<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id$
 */


/**
 * @see Zend_Cache_Backend_Interface
 */
require_once 'Zend/Cache/Backend/ExtendedInterface.php';

/**
 * @see Zend_Cache_Backend
 */
require_once 'Zend/Cache/Backend.php';


/**
 * @package    Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Cache_Backend_Memcached extends Zend_Cache_Backend implements Zend_Cache_Backend_ExtendedInterface
{
    /**
     * Default Values
     */
    const DEFAULT_HOST = '127.0.0.1';
    const DEFAULT_PORT =  11211;
    const DEFAULT_PERSISTENT = true;
    const DEFAULT_WEIGHT  = 1;
    const DEFAULT_TIMEOUT = 1;
    const DEFAULT_RETRY_INTERVAL = 15;
    const DEFAULT_STATUS = true;
    const DEFAULT_FAILURE_CALLBACK = null;

    /**
     * Log message
     */
    const TAGS_UNSUPPORTED_BY_CLEAN_OF_MEMCACHED_BACKEND = 'Zend_Cache_Backend_Memcached::clean() : tags are unsupported by the Memcached backend';
    const TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND =  'Zend_Cache_Backend_Memcached::save() : tags are unsupported by the Memcached backend';

    /**
     * Available options
     *
     * =====> (array) servers :
     * an array of memcached server ; each memcached server is described by an associative array :
     * 'host' => (string) : the name of the memcached server
     * 'port' => (int) : the port of the memcached server
     * 'persistent' => (bool) : use or not persistent connections to this memcached server
     * 'weight' => (int) : number of buckets to create for this server which in turn control its
     *                     probability of it being selected. The probability is relative to the total
     *                     weight of all servers.
     * 'timeout' => (int) : value in seconds which will be used for connecting to the daemon. Think twice
     *                      before changing the default value of 1 second - you can lose all the
     *                      advantages of caching if your connection is too slow.
     * 'retry_interval' => (int) : controls how often a failed server will be retried, the default value
     *                             is 15 seconds. Setting this parameter to -1 disables automatic retry.
     * 'status' => (bool) : controls if the server should be flagged as online.
     * 'failure_callback' => (callback) : Allows the user to specify a callback function to run upon
     *                                    encountering an error. The callback is run before failover
     *                                    is attempted. The function takes two parameters, the hostname
     *                                    and port of the failed server.
     *
     * =====> (boolean) compression :
     * true if you want to use on-the-fly compression
     *
     * =====> (boolean) compatibility :
     * true if you use old memcache server or extension
     *
     * @var array available options
     */
    protected $_options = [
        'servers' => [[
            'host' => self::DEFAULT_HOST,
            'port' => self::DEFAULT_PORT,
            'persistent' => self::DEFAULT_PERSISTENT,
            'weight'  => self::DEFAULT_WEIGHT,
            'timeout' => self::DEFAULT_TIMEOUT,
            'retry_interval' => self::DEFAULT_RETRY_INTERVAL,
            'status' => self::DEFAULT_STATUS,
            'failure_callback' => self::DEFAULT_FAILURE_CALLBACK
        ]],
        'compression' => false,
        'compatibility' => false,
    ];

    /**
     * Memcache object
     *
     * @var mixed memcache object
     */
    protected $_memcache = null;

    /**
     * Constructor
     *
     * @param array $options associative array of options
     * @throws Zend_Cache_Exception
     * @return void
     */
    public function __construct(array $options = [])
    {
        if (!extension_loaded('memcache')) {
            Zend_Cache::throwException('The memcache extension must be loaded for using this backend !');
        }
        parent::__construct($options);
        if (isset($this->_options['servers'])) {
            $value= $this->_options['servers'];
            if (isset($value['host'])) {
                // in this case, $value seems to be a simple associative array (one server only)
                $value = [0 => $value]; // let's transform it into a classical array of associative arrays
            }
            $this->setOption('servers', $value);
        }
        $this->_memcache = new Memcache;
        foreach ($this->_options['servers'] as $server) {
            if (!array_key_exists('port', $server)) {
                $server['port'] = self::DEFAULT_PORT;
            }
            if (!array_key_exists('persistent', $server)) {
                $server['persistent'] = self::DEFAULT_PERSISTENT;
            }
            if (!array_key_exists('weight', $server)) {
                $server['weight'] = self::DEFAULT_WEIGHT;
            }
            if (!array_key_exists('timeout', $server)) {
                $server['timeout'] = self::DEFAULT_TIMEOUT;
            }
            if (!array_key_exists('retry_interval', $server)) {
                $server['retry_interval'] = self::DEFAULT_RETRY_INTERVAL;
            }
            if (!array_key_exists('status', $server)) {
                $server['status'] = self::DEFAULT_STATUS;
            }
            if (!array_key_exists('failure_callback', $server)) {
                $server['failure_callback'] = self::DEFAULT_FAILURE_CALLBACK;
            }
            if ($this->_options['compatibility']) {
                // No status for compatibility mode (#ZF-5887)
                $this->_memcache->addServer($server['host'], $server['port'], $server['persistent'],
                                        $server['weight'], $server['timeout'],
                                        $server['retry_interval']);
            } else {
                $this->_memcache->addServer($server['host'], $server['port'], $server['persistent'],
                                        $server['weight'], $server['timeout'],
                                        $server['retry_interval'],
                                        $server['status'], $server['failure_callback']);
            }
        }
    }

