From fc67e008126d8b034a49ed24f6c94de2bf858981 Mon Sep 17 00:00:00 2001
From: Thomas Bruederli <thomas@roundcube.net>
Date: Mon, 14 May 2012 15:03:35 -0400
Subject: [PATCH] Larry: fix unfocused message thread row highlighting (#1488477)

---
 program/include/rcube_imap.php | 6758 +++++++++++++++++++++++++++++++++--------------------------
 1 files changed, 3,738 insertions(+), 3,020 deletions(-)

diff --git a/program/include/rcube_imap.php b/program/include/rcube_imap.php
index f66c082..4e1d571 100644
--- a/program/include/rcube_imap.php
+++ b/program/include/rcube_imap.php
@@ -4,16 +4,20 @@
  +-----------------------------------------------------------------------+
  | program/include/rcube_imap.php                                        |
  |                                                                       |
- | This file is part of the RoundCube Webmail client                     |
- | Copyright (C) 2005-2009, RoundCube Dev. - Switzerland                 |
- | Licensed under the GNU GPL                                            |
+ | This file is part of the Roundcube Webmail client                     |
+ | Copyright (C) 2005-2012, The Roundcube Dev Team                       |
+ | Copyright (C) 2011-2012, Kolab Systems AG                             |
+ |                                                                       |
+ | Licensed under the GNU General Public License version 3 or            |
+ | any later version with exceptions for skins & plugins.                |
+ | See the README file for a full license statement.                     |
  |                                                                       |
  | PURPOSE:                                                              |
- |   IMAP wrapper that implements the Iloha IMAP Library (IIL)           |
- |   See http://ilohamail.org/ for details                               |
+ |   IMAP Storage Engine                                                 |
  |                                                                       |
  +-----------------------------------------------------------------------+
  | Author: Thomas Bruederli <roundcube@gmail.com>                        |
+ | Author: Aleksander Machniak <alec@alec.pl>                            |
  +-----------------------------------------------------------------------+
 
  $Id$
@@ -21,3257 +25,3971 @@
 */
 
 
-/*
- * Obtain classes from the Iloha IMAP library
- */
-require_once('lib/imap.inc');
-require_once('lib/mime.inc');
-require_once('lib/tnef_decoder.inc');
-
-
 /**
  * Interface class for accessing an IMAP server
  *
- * This is a wrapper that implements the Iloha IMAP Library (IIL)
- *
  * @package    Mail
  * @author     Thomas Bruederli <roundcube@gmail.com>
- * @version    1.5
- * @link       http://ilohamail.org
+ * @author     Aleksander Machniak <alec@alec.pl>
+ * @version    2.0
  */
-class rcube_imap
+class rcube_imap extends rcube_storage
 {
-  var $db;
-  var $conn;
-  var $root_ns = '';
-  var $root_dir = '';
-  var $mailbox = 'INBOX';
-  var $list_page = 1;
-  var $page_size = 10;
-  var $sort_field = 'date';
-  var $sort_order = 'DESC';
-  var $index_sort = true;
-  var $delimiter = NULL;
-  var $caching_enabled = FALSE;
-  var $default_charset = 'ISO-8859-1';
-  var $struct_charset = NULL;
-  var $default_folders = array('INBOX');
-  var $fetch_add_headers = '';
-  var $cache = array();
-  var $cache_keys = array();  
-  var $cache_changes = array();
-  var $uid_id_map = array();
-  var $msg_headers = array();
-  var $skip_deleted = FALSE;
-  var $search_set = NULL;
-  var $search_string = '';
-  var $search_charset = '';
-  var $search_sort_field = '';  
-  var $debug_level = 1;
-  var $error_code = 0;
-  var $options = array('auth_method' => 'check');
-  
-  private $host, $user, $pass, $port, $ssl;
+    /**
+     * Instance of rcube_imap_generic
+     *
+     * @var rcube_imap_generic
+     */
+    public $conn;
+
+    /**
+     * Instance of rcube_imap_cache
+     *
+     * @var rcube_imap_cache
+     */
+    protected $mcache;
+
+    /**
+     * Instance of rcube_cache
+     *
+     * @var rcube_cache
+     */
+    protected $cache;
+
+    /**
+     * Internal (in-memory) cache
+     *
+     * @var array
+     */
+    protected $icache = array();
+
+    protected $list_page = 1;
+    protected $delimiter;
+    protected $namespace;
+    protected $sort_field = '';
+    protected $sort_order = 'DESC';
+    protected $struct_charset;
+    protected $uid_id_map = array();
+    protected $msg_headers = array();
+    protected $search_set;
+    protected $search_string = '';
+    protected $search_charset = '';
+    protected $search_sort_field = '';
+    protected $search_threads = false;
+    protected $search_sorted = false;
+    protected $options = array('auth_method' => 'check');
+    protected $caching = false;
+    protected $messages_caching = false;
+    protected $threading = false;
 
 
-  /**
-   * Object constructor
-   *
-   * @param object DB Database connection
-   */
-  function __construct($db_conn)
+    /**
+     * Object constructor.
+     */
+    public function __construct()
     {
-    $this->db = $db_conn;
-    }
+        $this->conn = new rcube_imap_generic();
 
-
-  /**
-   * Connect to an IMAP server
-   *
-   * @param  string   Host to connect
-   * @param  string   Username for IMAP account
-   * @param  string   Password for IMAP account
-   * @param  number   Port to connect to
-   * @param  string   SSL schema (either ssl or tls) or null if plain connection
-   * @return boolean  TRUE on success, FALSE on failure
-   * @access public
-   */
-  function connect($host, $user, $pass, $port=143, $use_ssl=null)
-    {
-    global $ICL_SSL, $ICL_PORT, $IMAP_USE_INTERNAL_DATE;
-    
-    // check for Open-SSL support in PHP build
-    if ($use_ssl && extension_loaded('openssl'))
-      $ICL_SSL = $use_ssl == 'imaps' ? 'ssl' : $use_ssl;
-    else if ($use_ssl) {
-      raise_error(array('code' => 403, 'type' => 'imap',
-        'file' => __FILE__, 'line' => __LINE__,
-        'message' => "Open SSL not available"), TRUE, FALSE);
-      $port = 143;
-    }
-
-    $ICL_PORT = $port;
-    $IMAP_USE_INTERNAL_DATE = false;
-
-    $attempt = 0;
-    do {
-      $data = rcmail::get_instance()->plugins->exec_hook('imap_connect', array('host' => $host, 'user' => $user, 'attempt' => ++$attempt));
-      if (!empty($data['pass']))
-        $pass = $data['pass'];
-
-      $this->conn = iil_Connect($data['host'], $data['user'], $pass, $this->options);
-    } while(!$this->conn && $data['retry']);
-
-    $this->host = $data['host'];
-    $this->user = $data['user'];
-    $this->pass = $pass;
-    $this->port = $port;
-    $this->ssl = $use_ssl;
-    
-    // print trace messages
-    if ($this->conn && ($this->debug_level & 8))
-      console($this->conn->message);
-    
-    // write error log
-    else if (!$this->conn && $GLOBALS['iil_error'])
-      {
-      $this->error_code = $GLOBALS['iil_errornum'];
-      raise_error(array('code' => 403, 'type' => 'imap',
-        'file' => __FILE__, 'line' => __LINE__,
-        'message' => $GLOBALS['iil_error']), TRUE, FALSE);
-      }
-
-    // get server properties
-    if ($this->conn)
-      {
-      if (!empty($this->conn->rootdir))
-        {
-        $this->set_rootdir($this->conn->rootdir);
-        $this->root_ns = preg_replace('/[.\/]$/', '', $this->conn->rootdir);
+        // Set namespace and delimiter from session,
+        // so some methods would work before connection
+        if (isset($_SESSION['imap_namespace'])) {
+            $this->namespace = $_SESSION['imap_namespace'];
         }
-      if (empty($this->delimiter))
-	$this->get_hierarchy_delimiter();
-      }
-
-    return $this->conn ? TRUE : FALSE;
+        if (isset($_SESSION['imap_delimiter'])) {
+            $this->delimiter = $_SESSION['imap_delimiter'];
+        }
     }
 
 
-  /**
-   * Close IMAP connection
-   * Usually done on script shutdown
-   *
-   * @access public
-   */
-  function close()
-    {    
-    if ($this->conn)
-      iil_Close($this->conn);
-    }
-
-
-  /**
-   * Close IMAP connection and re-connect
-   * This is used to avoid some strange socket errors when talking to Courier IMAP
-   *
-   * @access public
-   */
-  function reconnect()
+    /**
+     * Magic getter for backward compat.
+     *
+     * @deprecated.
+     */
+    public function __get($name)
     {
-    $this->close();
-    $this->connect($this->host, $this->user, $this->pass, $this->port, $this->ssl);
-    
-    // issue SELECT command to restore connection status
-    if ($this->mailbox)
-      iil_C_Select($this->conn, $this->mailbox);
+        if (isset($this->{$name})) {
+            return $this->{$name};
+        }
     }
 
-  /**
-   * Set options to be used in iil_Connect()
-   */
-  function set_options($opt)
-  {
-    $this->options = array_merge($this->options, (array)$opt);
-  }
 
-  /**
-   * Set a root folder for the IMAP connection.
-   *
-   * Only folders within this root folder will be displayed
-   * and all folder paths will be translated using this folder name
-   *
-   * @param  string   Root folder
-   * @access public
-   */
-  function set_rootdir($root)
+    /**
+     * Connect to an IMAP server
+     *
+     * @param  string   $host    Host to connect
+     * @param  string   $user    Username for IMAP account
+     * @param  string   $pass    Password for IMAP account
+     * @param  integer  $port    Port to connect to
+     * @param  string   $use_ssl SSL schema (either ssl or tls) or null if plain connection
+     *
+     * @return boolean  TRUE on success, FALSE on failure
+     */
+    public function connect($host, $user, $pass, $port=143, $use_ssl=null)
     {
-    if (preg_match('/[.\/]$/', $root)) //(substr($root, -1, 1)==='/')
-      $root = substr($root, 0, -1);
+        // check for OpenSSL support in PHP build
+        if ($use_ssl && extension_loaded('openssl')) {
+            $this->options['ssl_mode'] = $use_ssl == 'imaps' ? 'ssl' : $use_ssl;
+        }
+        else if ($use_ssl) {
+            raise_error(array('code' => 403, 'type' => 'imap',
+                'file' => __FILE__, 'line' => __LINE__,
+                'message' => "OpenSSL not available"), true, false);
+            $port = 143;
+        }
 
-    $this->root_dir = $root;
-    $this->options['rootdir'] = $root;
-    
-    if (empty($this->delimiter))
-      $this->get_hierarchy_delimiter();
+        $this->options['port'] = $port;
+
+        if ($this->options['debug']) {
+            $this->set_debug(true);
+
+            $this->options['ident'] = array(
+                'name' => 'Roundcube Webmail',
+                'version' => RCMAIL_VERSION,
+                'php' => PHP_VERSION,
+                'os' => PHP_OS,
+                'command' => $_SERVER['REQUEST_URI'],
+            );
+        }
+
+        $attempt = 0;
+        do {
+            $data = rcmail::get_instance()->plugins->exec_hook('imap_connect',
+                array_merge($this->options, array('host' => $host, 'user' => $user,
+                    'attempt' => ++$attempt)));
+
+            if (!empty($data['pass'])) {
+                $pass = $data['pass'];
+            }
+
+            $this->conn->connect($data['host'], $data['user'], $pass, $data);
+        } while(!$this->conn->connected() && $data['retry']);
+
+        $config = array(
+            'host'     => $data['host'],
+            'user'     => $data['user'],
+            'password' => $pass,
+            'port'     => $port,
+            'ssl'      => $use_ssl,
+        );
+
+        $this->options      = array_merge($this->options, $config);
+        $this->connect_done = true;
+
+        if ($this->conn->connected()) {
+            // get namespace and delimiter
+            $this->set_env();
+            return true;
+        }
+        // write error log
+        else if ($this->conn->error) {
+            if ($pass && $user) {
+                $message = sprintf("Login failed for %s from %s. %s",
+                    $user, rcmail_remote_ip(), $this->conn->error);
+
+                raise_error(array('code' => 403, 'type' => 'imap',
+                    'file' => __FILE__, 'line' => __LINE__,
+                    'message' => $message), true, false);
+            }
+        }
+
+        return false;
     }
 
 
-  /**
-   * Set default message charset
-   *
-   * This will be used for message decoding if a charset specification is not available
-   *
-   * @param  string   Charset string
-   * @access public
-   */
-  function set_charset($cs)
+    /**
+     * Close IMAP connection.
+     * Usually done on script shutdown
+     */
+    public function close()
     {
-    $this->default_charset = $cs;
+        $this->conn->closeConnection();
+        if ($this->mcache) {
+            $this->mcache->close();
+        }
     }
 
 
-  /**
-   * This list of folders will be listed above all other folders
-   *
-   * @param  array  Indexed list of folder names
-   * @access public
-   */
-  function set_default_mailboxes($arr)
+    /**
+     * Check connection state, connect if not connected.
+     *
+     * @return bool Connection state.
+     */
+    public function check_connection()
     {
-    if (is_array($arr))
-      {
-      $this->default_folders = $arr;
+        // Establish connection if it wasn't done yet
+        if (!$this->connect_done && !empty($this->options['user'])) {
+            return $this->connect(
+                $this->options['host'],
+                $this->options['user'],
+                $this->options['password'],
+                $this->options['port'],
+                $this->options['ssl']
+            );
+        }
 
-      // add inbox if not included
-      if (!in_array('INBOX', $this->default_folders))
-        array_unshift($this->default_folders, 'INBOX');
-      }
+        return $this->is_connected();
     }
 
 
-  /**
-   * Set internal mailbox reference.
-   *
-   * All operations will be perfomed on this mailbox/folder
-   *
-   * @param  string  Mailbox/Folder name
-   * @access public
-   */
-  function set_mailbox($new_mbox)
+    /**
+     * Checks IMAP connection.
+     *
+     * @return boolean  TRUE on success, FALSE on failure
+     */
+    public function is_connected()
     {
-    $mailbox = $this->mod_mailbox($new_mbox);
-
-    if ($this->mailbox == $mailbox)
-      return;
-
-    $this->mailbox = $mailbox;
-
-    // clear messagecount cache for this mailbox
-    $this->_clear_messagecount($mailbox);
+        return $this->conn->connected();
     }
 
 
-  /**
-   * Set internal list page
-   *
-   * @param  number  Page number to list
-   * @access public
-   */
-  function set_page($page)
+    /**
+     * Returns code of last error
+     *
+     * @return int Error code
+     */
+    public function get_error_code()
     {
-    $this->list_page = (int)$page;
+        return $this->conn->errornum;
     }
 
 
-  /**
-   * Set internal page size
-   *
-   * @param  number  Number of messages to display on one page
-   * @access public
-   */
-  function set_pagesize($size)
+    /**
+     * Returns text of last error
+     *
+     * @return string Error string
+     */
+    public function get_error_str()
     {
-    $this->page_size = (int)$size;
+        return $this->conn->error;
     }
-    
 
-  /**
-   * Save a set of message ids for future message listing methods
-   *
-   * @param  string  IMAP Search query
-   * @param  array   List of message ids or NULL if empty
-   * @param  string  Charset of search string
-   * @param  string  Sorting field
-   */
-  function set_search_set($str=null, $msgs=null, $charset=null, $sort_field=null)
+
+    /**
+     * Returns code of last command response
+     *
+     * @return int Response code
+     */
+    public function get_response_code()
     {
-    if (is_array($str) && $msgs == null)
-      list($str, $msgs, $charset, $sort_field) = $str;
-    if ($msgs != null && !is_array($msgs))
-      $msgs = explode(',', $msgs);
-      
-    $this->search_string = $str;
-    $this->search_set = $msgs;
-    $this->search_charset = $charset;
-    $this->search_sort_field = $sort_field;
+        switch ($this->conn->resultcode) {
+            case 'NOPERM':
+                return self::NOPERM;
+            case 'READ-ONLY':
+                return self::READONLY;
+            case 'TRYCREATE':
+                return self::TRYCREATE;
+            case 'INUSE':
+                return self::INUSE;
+            case 'OVERQUOTA':
+                return self::OVERQUOTA;
+            case 'ALREADYEXISTS':
+                return self::ALREADYEXISTS;
+            case 'NONEXISTENT':
+                return self::NONEXISTENT;
+            case 'CONTACTADMIN':
+                return self::CONTACTADMIN;
+            default:
+                return self::UNKNOWN;
+        }
     }
 
 
-  /**
-   * Return the saved search set as hash array
-   * @return array Search set
-   */
-  function get_search_set()
+    /**
+     * Activate/deactivate debug mode
+     *
+     * @param boolean $dbg True if IMAP conversation should be logged
+     */
+    public function set_debug($dbg = true)
     {
-    return array($this->search_string, $this->search_set, $this->search_charset, $this->search_sort_field);
+        $this->options['debug'] = $dbg;
+        $this->conn->setDebug($dbg, array($this, 'debug_handler'));
     }
 
 
-  /**
-   * Returns the currently used mailbox name
-   *
-   * @return  string Name of the mailbox/folder
-   * @access  public
-   */
-  function get_mailbox_name()
+    /**
+     * Set internal folder reference.
+     * All operations will be perfomed on this folder.
+     *
+     * @param  string $folder Folder name
+     */
+    public function set_folder($folder)
     {
-    return $this->conn ? $this->mod_mailbox($this->mailbox, 'out') : '';
+        if ($this->folder == $folder) {
+            return;
+        }
+
+        $this->folder = $folder;
+
+        // clear messagecount cache for this folder
+        $this->clear_messagecount($folder);
     }
 
 
-  /**
-   * Returns the IMAP server's capability
-   *
-   * @param   string  Capability name
-   * @return  mixed   Capability value or TRUE if supported, FALSE if not
-   * @access  public
-   */
-  function get_capability($cap)
+    /**
+     * Save a search result for future message listing methods
+     *
+     * @param  array  $set  Search set, result from rcube_imap::get_search_set():
+     *                      0 - searching criteria, string
+     *                      1 - search result, rcube_result_index|rcube_result_thread
+     *                      2 - searching character set, string
+     *                      3 - sorting field, string
+     *                      4 - true if sorted, bool
+     */
+    public function set_search_set($set)
     {
-    return iil_C_GetCapability($this->conn, strtoupper($cap));
+        $set = (array)$set;
+
+        $this->search_string     = $set[0];
+        $this->search_set        = $set[1];
+        $this->search_charset    = $set[2];
+        $this->search_sort_field = $set[3];
+        $this->search_sorted     = $set[4];
+        $this->search_threads    = is_a($this->search_set, 'rcube_result_thread');
     }
 
 
-  /**
-   * Checks the PERMANENTFLAGS capability of the current mailbox
-   * and returns true if the given flag is supported by the IMAP server
-   *
-   * @param   string  Permanentflag name
-   * @return  mixed   True if this flag is supported
-   * @access  public
-   */
-  function check_permflag($flag)
+    /**
+     * Return the saved search set as hash array
+     *
+     * @return array Search set
+     */
+    public function get_search_set()
     {
-    $flag = strtoupper($flag);
-    $imap_flag = $GLOBALS['IMAP_FLAGS'][$flag];
-    return (in_array_nocase($imap_flag, $this->conn->permanentflags));
+        if (empty($this->search_set)) {
+            return null;
+        }
+
+        return array(
+            $this->search_string,
+	        $this->search_set,
+        	$this->search_charset,
+        	$this->search_sort_field,
+        	$this->search_sorted,
+	    );
     }
 
 
-  /**
-   * Returns the delimiter that is used by the IMAP server for folder separation
-   *
-   * @return  string  Delimiter string
-   * @access  public
-   */
-  function get_hierarchy_delimiter()
+    /**
+     * Returns the IMAP server's capability.
+     *
+     * @param   string  $cap Capability name
+     *
+     * @return  mixed   Capability value or TRUE if supported, FALSE if not
+     */
+    public function get_capability($cap)
     {
-    if ($this->conn && empty($this->delimiter))
-      $this->delimiter = iil_C_GetHierarchyDelimiter($this->conn);
+        $cap      = strtoupper($cap);
+        $sess_key = "STORAGE_$cap";
 
-    if (empty($this->delimiter))
-      $this->delimiter = '/';
+        if (!isset($_SESSION[$sess_key])) {
+            if (!$this->check_connection()) {
+                return false;
+            }
 
-    return $this->delimiter;
+            $_SESSION[$sess_key] = $this->conn->getCapability($cap);
+        }
+
+        return $_SESSION[$sess_key];
     }
 
 
-  /**
-   * Public method for mailbox listing.
-   *
-   * Converts mailbox name with root dir first
-   *
-   * @param   string  Optional root folder
-   * @param   string  Optional filter for mailbox listing
-   * @return  array   List of mailboxes/folders
-   * @access  public
-   */
-  function list_mailboxes($root='', $filter='*')
+    /**
+     * Checks the PERMANENTFLAGS capability of the current folder
+     * and returns true if the given flag is supported by the IMAP server
+     *
+     * @param   string  $flag Permanentflag name
+     *
+     * @return  boolean True if this flag is supported
+     */
+    public function check_permflag($flag)
     {
-    $a_out = array();
-    $a_mboxes = $this->_list_mailboxes($root, $filter);
+        $flag = strtoupper($flag);
+        $imap_flag = $this->conn->flags[$flag];
 
-    foreach ($a_mboxes as $mbox_row)
-      {
-      $name = $this->mod_mailbox($mbox_row, 'out');
-      if (strlen($name))
-        $a_out[] = $name;
-      }
+        if ($this->folder !== null) {
+            $this->check_connection();
+        }
+        // @TODO: cache permanent flags (?)
 
