<?php

/**

 * MySQL CacheResource

 * CacheResource Implementation based on the Custom API to use

 * MySQL as the storage resource for Smarty's output caching.

 * Table definition:

 * <pre>CREATE TABLE IF NOT EXISTS `output_cache` (

 *   `id` CHAR(40) NOT NULL COMMENT 'sha1 hash',

 *   `name` VARCHAR(250) NOT NULL,

 *   `cache_id` VARCHAR(250) NULL DEFAULT NULL,

 *   `compile_id` VARCHAR(250) NULL DEFAULT NULL,

 *   `modified` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,

 *   `content` LONGTEXT NOT NULL,

 *   PRIMARY KEY (`id`),

 *   INDEX(`name`),

 *   INDEX(`cache_id`),

 *   INDEX(`compile_id`),

 *   INDEX(`modified`)

 * ) ENGINE = InnoDB;</pre>

 *

 * @package CacheResource-examples

 * @author  Rodney Rehm

 */

class Smarty_CacheResource_Mysql extends Smarty_CacheResource_Custom {

    // PDO instance

    protected $db;

    protected $fetch;

    protected $fetchTimestamp;

    protected $save;

    public function __construct() {

        try {

            $this->db = new PDO("mysql:dbname=test;host=127.0.0.1", "smarty");

        } catch (PDOException $e) {

            throw new SmartyException('Mysql Resource failed: ' . $e->getMessage());

        }

        $this->fetch = $this->db->prepare('SELECT modified, content FROM output_cache WHERE id = :id');

        $this->fetchTimestamp = $this->db->prepare('SELECT modified FROM output_cache WHERE id = :id');

        $this->save = $this->db->prepare('REPLACE INTO output_cache (id, name, cache_id, compile_id, content)

            VALUES  (:id, :name, :cache_id, :compile_id, :content)');

    }

    /**

     * fetch cached content and its modification time from data source

     *

     * @param  string $id unique cache content identifier

     * @param  string $name template name

     * @param  string $cache_id cache id

     * @param  string $compile_id compile id

     * @param  string $content cached content

     * @param  integer $mtime cache modification timestamp (epoch)

     *

     * @return void

     */

    protected function fetch($id, $name, $cache_id, $compile_id, &$content, &$mtime) {

        $this->fetch->execute(array('id' => $id));

        $row = $this->fetch->fetch();

        $this->fetch->closeCursor();

        if ($row) {

            $content = $row['content'];

            $mtime = strtotime($row['modified']);

        } else {

            $content = null;

            $mtime = null;

        }

    }

    /**

     * Fetch cached content's modification timestamp from data source

     *

     * @note implementing this method is optional. Only implement it if modification times can be accessed faster than loading the complete cached content.

     *

     * @param  string $id unique cache content identifier

     * @param  string $name template name

     * @param  string $cache_id cache id

     * @param  string $compile_id compile id

     *

     * @return integer|boolean timestamp (epoch) the template was modified, or false if not found

     */

    protected function fetchTimestamp($id, $name, $cache_id, $compile_id) {

        $this->fetchTimestamp->execute(array('id' => $id));

        $mtime = strtotime($this->fetchTimestamp->fetchColumn());

        $this->fetchTimestamp->closeCursor();

        return $mtime;

    }

    /**

     * Save content to cache

     *

     * @param  string $id unique cache content identifier

     * @param  string $name template name

     * @param  string $cache_id cache id

     * @param  string $compile_id compile id

     * @param  integer|null $exp_time seconds till expiration time in seconds or null

     * @param  string $content content to cache

     *

     * @return boolean      success

     */

    protected function save($id, $name, $cache_id, $compile_id, $exp_time, $content) {

        $this->save->execute(array(

            'id' => $id,

            'name' => $name,

            'cache_id' => $cache_id,

            'compile_id' => $compile_id,

            'content' => $content,

        ));

        return !!$this->save->rowCount();

    }

    /**

     * Delete content from cache

     *

     * @param  string $name template name

     * @param  string $cache_id cache id

     * @param  string $compile_id compile id

     * @param  integer|null $exp_time seconds till expiration or null

     *

     * @return integer      number of deleted caches

     */

    protected function delete($name, $cache_id, $compile_id, $exp_time) {

        // delete the whole cache

        if ($name === null && $cache_id === null && $compile_id === null && $exp_time === null) {

            // returning the number of deleted caches would require a second query to count them

            $query = $this->db->query('TRUNCATE TABLE output_cache');

            return -1;

        }

        // build the filter

        $where = array();

        // equal test name

        if ($name !== null) {

            $where[] = 'name = ' . $this->db->quote($name);

        }

        // equal test compile_id

        if ($compile_id !== null) {

            $where[] = 'compile_id = ' . $this->db->quote($compile_id);

        }

        // range test expiration time

        if ($exp_time !== null) {

            $where[] = 'modified < DATE_SUB(NOW(), INTERVAL ' . intval($exp_time) . ' SECOND)';

        }

        // equal test cache_id and match sub-groups

        if ($cache_id !== null) {

            $where[] = '(cache_id = ' . $this->db->quote($cache_id)

                . ' OR cache_id LIKE ' . $this->db->quote($cache_id . '|%') . ')';

        }

        // run delete query

        $query = $this->db->query('DELETE FROM output_cache WHERE ' . join(' AND ', $where));

        return $query->rowCount();

    }

}