    /**
     * Test if a cache is available for the given id and (if yes) return it (false else)
     *
     * @param  string  $id                     Cache id
     * @param  boolean $doNotTestCacheValidity If set to true, the cache validity won't be tested
     * @return string|false cached datas
     */
    public function load($id, $doNotTestCacheValidity = false)
    {
        $tmp = $this->_memcache->get($id);
        if (is_array($tmp) && isset($tmp[0])) {
            return $tmp[0];
        }
        return false;
    }

    /**
     * Test if a cache is available or not (for the given id)
     *
     * @param  string $id Cache id
     * @return mixed|false (a cache is not available) or "last modified" timestamp (int) of the available cache record
     */
    public function test($id)
    {
        $tmp = $this->_memcache->get($id);
        if (is_array($tmp)) {
            return $tmp[1];
        }
        return false;
    }

    /**
     * Save some string datas into a cache record
     *
     * Note : $data is always "string" (serialization is done by the
     * core not by the backend)
     *
     * @param  string $data             Datas to cache
     * @param  string $id               Cache id
     * @param  array  $tags             Array of strings, the cache record will be tagged by each string entry
     * @param  int    $specificLifetime If != false, set a specific lifetime for this cache record (null => infinite lifetime)
     * @return boolean True if no problem
     */
    public function save($data, $id, $tags = [], $specificLifetime = false)
    {
        $lifetime = $this->getLifetime($specificLifetime);
        if ($this->_options['compression']) {
            $flag = MEMCACHE_COMPRESSED;
        } else {
            $flag = 0;
        }

        // ZF-8856: using set because add needs a second request if item already exists
        $result = @$this->_memcache->set($id, [$data, time(), $lifetime], $flag, $lifetime);

        if (count($tags) > 0) {
            $this->_log(self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        }

        return $result;
    }

    /**
     * Remove a cache record
     *
     * @param  string $id Cache id
     * @return boolean True if no problem
     */
    public function remove($id)
    {
        return $this->_memcache->delete($id, 0);
    }

    /**
     * Clean some cache records
     *
     * Available modes are :
     * 'all' (default)  => remove all cache entries ($tags is not used)
     * 'old'            => unsupported
     * 'matchingTag'    => unsupported
     * 'notMatchingTag' => unsupported
     * 'matchingAnyTag' => unsupported
     *
     * @param  string $mode Clean mode
     * @param  array  $tags Array of tags
     * @throws Zend_Cache_Exception
     * @return boolean True if no problem
     */
    public function clean($mode = Zend_Cache::CLEANING_MODE_ALL, $tags = [])
    {
        switch ($mode) {
            case Zend_Cache::CLEANING_MODE_ALL:
                return $this->_memcache->flush();
                break;
            case Zend_Cache::CLEANING_MODE_OLD:
                $this->_log("Zend_Cache_Backend_Memcached::clean() : CLEANING_MODE_OLD is unsupported by the Memcached backend");
                break;
            case Zend_Cache::CLEANING_MODE_MATCHING_TAG:
            case Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG:
            case Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG:
                $this->_log(self::TAGS_UNSUPPORTED_BY_CLEAN_OF_MEMCACHED_BACKEND);
                break;
               default:
                Zend_Cache::throwException('Invalid mode for clean() method');
                   break;
        }
    }

    /**
     * Return true if the automatic cleaning is available for the backend
     *
     * @return boolean
     */
    public function isAutomaticCleaningAvailable()
    {
        return false;
    }

    /**
     * Set the frontend directives
     *
     * @param  array $directives Assoc of directives
     * @throws Zend_Cache_Exception
     * @return void
     */
    public function setDirectives($directives)
    {
        parent::setDirectives($directives);
        $lifetime = $this->getLifetime(false);
        if ($lifetime > 2592000) {
            // #ZF-3490 : For the memcached backend, there is a lifetime limit of 30 days (2592000 seconds)
            $this->_log('memcached backend has a limit of 30 days (2592000 seconds) for the lifetime');
        }
        if ($lifetime === null) {
            // #ZF-4614 : we tranform null to zero to get the maximal lifetime
            parent::setDirectives(['lifetime' => 0]);
        }
    }

    /**
     * Return an array of stored cache ids
     *
     * @return array array of stored cache ids (string)
     */
    public function getIds()
    {
        $this->_log("Zend_Cache_Backend_Memcached::save() : getting the list of cache ids is unsupported by the Memcache backend");
        return [];
    }