-    // INBOX should always be available
-    if (!in_array('INBOX', $a_out))
-      array_unshift($a_out, 'INBOX');
-
-    // sort mailboxes
-    $a_out = $this->_sort_mailbox_list($a_out);
-
-    return $a_out;
+        return (in_array_nocase($imap_flag, $this->conn->data['PERMANENTFLAGS']));
     }
 
 
-  /**
-   * Private method for mailbox listing
-   *
-   * @return  array   List of mailboxes/folders
-   * @see     rcube_imap::list_mailboxes()
-   * @access  private
-   */
-  private function _list_mailboxes($root='', $filter='*')
+    /**
+     * Returns the delimiter that is used by the IMAP server for folder separation
+     *
+     * @return  string  Delimiter string
+     * @access  public
+     */
+    public function get_hierarchy_delimiter()
     {
-    $a_defaults = $a_out = array();
-    
-    // get cached folder list    
-    $a_mboxes = $this->get_cache('mailboxes');
-    if (is_array($a_mboxes))
-      return $a_mboxes;
-
-    // Give plugins a chance to provide a list of mailboxes
-    $data = rcmail::get_instance()->plugins->exec_hook('list_mailboxes',array('root'=>$root,'filter'=>$filter));
-    if (isset($data['folders'])) {
-        $a_folders = $data['folders'];
-    }
-    else{
-        // retrieve list of folders from IMAP server
-        $a_folders = iil_C_ListSubscribed($this->conn, $this->mod_mailbox($root), $filter);
-    }
-
-    
-    if (!is_array($a_folders) || !sizeof($a_folders))
-      $a_folders = array();
-
-    // write mailboxlist to cache
-    $this->update_cache('mailboxes', $a_folders);
-    
-    return $a_folders;
+        return $this->delimiter;
     }
 
 
-  /**
-   * Get message count for a specific mailbox
-   *
-   * @param   string   Mailbox/folder name
-   * @param   string   Mode for count [ALL|UNSEEN|RECENT]
-   * @param   boolean  Force reading from server and update cache
-   * @return  int      Number of messages
-   * @access  public
-   */
-  function messagecount($mbox_name='', $mode='ALL', $force=FALSE)
+    /**
+     * Get namespace
+     *
+     * @param string $name Namespace array index: personal, other, shared, prefix
+     *
+     * @return  array  Namespace data
+     */
+    public function get_namespace($name = null)
     {
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-    return $this->_messagecount($mailbox, $mode, $force);
+        $ns = $this->namespace;
+
+        if ($name) {
+            return isset($ns[$name]) ? $ns[$name] : null;
+        }
+
+        unset($ns['prefix']);
+        return $ns;
     }
 
 
-  /**
-   * Private method for getting nr of messages
-   *
-   * @access  private
-   * @see     rcube_imap::messagecount()
-   */
-  private function _messagecount($mailbox='', $mode='ALL', $force=FALSE)
+    /**
+     * Sets delimiter and namespaces
+     */
+    protected function set_env()
     {
-    $mode = strtoupper($mode);
+        if ($this->delimiter !== null && $this->namespace !== null) {
+            return;
+        }
 
-    if (empty($mailbox))
-      $mailbox = $this->mailbox;
-      
-    // count search set
-    if ($this->search_string && $mailbox == $this->mailbox && $mode == 'ALL' && !$force)
-      return count((array)$this->search_set);
+        $config = rcmail::get_instance()->config;
+        $imap_personal  = $config->get('imap_ns_personal');
+        $imap_other     = $config->get('imap_ns_other');
+        $imap_shared    = $config->get('imap_ns_shared');
+        $imap_delimiter = $config->get('imap_delimiter');
 
-    $a_mailbox_cache = $this->get_cache('messagecount');
-    
-    // return cached value
-    if (!$force && is_array($a_mailbox_cache[$mailbox]) && isset($a_mailbox_cache[$mailbox][$mode]))
-      return $a_mailbox_cache[$mailbox][$mode];
+        if (!$this->check_connection()) {
+            return;
+        }
 
-    if (!is_array($a_mailbox_cache[$mailbox]))
-      $a_mailbox_cache[$mailbox] = array();
+        $ns = $this->conn->getNamespace();
 
-    // RECENT count is fetched a bit different
-    if ($mode == 'RECENT')
-       $count = iil_C_CheckForRecent($this->conn, $mailbox);
+        // Set namespaces (NAMESPACE supported)
+        if (is_array($ns)) {
+            $this->namespace = $ns;
+        }
+        else {
+            $this->namespace = array(
+                'personal' => NULL,
+                'other'    => NULL,
+                'shared'   => NULL,
+            );
+        }
 
-    // use SEARCH for message counting
-    else if ($this->skip_deleted)
-      {
-      $search_str = "ALL UNDELETED";
+        if ($imap_delimiter) {
+            $this->delimiter = $imap_delimiter;
+        }
+        if (empty($this->delimiter)) {
+            $this->delimiter = $this->namespace['personal'][0][1];
+        }
+        if (empty($this->delimiter)) {
+            $this->delimiter = $this->conn->getHierarchyDelimiter();
+        }
+        if (empty($this->delimiter)) {
+            $this->delimiter = '/';
+        }
 
-      // get message count and store in cache
-      if ($mode == 'UNSEEN')
-        $search_str .= " UNSEEN";
+        // Overwrite namespaces
+        if ($imap_personal !== null) {
+            $this->namespace['personal'] = NULL;
+            foreach ((array)$imap_personal as $dir) {
+                $this->namespace['personal'][] = array($dir, $this->delimiter);
+            }
+        }
+        if ($imap_other !== null) {
+            $this->namespace['other'] = NULL;
+            foreach ((array)$imap_other as $dir) {
+                if ($dir) {
+                    $this->namespace['other'][] = array($dir, $this->delimiter);
+                }
+            }
+        }
+        if ($imap_shared !== null) {
+            $this->namespace['shared'] = NULL;
+            foreach ((array)$imap_shared as $dir) {
+                if ($dir) {
+                    $this->namespace['shared'][] = array($dir, $this->delimiter);
+                }
+            }
+        }
 
-      // get message count using SEARCH
-      // not very performant but more precise (using UNDELETED)
-      $index = $this->_search_index($mailbox, $search_str);
-      $count = is_array($index) ? count($index) : 0;
-      }
-    else {
-      if ($mode == 'UNSEEN')
-        $count = iil_C_CountUnseen($this->conn, $mailbox);
-      else {
-        $count = iil_C_CountMessages($this->conn, $mailbox);
-        $_SESSION['maxuid'][$mailbox] = $count ? $this->_id2uid($count) : 0;
-      }
-    }
+        // Find personal namespace prefix for mod_folder()
+        // Prefix can be removed when there is only one personal namespace
+        if (is_array($this->namespace['personal']) && count($this->namespace['personal']) == 1) {
+            $this->namespace['prefix'] = $this->namespace['personal'][0][0];
+        }
 
-    $a_mailbox_cache[$mailbox][$mode] = (int)$count;
-
-    // write back to cache
-    $this->update_cache('messagecount', $a_mailbox_cache);
-
-    return (int)$count;
+        $_SESSION['imap_namespace'] = $this->namespace;
+        $_SESSION['imap_delimiter'] = $this->delimiter;
     }
 
 
-  /**
-   * Public method for listing headers
-   * convert mailbox name with root dir first
-   *
-   * @param   string   Mailbox/folder name
-   * @param   int      Current page to list
-   * @param   string   Header field to sort by
-   * @param   string   Sort order [ASC|DESC]
-   * @param   boolean  Number of slice items to extract from result array
-   * @return  array    Indexed array with message header objects
-   * @access  public   
-   */
-  function list_headers($mbox_name='', $page=NULL, $sort_field=NULL, $sort_order=NULL, $slice=0)
+    /**
+     * Get message count for a specific folder
+     *
+     * @param  string  $folder  Folder name
+     * @param  string  $mode    Mode for count [ALL|THREADS|UNSEEN|RECENT]
+     * @param  boolean $force   Force reading from server and update cache
+     * @param  boolean $status  Enables storing folder status info (max UID/count),
+     *                          required for folder_status()
+     *
+     * @return int     Number of messages
+     */
+    public function count($folder='', $mode='ALL', $force=false, $status=true)
     {
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-    return $this->_list_headers($mailbox, $page, $sort_field, $sort_order, false, $slice);
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        return $this->messagecount($folder, $mode, $force, $status);
     }
 
 
-  /**
-   * Private method for listing message headers
-   *
-   * @access  private
-   * @see     rcube_imap::list_headers
-   */
-  private function _list_headers($mailbox='', $page=NULL, $sort_field=NULL, $sort_order=NULL, $recursive=FALSE, $slice=0)
+    /**
+     * protected method for getting nr of messages
+     *
+     * @param string  $folder  Folder name
+     * @param string  $mode    Mode for count [ALL|THREADS|UNSEEN|RECENT]
+     * @param boolean $force   Force reading from server and update cache
+     * @param boolean $status  Enables storing folder status info (max UID/count),
+     *                         required for folder_status()
+     *
+     * @return int Number of messages
+     * @see rcube_imap::count()
+     */
+    protected function messagecount($folder, $mode='ALL', $force=false, $status=true)
     {
-    if (!strlen($mailbox))
-      return array();
+        $mode = strtoupper($mode);
 
-    // use saved message set
-    if ($this->search_string && $mailbox == $this->mailbox)
-      return $this->_list_header_set($mailbox, $page, $sort_field, $sort_order, $slice);
+        // count search set, assume search set is always up-to-date (don't check $force flag)
+        if ($this->search_string && $folder == $this->folder && ($mode == 'ALL' || $mode == 'THREADS')) {
+            if ($mode == 'ALL') {
+                return $this->search_set->count_messages();
+            }
+            else {
+                return $this->search_set->count();
+            }
+        }
 
-    $this->_set_sort_order($sort_field, $sort_order);
+        $a_folder_cache = $this->get_cache('messagecount');
 
-    $page = $page ? $page : $this->list_page;
-    $cache_key = $mailbox.'.msg';
-    $cache_status = $this->check_cache_status($mailbox, $cache_key);
+        // return cached value
+        if (!$force && is_array($a_folder_cache[$folder]) && isset($a_folder_cache[$folder][$mode])) {
+            return $a_folder_cache[$folder][$mode];
+        }
 
-    // cache is OK, we can get all messages from local cache
-    if ($cache_status>0)
-      {
-      $start_msg = ($page-1) * $this->page_size;
-      $a_msg_headers = $this->get_message_cache($cache_key, $start_msg, $start_msg+$this->page_size, $this->sort_field, $this->sort_order);
-      $result = array_values($a_msg_headers);
-      if ($slice)
-        $result = array_slice($result, -$slice, $slice);
-      return $result;
-      }
-    // cache is dirty, sync it
-    else if ($this->caching_enabled && $cache_status==-1 && !$recursive)
-      {
-      $this->sync_header_index($mailbox);
-      return $this->_list_headers($mailbox, $page, $this->sort_field, $this->sort_order, TRUE, $slice);
-      }
+        if (!is_array($a_folder_cache[$folder])) {
+            $a_folder_cache[$folder] = array();
+        }
 
-    // retrieve headers from IMAP
-    $a_msg_headers = array();
+        if ($mode == 'THREADS') {
+            $res   = $this->fetch_threads($folder, $force);
+            $count = $res->count();
 
-    // use message index sort for sorting by Date (for better performance)
-    if ($this->index_sort && $this->sort_field == 'date')
-      {
-        if ($this->skip_deleted) {
-          // @TODO: this could be cached
-	  if ($msg_index = $this->_search_index($mailbox, 'ALL UNDELETED')) {
-            $max = max($msg_index);
-            list($begin, $end) = $this->_get_message_range(count($msg_index), $page);
-            $msg_index = array_slice($msg_index, $begin, $end-$begin);
-	    }
-	} else if ($max = iil_C_CountMessages($this->conn, $mailbox)) {
-          list($begin, $end) = $this->_get_message_range($max, $page);
-	  $msg_index = range($begin+1, $end);
-	} else
-	  $msg_index = array();
+            if ($status) {
+                $msg_count = $res->count_messages();
+                $this->set_folder_stats($folder, 'cnt', $msg_count);
+                $this->set_folder_stats($folder, 'maxuid', $msg_count ? $this->id2uid($msg_count, $folder) : 0);
+            }
+        }
+        // Need connection here
+        else if (!$this->check_connection()) {
+            return 0;
+        }
+        // RECENT count is fetched a bit different
+        else if ($mode == 'RECENT') {
+            $count = $this->conn->countRecent($folder);
+        }
+        // use SEARCH for message counting
+        else if (!empty($this->options['skip_deleted'])) {
+            $search_str = "ALL UNDELETED";
+            $keys       = array('COUNT');
 
-        if ($slice)
-          $msg_index = array_slice($msg_index, ($this->sort_order == 'DESC' ? 0 : -$slice), $slice);
+            if ($mode == 'UNSEEN') {
+                $search_str .= " UNSEEN";
+            }
+            else {
+                if ($this->messages_caching) {
+                    $keys[] = 'ALL';
+                }
+                if ($status) {
+                    $keys[]   = 'MAX';
+                }
+            }
 
-        // fetch reqested headers from server
-	if ($msg_index)
-          $this->_fetch_headers($mailbox, join(",", $msg_index), $a_msg_headers, $cache_key);
-      }
-    // use SORT command
-    else if ($this->get_capability('sort') && ($msg_index = iil_C_Sort($this->conn, $mailbox, $this->sort_field, $this->skip_deleted ? 'UNDELETED' : '')))
-      {
-      list($begin, $end) = $this->_get_message_range(count($msg_index), $page);
-      $max = max($msg_index);
-      $msg_index = array_slice($msg_index, $begin, $end-$begin);
+            // @TODO: if $force==false && $mode == 'ALL' we could try to use cache index here
 
-      if ($slice)
-        $msg_index = array_slice($msg_index, ($this->sort_order == 'DESC' ? 0 : -$slice), $slice);
+            // get message count using (E)SEARCH
+            // not very performant but more precise (using UNDELETED)
+            $index = $this->conn->search($folder, $search_str, true, $keys);
+            $count = $index->count();
 
-      // fetch reqested headers from server
-      $this->_fetch_headers($mailbox, join(',', $msg_index), $a_msg_headers, $cache_key);
-      }
-    // fetch specified header for all messages and sort
-    else if ($a_index = iil_C_FetchHeaderIndex($this->conn, $mailbox, "1:*", $this->sort_field, $this->skip_deleted))
-      {
-      asort($a_index); // ASC
-      $msg_index = array_keys($a_index);
-      $max = max($msg_index);
-      list($begin, $end) = $this->_get_message_range(count($msg_index), $page);
-      $msg_index = array_slice($msg_index, $begin, $end-$begin);
+            if ($mode == 'ALL') {
+                // Cache index data, will be used in index_direct()
+                $this->icache['undeleted_idx'] = $index;
 
-      if ($slice)
-        $msg_index = array_slice($msg_index, ($this->sort_order == 'DESC' ? 0 : -$slice), $slice);
+                if ($status) {
+                    $this->set_folder_stats($folder, 'cnt', $count);
+                    $this->set_folder_stats($folder, 'maxuid', $index->max());
+                }
+            }
+        }
+        else {
+            if ($mode == 'UNSEEN') {
+                $count = $this->conn->countUnseen($folder);
+            }
+            else {
+                $count = $this->conn->countMessages($folder);
+                if ($status) {
+                    $this->set_folder_stats($folder,'cnt', $count);
+                    $this->set_folder_stats($folder, 'maxuid', $count ? $this->id2uid($count, $folder) : 0);
+                }
+            }
+        }
 
-      // fetch reqested headers from server
-      $this->_fetch_headers($mailbox, join(",", $msg_index), $a_msg_headers, $cache_key);
-      }
+        $a_folder_cache[$folder][$mode] = (int)$count;
 
-    // delete cached messages with a higher index than $max+1
-    // Changed $max to $max+1 to fix this bug : #1484295
-    $this->clear_message_cache($cache_key, $max + 1);
+        // write back to cache
+        $this->update_cache('messagecount', $a_folder_cache);
 
-    // kick child process to sync cache
-    // ...
-
-    // return empty array if no messages found
-    if (!is_array($a_msg_headers) || empty($a_msg_headers))
-      return array();
-    
-    // use this class for message sorting
-    $sorter = new rcube_header_sorter();
-    $sorter->set_sequence_numbers($msg_index);
-    $sorter->sort_headers($a_msg_headers);
-
-    if ($this->sort_order == 'DESC')
-      $a_msg_headers = array_reverse($a_msg_headers);	    
-
-    return array_values($a_msg_headers);
+        return (int)$count;
     }
 
 
-  /**
-   * Private method for listing a set of message headers (search results)
-   *
-   * @param   string   Mailbox/folder name
-   * @param   int      Current page to list
-   * @param   string   Header field to sort by
-   * @param   string   Sort order [ASC|DESC]
-   * @param   boolean  Number of slice items to extract from result array
-   * @return  array    Indexed array with message header objects
-   * @access  private
-   * @see     rcube_imap::list_header_set()
-   */
-  private function _list_header_set($mailbox, $page=NULL, $sort_field=NULL, $sort_order=NULL, $slice=0)
+    /**
+     * Public method for listing headers
+     *
+     * @param   string   $folder     Folder name
+     * @param   int      $page       Current page to list
+     * @param   string   $sort_field Header field to sort by
+     * @param   string   $sort_order Sort order [ASC|DESC]
+     * @param   int      $slice      Number of slice items to extract from result array
+     *
+     * @return  array    Indexed array with message header objects
+     */
+    public function list_messages($folder='', $page=NULL, $sort_field=NULL, $sort_order=NULL, $slice=0)
     {
-    if (!strlen($mailbox) || empty($this->search_set))
-      return array();
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
 
