<?php

/**
 * Memcache CacheResource
 * CacheResource Implementation based on the KeyValueStore API to use
 * memcache as the storage resource for Smarty's output caching.
 * Note that memcache has a limitation of 256 characters per cache-key.
 * To avoid complications all cache-keys are translated to a sha1 hash.
 *
 * @package CacheResource-examples
 * @author  Rodney Rehm
 */
class Smarty_CacheResource_Memcache extends Smarty_CacheResource_KeyValueStore
{
    /**
     * memcache instance
     *
     * @var Memcache
     */
    protected $memcache = null;

    /**
     * Smarty_CacheResource_Memcache constructor.
     */
    public function __construct()
    {
        if (class_exists('Memcached')) {
            $this->memcache = new Memcached();
        } else {
            $this->memcache = new Memcache();
        }
        $this->memcache->addServer('127.0.0.1', 11211);
    }

    /**
     * Read values for a set of keys from cache
     *
     * @param array $keys list of keys to fetch
     *
     * @return array   list of values with the given keys used as indexes
     * @return boolean true on success, false on failure
     */
    protected function read(array $keys)
    {
        $_keys = $lookup = array();
        foreach ($keys as $k) {
            $_k = sha1($k);
            $_keys[] = $_k;
            $lookup[ $_k ] = $k;
        }
        $_res = array();
        $res = $this->memcache->get($_keys);
        foreach ($res as $k => $v) {
            $_res[ $lookup[ $k ] ] = $v;
        }
        return $_res;
    }

    /**
     * Save values for a set of keys to cache
     *
     * @param array $keys   list of values to save
     * @param int   $expire expiration time
     *
     * @return boolean true on success, false on failure
     */
    protected function write(array $keys, $expire = null)
    {
        foreach ($keys as $k => $v) {
            $k = sha1($k);
            $this->memcache->set($k, $v, 0, $expire);
        }
        return true;
    }

    /**
     * Remove values from cache
     *
     * @param array $keys list of keys to delete
     *
     * @return boolean true on success, false on failure
     */
    protected function delete(array $keys)
    {
        foreach ($keys as $k) {
            $k = sha1($k);
            $this->memcache->delete($k);
        }
        return true;
    }

    /**
     * Remove *all* values from cache
     *
     * @return boolean true on success, false on failure
     */
    protected function purge()
    {
        return $this->memcache->flush();
    }
}
