<?php

/**

 * Smarty Internal Plugin

 *

 * @package Smarty

 * @subpackage Cacher

 */

/**

 * Smarty Cache Handler Base for Key/Value Storage Implementations

 *

 * This class implements the functionality required to use simple key/value stores

 * for hierarchical cache groups. key/value stores like memcache or APC do not support

 * wildcards in keys, therefore a cache group cannot be cleared like "a|*" - which

 * is no problem to filesystem and RDBMS implementations.

 *

 * This implementation is based on the concept of invalidation. While one specific cache

 * can be identified and cleared, any range of caches cannot be identified. For this reason

 * each level of the cache group hierarchy can have its own value in the store. These values

 * are nothing but microtimes, telling us when a particular cache group was cleared for the

 * last time. These keys are evaluated for every cache read to determine if the cache has

 * been invalidated since it was created and should hence be treated as inexistent.

 *

 * Although deep hierarchies are possible, they are not recommended. Try to keep your

 * cache groups as shallow as possible. Anything up 3-5 parents should be ok. So

 * »a|b|c« is a good depth where »a|b|c|d|e|f|g|h|i|j|k« isn't. Try to join correlating

 * cache groups: if your cache groups look somewhat like »a|b|$page|$items|$whatever«

 * consider using »a|b|c|$page-$items-$whatever« instead.

 *

 * @package Smarty

 * @subpackage Cacher

 * @author Rodney Rehm

 */

abstract class Smarty_CacheResource_KeyValueStore extends Smarty_CacheResource {

    /**

     * cache for contents

     * @var array

     */

    protected $contents = array();

    /**

     * cache for timestamps

     * @var array

     */

    protected $timestamps = array();

    /**

     * populate Cached Object with meta data from Resource

     *

     * @param Smarty_Template_Cached   $cached    cached object

     * @param Smarty_Internal_Template $_template template object

     * @return void

     */

    public function populate(Smarty_Template_Cached $cached, Smarty_Internal_Template $_template)

    {

        $cached->filepath = $_template->source->uid

                . '#' . $this->sanitize($cached->source->name)

                . '#' . $this->sanitize($cached->cache_id)

                . '#' . $this->sanitize($cached->compile_id);

        $this->populateTimestamp($cached);

    }

    /**

     * populate Cached Object with timestamp and exists from Resource

     *

     * @param Smarty_Template_Cached $cached cached object

     * @return void

     */

    public function populateTimestamp(Smarty_Template_Cached $cached)

    {

        if (!$this->fetch($cached->filepath, $cached->source->name, $cached->cache_id, $cached->compile_id, $content, $timestamp, $cached->source->uid)) {

            return;

        }

        $cached->content = $content;

        $cached->timestamp = (int) $timestamp;

        $cached->exists = $cached->timestamp;

    }

    /**

     * Read the cached template and process the header

     *

     * @param Smarty_Internal_Template $_template template object

     * @param Smarty_Template_Cached $cached cached object

     * @return booelan true or false if the cached content does not exist

     */

    public function process(Smarty_Internal_Template $_template, Smarty_Template_Cached $cached=null)

    {

        if (!$cached) {

            $cached = $_template->cached;

        }

        $content = $cached->content ? $cached->content : null;

        $timestamp = $cached->timestamp ? $cached->timestamp : null;

        if ($content === null || !$timestamp) {

            if (!$this->fetch($_template->cached->filepath, $_template->source->name, $_template->cache_id, $_template->compile_id, $content, $timestamp, $_template->source->uid)) {

                return false;

            }

        }

        if (isset($content)) {

            $_smarty_tpl = $_template;

            eval("?>" . $content);

            return true;

        }

        return false;

    }

    /**

     * Write the rendered template output to cache

     *

     * @param Smarty_Internal_Template $_template template object

     * @param string $content content to cache

     * @return boolean success

     */

    public function writeCachedContent(Smarty_Internal_Template $_template, $content)

    {

        $this->addMetaTimestamp($content);

        return $this->write(array($_template->cached->filepath => $content), $_template->properties['cache_lifetime']);

    }

    /**

     * Empty cache

     *

     * {@internal the $exp_time argument is ignored altogether }}

     *

     * @param Smarty  $smarty   Smarty object

     * @param integer $exp_time expiration time [being ignored]

     * @return integer number of cache files deleted [always -1]

     * @uses purge() to clear the whole store

     * @uses invalidate() to mark everything outdated if purge() is inapplicable

     */

    public function clearAll(Smarty $smarty, $exp_time=null)

    {

        if (!$this->purge()) {

            $this->invalidate(null);

        }

        return -1;

    }

    /**

     * Empty cache for a specific template

     *

     * {@internal the $exp_time argument is ignored altogether}}

     *

     * @param Smarty  $smarty        Smarty object

     * @param string  $resource_name template name

     * @param string  $cache_id      cache id

     * @param string  $compile_id    compile id

     * @param integer $exp_time      expiration time [being ignored]