-    $msgs = $this->search_set;
-    $a_msg_headers = array();
-    $page = $page ? $page : $this->list_page;
-    $start_msg = ($page-1) * $this->page_size;
+        return $this->_list_messages($folder, $page, $sort_field, $sort_order, $slice);
+    }
 
-    $this->_set_sort_order($sort_field, $sort_order);
 
-    // quickest method
-    if ($this->index_sort && $this->search_sort_field == 'date' && $this->sort_field == 'date')
-      {
-      if ($sort_order == 'DESC')
-        $msgs = array_reverse($msgs);
+    /**
+     * protected method for listing message headers
+     *
+     * @param   string   $folder     Folder name
+     * @param   int      $page       Current page to list
+     * @param   string   $sort_field Header field to sort by
+     * @param   string   $sort_order Sort order [ASC|DESC]
+     * @param   int      $slice      Number of slice items to extract from result array
+     *
+     * @return  array    Indexed array with message header objects
+     * @see     rcube_imap::list_messages
+     */
+    protected function _list_messages($folder='', $page=NULL, $sort_field=NULL, $sort_order=NULL, $slice=0)
+    {
+        if (!strlen($folder)) {
+            return array();
+        }
 
-      // get messages uids for one page
-      $msgs = array_slice(array_values($msgs), $start_msg, min(count($msgs)-$start_msg, $this->page_size));
+        $this->set_sort_order($sort_field, $sort_order);
+        $page = $page ? $page : $this->list_page;
 
-      if ($slice)
-        $msgs = array_slice($msgs, -$slice, $slice);
+        // use saved message set
+        if ($this->search_string && $folder == $this->folder) {
+            return $this->list_search_messages($folder, $page, $slice);
+        }
 
-      // fetch headers
-      $this->_fetch_headers($mailbox, join(',',$msgs), $a_msg_headers, NULL);
+        if ($this->threading) {
+            return $this->list_thread_messages($folder, $page, $slice);
+        }
 
-      // I didn't found in RFC that FETCH always returns messages sorted by index
-      $sorter = new rcube_header_sorter();
-      $sorter->set_sequence_numbers($msgs);
-      $sorter->sort_headers($a_msg_headers);
+        // get UIDs of all messages in the folder, sorted
+        $index = $this->index($folder, $this->sort_field, $this->sort_order);
 
-      return array_values($a_msg_headers);
-      }
-    // sorted messages, so we can first slice array and then fetch only wanted headers
-    if ($this->get_capability('sort') && (!$this->index_sort || $this->sort_field != 'date')) // SORT searching result
-      {
-      // reset search set if sorting field has been changed
-      if ($this->sort_field && $this->search_sort_field != $this->sort_field)
-        $msgs = $this->search('', $this->search_string, $this->search_charset, $this->sort_field);
+        if ($index->is_empty()) {
+            return array();
+        }
 
-      // return empty array if no messages found
-      if (empty($msgs))
-        return array();
+        $from = ($page-1) * $this->page_size;
+        $to   = $from + $this->page_size;
 
-      if ($sort_order == 'DESC')
-        $msgs = array_reverse($msgs);
+        $index->slice($from, $to - $from);
 
-      // get messages uids for one page
-      $msgs = array_slice(array_values($msgs), $start_msg, min(count($msgs)-$start_msg, $this->page_size));
+        if ($slice) {
+            $index->slice(-$slice, $slice);
+        }
 
-      if ($slice)
-        $msgs = array_slice($msgs, -$slice, $slice);
-
-      // fetch headers
-      $this->_fetch_headers($mailbox, join(',',$msgs), $a_msg_headers, NULL);
-
-      $sorter = new rcube_header_sorter();
-      $sorter->set_sequence_numbers($msgs);
-      $sorter->sort_headers($a_msg_headers);
-
-      return array_values($a_msg_headers);
-      }
-    else { // SEARCH searching result, need sorting
-      $cnt = count($msgs);
-      // 300: experimantal value for best result
-      if (($cnt > 300 && $cnt > $this->page_size) || ($this->index_sort && $this->sort_field == 'date')) {
-        // use memory less expensive (and quick) method for big result set
-	$a_index = $this->message_index('', $this->sort_field, $this->sort_order);
-        // get messages uids for one page...
-        $msgs = array_slice($a_index, $start_msg, min($cnt-$start_msg, $this->page_size));
-        if ($slice)
-          $msgs = array_slice($msgs, -$slice, $slice);
-	// ...and fetch headers
-        $this->_fetch_headers($mailbox, join(',', $msgs), $a_msg_headers, NULL);
-
-        // return empty array if no messages found
-        if (!is_array($a_msg_headers) || empty($a_msg_headers))
-          return array();
-
-        $sorter = new rcube_header_sorter();
-        $sorter->set_sequence_numbers($msgs);
-        $sorter->sort_headers($a_msg_headers);
+        // fetch reqested messages headers
+        $a_index = $index->get();
+        $a_msg_headers = $this->fetch_headers($folder, $a_index);
 
         return array_values($a_msg_headers);
+    }
+
+
+    /**
+     * protected method for listing message headers using threads
+     *
+     * @param   string   $folder     Folder name
+     * @param   int      $page       Current page to list
+     * @param   int      $slice      Number of slice items to extract from result array
+     *
+     * @return  array    Indexed array with message header objects
+     * @see     rcube_imap::list_messages
+     */
+    protected function list_thread_messages($folder, $page, $slice=0)
+    {
+        // get all threads (not sorted)
+        if ($mcache = $this->get_mcache_engine()) {
+            $threads = $mcache->get_thread($folder);
         }
-      else {
-        // for small result set we can fetch all messages headers
-        $this->_fetch_headers($mailbox, join(',', $msgs), $a_msg_headers, NULL);
-    
+        else {
+            $threads = $this->fetch_threads($folder);
+        }
+
+        return $this->fetch_thread_headers($folder, $threads, $page, $slice);
+    }
+
+    /**
+     * Method for fetching threads data
+     *
+     * @param  string $folder  Folder name
+     * @param  bool   $force   Use IMAP server, no cache
+     *
+     * @return rcube_imap_thread Thread data object
+     */
+    function fetch_threads($folder, $force = false)
+    {
+        if (!$force && ($mcache = $this->get_mcache_engine())) {
+            // don't store in self's internal cache, cache has it's own internal cache
+            return $mcache->get_thread($folder);
+        }
+
+        if (empty($this->icache['threads'])) {
+            if (!$this->check_connection()) {
+                return new rcube_result_thread();
+            }
+
+            // get all threads
+            $result = $this->conn->thread($folder, $this->threading,
+                $this->options['skip_deleted'] ? 'UNDELETED' : '', true);
+
+            // add to internal (fast) cache
+            $this->icache['threads'] = $result;
+        }
+
+        return $this->icache['threads'];
+    }
+
+
+    /**
+     * protected method for fetching threaded messages headers
+     *
+     * @param string              $folder     Folder name
+     * @param rcube_result_thread $threads    Threads data object
+     * @param int                 $page       List page number
+     * @param int                 $slice      Number of threads to slice
+     *
+     * @return array  Messages headers
+     */
+    protected function fetch_thread_headers($folder, $threads, $page, $slice=0)
+    {
+        // Sort thread structure
+        $this->sort_threads($threads);
+
+        $from = ($page-1) * $this->page_size;
+        $to   = $from + $this->page_size;
+
+        $threads->slice($from, $to - $from);
+
+        if ($slice) {
+            $threads->slice(-$slice, $slice);
+        }
+
+        // Get UIDs of all messages in all threads
+        $a_index = $threads->get();
+
+        // fetch reqested headers from server
+        $a_msg_headers = $this->fetch_headers($folder, $a_index);
+
+        unset($a_index);
+
+        // Set depth, has_children and unread_children fields in headers
+        $this->set_thread_flags($a_msg_headers, $threads);
+
+        return array_values($a_msg_headers);
+    }
+
+
+    /**
+     * protected method for setting threaded messages flags:
+     * depth, has_children and unread_children
+     *
+     * @param  array             $headers Reference to headers array indexed by message UID
+     * @param  rcube_imap_result $threads Threads data object
+     *
+     * @return array Message headers array indexed by message UID
+     */
+    protected function set_thread_flags(&$headers, $threads)
+    {
+        $parents = array();
+
+        list ($msg_depth, $msg_children) = $threads->get_thread_data();
+
+        foreach ($headers as $uid => $header) {
+            $depth = $msg_depth[$uid];
+            $parents = array_slice($parents, 0, $depth);
+
+            if (!empty($parents)) {
+                $headers[$uid]->parent_uid = end($parents);
+                if (empty($header->flags['SEEN']))
+                    $headers[$parents[0]]->unread_children++;
+            }
+            array_push($parents, $uid);
+
+            $headers[$uid]->depth = $depth;
+            $headers[$uid]->has_children = $msg_children[$uid];
+        }
+    }
+
+
+    /**
+     * protected method for listing a set of message headers (search results)
+     *
+     * @param   string   $folder   Folder name
+     * @param   int      $page     Current page to list
+     * @param   int      $slice    Number of slice items to extract from result array
+     *
+     * @return  array    Indexed array with message header objects
+     */
+    protected function list_search_messages($folder, $page, $slice=0)
+    {
+        if (!strlen($folder) || empty($this->search_set) || $this->search_set->is_empty()) {
+            return array();
+        }
+
+        // use saved messages from searching
+        if ($this->threading) {
+            return $this->list_search_thread_messages($folder, $page, $slice);
+        }
+
+        // search set is threaded, we need a new one
+        if ($this->search_threads) {
+            $this->search('', $this->search_string, $this->search_charset, $this->sort_field);
+        }
+
+        $index = clone $this->search_set;
+        $from  = ($page-1) * $this->page_size;
+        $to    = $from + $this->page_size;
+
         // return empty array if no messages found
-        if (!is_array($a_msg_headers) || empty($a_msg_headers))
-          return array();
+        if ($index->is_empty()) {
+            return array();
+        }
 
-        // if not already sorted
-        $a_msg_headers = iil_SortHeaders($a_msg_headers, $this->sort_field, $this->sort_order);
+        // quickest method (default sorting)
+        if (!$this->search_sort_field && !$this->sort_field) {
+            $got_index = true;
+        }
+        // sorted messages, so we can first slice array and then fetch only wanted headers
+        else if ($this->search_sorted) { // SORT searching result
+            $got_index = true;
+            // reset search set if sorting field has been changed
+            if ($this->sort_field && $this->search_sort_field != $this->sort_field) {
+                $this->search('', $this->search_string, $this->search_charset, $this->sort_field);
 
-        // only return the requested part of the set
-	$a_msg_headers = array_slice(array_values($a_msg_headers), $start_msg, min($cnt-$start_msg, $this->page_size));
-        if ($slice)
-          $a_msg_headers = array_slice($a_msg_headers, -$slice, $slice);
+                $index = clone $this->search_set;
+
+                // return empty array if no messages found
+                if ($index->is_empty()) {
+                    return array();
+                }
+            }
+        }
+
+        if ($got_index) {
+            if ($this->sort_order != $index->get_parameters('ORDER')) {
+                $index->revert();
+            }
+
+            // get messages uids for one page
+            $index->slice($from, $to-$from);
+
+            if ($slice) {
+                $index->slice(-$slice, $slice);
+            }
+
+            // fetch headers
+            $a_index       = $index->get();
+            $a_msg_headers = $this->fetch_headers($folder, $a_index);
+
+            return array_values($a_msg_headers);
+        }
+
+        // SEARCH result, need sorting
+        $cnt = $index->count();
+
+        // 300: experimantal value for best result
+        if (($cnt > 300 && $cnt > $this->page_size) || !$this->sort_field) {
+            // use memory less expensive (and quick) method for big result set
+            $index = clone $this->index('', $this->sort_field, $this->sort_order);
+            // get messages uids for one page...
+            $index->slice($start_msg, min($cnt-$from, $this->page_size));
+
+            if ($slice) {
+                $index->slice(-$slice, $slice);
+            }
+
+            // ...and fetch headers
+            $a_index       = $index->get();
+            $a_msg_headers = $this->fetch_headers($folder, $a_index);
+
+            return array_values($a_msg_headers);
+        }
+        else {
+            // for small result set we can fetch all messages headers
+            $a_index       = $index->get();
+            $a_msg_headers = $this->fetch_headers($folder, $a_index, false);
+
+            // return empty array if no messages found
+            if (!is_array($a_msg_headers) || empty($a_msg_headers)) {
+                return array();
+            }
+
+            if (!$this->check_connection()) {
+                return array();
+            }
+
+            // if not already sorted
+            $a_msg_headers = $this->conn->sortHeaders(
+                $a_msg_headers, $this->sort_field, $this->sort_order);
+
+            // only return the requested part of the set
+            $a_msg_headers = array_slice(array_values($a_msg_headers),
+                $from, min($cnt-$to, $this->page_size));
+
+            if ($slice) {
+                $a_msg_headers = array_slice($a_msg_headers, -$slice, $slice);
+            }
+
+            return $a_msg_headers;
+        }
+    }
+
+
+    /**
+     * protected method for listing a set of threaded message headers (search results)
+     *
+     * @param   string   $folder     Folder name
+     * @param   int      $page       Current page to list
+     * @param   int      $slice      Number of slice items to extract from result array
+     *
+     * @return  array    Indexed array with message header objects
+     * @see rcube_imap::list_search_messages()
+     */
+    protected function list_search_thread_messages($folder, $page, $slice=0)
+    {
+        // update search_set if previous data was fetched with disabled threading
+        if (!$this->search_threads) {
+            if ($this->search_set->is_empty()) {
+                return array();
+            }
+            $this->search('', $this->search_string, $this->search_charset, $this->sort_field);
+        }
+
+        return $this->fetch_thread_headers($folder, clone $this->search_set, $page, $slice);
+    }
+
+
+    /**
+     * Fetches messages headers (by UID)
+     *
+     * @param  string  $folder   Folder name
+     * @param  array   $msgs     Message UIDs
+     * @param  bool    $sort     Enables result sorting by $msgs
+     * @param  bool    $force    Disables cache use
+     *
+     * @return array Messages headers indexed by UID
+     */
+    function fetch_headers($folder, $msgs, $sort = true, $force = false)
+    {
+        if (empty($msgs)) {
+            return array();
+        }
+
+        if (!$force && ($mcache = $this->get_mcache_engine())) {
+            $headers = $mcache->get_messages($folder, $msgs);
+        }
+        else if (!$this->check_connection()) {
+            return array();
+        }
+        else {
+            // fetch reqested headers from server
+            $headers = $this->conn->fetchHeaders(
+                $folder, $msgs, true, false, $this->get_fetch_headers());
+        }
+
+        if (empty($headers)) {
+            return array();
+        }
+
+        foreach ($headers as $h) {
+            $a_msg_headers[$h->uid] = $h;
+        }
+
+        if ($sort) {
+            // use this class for message sorting
+            $sorter = new rcube_header_sorter();
+            $sorter->set_index($msgs);
+            $sorter->sort_headers($a_msg_headers);
+        }
 
         return $a_msg_headers;
+    }
+
+
+    /**
+     * Returns current status of folder
+     *
+     * We compare the maximum UID to determine the number of
+     * new messages because the RECENT flag is not reliable.
+     *
+     * @param string $folder Folder name
+     *
+     * @return int   Folder status
+     */
+    public function folder_status($folder = null)
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder;
         }
-      }
-    }
+        $old = $this->get_folder_stats($folder);
 
+        // refresh message count -> will update
+        $this->messagecount($folder, 'ALL', true);
 
-  /**
-   * Helper function to get first and last index of the requested set
-   *
-   * @param  int     message count
-   * @param  mixed   page number to show, or string 'all'
-   * @return array   array with two values: first index, last index
-   * @access private
-   */
-  private function _get_message_range($max, $page)
-    {
-    $start_msg = ($page-1) * $this->page_size;
-    
-    if ($page=='all')
-      {
-      $begin = 0;
-      $end = $max;
-      }
-    else if ($this->sort_order=='DESC')
-      {
-      $begin = $max - $this->page_size - $start_msg;
-      $end =   $max - $start_msg;
-      }
-    else
-      {
-      $begin = $start_msg;
-      $end   = $start_msg + $this->page_size;
-      }
+        $result = 0;
 
