/**
* Generate page header
*/
function page_header($page_title = '', $display_online_list = true, $item_id = 0, $item = 'forum')
{
    global $db, $config, $template, $SID, $_SID, $_EXTRA_URL, $user, $auth, $phpEx, $phpbb_root_path;
    if (defined('HEADER_INC')) {
        return;
    }
    define('HEADER_INC', true);
    // gzip_compression
    if ($config['gzip_compress']) {
        // to avoid partially compressed output resulting in blank pages in
        // the browser or error messages, compression is disabled in a few cases:
        //
        // 1) if headers have already been sent, this indicates plaintext output
        //    has been started so further content must not be compressed
        // 2) the length of the current output buffer is non-zero. This means
        //    there is already some uncompressed content in this output buffer
        //    so further output must not be compressed
        // 3) if more than one level of output buffering is used because we
        //    cannot test all output buffer level content lengths. One level
        //    could be caused by php.ini output_buffering. Anything
        //    beyond that is manual, so the code wrapping phpBB in output buffering
        //    can easily compress the output itself.
        //
        if (@extension_loaded('zlib') && !headers_sent() && ob_get_level() <= 1 && ob_get_length() == 0) {
            ob_start('ob_gzhandler');
        }
    }
    // Generate logged in/logged out status
    if ($user->data['user_id'] != ANONYMOUS) {
        $u_login_logout = append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=logout', true, $user->session_id);
        $l_login_logout = sprintf($user->lang['LOGOUT_USER'], $user->data['username']);
    } else {
        $u_login_logout = append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=login');
        $l_login_logout = $user->lang['LOGIN'];
    }
    // Last visit date/time
    $s_last_visit = $user->data['user_id'] != ANONYMOUS ? $user->format_date($user->data['session_last_visit']) : '';
    // Get users online list ... if required
    $l_online_users = $online_userlist = $l_online_record = $l_online_time = '';
    if ($config['load_online'] && $config['load_online_time'] && $display_online_list) {
        /**
         * Load online data:
         * For obtaining another session column use $item and $item_id in the function-parameter, whereby the column is session_{$item}_id.
         */
        $item_id = max($item_id, 0);
        $online_users = obtain_users_online($item_id, $item);
        $user_online_strings = obtain_users_online_string($online_users, $item_id, $item);
        $l_online_users = $user_online_strings['l_online_users'];
        $online_userlist = $user_online_strings['online_userlist'];
        $total_online_users = $online_users['total_online'];
        if ($total_online_users > $config['record_online_users']) {
            set_config('record_online_users', $total_online_users, true);
            set_config('record_online_date', time(), true);
        }
        $l_online_record = sprintf($user->lang['RECORD_ONLINE_USERS'], $config['record_online_users'], $user->format_date($config['record_online_date'], false, true));
        $l_online_time = $config['load_online_time'] == 1 ? 'VIEW_ONLINE_TIME' : 'VIEW_ONLINE_TIMES';
        $l_online_time = sprintf($user->lang[$l_online_time], $config['load_online_time']);
    }
    $l_privmsgs_text = $l_privmsgs_text_unread = '';
    $s_privmsg_new = false;
    // Obtain number of new private messages if user is logged in
    if (!empty($user->data['is_registered'])) {
        if ($user->data['user_new_privmsg']) {
            $l_message_new = $user->data['user_new_privmsg'] == 1 ? $user->lang['NEW_PM'] : $user->lang['NEW_PMS'];
            $l_privmsgs_text = sprintf($l_message_new, $user->data['user_new_privmsg']);
            if (!$user->data['user_last_privmsg'] || $user->data['user_last_privmsg'] > $user->data['session_last_visit']) {
                $sql = 'UPDATE ' . USERS_TABLE . '
					SET user_last_privmsg = ' . $user->data['session_last_visit'] . '
					WHERE user_id = ' . $user->data['user_id'];
                $db->sql_query($sql);
                $s_privmsg_new = true;
            } else {
                $s_privmsg_new = false;
            }
        } else {
            $l_privmsgs_text = $user->lang['NO_NEW_PM'];
            $s_privmsg_new = false;
        }
        $l_privmsgs_text_unread = '';
        if ($user->data['user_unread_privmsg'] && $user->data['user_unread_privmsg'] != $user->data['user_new_privmsg']) {
            $l_message_unread = $user->data['user_unread_privmsg'] == 1 ? $user->lang['UNREAD_PM'] : $user->lang['UNREAD_PMS'];
            $l_privmsgs_text_unread = sprintf($l_message_unread, $user->data['user_unread_privmsg']);
        }
    }
    $forum_id = request_var('f', 0);
    $topic_id = request_var('t', 0);
    $s_feed_news = false;
    // Get option for news
    if ($config['feed_enable']) {
        $sql = 'SELECT forum_id
			FROM ' . FORUMS_TABLE . '
			WHERE ' . $db->sql_bit_and('forum_options', FORUM_OPTION_FEED_NEWS, '<> 0');
        $result = $db->sql_query_limit($sql, 1, 0, 600);
        $s_feed_news = (int) $db->sql_fetchfield('forum_id');
        $db->sql_freeresult($result);
    }
    // Determine board url - we may need it later
    $board_url = generate_board_url() . '/';
    $web_path = defined('PHPBB_USE_BOARD_URL_PATH') && PHPBB_USE_BOARD_URL_PATH ? $board_url : $phpbb_root_path;
    // Which timezone?