     * @return integer number of cache files deleted [always -1]

     * @uses buildCachedFilepath() to generate the CacheID

     * @uses invalidate() to mark CacheIDs parent chain as outdated

     * @uses delete() to remove CacheID from cache

     */

    public function clear(Smarty $smarty, $resource_name, $cache_id, $compile_id, $exp_time)

    {

        $uid = $this->getTemplateUid($smarty, $resource_name, $cache_id, $compile_id);

        $cid = $uid . '#' . $this->sanitize($resource_name) . '#' . $this->sanitize($cache_id) . '#' . $this->sanitize($compile_id);

        $this->delete(array($cid));

        $this->invalidate($cid, $resource_name, $cache_id, $compile_id, $uid);

        return -1;

    }

    /**

     * Get template's unique ID

     *

     * @param Smarty $smarty        Smarty object

     * @param string $resource_name template name

     * @param string $cache_id      cache id

     * @param string $compile_id    compile id

     * @return string filepath of cache file

     */

    protected function getTemplateUid(Smarty $smarty, $resource_name, $cache_id, $compile_id)

    {

        $uid = '';

        if (isset($resource_name)) {

            $tpl = new $smarty->template_class($resource_name, $smarty);

            if ($tpl->source->exists) {

                $uid = $tpl->source->uid;

            }

            // remove from template cache

            if ($smarty->allow_ambiguous_resources) {

                $_templateId = $tpl->source->unique_resource . $tpl->cache_id . $tpl->compile_id;

            } else {

                $_templateId = $smarty->joined_template_dir . '#' . $resource_name . $tpl->cache_id . $tpl->compile_id;

            }

            if (isset($_templateId[150])) {

                $_templateId = sha1($_templateId);

            }

            unset($smarty->template_objects[$_templateId]);

        }

        return $uid;

    }

    /**

     * Sanitize CacheID components

     *

     * @param string $string CacheID component to sanitize

     * @return string sanitized CacheID component

     */

    protected function sanitize($string)

    {

        // some poeple smoke bad weed

        $string = trim($string, '|');

        if (!$string) {

            return null;

        }

        return preg_replace('#[^\w\|]+#S', '_', $string);

    }

    /**

     * Fetch and prepare a cache object.

     *

     * @param string  $cid           CacheID to fetch

     * @param string  $resource_name template name

     * @param string  $cache_id      cache id

     * @param string  $compile_id    compile id

     * @param string  $content       cached content

     * @param integer &$timestamp    cached timestamp (epoch)

     * @param string  $resource_uid  resource's uid

     * @return boolean success

     */

    protected function fetch($cid, $resource_name = null, $cache_id = null, $compile_id = null, &$content = null, &$timestamp = null, $resource_uid = null)

    {

        $t = $this->read(array($cid));

        $content = !empty($t[$cid]) ? $t[$cid] : null;

        $timestamp = null;

        if ($content && ($timestamp = $this->getMetaTimestamp($content))) {

            $invalidated = $this->getLatestInvalidationTimestamp($cid, $resource_name, $cache_id, $compile_id, $resource_uid);

            if ($invalidated > $timestamp) {

                $timestamp = null;

                $content = null;

            }

        }

        return !!$content;

    }

    /**

     * Add current microtime to the beginning of $cache_content

     *

     * {@internal the header uses 8 Bytes, the first 4 Bytes are the seconds, the second 4 Bytes are the microseconds}}

     *

     * @param string &$content the content to be cached

     */

    protected function addMetaTimestamp(&$content)

    {

        $mt = explode(" ", microtime());

        $ts = pack("NN", $mt[1], (int) ($mt[0] * 100000000));

        $content = $ts . $content;

    }

    /**

     * Extract the timestamp the $content was cached

     *

     * @param string &$content the cached content

     * @return float the microtime the content was cached

     */

    protected function getMetaTimestamp(&$content)

    {

        $s = unpack("N", substr($content, 0, 4));

        $m = unpack("N", substr($content, 4, 4));

        $content = substr($content, 8);

        return $s[1] + ($m[1] / 100000000);

    }

    /**

     * Invalidate CacheID

     *

     * @param string $cid           CacheID

     * @param string $resource_name template name

     * @param string $cache_id      cache id

     * @param string $compile_id    compile id

     * @param string $resource_uid  source's uid

     * @return void

     */

    protected function invalidate($cid = null, $resource_name = null, $cache_id = null, $compile_id = null, $resource_uid = null)

    {

        $now = microtime(true);

        $key = null;

        // invalidate everything

        if (!$resource_name && !$cache_id && !$compile_id) {

            $key = 'IVK#ALL';

        }

        // invalidate all caches by template

        else if ($resource_name && !$cache_id && !$compile_id) {

            $key = 'IVK#TEMPLATE#' . $resource_uid . '#' . $this->sanitize($resource_name);