    /**
     * Return an array of stored tags
     *
     * @return array array of stored tags (string)
     */
    public function getTags()
    {
        $this->_log(self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return [];
    }

    /**
     * Return an array of stored cache ids which match given tags
     *
     * In case of multiple tags, a logical AND is made between tags
     *
     * @param array $tags array of tags
     * @return array array of matching cache ids (string)
     */
    public function getIdsMatchingTags($tags = [])
    {
        $this->_log(self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return [];
    }

    /**
     * Return an array of stored cache ids which don't match given tags
     *
     * In case of multiple tags, a logical OR is made between tags
     *
     * @param array $tags array of tags
     * @return array array of not matching cache ids (string)
     */
    public function getIdsNotMatchingTags($tags = [])
    {
        $this->_log(self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return [];
    }

    /**
     * Return an array of stored cache ids which match any given tags
     *
     * In case of multiple tags, a logical AND is made between tags
     *
     * @param array $tags array of tags
     * @return array array of any matching cache ids (string)
     */
    public function getIdsMatchingAnyTags($tags = [])
    {
        $this->_log(self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return [];
    }

    /**
     * Return the filling percentage of the backend storage
     *
     * @throws Zend_Cache_Exception
     * @return int integer between 0 and 100
     */
    public function getFillingPercentage()
    {
        $mems = $this->_memcache->getExtendedStats();

        $memSize = null;
        $memUsed = null;
        foreach ($mems as $key => $mem) {
            if ($mem === false) {
                $this->_log('can\'t get stat from ' . $key);
                continue;
            }

            $eachSize = $mem['limit_maxbytes'];

            /**
             * Couchbase 1.x uses 'mem_used' instead of 'bytes'
             * @see https://www.couchbase.com/issues/browse/MB-3466
             */
            $eachUsed = isset($mem['bytes']) ? $mem['bytes'] : $mem['mem_used'];
            if ($eachUsed > $eachSize) {
                $eachUsed = $eachSize;
            }

            $memSize += $eachSize;
            $memUsed += $eachUsed;
        }

        if ($memSize === null || $memUsed === null) {
            Zend_Cache::throwException('Can\'t get filling percentage');
        }

        return ((int) (100. * ($memUsed / $memSize)));
    }

    /**
     * Return an array of metadatas for the given cache id
     *
     * The array must include these keys :
     * - expire : the expire timestamp
     * - tags : a string array of tags
     * - mtime : timestamp of last modification time
     *
     * @param string $id cache id
     * @return array array of metadatas (false if the cache id is not found)
     */
    public function getMetadatas($id)
    {
        $tmp = $this->_memcache->get($id);
        if (is_array($tmp)) {
            $data = $tmp[0];
            $mtime = $tmp[1];
            if (!isset($tmp[2])) {
                // because this record is only with 1.7 release
                // if old cache records are still there...
                return false;
            }
            $lifetime = $tmp[2];
            return [
                'expire' => $mtime + $lifetime,
                'tags' => [],
                'mtime' => $mtime
            ];
        }
        return false;
    }

    /**
     * Give (if possible) an extra lifetime to the given cache id
     *
     * @param string $id cache id
     * @param int $extraLifetime
     * @return boolean true if ok
     */
    public function touch($id, $extraLifetime)
    {
        if ($this->_options['compression']) {
            $flag = MEMCACHE_COMPRESSED;
        } else {
            $flag = 0;
        }
        $tmp = $this->_memcache->get($id);
        if (is_array($tmp)) {
            $data = $tmp[0];
            $mtime = $tmp[1];
            if (!isset($tmp[2])) {
                // because this record is only with 1.7 release
                // if old cache records are still there...
                return false;
            }
            $lifetime = $tmp[2];
            $newLifetime = $lifetime - (time() - $mtime) + $extraLifetime;
            if ($newLifetime <=0) {
                return false;
            }
            // #ZF-5702 : we try replace() first becase set() seems to be slower
            if (!($result = $this->_memcache->replace($id, [$data, time(), $newLifetime], $flag, $newLifetime))) {
                $result = $this->_memcache->set($id, [$data, time(), $newLifetime], $flag, $newLifetime);
            }
            return $result;
        }
        return false;
    }

    /**
     * Return an associative array of capabilities (booleans) of the backend
     *
     * The array must include these keys :
     * - automatic_cleaning (is automating cleaning necessary)
     * - tags (are tags supported)
     * - expired_read (is it possible to read expired cache records
     *                 (for doNotTestCacheValidity option for example))
     * - priority does the backend deal with priority when saving
     * - infinite_lifetime (is infinite lifetime can work with this backend)
     * - get_list (is it possible to get the list of cache ids and the complete list of tags)
     *
     * @return array associative of with capabilities
     */
    public function getCapabilities()
    {
        return [
            'automatic_cleaning' => false,
            'tags' => false,
            'expired_read' => false,
            'priority' => false,
            'infinite_lifetime' => false,
            'get_list' => false
        ];
    }

}