-    if ($begin < 0) $begin = 0;
-    if ($end < 0) $end = $max;
-    if ($end > $max) $end = $max;
-    
-    return array($begin, $end);
-    }
-    
-
-  /**
-   * Fetches message headers
-   * Used for loop
-   *
-   * @param  string  Mailbox name
-   * @param  string  Message index to fetch
-   * @param  array   Reference to message headers array
-   * @param  array   Array with cache index
-   * @return int     Messages count
-   * @access private
-   */
-  private function _fetch_headers($mailbox, $msgs, &$a_msg_headers, $cache_key)
-    {
-    // fetch reqested headers from server
-    $a_header_index = iil_C_FetchHeaders($this->conn, $mailbox, $msgs, false, false, $this->fetch_add_headers);
-
-    if (!empty($a_header_index))
-      {
-      // cache is incomplete
-      $cache_index = $this->get_message_cache_index($cache_key);
-
-      foreach ($a_header_index as $i => $headers) {
-        if ($this->caching_enabled && $cache_index[$headers->id] != $headers->uid) {
-	  // prevent index duplicates
-	  if ($cache_index[$headers->id]) {
-	    $this->remove_message_cache($cache_key, $headers->id, true);
-	    unset($cache_index[$headers->id]);
-	    }
-          // add message to cache
-	  $this->add_message_cache($cache_key, $headers->id, $headers, NULL,
-	    !in_array($headers->uid, $cache_index));
-	  }
-
-        $a_msg_headers[$headers->uid] = $headers;
-        }
-      }
-
-    return count($a_msg_headers);
-    }
-  
-  /**
-   * Fetches IDS of pseudo recent messages.
-   *
-   * We compare the maximum UID to determine the number of
-   * new messages because the RECENT flag is not reliable.
-   *
-   * @param string  Mailbox/folder name
-   * @return array  List of recent message UIDs
-   */
-  function recent_uids($mbox_name = null, $nofetch = false)
-  {
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-    $old_maxuid = intval($_SESSION['maxuid'][$mailbox]);
-    
-    // refresh message count -> will update $_SESSION['maxuid'][$mailbox]
-    $this->_messagecount($mailbox, 'ALL', true);
-    
-    if ($_SESSION['maxuid'][$mailbox] > $old_maxuid) {
-      $maxuid = max(1, $old_maxuid+1);
-      return array_values((array)iil_C_FetchHeaderIndex($this->conn, $mailbox, "$maxuid:*", 'UID', $this->skip_deleted, true));
-    }
-    
-    return array();
-  }
-  
-  /**
-   * Return sorted array of message IDs (not UIDs)
-   *
-   * @param string Mailbox to get index from
-   * @param string Sort column
-   * @param string Sort order [ASC, DESC]
-   * @return array Indexed array with message ids
-   */
-  function message_index($mbox_name='', $sort_field=NULL, $sort_order=NULL)
-    {
-    $this->_set_sort_order($sort_field, $sort_order);
-
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-    $key = "{$mailbox}:{$this->sort_field}:{$this->sort_order}:{$this->search_string}.msgi";
-
-    // we have a saved search result, get index from there
-    if (!isset($this->cache[$key]) && $this->search_string && $mailbox == $this->mailbox)
-    {
-      $this->cache[$key] = array();
-      
-      // use message index sort for sorting by Date
-      if ($this->index_sort && $this->sort_field == 'date')
-        {
-	$msgs = $this->search_set;
-	
-	if ($this->search_sort_field != 'date')
-	  sort($msgs);
-	
-        if ($this->sort_order == 'DESC')
-          $this->cache[$key] = array_reverse($msgs);
-        else
-          $this->cache[$key] = $msgs;
-        }
-      // sort with SORT command
-      else if ($this->get_capability('sort'))
-        {
-        if ($this->sort_field && $this->search_sort_field != $this->sort_field)
-          $this->search('', $this->search_string, $this->search_charset, $this->sort_field);
-
-        if ($this->sort_order == 'DESC')
-          $this->cache[$key] = array_reverse($this->search_set);
-        else
-          $this->cache[$key] = $this->search_set;
-        }
-      else
-        {
-        $a_index = iil_C_FetchHeaderIndex($this->conn, $mailbox, join(',', $this->search_set), $this->sort_field, $this->skip_deleted);
-
-        if ($this->sort_order=="ASC")
-          asort($a_index);
-        else if ($this->sort_order=="DESC")
-          arsort($a_index);
-
-        $this->cache[$key] = array_keys($a_index);
-	}
-    }
-
-    // have stored it in RAM
-    if (isset($this->cache[$key]))
-      return $this->cache[$key];
-
-    // check local cache
-    $cache_key = $mailbox.'.msg';
-    $cache_status = $this->check_cache_status($mailbox, $cache_key);
-
-    // cache is OK
-    if ($cache_status>0)
-      {
-      $a_index = $this->get_message_cache_index($cache_key, TRUE, $this->sort_field, $this->sort_order);
-      return array_keys($a_index);
-      }
-
-    // use message index sort for sorting by Date
-    if ($this->index_sort && $this->sort_field == 'date')
-      {
-      if ($this->skip_deleted) {
-        $a_index = $this->_search_index($mailbox, 'ALL');
-      } else if ($max = $this->_messagecount($mailbox)) {
-        $a_index = range(1, $max);
-      }
-
-      if ($this->sort_order == 'DESC')
-        $a_index = array_reverse($a_index);
-
-      $this->cache[$key] = $a_index;
-      }
-    // fetch complete message index
-    else if ($this->get_capability('sort') && ($a_index = iil_C_Sort($this->conn, $mailbox, $this->sort_field, $this->skip_deleted ? 'UNDELETED' : '')))
-      {
-      if ($this->sort_order == 'DESC')
-        $a_index = array_reverse($a_index);
-
-      $this->cache[$key] = $a_index;
-      }
-    else
-      {
-      $a_index = iil_C_FetchHeaderIndex($this->conn, $mailbox, "1:*", $this->sort_field, $this->skip_deleted);
-
-      if ($this->sort_order=="ASC")
-        asort($a_index);
-      else if ($this->sort_order=="DESC")
-        arsort($a_index);
-        
-      $this->cache[$key] = array_keys($a_index);
-      }
-
-    return $this->cache[$key];
-    }
-
-
-  /**
-   * @access private
-   */
-  function sync_header_index($mailbox)
-    {
-    $cache_key = $mailbox.'.msg';
-    $cache_index = $this->get_message_cache_index($cache_key);
-
-    // fetch complete message index
-    $a_message_index = iil_C_FetchHeaderIndex($this->conn, $mailbox, "1:*", 'UID', $this->skip_deleted);
-    
-    if ($a_message_index === false)
-      return false;
-        
-    foreach ($a_message_index as $id => $uid)
-      {
-      // message in cache at correct position
-      if ($cache_index[$id] == $uid)
-        {
-        unset($cache_index[$id]);
-        continue;
-        }
-        
-      // message in cache but in wrong position
-      if (in_array((string)$uid, $cache_index, TRUE))
-        {
-        unset($cache_index[$id]);
-        }
-      
-      // other message at this position
-      if (isset($cache_index[$id]))
-        {
-	$for_remove[] = $cache_index[$id];
-        unset($cache_index[$id]);
-        }
-        
-	$for_update[] = $id;
-      }
-
-    // clear messages at wrong positions and those deleted that are still in cache_index      
-    if (!empty($for_remove))
-      $cache_index = array_merge($cache_index, $for_remove);
-    
-    if (!empty($cache_index))
-      $this->remove_message_cache($cache_key, $cache_index);
-
-    // fetch complete headers and add to cache
-    if (!empty($for_update)) {
-      if ($headers = iil_C_FetchHeader($this->conn, $mailbox, join(',', $for_update), false, $this->fetch_add_headers))
-        foreach ($headers as $header)
-          $this->add_message_cache($cache_key, $header->id, $header, NULL,
-		in_array($header->uid, (array)$for_remove));
-      }
-    }
-
-
-  /**
-   * Invoke search request to IMAP server
-   *
-   * @param  string  mailbox name to search in
-   * @param  string  search string
-   * @param  string  search string charset
-   * @param  string  header field to sort by
-   * @return array   search results as list of message ids
-   * @access public
-   */
-  function search($mbox_name='', $str=NULL, $charset=NULL, $sort_field=NULL)
-    {
-    if (!$str)
-      return false;
-    
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-
-    $results = $this->_search_index($mailbox, $str, $charset, $sort_field);
-
-    // try search with US-ASCII charset (should be supported by server)
-    // only if UTF-8 search is not supported
-    if (empty($results) && !is_array($results) && !empty($charset) && $charset != 'US-ASCII')
-      {
-	// convert strings to US_ASCII
-        if(preg_match_all('/\{([0-9]+)\}\r\n/', $str, $matches, PREG_OFFSET_CAPTURE))
-	  {
-	  $last = 0; $res = '';
-	  foreach($matches[1] as $m)
-	    {
-	    $string_offset = $m[1] + strlen($m[0]) + 4; // {}\r\n
-	    $string = substr($str, $string_offset - 1, $m[0]);
-	    $string = rcube_charset_convert($string, $charset, 'US-ASCII');
-	    if (!$string) continue;
-	    $res .= sprintf("%s{%d}\r\n%s", substr($str, $last, $m[1] - $last - 1), strlen($string), $string);
-	    $last = $m[0] + $string_offset - 1;
-	    }
-	    if ($last < strlen($str))
-	      $res .= substr($str, $last, strlen($str)-$last);
-	  }
-	else // strings for conversion not found
-	  $res = $str;
-	  
-	$results = $this->search($mbox_name, $res, NULL, $sort_field);
-      }
-
-    $this->set_search_set($str, $results, $charset, $sort_field);
-
-    return $results;
-    }
-
-
-  /**
-   * Private search method
-   *
-   * @return array   search results as list of message ids
-   * @access private
-   * @see rcube_imap::search()
-   */
-  private function _search_index($mailbox, $criteria='ALL', $charset=NULL, $sort_field=NULL)
-    {
-    $orig_criteria = $criteria;
-
-    if ($this->skip_deleted && !preg_match('/UNDELETED/', $criteria))
-      $criteria = 'UNDELETED '.$criteria;
-
-    if ($sort_field && $this->get_capability('sort') && (!$this->index_sort || $sort_field != 'date')) {
-      $charset = $charset ? $charset : $this->default_charset;
-      $a_messages = iil_C_Sort($this->conn, $mailbox, $sort_field, $criteria, FALSE, $charset);
-      }
-    else {
-      if ($orig_criteria == 'ALL') {
-        $max = $this->_messagecount($mailbox);
-        $a_messages = $max ? range(1, $max) : array();
-        }
-      else {
-        $a_messages = iil_C_Search($this->conn, $mailbox, ($charset ? "CHARSET $charset " : '') . $criteria);
-    
-        // I didn't found that SEARCH always returns sorted IDs
-        if ($this->index_sort && $this->sort_field == 'date')
-          sort($a_messages);
-        }
-      }
-    // update messagecount cache ?
-//    $a_mailbox_cache = get_cache('messagecount');
-//    $a_mailbox_cache[$mailbox][$criteria] = sizeof($a_messages);
-//    $this->update_cache('messagecount', $a_mailbox_cache);
-        
-    return $a_messages;
-    }
-    
-  
-  /**
-   * Refresh saved search set
-   *
-   * @return array Current search set
-   */
-  function refresh_search()
-    {
-    if (!empty($this->search_string))
-      $this->search_set = $this->search('', $this->search_string, $this->search_charset, $this->search_sort_field);
-      
-    return $this->get_search_set();
-    }
-  
-  
-  /**
-   * Check if the given message ID is part of the current search set
-   *
-   * @return boolean True on match or if no search request is stored
-   */
-  function in_searchset($msgid)
-  {
-    if (!empty($this->search_string))
-      return in_array("$msgid", (array)$this->search_set, true);
-    else
-      return true;
-  }
-
-
-  /**
-   * Return message headers object of a specific message
-   *
-   * @param int     Message ID
-   * @param string  Mailbox to read from 
-   * @param boolean True if $id is the message UID
-   * @param boolean True if we need also BODYSTRUCTURE in headers
-   * @return object Message headers representation
-   */
-  function get_headers($id, $mbox_name=NULL, $is_uid=TRUE, $bodystr=FALSE)
-    {
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-    $uid = $is_uid ? $id : $this->_id2uid($id);
-
-    // get cached headers
-    if ($uid && ($headers = &$this->get_cached_message($mailbox.'.msg', $uid)))
-      return $headers;
-
-    $headers = iil_C_FetchHeader($this->conn, $mailbox, $id, $is_uid, $bodystr, $this->fetch_add_headers);
-
-    // write headers cache
-    if ($headers)
-      {
-      if ($headers->uid && $headers->id)
-        $this->uid_id_map[$mailbox][$headers->uid] = $headers->id;
-
-      $this->add_message_cache($mailbox.'.msg', $headers->id, $headers, NULL, true);
-      }
-
-    return $headers;
-    }
-
-
-  /**
-   * Fetch body structure from the IMAP server and build
-   * an object structure similar to the one generated by PEAR::Mail_mimeDecode
-   *
-   * @param int Message UID to fetch
-   * @param string Message BODYSTRUCTURE string (optional)
-   * @return object rcube_message_part Message part tree or False on failure
-   */
-  function &get_structure($uid, $structure_str='')
-    {
-    $cache_key = $this->mailbox.'.msg';
-    $headers = &$this->get_cached_message($cache_key, $uid);
-
-    // return cached message structure
-    if (is_object($headers) && is_object($headers->structure)) {
-      return $headers->structure;
-    }
-
-    if (!$structure_str)
-      $structure_str = iil_C_FetchStructureString($this->conn, $this->mailbox, $uid, true);
-    $structure = iml_GetRawStructureArray($structure_str);
-    $struct = false;
-
-    // parse structure and add headers
-    if (!empty($structure))
-      {
-      $headers = $this->get_headers($uid);
-      $this->_msg_id = $headers->id;
-
-      // set message charset from message headers
-      if ($headers->charset)
-        $this->struct_charset = $headers->charset;
-      else
-        $this->struct_charset = $this->_structure_charset($structure);
-
-      // Here we can recognize malformed BODYSTRUCTURE and 
-      // 1. [@TODO] parse the message in other way to create our own message structure
-      // 2. or just show the raw message body.
-      // Example of structure for malformed MIME message:
-      // ("text" "plain" ("charset" "us-ascii") NIL NIL "7bit" 2154 70 NIL NIL NIL)
-      if ($headers->ctype && $headers->ctype != 'text/plain'
-	  && $structure[0] == 'text' && $structure[1] == 'plain') {
-	return false;  
-	}
-
-      $struct = &$this->_structure_part($structure);
-      $struct->headers = get_object_vars($headers);
-
-      // don't trust given content-type
-      if (empty($struct->parts) && !empty($struct->headers['ctype']))
-        {
-        $struct->mime_id = '1';
-        $struct->mimetype = strtolower($struct->headers['ctype']);
-        list($struct->ctype_primary, $struct->ctype_secondary) = explode('/', $struct->mimetype);
+        if (empty($old)) {
+            return $result;
         }
 
-      // write structure to cache
-      if ($this->caching_enabled)
-        $this->add_message_cache($cache_key, $this->_msg_id, $headers, $struct);
-      }
+        $new = $this->get_folder_stats($folder);
 
-    return $struct;
+        // got new messages
+        if ($new['maxuid'] > $old['maxuid']) {
+            $result += 1;
+        }
+        // some messages has been deleted
+        if ($new['cnt'] < $old['cnt']) {
+            $result += 2;
+        }
+
+        // @TODO: optional checking for messages flags changes (?)
+        // @TODO: UIDVALIDITY checking
+
+        return $result;
     }
 
-  
-  /**
-   * Build message part object
-   *
-   * @access private
-   */
-  function &_structure_part($part, $count=0, $parent='', $mime_headers=null, $raw_headers=null)
+
+    /**
+     * Stores folder statistic data in session
+     * @TODO: move to separate DB table (cache?)
+     *
+     * @param string $folder  Folder name
+     * @param string $name    Data name
+     * @param mixed  $data    Data value
+     */
+    protected function set_folder_stats($folder, $name, $data)
     {
-    $struct = new rcube_message_part;
-    $struct->mime_id = empty($parent) ? (string)$count : "$parent.$count";
+        $_SESSION['folders'][$folder][$name] = $data;
+    }
 
-    // multipart
-    if (is_array($part[0]))
-      {
-      $struct->ctype_primary = 'multipart';
-      
-      // find first non-array entry
-      for ($i=1; $i<count($part); $i++)
-        if (!is_array($part[$i]))
-          {
-          $struct->ctype_secondary = strtolower($part[$i]);
-          break;
-          }
-          
-      $struct->mimetype = 'multipart/'.$struct->ctype_secondary;
 
-      // build parts list for headers pre-fetching
-      for ($i=0, $count=0; $i<count($part); $i++)
-        if (is_array($part[$i]) && count($part[$i]) > 3) {
-          // fetch message headers if message/rfc822 or named part (could contain Content-Location header)
-	  if (!is_array($part[$i][0])) {
-            $tmp_part_id = $struct->mime_id ? $struct->mime_id.'.'.($i+1) : $i+1;
-            if (strtolower($part[$i][0]) == 'message' && strtolower($part[$i][1]) == 'rfc822') {
-	      $raw_part_headers[] = $tmp_part_id;
-	      $mime_part_headers[] = $tmp_part_id;
-              }
-            else if (in_array('name', (array)$part[$i][2]) && (empty($part[$i][3]) || $part[$i][3]=='NIL')) {
-	      $mime_part_headers[] = $tmp_part_id;
-	      }
+    /**
+     * Gets folder statistic data
+     *
+     * @param string $folder Folder name
+     *
+     * @return array Stats data
+     */
+    protected function get_folder_stats($folder)
+    {
+        if ($_SESSION['folders'][$folder]) {
+            return (array) $_SESSION['folders'][$folder];
+        }
+
+        return array();
+    }
+
+
+    /**
+     * Return sorted list of message UIDs
+     *
+     * @param string $folder     Folder to get index from
+     * @param string $sort_field Sort column
+     * @param string $sort_order Sort order [ASC, DESC]
+     *
+     * @return rcube_result_index|rcube_result_thread List of messages (UIDs)
+     */
+    public function index($folder = '', $sort_field = NULL, $sort_order = NULL)
+    {
+        if ($this->threading) {
+            return $this->thread_index($folder, $sort_field, $sort_order);
+        }
+
+        $this->set_sort_order($sort_field, $sort_order);
+
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        // we have a saved search result, get index from there
+        if ($this->search_string) {
+            if ($this->search_threads) {
+                $this->search($folder, $this->search_string, $this->search_charset, $this->sort_field);
             }
-          }
-        
-      // pre-fetch headers of all parts (in one command for better performance)
-      // @TODO: we could do this before _structure_part() call, to fetch
-      // headers for parts on all levels
-      if ($mime_part_headers)
-        $mime_part_headers = iil_C_FetchMIMEHeaders($this->conn, $this->mailbox,
-          $this->_msg_id, $mime_part_headers);
-      // we'll need a real content-type of message/rfc822 part
-      if ($raw_part_headers)
-        $raw_part_headers = iil_C_FetchMIMEHeaders($this->conn, $this->mailbox,
-          $this->_msg_id, $raw_part_headers, false);
 
-      $struct->parts = array();
-      for ($i=0, $count=0; $i<count($part); $i++)
-        if (is_array($part[$i]) && count($part[$i]) > 3) {
-          $tmp_part_id = $struct->mime_id ? $struct->mime_id.'.'.($i+1) : $i+1;
-          $struct->parts[] = $this->_structure_part($part[$i], ++$count, $struct->mime_id,
-	    $mime_part_headers[$tmp_part_id], $raw_part_headers[$tmp_part_id]);
-	}
+            // use message index sort as default sorting
+            if (!$this->sort_field || $this->search_sorted) {
+                if ($this->sort_field && $this->search_sort_field != $this->sort_field) {
+                    $this->search($folder, $this->search_string, $this->search_charset, $this->sort_field);
+                }
+                $index = $this->search_set;
+            }
+            else if (!$this->check_connection()) {
+                return new rcube_result_index();
+            }
+            else {
+                $index = $this->conn->index($folder, $this->search_set->get(),
+                    $this->sort_field, $this->options['skip_deleted'], true, true);
+            }
 
-      return $struct;
-      }
+            if ($this->sort_order != $index->get_parameters('ORDER')) {
+                $index->revert();
+            }
 
-
-    // regular part
-    $struct->ctype_primary = strtolower($part[0]);
-    $struct->ctype_secondary = strtolower($part[1]);
-    $struct->mimetype = $struct->ctype_primary.'/'.$struct->ctype_secondary;
-
-    // read content type parameters
-    if (is_array($part[2]))
-      {
-      $struct->ctype_parameters = array();
-      for ($i=0; $i<count($part[2]); $i+=2)
-        $struct->ctype_parameters[strtolower($part[2][$i])] = $part[2][$i+1];
-        
-      if (isset($struct->ctype_parameters['charset']))
-        $struct->charset = $struct->ctype_parameters['charset'];
-      }
-    
-    // read content encoding
-    if (!empty($part[5]) && $part[5]!='NIL')
-      {
-      $struct->encoding = strtolower($part[5]);
-      $struct->headers['content-transfer-encoding'] = $struct->encoding;
-      }
-    
-    // get part size
-    if (!empty($part[6]) && $part[6]!='NIL')
-      $struct->size = intval($part[6]);
-
-    // read part disposition
-    $di = count($part) - 2;
-    if ((is_array($part[$di]) && count($part[$di]) == 2 && is_array($part[$di][1])) ||
-        (is_array($part[--$di]) && count($part[$di]) == 2))
-      {
-      $struct->disposition = strtolower($part[$di][0]);
-
-      if (is_array($part[$di][1]))
-        for ($n=0; $n<count($part[$di][1]); $n+=2)
-          $struct->d_parameters[strtolower($part[$di][1][$n])] = $part[$di][1][$n+1];
-      }
-      
-    // get child parts
-    if (is_array($part[8]) && $di != 8)
-      {
-      $struct->parts = array();
-      for ($i=0, $count=0; $i<count($part[8]); $i++)
-        if (is_array($part[8][$i]) && count($part[8][$i]) > 5)
-          $struct->parts[] = $this->_structure_part($part[8][$i], ++$count, $struct->mime_id);
-      }
-
-    // get part ID
-    if (!empty($part[3]) && $part[3]!='NIL')
-      {
-      $struct->content_id = $part[3];
-      $struct->headers['content-id'] = $part[3];
-    
-      if (empty($struct->disposition))
-        $struct->disposition = 'inline';
-      }
-    
-    // fetch message headers if message/rfc822 or named part (could contain Content-Location header)
-    if ($struct->ctype_primary == 'message' || ($struct->ctype_parameters['name'] && !$struct->content_id)) {
-      if (empty($mime_headers))
-        $mime_headers = iil_C_FetchPartHeader($this->conn, $this->mailbox, $this->_msg_id, false, $struct->mime_id);
-      $struct->headers = $this->_parse_headers($mime_headers) + $struct->headers;
-
-      // get real headers for message of type 'message/rfc822'
-      if ($struct->mimetype == 'message/rfc822') {
-        if (empty($raw_headers))
-          $raw_headers = iil_C_FetchMIMEHeaders($this->conn, $this->mailbox, $this->_msg_id, (array)$struct->mime_id, false);
-        $struct->real_headers = $this->_parse_headers($raw_headers);
-
-        // get real content-type of message/rfc822
-        if (preg_match('/^([a-z0-9_\/-]+)/i', $struct->real_headers['content-type'], $matches)) {
-          $struct->real_mimetype = strtolower($matches[1]);
-          }                                                    
+            return $index;
         }
-      }
 
