValid($this->getCacheKey($key), $modified_time) : false;
	}

	/**
	 * Truncate all cache
	 *
	 * @return bool|void Returns true on success or false on failure. If use CacheFile, returns void.
	 */
	public function truncate()
	{
		return $this->handler ? $this->handler->truncate() : false;
	}

	/**
	 * Function used for generating keys for similar objects.
	 *
	 * Ex: 1:document:123
	 *     1:document:777
	 *
	 * This allows easily removing all object of type "document"
	 * from cache by simply invalidating the group key.
	 *
	 * The new key will be 2:document:123, thus forcing the document
	 * to be reloaded from the database.
	 *
	 * @param string $keyGroupName Group name
	 * @param string $key Cache key
	 * @return string
	 */
	public function getGroupKey($keyGroupName, $key)
	{
		if(!$this->keyGroupVersions[$keyGroupName])
		{
			$this->keyGroupVersions[$keyGroupName] = 1;
			$this->handler->put('key_group_versions', $this->keyGroupVersions, 0);
		}

		return 'cache_group_' . $this->keyGroupVersions[$keyGroupName] . ':' . $keyGroupName . ':' . $key;
	}

	/**
	 * Make invalid group key (like delete group key)
	 *
	 * @param string $keyGroupName Group name
	 * @return void
	 */
	public function invalidateGroupKey($keyGroupName)
	{
		$this->keyGroupVersions[$keyGroupName]++;
		$this->handler->put('key_group_versions', $this->keyGroupVersions, 0);
	}
}

/**
 * Base class of Cache
 *
 * @author NAVER (developer@xpressengine.com)
 */
class CacheBase
{
	/**
	 * Default valid time
	 * @var int
	 */
	public $valid_time = 36000;

	/**
	 * Get cached data
	 *
	 * @param string $key Cache key
	 * @param int $modified_time 	Unix time of data modified.
	 * 								If stored time is older then modified time, return false.
	 * @return false|mixed Return false on failure or older then modified time. Return the string associated with the $key on success.
	 */
	public function get($key, $modified_time = 0)
	{
		return false;
	}

	/**
	 * Put data into cache
	 *
	 * @param string $key Cache key
	 * @param mixed $obj	Value of a variable to store. $value supports all data types except resources, such as file handlers.
	 * @param int $valid_time	Time for the variable to live in the cache in seconds.
	 * 							After the value specified in ttl has passed the stored variable will be deleted from the cache.
	 * 							If no ttl is supplied, use the default valid time.
	 * @return bool|void Returns true on success or false on failure. If use CacheFile, returns void.
	 */
	public function put($key, $obj, $valid_time = 0)
	{
		return false;
	}
	
	/**
	 * Alias of put()
	 */
	public function set($key, $obj, $valid_time = 0)
	{
		return $this->put($key, $obj, $valid_time = 0);
	}

	/**
	 * Return whether cache is valid or invalid
	 *
	 * @param string $key Cache key
	 * @param int $modified_time 	Unix time of data modified.
	 * 								If stored time is older then modified time, the data is invalid.
	 * @return bool Return true on valid or false on invalid.
	 */
	public function isValid($key, $modified_time = 0)
	{
		return false;
	}

	/**
	 * Return whether support or not support cache
	 *
	 * @return boolean
	 */
	public function isSupport()
	{
		return false;
	}

	/**
	 * Truncate all cache
	 *
	 * @return bool|void Returns true on success or false on failure. If use CacheFile, returns void.
	 */
	public function truncate()
	{
		return false;
	}

}
/* End of file CacheHandler.class.php */
/* Location: ./classes/cache/CacheHandler.class.php */