        }

        // invalidate all caches by cache group

        else if (!$resource_name && $cache_id && !$compile_id) {

            $key = 'IVK#CACHE#' . $this->sanitize($cache_id);

        }

        // invalidate all caches by compile id

        else if (!$resource_name && !$cache_id && $compile_id) {

            $key = 'IVK#COMPILE#' . $this->sanitize($compile_id);

        }

        // invalidate by combination

        else {

            $key = 'IVK#CID#' . $cid;

        }

        $this->write(array($key => $now));

    }

    /**

     * Determine the latest timestamp known to the invalidation chain

     *

     * @param string $cid           CacheID to determine latest invalidation timestamp of

     * @param string $resource_name template name

     * @param string $cache_id      cache id

     * @param string $compile_id    compile id

     * @param string $resource_uid  source's filepath

     * @return float the microtime the CacheID was invalidated

     */

    protected function getLatestInvalidationTimestamp($cid, $resource_name = null, $cache_id = null, $compile_id = null, $resource_uid = null)

    {

        // abort if there is no CacheID

        if (false && !$cid) {

            return 0;

        }

        // abort if there are no InvalidationKeys to check

        if (!($_cid = $this->listInvalidationKeys($cid, $resource_name, $cache_id, $compile_id, $resource_uid))) {

            return 0;

        }

        // there are no InValidationKeys

        if (!($values = $this->read($_cid))) {

            return 0;

        }

        // make sure we're dealing with floats

        $values = array_map('floatval', $values);

        return max($values);

    }

    /**

     * Translate a CacheID into the list of applicable InvalidationKeys.

     *

     * Splits "some|chain|into|an|array" into array( '#clearAll#', 'some', 'some|chain', 'some|chain|into', ... )

     *

     * @param string $cid           CacheID to translate

     * @param string $resource_name template name

     * @param string $cache_id      cache id

     * @param string $compile_id    compile id

     * @param string $resource_uid  source's filepath

     * @return array list of InvalidationKeys

     * @uses $invalidationKeyPrefix to prepend to each InvalidationKey

     */

    protected function listInvalidationKeys($cid, $resource_name = null, $cache_id = null, $compile_id = null, $resource_uid = null)

    {

        $t = array('IVK#ALL');

        $_name = $_compile = '#';

        if ($resource_name) {

            $_name .= $resource_uid . '#' . $this->sanitize($resource_name);

            $t[] = 'IVK#TEMPLATE' . $_name;

        }

        if ($compile_id) {

            $_compile .= $this->sanitize($compile_id);

            $t[] = 'IVK#COMPILE' . $_compile;

        }

        $_name .= '#';

        // some poeple smoke bad weed

        $cid = trim($cache_id, '|');

        if (!$cid) {

            return $t;

        }

        $i = 0;

        while (true) {

            // determine next delimiter position

            $i = strpos($cid, '|', $i);

            // add complete CacheID if there are no more delimiters

            if ($i === false) {

                $t[] = 'IVK#CACHE#' . $cid;

                $t[] = 'IVK#CID' . $_name . $cid . $_compile;

                $t[] = 'IVK#CID' . $_name . $_compile;

                break;

            }

            $part = substr($cid, 0, $i);

            // add slice to list

            $t[] = 'IVK#CACHE#' . $part;

            $t[] = 'IVK#CID' . $_name . $part . $_compile;

            // skip past delimiter position

            $i++;

        }

        return $t;

    }

    /**

     * Check is cache is locked for this template

     *

     * @param Smarty $smarty Smarty object

     * @param Smarty_Template_Cached $cached cached object

     * @return booelan true or false if cache is locked

     */

    public function hasLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        $key = 'LOCK#' . $cached->filepath;

        $data = $this->read(array($key));

        return $data && time() - $data[$key] < $smarty->locking_timeout;

    }

    /**

     * Lock cache for this template

     *

     * @param Smarty $smarty Smarty object

     * @param Smarty_Template_Cached $cached cached object

     */

    public function acquireLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        $cached->is_locked = true;

        $key = 'LOCK#' . $cached->filepath;

        $this->write(array($key => time()), $smarty->locking_timeout);

    }

    /**

     * Unlock cache for this template

     *

     * @param Smarty $smarty Smarty object

     * @param Smarty_Template_Cached $cached cached object

     */

    public function releaseLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        $cached->is_locked = false;

        $key = 'LOCK#' . $cached->filepath;

        $this->delete(array($key));

    }

    /**

     * 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

     */

    protected abstract function read(array $keys);

    /**

     * 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 abstract function write(array $keys, $expire=null);

    /**

     * Remove values from cache

     *

     * @param array $keys list of keys to delete

     * @return boolean true on success, false on failure

     */

    protected abstract function delete(array $keys);

    /**

     * Remove *all* values from cache

     *

     * @return boolean true on success, false on failure

     */

    protected function purge()

    {

        return false;

    }

}

?>