-    if ($struct->ctype_primary=='message') {
-      if (is_array($part[8]) && $di != 8 && empty($struct->parts))
-        $struct->parts[] = $this->_structure_part($part[8], ++$count, $struct->mime_id);
-      }
+        // check local cache
+        if ($mcache = $this->get_mcache_engine()) {
+            $index = $mcache->get_index($folder, $this->sort_field, $this->sort_order);
+        }
+        // fetch from IMAP server
+        else {
+            $index = $this->index_direct(
+                $folder, $this->sort_field, $this->sort_order);
+        }
 
-    // normalize filename property
-    $this->_set_part_filename($struct, $mime_headers);
-
-    return $struct;
+        return $index;
     }
-    
 
-  /**
-   * Set attachment filename from message part structure 
-   *
-   * @access private
-   * @param  object rcube_message_part Part object
-   * @param  string Part's raw headers
-   */
-  private function _set_part_filename(&$part, $headers=null)
+
+    /**
+     * Return sorted list of message UIDs ignoring current search settings.
+     * Doesn't uses cache by default.
+     *
+     * @param string $folder     Folder to get index from
+     * @param string $sort_field Sort column
+     * @param string $sort_order Sort order [ASC, DESC]
+     * @param bool   $skip_cache Disables cache usage
+     *
+     * @return rcube_result_index Sorted list of message UIDs
+     */
+    public function index_direct($folder, $sort_field = null, $sort_order = null, $skip_cache = true)
     {
-    if (!empty($part->d_parameters['filename']))
-      $filename_mime = $part->d_parameters['filename'];
-    else if (!empty($part->d_parameters['filename*']))
-      $filename_encoded = $part->d_parameters['filename*'];
-    else if (!empty($part->ctype_parameters['name*']))
-      $filename_encoded = $part->ctype_parameters['name*'];
-    // RFC2231 value continuations
-    // TODO: this should be rewrited to support RFC2231 4.1 combinations
-    else if (!empty($part->d_parameters['filename*0'])) {
-      $i = 0;
-      while (isset($part->d_parameters['filename*'.$i])) {
-        $filename_mime .= $part->d_parameters['filename*'.$i];
-        $i++;
-      }
-      // some servers (eg. dovecot-1.x) have no support for parameter value continuations
-      // we must fetch and parse headers "manually"
-      if ($i<2) {
-	if (!$headers)
-          $headers = iil_C_FetchPartHeader($this->conn, $this->mailbox, $this->_msg_id, false, $part->mime_id);
-        $filename_mime = '';
-        $i = 0;
-        while (preg_match('/filename\*'.$i.'\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
-          $filename_mime .= $matches[1];
-          $i++;
+        if (!$skip_cache && ($mcache = $this->get_mcache_engine())) {
+            $index = $mcache->get_index($folder, $sort_field, $sort_order);
         }
-      }
-    }
-    else if (!empty($part->d_parameters['filename*0*'])) {
-      $i = 0;
-      while (isset($part->d_parameters['filename*'.$i.'*'])) {
-        $filename_encoded .= $part->d_parameters['filename*'.$i.'*'];
-        $i++;
-      }
-      if ($i<2) {
-	if (!$headers)
-          $headers = iil_C_FetchPartHeader($this->conn, $this->mailbox, $this->_msg_id, false, $part->mime_id);
-        $filename_encoded = '';
-        $i = 0; $matches = array();
-        while (preg_match('/filename\*'.$i.'\*\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
-          $filename_encoded .= $matches[1];
-          $i++;
+        // use message index sort as default sorting
+        else if (!$sort_field) {
+            // use search result from count() if possible
+            if ($this->options['skip_deleted'] && !empty($this->icache['undeleted_idx'])
+                && $this->icache['undeleted_idx']->get_parameters('ALL') !== null
+                && $this->icache['undeleted_idx']->get_parameters('MAILBOX') == $folder
+            ) {
+                $index = $this->icache['undeleted_idx'];
+            }
+            else if (!$this->check_connection()) {
+                return new rcube_result_index();
+            }
+            else {
+                $index = $this->conn->search($folder,
+                    'ALL' .($this->options['skip_deleted'] ? ' UNDELETED' : ''), true);
+            }
         }
-      }
-    }
-    else if (!empty($part->ctype_parameters['name*0'])) {
-      $i = 0;
-      while (isset($part->ctype_parameters['name*'.$i])) {
-        $filename_mime .= $part->ctype_parameters['name*'.$i];
-        $i++;
-      }
-      if ($i<2) {
-	if (!$headers)
-          $headers = iil_C_FetchPartHeader($this->conn, $this->mailbox, $this->_msg_id, false, $part->mime_id);
-        $filename_mime = '';
-        $i = 0; $matches = array();
-        while (preg_match('/\s+name\*'.$i.'\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
-          $filename_mime .= $matches[1];
-          $i++;
+        else if (!$this->check_connection()) {
+            return new rcube_result_index();
         }
-      }
-    }
-    else if (!empty($part->ctype_parameters['name*0*'])) {
-      $i = 0;
-      while (isset($part->ctype_parameters['name*'.$i.'*'])) {
-        $filename_encoded .= $part->ctype_parameters['name*'.$i.'*'];
-        $i++;
-      }
-      if ($i<2) {
-	if (!$headers)
-          $headers = iil_C_FetchPartHeader($this->conn, $this->mailbox, $this->_msg_id, false, $part->mime_id);
-        $filename_encoded = '';
-        $i = 0; $matches = array();
-        while (preg_match('/\s+name\*'.$i.'\*\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
-          $filename_encoded .= $matches[1];
-          $i++;
-        }
-      }
-    }
-    // read 'name' after rfc2231 parameters as it may contains truncated filename (from Thunderbird)
-    else if (!empty($part->ctype_parameters['name']))
-      $filename_mime = $part->ctype_parameters['name'];
-    // Content-Disposition
-    else if (!empty($part->headers['content-description']))
-      $filename_mime = $part->headers['content-description'];
-    else
-      return;
+        // fetch complete message index
+        else {
+            if ($this->get_capability('SORT')) {
+                $index = $this->conn->sort($folder, $sort_field,
+                    $this->options['skip_deleted'] ? 'UNDELETED' : '', true);
+            }
 
-    // decode filename
-    if (!empty($filename_mime)) {
-      $part->filename = rcube_imap::decode_mime_string($filename_mime, 
-        $part->charset ? $part->charset : $this->struct_charset ? $this->struct_charset :
-	    rc_detect_encoding($filename_mime, $this->default_charset));
-      } 
-    else if (!empty($filename_encoded)) {
-      // decode filename according to RFC 2231, Section 4
-      if (preg_match("/^([^']*)'[^']*'(.*)$/", $filename_encoded, $fmatches)) {
-        $filename_charset = $fmatches[1];
-        $filename_encoded = $fmatches[2];
+            if (empty($index) || $index->is_error()) {
+                $index = $this->conn->index($folder, "1:*", $sort_field,
+                    $this->options['skip_deleted'], false, true);
+            }
         }
-      $part->filename = rcube_charset_convert(urldecode($filename_encoded), $filename_charset);
-      }
+
+        if ($sort_order != $index->get_parameters('ORDER')) {
+            $index->revert();
+        }
+
+        return $index;
     }
 
 
-  /**
-   * Get charset name from message structure (first part)
-   *
-   * @access private
-   * @param  array  Message structure
-   * @return string Charset name
-   */
-  function _structure_charset($structure)
+    /**
+     * Return index of threaded message UIDs
+     *
+     * @param string $folder     Folder to get index from
+     * @param string $sort_field Sort column
+     * @param string $sort_order Sort order [ASC, DESC]
+     *
+     * @return rcube_result_thread Message UIDs
+     */
+    public function thread_index($folder='', $sort_field=NULL, $sort_order=NULL)
     {
-      while (is_array($structure)) {
-	if (is_array($structure[2]) && $structure[2][0] == 'charset')
-	  return $structure[2][1];
-	$structure = $structure[0];
-	}
-    } 
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        // we have a saved search result, get index from there
+        if ($this->search_string && $this->search_threads && $folder == $this->folder) {
+            $threads = $this->search_set;
+        }
+        else {
+            // get all threads (default sort order)
+            $threads = $this->fetch_threads($folder);
+        }
+
+        $this->set_sort_order($sort_field, $sort_order);
+        $this->sort_threads($threads);
+
+        return $threads;
+    }
 