    $tz = $user->data['user_id'] != ANONYMOUS ? strval(doubleval($user->data['user_timezone'])) : strval(doubleval($config['board_timezone']));
    // Send a proper content-language to the output
    $user_lang = $user->lang['USER_LANG'];
    if (strpos($user_lang, '-x-') !== false) {
        $user_lang = substr($user_lang, 0, strpos($user_lang, '-x-'));
    }
    $s_search_hidden_fields = array();
    if ($_SID) {
        $s_search_hidden_fields['sid'] = $_SID;
    }
    if (!empty($_EXTRA_URL)) {
        foreach ($_EXTRA_URL as $url_param) {
            $url_param = explode('=', $url_param, 2);
            $s_search_hidden_fields[$url_param[0]] = $url_param[1];
        }
    }
    // The following assigns all _common_ variables that may be used at any point in a template.
    $template->assign_vars(array('SITENAME' => $config['sitename'], 'SITE_DESCRIPTION' => $config['site_desc'], 'PAGE_TITLE' => $page_title, 'SCRIPT_NAME' => str_replace('.' . $phpEx, '', $user->page['page_name']), 'LAST_VISIT_DATE' => sprintf($user->lang['YOU_LAST_VISIT'], $s_last_visit), 'LAST_VISIT_YOU' => $s_last_visit, 'CURRENT_TIME' => sprintf($user->lang['CURRENT_TIME'], $user->format_date(time(), false, true)), 'TOTAL_USERS_ONLINE' => $l_online_users, 'LOGGED_IN_USER_LIST' => $online_userlist, 'RECORD_USERS' => $l_online_record, 'PRIVATE_MESSAGE_INFO' => $l_privmsgs_text, 'PRIVATE_MESSAGE_INFO_UNREAD' => $l_privmsgs_text_unread, 'S_USER_NEW_PRIVMSG' => $user->data['user_new_privmsg'], 'S_USER_UNREAD_PRIVMSG' => $user->data['user_unread_privmsg'], 'S_USER_NEW' => $user->data['user_new'], 'SID' => $SID, '_SID' => $_SID, 'SESSION_ID' => $user->session_id, 'ROOT_PATH' => $phpbb_root_path, 'BOARD_URL' => $board_url, 'L_LOGIN_LOGOUT' => $l_login_logout, 'L_INDEX' => $user->lang['FORUM_INDEX'], 'L_ONLINE_EXPLAIN' => $l_online_time, 'U_PRIVATEMSGS' => append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'i=pm&amp;folder=inbox'), 'U_RETURN_INBOX' => append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'i=pm&amp;folder=inbox'), 'U_POPUP_PM' => append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'i=pm&amp;mode=popup'), 'UA_POPUP_PM' => addslashes(append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'i=pm&amp;mode=popup')), 'U_MEMBERLIST' => append_sid("{$phpbb_root_path}memberlist.{$phpEx}"), 'U_VIEWONLINE' => $auth->acl_gets('u_viewprofile', 'a_user', 'a_useradd', 'a_userdel') ? append_sid("{$phpbb_root_path}viewonline.{$phpEx}") : '', 'U_LOGIN_LOGOUT' => $u_login_logout, 'U_INDEX' => append_sid("{$phpbb_root_path}index.{$phpEx}"), 'U_SEARCH' => append_sid("{$phpbb_root_path}search.{$phpEx}"), 'U_REGISTER' => append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=register'), 'U_PROFILE' => append_sid("{$phpbb_root_path}ucp.{$phpEx}"), 'U_MODCP' => append_sid("{$phpbb_root_path}mcp.{$phpEx}", false, true, $user->session_id), 'U_FAQ' => append_sid("{$phpbb_root_path}faq.{$phpEx}"), 'U_SEARCH_SELF' => append_sid("{$phpbb_root_path}search.{$phpEx}", 'search_id=egosearch'), 'U_SEARCH_NEW' => append_sid("{$phpbb_root_path}search.{$phpEx}", 'search_id=newposts'), 'U_SEARCH_UNANSWERED' => append_sid("{$phpbb_root_path}search.