Method update

/**
 * Custom update method
 *
 * @return  boolean  True on success, false on failure
 *
 * @since   3.1
 */
public function update()
{
    $xml = $this->parent->getManifest();
    $this->setManifest($xml);
    $cname = $xml->attributes()->client;
    // Attempt to map the client to a base path
    $client = ApplicationHelper::getClientInfo($cname, true);
    if ($client === null || empty($cname) && $cname !== 0) {
        $this->parent->abort(Text::sprintf('JLIB_INSTALLER_ABORT', Text::sprintf('JLIB_INSTALLER_ERROR_UNKNOWN_CLIENT_TYPE', $cname)));
        return false;
    }
    $basePath = $client->path;
    $clientId = $client->id;
    // Get the language name
    // Set the extensions name
    $name = (string) $this->getManifest()->name;
    $name = InputFilter::getInstance()->clean($name, 'string');
    $this->name = $name;
    // Get the Language tag [ISO tag, eg. en-GB]
    $tag = (string) $xml->tag;
    // Check if we found the tag - if we didn't, we may be trying to install from an older language package
    if (!$tag) {
        $this->parent->abort(Text::sprintf('JLIB_INSTALLER_ABORT', Text::_('JLIB_INSTALLER_ERROR_NO_LANGUAGE_TAG')));
        return false;
    }
    $this->tag = $tag;
    // Set the language installation path
    $this->parent->setPath('extension_site', $basePath . '/language/' . $tag);
    // Do we have a meta file in the file list?  In other words... is this a core language pack?
    if (\count($xml->files->children())) {
        foreach ($xml->files->children() as $file) {
            if ((string) $file->attributes()->file === 'meta') {
                $this->core = true;
                break;
            }
        }
    }
    // Copy all the necessary files
    if ($this->parent->parseFiles($xml->files) === false) {
        // Install failed, rollback changes
        $this->parent->abort();
        return false;
    }
    // Parse optional tags
    $this->parent->parseMedia($xml->media);
    // Get the language description and set it as message
    $this->parent->set('message', (string) $xml->description);
    /**
     * ---------------------------------------------------------------------------------------------
     * Finalization and Cleanup Section
     * ---------------------------------------------------------------------------------------------
     */
    // Clobber any possible pending updates
    $update = Table::getInstance('update');
    $uid = $update->find(array('element' => $this->tag, 'type' => 'language', 'client_id' => $clientId));
    if ($uid) {
        $update->delete($uid);
    }
    // Update an entry to the extension table
    $row = Table::getInstance('extension');
    $eid = $row->find(array('element' => $this->tag, 'type' => 'language', 'client_id' => $clientId));
    if ($eid) {
        $row->load($eid);
    } else {
        // Set the defaults
        // There is no folder for language
        $row->set('folder', '');
        $row->set('enabled', 1);
        $row->set('protected', 0);
        $row->set('access', 0);
        $row->set('client_id', $clientId);
        $row->set('params', $this->parent->getParams());
    }
    $row->set('name', $this->name);
    $row->set('type', 'language');
    $row->set('element', $this->tag);
    $row->set('manifest_cache', $this->parent->generateManifestCache());
    $row->set('changelogurl', (string) $this->getManifest()->changelogurl);
    // Clean installed languages cache.
    Factory::getCache()->clean('com_languages');
    if (!$row->check() || !$row->store()) {
        // Install failed, roll back changes
        $this->parent->abort(Text::sprintf('JLIB_INSTALLER_ABORT', $row->getError()));
        return false;
    }
    if ($clientId === 0) {
        $this->createContentLanguage($this->tag);
    }
    return $row->get('extension_id');
}