 
-  /**
-   * Fetch message body of a specific message from the server
-   *
-   * @param  int    Message UID
-   * @param  string Part number
-   * @param  object rcube_message_part Part object created by get_structure()
-   * @param  mixed  True to print part, ressource to write part contents in
-   * @param  resource File pointer to save the message part
-   * @return string Message/part body if not printed
-   */
-  function &get_message_part($uid, $part=1, $o_part=NULL, $print=NULL, $fp=NULL)
+    /**
+     * Sort threaded result, using THREAD=REFS method
+     *
+     * @param rcube_result_thread $threads  Threads result set
+     */
+    protected function sort_threads($threads)
     {
-    // get part encoding if not provided
-    if (!is_object($o_part))
-      {
-      $structure_str = iil_C_FetchStructureString($this->conn, $this->mailbox, $uid, true); 
-      $structure = iml_GetRawStructureArray($structure_str);
-      // error or message not found
-      if (empty($structure))
+        if ($threads->is_empty()) {
+            return;
+        }
+
+        // THREAD=ORDEREDSUBJECT: sorting by sent date of root message
+        // THREAD=REFERENCES:     sorting by sent date of root message
+        // THREAD=REFS:           sorting by the most recent date in each thread
+
+        if ($this->sort_field && ($this->sort_field != 'date' || $this->get_capability('THREAD') != 'REFS')) {
+            $index = $this->index_direct($this->folder, $this->sort_field, $this->sort_order, false);
+
+            if (!$index->is_empty()) {
+                $threads->sort($index);
+            }
+        }
+        else {
+            if ($this->sort_order != $threads->get_parameters('ORDER')) {
+                $threads->revert();
+            }
+        }
+    }
+
+
+    /**
+     * Invoke search request to IMAP server
+     *
+     * @param  string  $folder     Folder name to search in
+     * @param  string  $str        Search criteria
+     * @param  string  $charset    Search charset
+     * @param  string  $sort_field Header field to sort by
+     *
+     * @todo: Search criteria should be provided in non-IMAP format, eg. array
+     */
+    public function search($folder='', $str='ALL', $charset=NULL, $sort_field=NULL)
+    {
+        if (!$str) {
+            $str = 'ALL';
+        }
+
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        $results = $this->search_index($folder, $str, $charset, $sort_field);
+
+        $this->set_search_set(array($str, $results, $charset, $sort_field,
+            $this->threading || $this->search_sorted ? true : false));
+    }
+
+
+    /**
+     * Direct (real and simple) SEARCH request (without result sorting and caching).
+     *
+     * @param  string  $mailbox Mailbox name to search in
+     * @param  string  $str     Search string
+     *
+     * @return rcube_result_index  Search result (UIDs)
+     */
+    public function search_once($folder = null, $str = 'ALL')
+    {
+        if (!$str) {
+            return 'ALL';
+        }
+
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        if (!$this->check_connection()) {
+            return new rcube_result_index();
+        }
+
+        $index = $this->conn->search($folder, $str, true);
+
+        return $index;
+    }
+
+
+    /**
+     * protected search method
+     *
+     * @param string $folder     Folder name
+     * @param string $criteria   Search criteria
+     * @param string $charset    Charset
+     * @param string $sort_field Sorting field
+     *
+     * @return rcube_result_index|rcube_result_thread  Search results (UIDs)
+     * @see rcube_imap::search()
+     */
+    protected function search_index($folder, $criteria='ALL', $charset=NULL, $sort_field=NULL)
+    {
+        $orig_criteria = $criteria;
+
+        if (!$this->check_connection()) {
+            if ($this->threading) {
+                return new rcube_result_thread();
+            }
+            else {
+                return new rcube_result_index();
+            }
+        }
+
+        if ($this->options['skip_deleted'] && !preg_match('/UNDELETED/', $criteria)) {
+            $criteria = 'UNDELETED '.$criteria;
+        }
+
+        if ($this->threading) {
+            $threads = $this->conn->thread($folder, $this->threading, $criteria, true, $charset);
+
+            // Error, try with US-ASCII (RFC5256: SORT/THREAD must support US-ASCII and UTF-8,
+            // but I've seen that Courier doesn't support UTF-8)
+            if ($threads->is_error() && $charset && $charset != 'US-ASCII') {
+                $threads = $this->conn->thread($folder, $this->threading,
+                    $this->convert_criteria($criteria, $charset), true, 'US-ASCII');
+            }
+
+            return $threads;
+        }
+
+        if ($sort_field && $this->get_capability('SORT')) {
+            $charset  = $charset ? $charset : $this->default_charset;
+            $messages = $this->conn->sort($folder, $sort_field, $criteria, true, $charset);
+
+            // Error, try with US-ASCII (RFC5256: SORT/THREAD must support US-ASCII and UTF-8,
+            // but I've seen Courier with disabled UTF-8 support)
+            if ($messages->is_error() && $charset && $charset != 'US-ASCII') {
+                $messages = $this->conn->sort($folder, $sort_field,
+                    $this->convert_criteria($criteria, $charset), true, 'US-ASCII');
+            }
+
+            if (!$messages->is_error()) {
+                $this->search_sorted = true;
+                return $messages;
+            }
+        }
+
+        $messages = $this->conn->search($folder,
+            ($charset ? "CHARSET $charset " : '') . $criteria, true);
+
+        // Error, try with US-ASCII (some servers may support only US-ASCII)
+        if ($messages->is_error() && $charset && $charset != 'US-ASCII') {
+            $messages = $this->conn->search($folder,
+                $this->convert_criteria($criteria, $charset), true);
+        }
+
+        $this->search_sorted = false;
+
+        return $messages;
+    }
+
+
+    /**
+     * Converts charset of search criteria string
+     *
+     * @param  string  $str          Search string
+     * @param  string  $charset      Original charset
+     * @param  string  $dest_charset Destination charset (default US-ASCII)
+     *
+     * @return string  Search string
+     */
+    protected function convert_criteria($str, $charset, $dest_charset='US-ASCII')
+    {
+        // convert strings to US_ASCII
+        if (preg_match_all('/\{([0-9]+)\}\r\n/', $str, $matches, PREG_OFFSET_CAPTURE)) {
+            $last = 0; $res = '';
+            foreach ($matches[1] as $m) {
+                $string_offset = $m[1] + strlen($m[0]) + 4; // {}\r\n
+                $string = substr($str, $string_offset - 1, $m[0]);
+                $string = rcube_charset_convert($string, $charset, $dest_charset);
+                if ($string === false) {
+                    continue;
+                }
+                $res .= substr($str, $last, $m[1] - $last - 1) . rcube_imap_generic::escape($string);
+                $last = $m[0] + $string_offset - 1;
+            }
+            if ($last < strlen($str)) {
+                $res .= substr($str, $last, strlen($str)-$last);
+            }
+        }
+        // strings for conversion not found
+        else {
+            $res = $str;
+        }
+
+        return $res;
+    }
+
+
+    /**
+     * Refresh saved search set
+     *
+     * @return array Current search set
+     */
+    public function refresh_search()
+    {
+        if (!empty($this->search_string)) {
+            $this->search('', $this->search_string, $this->search_charset, $this->search_sort_field);
+        }
+
+        return $this->get_search_set();
+    }
+
+
+    /**
+     * Return message headers object of a specific message
+     *
+     * @param int     $id       Message UID
+     * @param string  $folder   Folder to read from
+     * @param bool    $force    True to skip cache
+     *
+     * @return rcube_mail_header Message headers
+     */
+    public function get_message_headers($uid, $folder = null, $force = false)
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        // get cached headers
+        if (!$force && $uid && ($mcache = $this->get_mcache_engine())) {
+            $headers = $mcache->get_message($folder, $uid);
+        }
+        else if (!$this->check_connection()) {
+            $headers = false;
+        }
+        else {
+            $headers = $this->conn->fetchHeader(
+                $folder, $uid, true, true, $this->get_fetch_headers());
+        }
+
+        return $headers;
+    }
+
+
+    /**
+     * Fetch message headers and body structure from the IMAP server and build
+     * an object structure similar to the one generated by PEAR::Mail_mimeDecode
+     *
+     * @param int     $uid      Message UID to fetch
+     * @param string  $folder   Folder to read from
+     *
+     * @return object rcube_mail_header Message data
+     */
+    public function get_message($uid, $folder = null)
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        // Check internal cache
+        if (!empty($this->icache['message'])) {
+            if (($headers = $this->icache['message']) && $headers->uid == $uid) {
+                return $headers;
+            }
+        }
+
+        $headers = $this->get_message_headers($uid, $folder);
+
+        // message doesn't exist?
+        if (empty($headers)) {
+            return null;
+        }
+
+        // structure might be cached
+        if (!empty($headers->structure)) {
+            return $headers;
+        }
+
+        $this->msg_uid = $uid;
+
+        if (!$this->check_connection()) {
+            return $headers;
+        }
+
+        if (empty($headers->bodystructure)) {
+            $headers->bodystructure = $this->conn->getStructure($folder, $uid, true);
+        }
+
+        $structure = $headers->bodystructure;
+
+        if (empty($structure)) {
+            return $headers;
+        }
+
+        // set message charset from message headers
+        if ($headers->charset) {
+            $this->struct_charset = $headers->charset;
+        }
+        else {
+            $this->struct_charset = $this->structure_charset($structure);
+        }
+
+        $headers->ctype = strtolower($headers->ctype);
+
+        // Here we can recognize malformed BODYSTRUCTURE and
+        // 1. [@TODO] parse the message in other way to create our own message structure
+        // 2. or just show the raw message body.
+        // Example of structure for malformed MIME message:
+        // ("text" "plain" NIL NIL NIL "7bit" 2154 70 NIL NIL NIL)
+        if ($headers->ctype && !is_array($structure[0]) && $headers->ctype != 'text/plain'
+            && strtolower($structure[0].'/'.$structure[1]) == 'text/plain') {
+            // we can handle single-part messages, by simple fix in structure (#1486898)
+            if (preg_match('/^(text|application)\/(.*)/', $headers->ctype, $m)) {
+                $structure[0] = $m[1];
+                $structure[1] = $m[2];
+            }
+            else {
+                return $headers;
+            }
+        }
+
+        $struct = $this->structure_part($structure, 0, '', $headers);
+
+        // don't trust given content-type
+        if (empty($struct->parts) && !empty($headers->ctype)) {
+            $struct->mime_id = '1';
+            $struct->mimetype = strtolower($headers->ctype);
+            list($struct->ctype_primary, $struct->ctype_secondary) = explode('/', $struct->mimetype);
+        }
+
+        $headers->structure = $struct;
+
+        return $this->icache['message'] = $headers;
+    }
+
+
+    /**
+     * Build message part object
+     *
+     * @param array  $part
+     * @param int    $count
+     * @param string $parent
+     */
+    protected function structure_part($part, $count=0, $parent='', $mime_headers=null)
+    {
+        $struct = new rcube_message_part;
+        $struct->mime_id = empty($parent) ? (string)$count : "$parent.$count";
+
+        // multipart
+        if (is_array($part[0])) {
+            $struct->ctype_primary = 'multipart';
+
+        /* RFC3501: BODYSTRUCTURE fields of multipart part
+            part1 array
+            part2 array
+            part3 array
+            ....
+            1. subtype
+            2. parameters (optional)
+            3. description (optional)
+            4. language (optional)
+            5. location (optional)
+        */
+
+            // find first non-array entry
+            for ($i=1; $i<count($part); $i++) {
+                if (!is_array($part[$i])) {
+                    $struct->ctype_secondary = strtolower($part[$i]);
+                    break;
+                }
+            }
+
+            $struct->mimetype = 'multipart/'.$struct->ctype_secondary;
+
+            // build parts list for headers pre-fetching
+            for ($i=0; $i<count($part); $i++) {
+                if (!is_array($part[$i])) {
+                    break;
+                }
+                // fetch message headers if message/rfc822
+                // or named part (could contain Content-Location header)
+                if (!is_array($part[$i][0])) {
+                    $tmp_part_id = $struct->mime_id ? $struct->mime_id.'.'.($i+1) : $i+1;
+                    if (strtolower($part[$i][0]) == 'message' && strtolower($part[$i][1]) == 'rfc822') {
+                        $mime_part_headers[] = $tmp_part_id;
+                    }
+                    else if (in_array('name', (array)$part[$i][2]) && empty($part[$i][3])) {
+                        $mime_part_headers[] = $tmp_part_id;
+                    }
+                }
+            }
+
+            // pre-fetch headers of all parts (in one command for better performance)
+            // @TODO: we could do this before _structure_part() call, to fetch
+            // headers for parts on all levels
+            if ($mime_part_headers) {
+                $mime_part_headers = $this->conn->fetchMIMEHeaders($this->folder,
+                    $this->msg_uid, $mime_part_headers);
+            }
+
+            $struct->parts = array();
+            for ($i=0, $count=0; $i<count($part); $i++) {
+                if (!is_array($part[$i])) {
+                    break;
+                }
+                $tmp_part_id = $struct->mime_id ? $struct->mime_id.'.'.($i+1) : $i+1;
+                $struct->parts[] = $this->structure_part($part[$i], ++$count, $struct->mime_id,
+                    $mime_part_headers[$tmp_part_id]);
+            }
+
+            return $struct;
+        }
+
+        /* RFC3501: BODYSTRUCTURE fields of non-multipart part
+            0. type
+            1. subtype
+            2. parameters
+            3. id
+            4. description
+            5. encoding
+            6. size
+          -- text
+            7. lines
+          -- message/rfc822
+            7. envelope structure
+            8. body structure
+            9. lines
+          --
+            x. md5 (optional)
+            x. disposition (optional)
+            x. language (optional)
+            x. location (optional)
+        */
+
+        // regular part
+        $struct->ctype_primary = strtolower($part[0]);
+        $struct->ctype_secondary = strtolower($part[1]);
+        $struct->mimetype = $struct->ctype_primary.'/'.$struct->ctype_secondary;
+
+        // read content type parameters
+        if (is_array($part[2])) {
+            $struct->ctype_parameters = array();
+            for ($i=0; $i<count($part[2]); $i+=2) {
+                $struct->ctype_parameters[strtolower($part[2][$i])] = $part[2][$i+1];
+            }
+
+            if (isset($struct->ctype_parameters['charset'])) {
+                $struct->charset = $struct->ctype_parameters['charset'];
+            }
+        }
+
+        // #1487700: workaround for lack of charset in malformed structure
+        if (empty($struct->charset) && !empty($mime_headers) && $mime_headers->charset) {
+            $struct->charset = $mime_headers->charset;
+        }
+
+        // read content encoding
+        if (!empty($part[5])) {
+            $struct->encoding = strtolower($part[5]);
+            $struct->headers['content-transfer-encoding'] = $struct->encoding;
+        }
+
+        // get part size
+        if (!empty($part[6])) {
+            $struct->size = intval($part[6]);
+        }
+
+        // read part disposition
+        $di = 8;
+        if ($struct->ctype_primary == 'text') {
+            $di += 1;
+        }
+        else if ($struct->mimetype == 'message/rfc822') {
+            $di += 3;
+        }
+
+        if (is_array($part[$di]) && count($part[$di]) == 2) {
+            $struct->disposition = strtolower($part[$di][0]);
+
+            if (is_array($part[$di][1])) {
+                for ($n=0; $n<count($part[$di][1]); $n+=2) {
+                    $struct->d_parameters[strtolower($part[$di][1][$n])] = $part[$di][1][$n+1];
+                }
+            }
+        }
+
+        // get message/rfc822's child-parts
+        if (is_array($part[8]) && $di != 8) {
+            $struct->parts = array();
+            for ($i=0, $count=0; $i<count($part[8]); $i++) {
+                if (!is_array($part[8][$i])) {
+                    break;
+                }
+                $struct->parts[] = $this->structure_part($part[8][$i], ++$count, $struct->mime_id);
+            }
+        }
+
+        // get part ID
+        if (!empty($part[3])) {
+            $struct->content_id = $part[3];
+            $struct->headers['content-id'] = $part[3];
+
+            if (empty($struct->disposition)) {
+                $struct->disposition = 'inline';
+            }
+        }
+
+        // fetch message headers if message/rfc822 or named part (could contain Content-Location header)
+        if ($struct->ctype_primary == 'message' || ($struct->ctype_parameters['name'] && !$struct->content_id)) {
+            if (empty($mime_headers)) {
+                $mime_headers = $this->conn->fetchPartHeader(
+                    $this->folder, $this->msg_uid, true, $struct->mime_id);
+            }
+
+            if (is_string($mime_headers)) {
+                $struct->headers = rcube_mime::parse_headers($mime_headers) + $struct->headers;
+            }
+            else if (is_object($mime_headers)) {
+                $struct->headers = get_object_vars($mime_headers) + $struct->headers;
+            }
+
+            // get real content-type of message/rfc822
+            if ($struct->mimetype == 'message/rfc822') {
+                // single-part
+                if (!is_array($part[8][0])) {
+                    $struct->real_mimetype = strtolower($part[8][0] . '/' . $part[8][1]);
+                }
+                // multi-part
+                else {
+                    for ($n=0; $n<count($part[8]); $n++) {
+                        if (!is_array($part[8][$n])) {
+                            break;
+                        }
+                    }
+                    $struct->real_mimetype = 'multipart/' . strtolower($part[8][$n]);
+                }
+            }
+
+            if ($struct->ctype_primary == 'message' && empty($struct->parts)) {
+                if (is_array($part[8]) && $di != 8) {
+                    $struct->parts[] = $this->structure_part($part[8], ++$count, $struct->mime_id);
+                }
+            }
+        }
+
+        // normalize filename property
+        $this->set_part_filename($struct, $mime_headers);
+
+        return $struct;
+    }
+
+
+    /**
+     * Set attachment filename from message part structure
+     *
+     * @param  rcube_message_part $part    Part object
+     * @param  string             $headers Part's raw headers
+     */
+    protected function set_part_filename(&$part, $headers=null)
+    {
+        if (!empty($part->d_parameters['filename'])) {
+            $filename_mime = $part->d_parameters['filename'];
+        }
+        else if (!empty($part->d_parameters['filename*'])) {
+            $filename_encoded = $part->d_parameters['filename*'];
+        }
+        else if (!empty($part->ctype_parameters['name*'])) {
+            $filename_encoded = $part->ctype_parameters['name*'];
+        }
+        // RFC2231 value continuations
+        // TODO: this should be rewrited to support RFC2231 4.1 combinations
+        else if (!empty($part->d_parameters['filename*0'])) {
+            $i = 0;
+            while (isset($part->d_parameters['filename*'.$i])) {
+                $filename_mime .= $part->d_parameters['filename*'.$i];
+                $i++;
+            }
+            // some servers (eg. dovecot-1.x) have no support for parameter value continuations
+            // we must fetch and parse headers "manually"
+            if ($i<2) {
+                if (!$headers) {
+                    $headers = $this->conn->fetchPartHeader(
+                        $this->folder, $this->msg_uid, true, $part->mime_id);
+                }
+                $filename_mime = '';
+                $i = 0;
+                while (preg_match('/filename\*'.$i.'\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
+                    $filename_mime .= $matches[1];
+                    $i++;
+                }
+            }
+        }
+        else if (!empty($part->d_parameters['filename*0*'])) {
+            $i = 0;
+            while (isset($part->d_parameters['filename*'.$i.'*'])) {
+                $filename_encoded .= $part->d_parameters['filename*'.$i.'*'];
+                $i++;
+            }
+            if ($i<2) {
+                if (!$headers) {
+                    $headers = $this->conn->fetchPartHeader(
+                            $this->folder, $this->msg_uid, true, $part->mime_id);
+                }
+                $filename_encoded = '';
+                $i = 0; $matches = array();
+                while (preg_match('/filename\*'.$i.'\*\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
+                    $filename_encoded .= $matches[1];
+                    $i++;
+                }
+            }
+        }
+        else if (!empty($part->ctype_parameters['name*0'])) {
+            $i = 0;
+            while (isset($part->ctype_parameters['name*'.$i])) {
+                $filename_mime .= $part->ctype_parameters['name*'.$i];
+                $i++;
+            }
+            if ($i<2) {
+                if (!$headers) {
+                    $headers = $this->conn->fetchPartHeader(
+                        $this->folder, $this->msg_uid, true, $part->mime_id);
+                }
+                $filename_mime = '';
+                $i = 0; $matches = array();
+                while (preg_match('/\s+name\*'.$i.'\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
+                    $filename_mime .= $matches[1];
+                    $i++;
+                }
+            }
+        }
+        else if (!empty($part->ctype_parameters['name*0*'])) {
+            $i = 0;
+            while (isset($part->ctype_parameters['name*'.$i.'*'])) {
+                $filename_encoded .= $part->ctype_parameters['name*'.$i.'*'];
+                $i++;
+            }
+            if ($i<2) {
+                if (!$headers) {
+                    $headers = $this->conn->fetchPartHeader(
+                        $this->folder, $this->msg_uid, true, $part->mime_id);
+                }
+                $filename_encoded = '';
+                $i = 0; $matches = array();
+                while (preg_match('/\s+name\*'.$i.'\*\s*=\s*"*([^"\n;]+)[";]*/', $headers, $matches)) {
+                    $filename_encoded .= $matches[1];
+                    $i++;
+                }
+            }
+        }
+        // read 'name' after rfc2231 parameters as it may contains truncated filename (from Thunderbird)
+        else if (!empty($part->ctype_parameters['name'])) {
+            $filename_mime = $part->ctype_parameters['name'];
+        }
+        // Content-Disposition
+        else if (!empty($part->headers['content-description'])) {
+            $filename_mime = $part->headers['content-description'];
+        }
+        else {
+            return;
+        }
+
+        // decode filename
+        if (!empty($filename_mime)) {
+            if (!empty($part->charset)) {
+                $charset = $part->charset;
+            }
+            else if (!empty($this->struct_charset)) {
+                $charset = $this->struct_charset;
+            }
+            else {
+                $charset = rc_detect_encoding($filename_mime, $this->default_charset);
+            }
+
+            $part->filename = rcube_mime::decode_mime_string($filename_mime, $charset);
+        }
+        else if (!empty($filename_encoded)) {
+            // decode filename according to RFC 2231, Section 4
+            if (preg_match("/^([^']*)'[^']*'(.*)$/", $filename_encoded, $fmatches)) {
+                $filename_charset = $fmatches[1];
+                $filename_encoded = $fmatches[2];
+            }
+
+            $part->filename = rcube_charset_convert(urldecode($filename_encoded), $filename_charset);
+        }
+    }
+
+
+    /**
+     * Get charset name from message structure (first part)
+     *
+     * @param  array $structure Message structure
+     *
+     * @return string Charset name
+     */
+    protected function structure_charset($structure)
+    {
+        while (is_array($structure)) {
+            if (is_array($structure[2]) && $structure[2][0] == 'charset') {
+                return $structure[2][1];
+            }
+            $structure = $structure[0];
+        }
+    }
+
+
+    /**
+     * Fetch message body of a specific message from the server
+     *
+     * @param  int                $uid    Message UID
+     * @param  string             $part   Part number
+     * @param  rcube_message_part $o_part Part object created by get_structure()
+     * @param  mixed              $print  True to print part, ressource to write part contents in
+     * @param  resource           $fp     File pointer to save the message part
+     * @param  boolean            $skip_charset_conv Disables charset conversion
+     *
+     * @return string Message/part body if not printed
+     */
+    public function get_message_part($uid, $part=1, $o_part=NULL, $print=NULL, $fp=NULL, $skip_charset_conv=false)
+    {
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        // get part data if not provided
+        if (!is_object($o_part)) {
+            $structure = $this->conn->getStructure($this->folder, $uid, true);
+            $part_data = rcube_imap_generic::getStructurePartData($structure, $part);
+
+            $o_part = new rcube_message_part;
+            $o_part->ctype_primary = $part_data['type'];
+            $o_part->encoding      = $part_data['encoding'];
+            $o_part->charset       = $part_data['charset'];
+            $o_part->size          = $part_data['size'];
+        }
+
+        if ($o_part && $o_part->size) {
+            $body = $this->conn->handlePartBody($this->folder, $uid, true,
+                $part ? $part : 'TEXT', $o_part->encoding, $print, $fp);
+        }
+
+        if ($fp || $print) {
+            return true;
+        }
+
+        // convert charset (if text or message part)
+        if ($body && preg_match('/^(text|message)$/', $o_part->ctype_primary)) {
+            // Remove NULL characters if any (#1486189)
+            if (strpos($body, "\x00") !== false) {
+                $body = str_replace("\x00", '', $body);
+            }
+
+            if (!$skip_charset_conv) {
+                if (!$o_part->charset || strtoupper($o_part->charset) == 'US-ASCII') {
+                    // try to extract charset information from HTML meta tag (#1488125)
+                    if ($o_part->ctype_secondary == 'html' && preg_match('/<meta[^>]+charset=([a-z0-9-_]+)/i', $body, $m)) {
+                        $o_part->charset = strtoupper($m[1]);
+                    }
+                    else {
+                        $o_part->charset = $this->default_charset;
+                    }
+                }
+                $body = rcube_charset_convert($body, $o_part->charset);
+            }
+        }
+
+        return $body;
+    }
+
+
+    /**
+     * Returns the whole message source as string (or saves to a file)
+     *
+     * @param int      $uid Message UID
+     * @param resource $fp  File pointer to save the message
+     *
+     * @return string Message source string
+     */
+    public function get_raw_body($uid, $fp=null)
+    {
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        return $this->conn->handlePartBody($this->folder, $uid,
+            true, null, null, false, $fp);
+    }
+
+
+    /**
+     * Returns the message headers as string
+     *
+     * @param int $uid  Message UID
+     *
+     * @return string Message headers string
+     */
+    public function get_raw_headers($uid)
+    {
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        return $this->conn->fetchPartHeader($this->folder, $uid, true);
+    }
+
+
+    /**
+     * Sends the whole message source to stdout
+     */
+    public function print_raw_body($uid)
+    {
+        if (!$this->check_connection()) {
+            return;
+        }
+
+        $this->conn->handlePartBody($this->folder, $uid, true, NULL, NULL, true);
+    }
+
+
+    /**
+     * Set message flag to one or several messages
+     *
+     * @param mixed   $uids       Message UIDs as array or comma-separated string, or '*'
+     * @param string  $flag       Flag to set: SEEN, UNDELETED, DELETED, RECENT, ANSWERED, DRAFT, MDNSENT
+     * @param string  $folder    Folder name
+     * @param boolean $skip_cache True to skip message cache clean up
+     *
+     * @return boolean  Operation status
+     */
+    public function set_flag($uids, $flag, $folder=null, $skip_cache=false)
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        $flag = strtoupper($flag);
+        list($uids, $all_mode) = $this->parse_uids($uids);
+
+        if (strpos($flag, 'UN') === 0) {
+            $result = $this->conn->unflag($folder, $uids, substr($flag, 2));
+        }
+        else {
+            $result = $this->conn->flag($folder, $uids, $flag);
+        }
+
+        if ($result) {
+            // reload message headers if cached
+            // @TODO: update flags instead removing from cache
+            if (!$skip_cache && ($mcache = $this->get_mcache_engine())) {
+                $status = strpos($flag, 'UN') !== 0;
+                $mflag  = preg_replace('/^UN/', '', $flag);
+                $mcache->change_flag($folder, $all_mode ? null : explode(',', $uids),
+                    $mflag, $status);
+            }
+
+            // clear cached counters
+            if ($flag == 'SEEN' || $flag == 'UNSEEN') {
+                $this->clear_messagecount($folder, 'SEEN');
+                $this->clear_messagecount($folder, 'UNSEEN');
+            }
+            else if ($flag == 'DELETED') {
+                $this->clear_messagecount($folder, 'DELETED');
+            }
+        }
+
+        return $result;
+    }
+
+
+    /**
+     * Append a mail message (source) to a specific folder
+     *
+     * @param string  $folder  Target folder
+     * @param string  $message The message source string or filename
+     * @param string  $headers Headers string if $message contains only the body
+     * @param boolean $is_file True if $message is a filename
+     *
+     * @return int|bool Appended message UID or True on success, False on error
+     */
+    public function save_message($folder, &$message, $headers='', $is_file=false)
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        // make sure folder exists
+        if ($this->folder_exists($folder)) {
+            if ($is_file) {
+                $saved = $this->conn->appendFromFile($folder, $message, $headers);
+            }
+            else {
+                $saved = $this->conn->append($folder, $message);
+            }
+        }
+
+        if ($saved) {
+            // increase messagecount of the target folder
+            $this->set_messagecount($folder, 'ALL', 1);
+        }
+
+        return $saved;
+    }
+
+
+    /**
+     * Move a message from one folder to another
+     *
+     * @param mixed  $uids      Message UIDs as array or comma-separated string, or '*'
+     * @param string $to_mbox   Target folder
+     * @param string $from_mbox Source folder
+     *
+     * @return boolean True on success, False on error
+     */
+    public function move_message($uids, $to_mbox, $from_mbox='')
+    {
+        if (!strlen($from_mbox)) {
+            $from_mbox = $this->folder;
+        }
+
+        if ($to_mbox === $from_mbox) {
+            return false;
+        }
+
+        list($uids, $all_mode) = $this->parse_uids($uids);
+
+        // exit if no message uids are specified
+        if (empty($uids)) {
+            return false;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        // make sure folder exists
+        if ($to_mbox != 'INBOX' && !$this->folder_exists($to_mbox)) {
+            if (in_array($to_mbox, $this->default_folders)) {
+                if (!$this->create_folder($to_mbox, true)) {
+                    return false;
+                }
+            }
+            else {
+                return false;
+            }
+        }
+
+        $config = rcmail::get_instance()->config;
+        $to_trash = $to_mbox == $config->get('trash_mbox');
+
+        // flag messages as read before moving them
+        if ($to_trash && $config->get('read_when_deleted')) {
+            // don't flush cache (4th argument)
+            $this->set_flag($uids, 'SEEN', $from_mbox, true);
+        }
+
+        // move messages
+        $moved = $this->conn->move($uids, $from_mbox, $to_mbox);
+
+        // send expunge command in order to have the moved message
+        // really deleted from the source folder
+        if ($moved) {
+            $this->expunge_message($uids, $from_mbox, false);
+            $this->clear_messagecount($from_mbox);
+            $this->clear_messagecount($to_mbox);
+        }
+        // moving failed
+        else if ($to_trash && $config->get('delete_always', false)) {
+            $moved = $this->delete_message($uids, $from_mbox);
+        }
+
+        if ($moved) {
+            // unset threads internal cache
+            unset($this->icache['threads']);
+
+            // remove message ids from search set
+            if ($this->search_set && $from_mbox == $this->folder) {
+                // threads are too complicated to just remove messages from set
+                if ($this->search_threads || $all_mode) {
+                    $this->refresh_search();
+                }
+                else {
+                    $this->search_set->filter(explode(',', $uids));
+                }
+            }
+
+            // remove cached messages
+            // @TODO: do cache update instead of clearing it
+            $this->clear_message_cache($from_mbox, $all_mode ? null : explode(',', $uids));
+        }
+
+        return $moved;
+    }
+
+
+    /**
+     * Copy a message from one folder to another
+     *
+     * @param mixed  $uids      Message UIDs as array or comma-separated string, or '*'
+     * @param string $to_mbox   Target folder
+     * @param string $from_mbox Source folder
+     *
+     * @return boolean True on success, False on error
+     */
+    public function copy_message($uids, $to_mbox, $from_mbox='')
+    {
+        if (!strlen($from_mbox)) {
+            $from_mbox = $this->folder;
+        }
+
+        list($uids, $all_mode) = $this->parse_uids($uids);
+
+        // exit if no message uids are specified
+        if (empty($uids)) {
+            return false;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        // make sure folder exists
+        if ($to_mbox != 'INBOX' && !$this->folder_exists($to_mbox)) {
+            if (in_array($to_mbox, $this->default_folders)) {
+                if (!$this->create_folder($to_mbox, true)) {
+                    return false;
+                }
+            }
+            else {
+                return false;
+            }
+        }
+
+        // copy messages
+        $copied = $this->conn->copy($uids, $from_mbox, $to_mbox);
+
+        if ($copied) {
+            $this->clear_messagecount($to_mbox);
+        }
+
+        return $copied;
+    }
+
+
+    /**
+     * Mark messages as deleted and expunge them
+     *
+     * @param mixed  $uids    Message UIDs as array or comma-separated string, or '*'
+     * @param string $folder  Source folder
+     *
+     * @return boolean True on success, False on error
+     */
+    public function delete_message($uids, $folder='')
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        list($uids, $all_mode) = $this->parse_uids($uids);
+
+        // exit if no message uids are specified
+        if (empty($uids)) {
+            return false;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        $deleted = $this->conn->flag($folder, $uids, 'DELETED');
+
+        if ($deleted) {
+            // send expunge command in order to have the deleted message
+            // really deleted from the folder
+            $this->expunge_message($uids, $folder, false);
+            $this->clear_messagecount($folder);
+            unset($this->uid_id_map[$folder]);
+
+            // unset threads internal cache
+            unset($this->icache['threads']);
+
+            // remove message ids from search set
+            if ($this->search_set && $folder == $this->folder) {
+                // threads are too complicated to just remove messages from set
+                if ($this->search_threads || $all_mode) {
+                    $this->refresh_search();
+                }
+                else {
+                    $this->search_set->filter(explode(',', $uids));
+                }
+            }
+
+            // remove cached messages
+            $this->clear_message_cache($folder, $all_mode ? null : explode(',', $uids));
+        }
+
+        return $deleted;
+    }
+
+
+    /**
+     * Send IMAP expunge command and clear cache
+     *
+     * @param mixed   $uids        Message UIDs as array or comma-separated string, or '*'
+     * @param string  $folder      Folder name
+     * @param boolean $clear_cache False if cache should not be cleared
+     *
+     * @return boolean True on success, False on failure
+     */
+    public function expunge_message($uids, $folder = null, $clear_cache = true)
+    {
+        if ($uids && $this->get_capability('UIDPLUS')) {
+            list($uids, $all_mode) = $this->parse_uids($uids);
+        }
+        else {
+            $uids = null;
+        }
+
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        // force folder selection and check if folder is writeable
+        // to prevent a situation when CLOSE is executed on closed
+        // or EXPUNGE on read-only folder
+        $result = $this->conn->select($folder);
+        if (!$result) {
+            return false;
+        }
+
+        if (!$this->conn->data['READ-WRITE']) {
+            $this->conn->setError(rcube_imap_generic::ERROR_READONLY, "Folder is read-only");
+            return false;
+        }
+
+        // CLOSE(+SELECT) should be faster than EXPUNGE
+        if (empty($uids) || $all_mode) {
+            $result = $this->conn->close();
+        }
+        else {
+            $result = $this->conn->expunge($folder, $uids);
+        }
+
+        if ($result && $clear_cache) {
+            $this->clear_message_cache($folder, $all_mode ? null : explode(',', $uids));
+            $this->clear_messagecount($folder);
+        }
+
+        return $result;
+    }
+
+
+    /* --------------------------------
+     *        folder managment
+     * --------------------------------*/
+
+    /**
+     * Public method for listing subscribed folders.
+     *
+     * @param   string  $root      Optional root folder
+     * @param   string  $name      Optional name pattern
+     * @param   string  $filter    Optional filter
+     * @param   string  $rights    Optional ACL requirements
+     * @param   bool    $skip_sort Enable to return unsorted list (for better performance)
+     *
+     * @return  array   List of folders
+     */
+    public function list_folders_subscribed($root='', $name='*', $filter=null, $rights=null, $skip_sort=false)
+    {
+        $cache_key = $root.':'.$name;
+        if (!empty($filter)) {
+            $cache_key .= ':'.(is_string($filter) ? $filter : serialize($filter));
+        }
+        $cache_key .= ':'.$rights;
+        $cache_key = 'mailboxes.'.md5($cache_key);
+
+        // get cached folder list
+        $a_mboxes = $this->get_cache($cache_key);
+        if (is_array($a_mboxes)) {
+            return $a_mboxes;
+        }
+
+        $a_mboxes = $this->_list_folders_subscribed($root, $name, $filter, $rights);
+
+        if (!is_array($a_mboxes)) {
+            return array();
+        }
+
+        // filter folders list according to rights requirements
+        if ($rights && $this->get_capability('ACL')) {
+            $a_mboxes = $this->filter_rights($a_mboxes, $rights);
+        }
+
+        // INBOX should always be available
+        if ((!$filter || $filter == 'mail') && !in_array('INBOX', $a_mboxes)) {
+            array_unshift($a_mboxes, 'INBOX');
+        }
+
+        // sort folders (always sort for cache)
+        if (!$skip_sort || $this->cache) {
+            $a_mboxes = $this->sort_folder_list($a_mboxes);
+        }
+
+        // write folders list to cache
+        $this->update_cache($cache_key, $a_mboxes);
+
+        return $a_mboxes;
+    }
+
+
+    /**
+     * protected method for folders listing (LSUB)
+     *
+     * @param   string  $root   Optional root folder
+     * @param   string  $name   Optional name pattern
+     * @param   mixed   $filter Optional filter
+     * @param   string  $rights Optional ACL requirements
+     *
+     * @return  array   List of subscribed folders
+     * @see     rcube_imap::list_folders_subscribed()
+     */
+    protected function _list_folders_subscribed($root='', $name='*', $filter=null, $rights=null)
+    {
+        $a_defaults = $a_out = array();
+
+        // Give plugins a chance to provide a list of folders
+        $data = rcmail::get_instance()->plugins->exec_hook('storage_folders',
+            array('root' => $root, 'name' => $name, 'filter' => $filter, 'mode' => 'LSUB'));
+
+        if (isset($data['folders'])) {
+            $a_folders = $data['folders'];
+        }
+        else if (!$this->check_connection()) {
+           return null;
+        }
+        else {
+            // Server supports LIST-EXTENDED, we can use selection options
+            $config = rcmail::get_instance()->config;
+            // #1486225: Some dovecot versions returns wrong result using LIST-EXTENDED
+            if (!$config->get('imap_force_lsub') && $this->get_capability('LIST-EXTENDED')) {
+                // This will also set folder options, LSUB doesn't do that
+                $a_folders = $this->conn->listMailboxes($root, $name,
+                    NULL, array('SUBSCRIBED'));
+
+                // unsubscribe non-existent folders, remove from the list
+                // we can do this only when LIST response is available
+                if (is_array($a_folders) && $name == '*' && !empty($this->conn->data['LIST'])) {
+                    foreach ($a_folders as $idx => $folder) {
+                        if (($opts = $this->conn->data['LIST'][$folder])
+                            && in_array('\\NonExistent', $opts)
+                        ) {
+                            $this->conn->unsubscribe($folder);
+                            unset($a_folders[$idx]);
+                        }
+                    }
+                }
+            }
+            // retrieve list of folders from IMAP server using LSUB
+            else {
+                $a_folders = $this->conn->listSubscribed($root, $name);
+
+                // unsubscribe non-existent folders, remove them from the list,
+                // we can do this only when LIST response is available
+                if (is_array($a_folders) && $name == '*' && !empty($this->conn->data['LIST'])) {
+                    foreach ($a_folders as $idx => $folder) {
+                        if (!isset($this->conn->data['LIST'][$folder])
+                            || in_array('\\Noselect', $this->conn->data['LIST'][$folder])
+                        ) {
+                            // Some servers returns \Noselect for existing folders
+                            if (!$this->folder_exists($folder)) {
+                                $this->conn->unsubscribe($folder);
+                                unset($a_folders[$idx]);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        if (!is_array($a_folders) || !sizeof($a_folders)) {
+            $a_folders = array();
+        }
+
+        return $a_folders;
+    }
+
+
+    /**
+     * Get a list of all folders available on the server
+     *
+     * @param string  $root      IMAP root dir
+     * @param string  $name      Optional name pattern
+     * @param mixed   $filter    Optional filter
+     * @param string  $rights    Optional ACL requirements
+     * @param bool    $skip_sort Enable to return unsorted list (for better performance)
+     *
+     * @return array Indexed array with folder names
+     */
+    public function list_folders($root='', $name='*', $filter=null, $rights=null, $skip_sort=false)
+    {
+        $cache_key = $root.':'.$name;
+        if (!empty($filter)) {
+            $cache_key .= ':'.(is_string($filter) ? $filter : serialize($filter));
+        }
+        $cache_key .= ':'.$rights;
+        $cache_key = 'mailboxes.list.'.md5($cache_key);
+
+        // get cached folder list
+        $a_mboxes = $this->get_cache($cache_key);
+        if (is_array($a_mboxes)) {
+            return $a_mboxes;
+        }
+
+        // Give plugins a chance to provide a list of folders
+        $data = rcmail::get_instance()->plugins->exec_hook('storage_folders',
+            array('root' => $root, 'name' => $name, 'filter' => $filter, 'mode' => 'LIST'));
+
+        if (isset($data['folders'])) {
+            $a_mboxes = $data['folders'];
+        }
+        else {
+            // retrieve list of folders from IMAP server
+            $a_mboxes = $this->_list_folders($root, $name);
+        }
+
+        if (!is_array($a_mboxes)) {
+            $a_mboxes = array();
+        }
+
+        // INBOX should always be available
+        if ((!$filter || $filter == 'mail') && !in_array('INBOX', $a_mboxes)) {
+            array_unshift($a_mboxes, 'INBOX');
+        }
+
+        // cache folder attributes
+        if ($root == '' && $name == '*' && empty($filter) && !empty($this->conn->data)) {
+            $this->update_cache('mailboxes.attributes', $this->conn->data['LIST']);
+        }
+
+        // filter folders list according to rights requirements
+        if ($rights && $this->get_capability('ACL')) {
+            $a_folders = $this->filter_rights($a_folders, $rights);
+        }
+
+        // filter folders and sort them
+        if (!$skip_sort) {
+            $a_mboxes = $this->sort_folder_list($a_mboxes);
+        }
+
+        // write folders list to cache
+        $this->update_cache($cache_key, $a_mboxes);
+
+        return $a_mboxes;
+    }
+
+
+    /**
+     * protected method for folders listing (LIST)
+     *
+     * @param   string  $root   Optional root folder
+     * @param   string  $name   Optional name pattern
+     *
+     * @return  array   List of folders
+     * @see     rcube_imap::list_folders()
+     */
+    protected function _list_folders($root='', $name='*')
+    {
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        $result = $this->conn->listMailboxes($root, $name);
+
+        if (!is_array($result)) {
+            return array();
+        }
+
+        // #1486796: some server configurations doesn't
+        // return folders in all namespaces, we'll try to detect that situation
+        // and ask for these namespaces separately
+        if ($root == '' && $name == '*') {
+            $delim     = $this->get_hierarchy_delimiter();
+            $namespace = $this->get_namespace();
+            $search    = array();
+
+            // build list of namespace prefixes
+            foreach ((array)$namespace as $ns) {
+                if (is_array($ns)) {
+                    foreach ($ns as $ns_data) {
+                        if (strlen($ns_data[0])) {
+                            $search[] = $ns_data[0];
+                        }
+                    }
+                }
+            }
+
+            if (!empty($search)) {
+                // go through all folders detecting namespace usage
+                foreach ($result as $folder) {
+                    foreach ($search as $idx => $prefix) {
+                        if (strpos($folder, $prefix) === 0) {
+                            unset($search[$idx]);
+                        }
+                    }
+                    if (empty($search)) {
+                        break;
+                    }
+                }
+
+                // get folders in hidden namespaces and add to the result
+                foreach ($search as $prefix) {
+                    $list = $this->conn->listMailboxes($prefix, $name);
+
+                    if (!empty($list)) {
+                        $result = array_merge($result, $list);
+                    }
+                }
+            }
+        }
+
+        return $result;
+    }
+
+
+    /**
+     * Filter the given list of folders according to access rights
+     */
+    protected function filter_rights($a_folders, $rights)
+    {
+        $regex = '/('.$rights.')/';
+        foreach ($a_folders as $idx => $folder) {
+            $myrights = join('', (array)$this->my_rights($folder));
+            if ($myrights !== null && !preg_match($regex, $myrights)) {
+                unset($a_folders[$idx]);
+            }
+        }
+
+        return $a_folders;
+    }
+
+
+    /**
+     * Get mailbox quota information
+     * added by Nuny
+     *
+     * @return mixed Quota info or False if not supported
+     */
+    public function get_quota()
+    {
+        if ($this->get_capability('QUOTA') && $this->check_connection()) {
+            return $this->conn->getQuota();
+        }
+
         return false;
-
-      $part_type = iml_GetPartTypeCode($structure, $part);
-      $o_part = new rcube_message_part;
-      $o_part->ctype_primary = $part_type==0 ? 'text' : ($part_type==2 ? 'message' : 'other');
-      $o_part->encoding = strtolower(iml_GetPartEncodingString($structure, $part));
-      $o_part->charset = iml_GetPartCharset($structure, $part);
-      }
-      
-    // TODO: Add caching for message parts
-
-    if (!$part) $part = 'TEXT';
-
-    $body = iil_C_HandlePartBody($this->conn, $this->mailbox, $uid, true, $part,
-        $o_part->encoding, $print, $fp);
-
-    if ($fp || $print)
-      return true;
-
-    // convert charset (if text or message part)
-    if ($o_part->ctype_primary=='text' || $o_part->ctype_primary=='message') {
-      // assume default if no charset specified
-      if (empty($o_part->charset) || strtolower($o_part->charset) == 'us-ascii')
-        $o_part->charset = $this->default_charset;
-
-      $body = rcube_charset_convert($body, $o_part->charset);
-      }
-    
-    return $body;
     }
 