{$phpEx}", 'search_id=unanswered'), 'U_SEARCH_UNREAD' => append_sid("{$phpbb_root_path}search.{$phpEx}", 'search_id=unreadposts'), 'U_SEARCH_ACTIVE_TOPICS' => append_sid("{$phpbb_root_path}search.{$phpEx}", 'search_id=active_topics'), 'U_DELETE_COOKIES' => append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=delete_cookies'), 'U_TEAM' => $user->data['user_id'] != ANONYMOUS && !$auth->acl_get('u_viewprofile') ? '' : append_sid("{$phpbb_root_path}memberlist.{$phpEx}", 'mode=leaders'), 'U_TERMS_USE' => append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=terms'), 'U_PRIVACY' => append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=privacy'), 'U_RESTORE_PERMISSIONS' => $user->data['user_perm_from'] && $auth->acl_get('a_switchperm') ? append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=restore_perm') : '', 'U_FEED' => generate_board_url() . "/feed.{$phpEx}", 'S_USER_LOGGED_IN' => $user->data['user_id'] != ANONYMOUS ? true : false, 'S_AUTOLOGIN_ENABLED' => $config['allow_autologin'] ? true : false, 'S_BOARD_DISABLED' => $config['board_disable'] ? true : false, 'S_REGISTERED_USER' => !empty($user->data['is_registered']) ? true : false, 'S_IS_BOT' => !empty($user->data['is_bot']) ? true : false, 'S_USER_PM_POPUP' => $user->optionget('popuppm'), 'S_USER_LANG' => $user_lang, 'S_USER_BROWSER' => isset($user->data['session_browser']) ? $user->data['session_browser'] : $user->lang['UNKNOWN_BROWSER'], 'S_USERNAME' => $user->data['username'], 'S_CONTENT_DIRECTION' => $user->lang['DIRECTION'], 'S_CONTENT_FLOW_BEGIN' => $user->lang['DIRECTION'] == 'ltr' ? 'left' : 'right', 'S_CONTENT_FLOW_END' => $user->lang['DIRECTION'] == 'ltr' ? 'right' : 'left', 'S_CONTENT_ENCODING' => 'UTF-8', 'S_TIMEZONE' => $user->data['user_dst'] || $user->data['user_id'] == ANONYMOUS && $config['board_dst'] ? sprintf($user->lang['ALL_TIMES'], $user->lang['tz'][$tz], $user->lang['tz']['dst']) : sprintf($user->lang['ALL_TIMES'], $user->lang['tz'][$tz], ''), 'S_DISPLAY_ONLINE_LIST' => $l_online_time ? 1 : 0, 'S_DISPLAY_SEARCH' => !$config['load_search'] ? 0 : (isset($auth) ? $auth->acl_get('u_search') && $auth->acl_getf_global('f_search') : 1), 'S_DISPLAY_PM' => $config['allow_privmsg'] && !empty($user->data['is_registered']) && ($auth->acl_get('u_readpm') || $auth->acl_get('u_sendpm')) ? true : false, 'S_DISPLAY_MEMBERLIST' => isset($auth) ? $auth->acl_get('u_viewprofile') : 0, 'S_NEW_PM' => $s_privmsg_new ? 1 : 0, 'S_REGISTER_ENABLED' => $config['require_activation'] != USER_ACTIVATION_DISABLE ? true : false, 'S_FORUM_ID' => $forum_id, 'S_TOPIC_ID' => $topic_id, 'S_LOGIN_ACTION' => !defined('ADMIN_START') ? append_sid("{$phpbb_root_path}ucp.{$phpEx}", 'mode=login') : append_sid("index.{$phpEx}", false, true, $user->session_id), 'S_LOGIN_REDIRECT' => build_hidden_fields(array('redirect' => build_url())), 'S_ENABLE_FEEDS' => $config['feed_enable'] ? true : false, 'S_ENABLE_FEEDS_OVERALL' => $config['feed_overall'] ? true : false, 'S_ENABLE_FEEDS_FORUMS' => $config['feed_overall_forums'] ? true : false, 'S_ENABLE_FEEDS_TOPICS' => $config['feed_topics_new'] ? true : false, 'S_ENABLE_FEEDS_TOPICS_ACTIVE' => $config['feed_topics_active'] ? true : false, 