<?php
/**
 * Translation table cache.
 * @author $Author: weizhuo $
 * @version $Id: MessageCache.php,v 1.3 2005/01/05 03:15:14 weizhuo Exp $
 * @package System.I18N.core
 */

/**
 * Load the cache lite library.
 */
require_once (dirname(__FILE__) . '/TCache_Lite.php');

/**
 * Cache the translation table into the file system.
 * It can cache each cataloug+variant or just the whole section.
 *
 * @package System.I18N.core
 * @author $Author: weizhuo $
 * @version $Id: MessageCache.php,v 1.3 2005/01/05 03:15:14 weizhuo Exp $
 */
class MessageCache
{

    /**
     * Cache Lite instance.
     *
     * @var TCache_Lite
     */
    protected $cache;

    /**
     * Caceh life time, default is 1 year.
     */
    protected $lifetime = 3153600;

    /**
     * Create a new Translation cache.
     *
     * @param string $cacheDir
     *            Directory to store the cache files.
     */
    public function __construct($cacheDir)
    {
        $cacheDir = $cacheDir . '/';
        
        if (! is_dir($cacheDir))
            throw new Exception('The cache directory ' . $cacheDir . ' does not exists.' . 'The cache directory must be writable by the server.');
        if (! is_writable($cacheDir))
            throw new Exception('The cache directory ' . $cacheDir . ' must be writable ' . 'by the server.');
        
        $options = array(
            'cacheDir' => $cacheDir,
            'lifeTime' => $this->getLifeTime(),
            'automaticSerialization' => true
        );
        
        $this->cache = new TCache_Lite($options);
    }

    /**
     * Get the cache life time.
     *
     * @return int Cache life time.
     */
    public function getLifeTime()
    {
        return $this->lifetime;
    }

    /**
     * Set the cache life time.
     *
     * @param int $time
     *            Cache life time.
     */
    public function setLifeTime($time)
    {
        $this->lifetime = intval($time);
    }

    /**
     * Get the cache file ID based section and locale.
     *
     * @param string $catalogue
     *            The translation section.
     * @param string $culture
     *            The translation locale, e.g. "en_AU".
     */
    protected function getID($catalogue, $culture)
    {
        return $catalogue . ':' . $culture;
    }

    /**
     * Get the cache file GROUP based section and locale.
     *
     * @param string $catalogue
     *            The translation section.
     * @param string $culture
     *            The translation locale, e.g. "en_AU".
     */
    protected function getGroup($catalogue, $culture)
    {
        return $catalogue . ':' . get_class($this);
    }

    /**
     * Get the data from the cache.
     *
     * @param string $catalogue
     *            The translation section.
     * @param string $culture
     *            The translation locale, e.g. "en_AU".
     * @param string $filename
     *            If the source is a file, this file's modified
     *            time is newer than the cache's modified time, no cache hit.
     * @return mixed Boolean FALSE if no cache hit. Otherwise, translation
     *         table data for the specified section and locale.
     */
    public function get($catalogue, $culture, $lastmodified = 0)
    {
        $ID = $this->getID($catalogue, $culture);
        $group = $this->getGroup($catalogue, $culture);
        
        $this->cache->_setFileName($ID, $group);
        
        $cache = $this->cache->getCacheFile();
        
        if (is_file($cache) == false)
            return false;
        
        $lastmodified = intval($lastmodified);
        
        if ($lastmodified <= 0 || $lastmodified > filemtime($cache))
            return false;
            
            // echo '@@ Cache hit: "'.$ID.'" : "'.$group.'"';
            // echo "<br>\n";
        
        return $this->cache->get($ID, $group);
    }

    /**
     * Save the data to cache for the specified section and locale.
     *
     * @param array $data
     *            The data to save.
     * @param string $catalogue
     *            The translation section.
     * @param string $culture
     *            The translation locale, e.g. "en_AU".
     */
    public function save($data, $catalogue, $culture)
    {
        $ID = $this->getID($catalogue, $culture);
        $group = $this->getGroup($catalogue, $culture);
        
        // echo '## Cache save: "'.$ID.'" : "'.$group.'"';
        // echo "<br>\n";
        
        return $this->cache->save($data, $ID, $group);
    }

    /**
     * Clean up the cache for the specified section and locale.
     *
     * @param string $catalogue
     *            The translation section.
     * @param string $culture
     *            The translation locale, e.g. "en_AU".
     */
    public function clean($catalogue, $culture)
    {
        $group = $this->getGroup($catalogue, $culture);
        $this->cache->clean($group);
    }

    /**
     * Flush the cache.
     * Deletes all the cache files.
     */
    public function clear()
    {
        $this->cache->clean();
    }
}

?>