 
-  /**
-   * Fetch message body of a specific message from the server
-   *
-   * @param  int    Message UID
-   * @return string Message/part body
-   * @see    rcube_imap::get_message_part()
-   */
-  function &get_body($uid, $part=1)
+    /**
+     * Get folder size (size of all messages in a folder)
+     *
+     * @param string $folder Folder name
+     *
+     * @return int Folder size in bytes, False on error
+     */
+    public function folder_size($folder)
     {
-    $headers = $this->get_headers($uid);
-    return rcube_charset_convert($this->get_message_part($uid, $part, NULL),
-      $headers->charset ? $headers->charset : $this->default_charset);
-    }
-
-
-  /**
-   * Returns the whole message source as string
-   *
-   * @param int  Message UID
-   * @return string Message source string
-   */
-  function &get_raw_body($uid)
-    {
-    return iil_C_HandlePartBody($this->conn, $this->mailbox, $uid, true);
-    }
-
-
-  /**
-   * Returns the message headers as string
-   *
-   * @param int  Message UID
-   * @return string Message headers string
-   */
-  function &get_raw_headers($uid)
-    {
-    return iil_C_FetchPartHeader($this->conn, $this->mailbox, $uid, true);
-    }
-    
-
-  /**
-   * Sends the whole message source to stdout
-   *
-   * @param int  Message UID
-   */ 
-  function print_raw_body($uid)
-    {
-    iil_C_HandlePartBody($this->conn, $this->mailbox, $uid, true, NULL, NULL, true);
-    }
-
-
-  /**
-   * Set message flag to one or several messages
-   *
-   * @param mixed  Message UIDs as array or as comma-separated string
-   * @param string Flag to set: SEEN, UNDELETED, DELETED, RECENT, ANSWERED, DRAFT, MDNSENT
-   * @param string Folder name
-   * @param boolean True to skip message cache clean up
-   * @return boolean True on success, False on failure
-   */
-  function set_flag($uids, $flag, $mbox_name=NULL, $skip_cache=false)
-    {
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-
-    $flag = strtoupper($flag);
-    if (!is_array($uids))
-      $uids = explode(',',$uids);
-      
-    if (strpos($flag, 'UN') === 0)
-      $result = iil_C_UnFlag($this->conn, $mailbox, join(',', $uids), substr($flag, 2));
-    else
-      $result = iil_C_Flag($this->conn, $mailbox, join(',', $uids), $flag);
-
-    // reload message headers if cached
-    if ($this->caching_enabled && !$skip_cache) {
-      $cache_key = $mailbox.'.msg';
-      $this->remove_message_cache($cache_key, $uids);
-      }
-
-    // set nr of messages that were flaged
-    $count = count($uids);
-
-    // clear message count cache
-    if ($result && $flag=='SEEN')
-      $this->_set_messagecount($mailbox, 'UNSEEN', $count*(-1));
-    else if ($result && $flag=='UNSEEN')
-      $this->_set_messagecount($mailbox, 'UNSEEN', $count);
-    else if ($result && $flag=='DELETED')
-      $this->_set_messagecount($mailbox, 'ALL', $count*(-1));
-
-    return $result;
-    }
-
-
-  /**
-   * Remove message flag for one or several messages
-   *
-   * @param mixed  Message UIDs as array or as comma-separated string
-   * @param string Flag to unset: SEEN, DELETED, RECENT, ANSWERED, DRAFT, MDNSENT
-   * @param string Folder name
-   * @return boolean True on success, False on failure
-   * @see set_flag
-   */
-  function unset_flag($uids, $flag, $mbox_name=NULL)
-    {
-    return $this->set_flag($uids, 'UN'.$flag, $mbox_name);
-    }
-
-
-  /**
-   * Append a mail message (source) to a specific mailbox
-   *
-   * @param string   Target mailbox
-   * @param string   The message source string or filename
-   * @param string   Headers string if $message contains only the body
-   * @param boolean  True if $message is a filename
-   *
-   * @return boolean True on success, False on error
-   */
-  function save_message($mbox_name, &$message, $headers='', $is_file=false)
-    {
-    $mailbox = $this->mod_mailbox($mbox_name);
-
-    // make sure mailbox exists
-    if (($mailbox == 'INBOX') || in_array($mailbox, $this->_list_mailboxes())) {
-      if ($is_file) {
-        $separator = rcmail::get_instance()->config->header_delimiter();
-        $saved = iil_C_AppendFromFile($this->conn, $mailbox, $message,
-          $headers, $separator.$separator);
+        if (!$this->check_connection()) {
+            return 0;
         }
-      else
-        $saved = iil_C_Append($this->conn, $mailbox, $message);
-      }
 