'S_ENABLE_FEEDS_NEWS' => $s_feed_news ? true : false, 'S_LOAD_UNREADS' => $config['load_unreads_search'] && ($config['load_anon_lastread'] || $user->data['is_registered']) ? true : false, 'S_SEARCH_HIDDEN_FIELDS' => build_hidden_fields($s_search_hidden_fields), 'T_THEME_PATH' => "{$web_path}styles/" . rawurlencode($user->theme['theme_path']) . '/theme', 'T_TEMPLATE_PATH' => "{$web_path}styles/" . rawurlencode($user->theme['template_path']) . '/template', 'T_SUPER_TEMPLATE_PATH' => isset($user->theme['template_inherit_path']) && $user->theme['template_inherit_path'] ? "{$web_path}styles/" . rawurlencode($user->theme['template_inherit_path']) . '/template' : "{$web_path}styles/" . rawurlencode($user->theme['template_path']) . '/template', 'T_IMAGESET_PATH' => "{$web_path}styles/" . rawurlencode($user->theme['imageset_path']) . '/imageset', 'T_IMAGESET_LANG_PATH' => "{$web_path}styles/" . rawurlencode($user->theme['imageset_path']) . '/imageset/' . $user->lang_name, 'T_IMAGES_PATH' => "{$web_path}images/", 'T_SMILIES_PATH' => "{$web_path}{$config['smilies_path']}/", 'T_AVATAR_PATH' => "{$web_path}{$config['avatar_path']}/", 'T_AVATAR_GALLERY_PATH' => "{$web_path}{$config['avatar_gallery_path']}/", 'T_ICONS_PATH' => "{$web_path}{$config['icons_path']}/", 'T_RANKS_PATH' => "{$web_path}{$config['ranks_path']}/", 'T_UPLOAD_PATH' => "{$web_path}{$config['upload_path']}/", 'T_STYLESHEET_LINK' => !$user->theme['theme_storedb'] ? "{$web_path}styles/" . rawurlencode($user->theme['theme_path']) . '/theme/stylesheet.css' : append_sid("{$phpbb_root_path}style.{$phpEx}", 'id=' . $user->theme['style_id'] . '&amp;lang=' . $user->lang_name), 'T_STYLESHEET_NAME' => $user->theme['theme_name'], 'T_THEME_NAME' => rawurlencode($user->theme['theme_path']), 'T_TEMPLATE_NAME' => rawurlencode($user->theme['template_path']), 'T_SUPER_TEMPLATE_NAME' => rawurlencode(isset($user->theme['template_inherit_path']) && $user->theme['template_inherit_path'] ? $user->theme['template_inherit_path'] : $user->theme['template_path']), 'T_IMAGESET_NAME' => rawurlencode($user->theme['imageset_path']), 'T_IMAGESET_LANG_NAME' => $user->data['user_lang'], 'T_IMAGES' => 'images', 'T_SMILIES' => $config['smilies_path'], 'T_AVATAR' => $config['avatar_path'], 'T_AVATAR_GALLERY' => $config['avatar_gallery_path'], 'T_ICONS' => $config['icons_path'], 'T_RANKS' => $config['ranks_path'], 'T_UPLOAD' => $config['upload_path'], 'SITE_LOGO_IMG' => $user->img('site_logo'), 'A_COOKIE_SETTINGS' => addslashes('; path=' . $config['cookie_path'] . (!$config['cookie_domain'] || $config['cookie_domain'] == 'localhost' || $config['cookie_domain'] == '127.0.0.1' ? '' : '; domain=' . $config['cookie_domain']) . (!$config['cookie_secure'] ? '' : '; secure'))));
    // START Anti-Spam ACP
    antispam::page_header();
    // END Anti-Spam ACP
    // application/xhtml+xml not used because of IE
    header('Content-type: text/html; charset=UTF-8');
    header('Cache-Control: private, no-cache="set-cookie"');
    header('Expires: 0');
    header('Pragma: no-cache');
    if (!empty($user->data['is_bot'])) {
        // Let reverse proxies know we detected a bot.
        header('X-PHPBB-IS-BOT: yes');
    }
    return;
}