-    if ($saved)
-      {
-      // increase messagecount of the target mailbox
-      $this->_set_messagecount($mailbox, 'ALL', 1);
-      }
-          
-    return $saved;
-    }
+        // @TODO: could we try to use QUOTA here?
+        $result = $this->conn->fetchHeaderIndex($folder, '1:*', 'SIZE', false);
 
-
-  /**
-   * Move a message from one mailbox to another
-   *
-   * @param string List of UIDs to move, separated by comma
-   * @param string Target mailbox
-   * @param string Source mailbox
-   * @return boolean True on success, False on error
-   */
-  function move_message($uids, $to_mbox, $from_mbox='')
-    {
-    $fbox = $from_mbox;
-    $tbox = $to_mbox;
-    $to_mbox = $this->mod_mailbox($to_mbox);
-    $from_mbox = $from_mbox ? $this->mod_mailbox($from_mbox) : $this->mailbox;
-
-    // make sure mailbox exists
-    if ($to_mbox != 'INBOX' && !in_array($to_mbox, $this->_list_mailboxes()))
-      {
-      if (in_array($tbox, $this->default_folders))
-        $this->create_mailbox($tbox, TRUE);
-      else
-        return FALSE;
-      }
-
-    // convert the list of uids to array
-    $a_uids = is_string($uids) ? explode(',', $uids) : (is_array($uids) ? $uids : NULL);
-
-    // exit if no message uids are specified
-    if (!is_array($a_uids) || empty($a_uids))
-      return false;
-
-    // flag messages as read before moving them
-    $config = rcmail::get_instance()->config;
-    if ($config->get('read_when_deleted') && $tbox == $config->get('trash_mbox')) {
-      // don't flush cache (4th argument)
-      $this->set_flag($uids, 'SEEN', $fbox, true);
-      }
-
-    // move messages
-    $iil_move = iil_C_Move($this->conn, join(',', $a_uids), $from_mbox, $to_mbox);
-    $moved = !($iil_move === false || $iil_move < 0);
-    
-    // send expunge command in order to have the moved message
-    // really deleted from the source mailbox
-    if ($moved) {
-      $this->_expunge($from_mbox, FALSE, $a_uids);
-      $this->_clear_messagecount($from_mbox);
-      $this->_clear_messagecount($to_mbox);
-    }
-    // moving failed
-    else if (rcmail::get_instance()->config->get('delete_always', false)) {
-      return iil_C_Delete($this->conn, $from_mbox, join(',', $a_uids));
-    }
-
-    // remove message ids from search set
-    if ($moved && $this->search_set && $from_mbox == $this->mailbox) {
-      foreach ($a_uids as $uid)
-        $a_mids[] = $this->_uid2id($uid, $from_mbox);
-      $this->search_set = array_diff($this->search_set, $a_mids);
-    }
-
-    // update cached message headers
-    $cache_key = $from_mbox.'.msg';
-    if ($moved && $start_index = $this->get_message_cache_index_min($cache_key, $a_uids)) {
-      // clear cache from the lowest index on
-      $this->clear_message_cache($cache_key, $start_index);
-      }
-
-    return $moved;
-    }
-
-
-  /**
-   * Mark messages as deleted and expunge mailbox
-   *
-   * @param string List of UIDs to move, separated by comma
-   * @param string Source mailbox
-   * @return boolean True on success, False on error
-   */
-  function delete_message($uids, $mbox_name='')
-    {
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-
-    // convert the list of uids to array
-    $a_uids = is_string($uids) ? explode(',', $uids) : (is_array($uids) ? $uids : NULL);
-    
-    // exit if no message uids are specified
-    if (!is_array($a_uids) || empty($a_uids))
-      return false;
-
-    $deleted = iil_C_Delete($this->conn, $mailbox, join(',', $a_uids));
-
-    // send expunge command in order to have the deleted message
-    // really deleted from the mailbox
-    if ($deleted)
-      {
-      $this->_expunge($mailbox, FALSE, $a_uids);
-      $this->_clear_messagecount($mailbox);
-      unset($this->uid_id_map[$mailbox]);
-      }
-
-    // remove message ids from search set
-    if ($deleted && $this->search_set && $mailbox == $this->mailbox) {
-      foreach ($a_uids as $uid)
-        $a_mids[] = $this->_uid2id($uid, $mailbox);
-      $this->search_set = array_diff($this->search_set, $a_mids);
-    }
-
-    // remove deleted messages from cache
-    $cache_key = $mailbox.'.msg';
-    if ($deleted && $start_index = $this->get_message_cache_index_min($cache_key, $a_uids)) {
-      // clear cache from the lowest index on
-      $this->clear_message_cache($cache_key, $start_index);
-      }
-
-    return $deleted;
-    }
-
-
-  /**
-   * Clear all messages in a specific mailbox
-   *
-   * @param string Mailbox name
-   * @return int Above 0 on success
-   */
-  function clear_mailbox($mbox_name=NULL)
-    {
-    $mailbox = !empty($mbox_name) ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-    $msg_count = $this->_messagecount($mailbox, 'ALL');
-    
-    if ($msg_count>0)
-      {
-      $cleared = iil_C_ClearFolder($this->conn, $mailbox);
-      
-      // make sure the message count cache is cleared as well
-      if ($cleared)
-        {
-        $this->clear_message_cache($mailbox.'.msg');      
-        $a_mailbox_cache = $this->get_cache('messagecount');
-        unset($a_mailbox_cache[$mailbox]);
-        $this->update_cache('messagecount', $a_mailbox_cache);
+        if (is_array($result)) {
+            $result = array_sum($result);
         }
-        
-      return $cleared;
-      }
-    else
-      return 0;
+
+        return $result;
     }
 
 
-  /**
-   * Send IMAP expunge command and clear cache
-   *
-   * @param string Mailbox name
-   * @param boolean False if cache should not be cleared
-   * @return boolean True on success
-   */
-  function expunge($mbox_name='', $clear_cache=TRUE)
+    /**
+     * Subscribe to a specific folder(s)
+     *
+     * @param array $folders Folder name(s)
+     *
+     * @return boolean True on success
+     */
+    public function subscribe($folders)
     {
-    $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-    return $this->_expunge($mailbox, $clear_cache);
+        // let this common function do the main work
+        return $this->change_subscription($folders, 'subscribe');
     }
 
 
-  /**
-   * Send IMAP expunge command and clear cache
-   *
-   * @see rcube_imap::expunge()
-   * @param string 	Mailbox name
-   * @param boolean 	False if cache should not be cleared
-   * @param string 	List of UIDs to remove, separated by comma
-   * @return boolean True on success
-   * @access private
-   */
-  private function _expunge($mailbox, $clear_cache=TRUE, $uids=NULL)
+    /**
+     * Unsubscribe folder(s)
+     *
+     * @param array $a_mboxes Folder name(s)
+     *
+     * @return boolean True on success
+     */
+    public function unsubscribe($folders)
     {
-    if ($uids && $this->get_capability('UIDPLUS')) 
-      $a_uids = is_array($uids) ? join(',', $uids) : $uids;
-    else
-      $a_uids = NULL;
-
-    $result = iil_C_Expunge($this->conn, $mailbox, $a_uids);
-
-    if ($result>=0 && $clear_cache)
-      {
-      $this->clear_message_cache($mailbox.'.msg');
-      $this->_clear_messagecount($mailbox);
-      }
-      
-    return $result;
+        // let this common function do the main work
+        return $this->change_subscription($folders, 'unsubscribe');
     }
 
 
-  /* --------------------------------
-   *        folder managment
-   * --------------------------------*/
-
-
-  /**
-   * Get a list of all folders available on the IMAP server
-   * 
-   * @param string IMAP root dir
-   * @return array Indexed array with folder names
-   */
-  function list_unsubscribed($root='')
+    /**
+     * Create a new folder on the server and register it in local cache
+     *
+     * @param string  $folder    New folder name
+     * @param boolean $subscribe True if the new folder should be subscribed
+     *
+     * @return boolean True on success
+     */
+    public function create_folder($folder, $subscribe=false)
     {
-    static $sa_unsubscribed;
-    
-    if (is_array($sa_unsubscribed))
-      return $sa_unsubscribed;
-      
-    // retrieve list of folders from IMAP server
-    $a_mboxes = iil_C_ListMailboxes($this->conn, $this->mod_mailbox($root), '*');
+        if (!$this->check_connection()) {
+            return false;
+        }
 
-    // modify names with root dir
-    foreach ($a_mboxes as $mbox_name)
-      {
-      $name = $this->mod_mailbox($mbox_name, 'out');
-      if (strlen($name))
-        $a_folders[] = $name;
-      }
+        $result = $this->conn->createFolder($folder);
 
-    // filter folders and sort them
-    $sa_unsubscribed = $this->_sort_mailbox_list($a_folders);
-    return $sa_unsubscribed;
+        // try to subscribe it
+        if ($result) {
+            // clear cache
+            $this->clear_cache('mailboxes', true);
+
+            if ($subscribe) {
+                $this->subscribe($folder);
+            }
+        }
+
+        return $result;
     }
 
 
-  /**
-   * Get mailbox quota information
-   * added by Nuny
-   * 
-   * @return mixed Quota info or False if not supported
-   */
-  function get_quota()
+    /**
+     * Set a new name to an existing folder
+     *
+     * @param string $folder   Folder to rename
+     * @param string $new_name New folder name
+     *
+     * @return boolean True on success
+     */
+    public function rename_folder($folder, $new_name)
     {
-    if ($this->get_capability('QUOTA'))
-      return iil_C_GetQuota($this->conn);
-	
-    return FALSE;
+        if (!strlen($new_name)) {
+            return false;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        $delm = $this->get_hierarchy_delimiter();
+
+        // get list of subscribed folders
+        if ((strpos($folder, '%') === false) && (strpos($folder, '*') === false)) {
+            $a_subscribed = $this->_list_folders_subscribed('', $folder . $delm . '*');
+            $subscribed   = $this->folder_exists($folder, true);
+        }
+        else {
+            $a_subscribed = $this->_list_folders_subscribed();
+            $subscribed   = in_array($folder, $a_subscribed);
+        }
+
+        $result = $this->conn->renameFolder($folder, $new_name);
+
+        if ($result) {
+            // unsubscribe the old folder, subscribe the new one
+            if ($subscribed) {
+                $this->conn->unsubscribe($folder);
+                $this->conn->subscribe($new_name);
+            }
+
+            // check if folder children are subscribed
+            foreach ($a_subscribed as $c_subscribed) {
+                if (strpos($c_subscribed, $folder.$delm) === 0) {
+                    $this->conn->unsubscribe($c_subscribed);
+                    $this->conn->subscribe(preg_replace('/^'.preg_quote($folder, '/').'/',
+                        $new_name, $c_subscribed));
+
+                    // clear cache
+                    $this->clear_message_cache($c_subscribed);
+                }
+            }
+
+            // clear cache
+            $this->clear_message_cache($folder);
+            $this->clear_cache('mailboxes', true);
+        }
+
+        return $result;
     }
 
 
-  /**
-   * Subscribe to a specific mailbox(es)
-   *
-   * @param array Mailbox name(s)
-   * @return boolean True on success
-   */ 
-  function subscribe($a_mboxes)
+    /**
+     * Remove folder from server
+     *
+     * @param string $folder Folder name
+     *
+     * @return boolean True on success
+     */
+    function delete_folder($folder)
     {
-    if (!is_array($a_mboxes))
-      $a_mboxes = array($a_mboxes);
+        $delm = $this->get_hierarchy_delimiter();
 
-    // let this common function do the main work
-    return $this->_change_subscription($a_mboxes, 'subscribe');
-    }
+        if (!$this->check_connection()) {
+            return false;
+        }
 
-
-  /**
-   * Unsubscribe mailboxes
-   *
-   * @param array Mailbox name(s)
-   * @return boolean True on success
-   */
-  function unsubscribe($a_mboxes)
-    {
-    if (!is_array($a_mboxes))
-      $a_mboxes = array($a_mboxes);
-
-    // let this common function do the main work
-    return $this->_change_subscription($a_mboxes, 'unsubscribe');
-    }
-
-
-  /**
-   * Create a new mailbox on the server and register it in local cache
-   *
-   * @param string  New mailbox name (as utf-7 string)
-   * @param boolean True if the new mailbox should be subscribed
-   * @param string  Name of the created mailbox, false on error
-   */
-  function create_mailbox($name, $subscribe=FALSE)
-    {
-    $result = FALSE;
-    
-    // reduce mailbox name to 100 chars
-    $name = substr($name, 0, 100);
-
-    $abs_name = $this->mod_mailbox($name);
-    $a_mailbox_cache = $this->get_cache('mailboxes');
-
-    if (strlen($abs_name) && (!is_array($a_mailbox_cache) || !in_array($abs_name, $a_mailbox_cache)))
-      $result = iil_C_CreateFolder($this->conn, $abs_name);
-
-    // try to subscribe it
-    if ($result && $subscribe)
-      $this->subscribe($name);
-
-    return $result ? $name : FALSE;
-    }
-
-
-  /**
-   * Set a new name to an existing mailbox
-   *
-   * @param string Mailbox to rename (as utf-7 string)
-   * @param string New mailbox name (as utf-7 string)
-   * @return string Name of the renames mailbox, False on error
-   */
-  function rename_mailbox($mbox_name, $new_name)
-    {
-    $result = FALSE;
-
-    // encode mailbox name and reduce it to 100 chars
-    $name = substr($new_name, 0, 100);
-
-    // make absolute path
-    $mailbox = $this->mod_mailbox($mbox_name);
-    $abs_name = $this->mod_mailbox($name);
-    
-    // check if mailbox is subscribed
-    $a_subscribed = $this->_list_mailboxes();
-    $subscribed = in_array($mailbox, $a_subscribed);
-    
-    // unsubscribe folder
-    if ($subscribed)
-      iil_C_UnSubscribe($this->conn, $mailbox);
-
-    if (strlen($abs_name))
-      $result = iil_C_RenameFolder($this->conn, $mailbox, $abs_name);
-
-    if ($result)
-      {
-      $delm = $this->get_hierarchy_delimiter();
-      
-      // check if mailbox children are subscribed
-      foreach ($a_subscribed as $c_subscribed)
-        if (preg_match('/^'.preg_quote($mailbox.$delm, '/').'/', $c_subscribed))
-          {
-          iil_C_UnSubscribe($this->conn, $c_subscribed);
-          iil_C_Subscribe($this->conn, preg_replace('/^'.preg_quote($mailbox, '/').'/', $abs_name, $c_subscribed));
-          }
-
-      // clear cache
-      $this->clear_message_cache($mailbox.'.msg');
-      $this->clear_cache('mailboxes');      
-      }
-
-    // try to subscribe it
-    if ($result && $subscribed)
-      iil_C_Subscribe($this->conn, $abs_name);
-
-    return $result ? $name : FALSE;
-    }
-
-
-  /**
-   * Remove mailboxes from server
-   *
-   * @param string Mailbox name(s) string/array
-   * @return boolean True on success
-   */
-  function delete_mailbox($mbox_name)
-    {
-    $deleted = FALSE;
-
-    if (is_array($mbox_name))
-      $a_mboxes = $mbox_name;
-    else if (is_string($mbox_name) && strlen($mbox_name))
-      $a_mboxes = explode(',', $mbox_name);
-
-    $all_mboxes = iil_C_ListMailboxes($this->conn, $this->mod_mailbox($root), '*');
-
-    if (is_array($a_mboxes))
-      foreach ($a_mboxes as $mbox_name)
-        {
-        $mailbox = $this->mod_mailbox($mbox_name);
-
-        // unsubscribe mailbox before deleting
-        iil_C_UnSubscribe($this->conn, $mailbox);
+        // get list of folders
+        if ((strpos($folder, '%') === false) && (strpos($folder, '*') === false)) {
+            $sub_mboxes = $this->list_folders('', $folder . $delm . '*');
+        }
+        else {
+            $sub_mboxes = $this->list_folders();
+        }
 
         // send delete command to server
-        $result = iil_C_DeleteFolder($this->conn, $mailbox);
-        if ($result >= 0) {
-          $deleted = TRUE;
-          $this->clear_message_cache($mailbox.'.msg');
-	  }
-	  
-        foreach ($all_mboxes as $c_mbox)
-          {
-          $regex = preg_quote($mailbox . $this->delimiter, '/');
-          $regex = '/^' . $regex . '/';
-          if (preg_match($regex, $c_mbox))
-            {
-            iil_C_UnSubscribe($this->conn, $c_mbox);
-            $result = iil_C_DeleteFolder($this->conn, $c_mbox);
-            if ($result >= 0) {
-              $deleted = TRUE;
-    	      $this->clear_message_cache($c_mbox.'.msg');
-              }
-	    }
-          }
+        $result = $this->conn->deleteFolder($folder);
+
+        if ($result) {
+            // unsubscribe folder
+            $this->conn->unsubscribe($folder);
+
+            foreach ($sub_mboxes as $c_mbox) {
+                if (strpos($c_mbox, $folder.$delm) === 0) {
+                    $this->conn->unsubscribe($c_mbox);
+                    if ($this->conn->deleteFolder($c_mbox)) {
+	                    $this->clear_message_cache($c_mbox);
+                    }
+                }
+            }
+
+            // clear folder-related cache
+            $this->clear_message_cache($folder);
+            $this->clear_cache('mailboxes', true);
         }
 
-    // clear mailboxlist cache
-    if ($deleted)
-      $this->clear_cache('mailboxes');
-
-    return $deleted;
+        return $result;
     }
 
 
-  /**
-   * Create all folders specified as default
-   */
-  function create_default_folders()
+    /**
+     * Create all folders specified as default
+     */
+    public function create_default_folders()
     {
-    $a_folders = iil_C_ListMailboxes($this->conn, $this->mod_mailbox(''), '*');
-    $a_subscribed = iil_C_ListSubscribed($this->conn, $this->mod_mailbox(''), '*');
-    
-    // create default folders if they do not exist
-    foreach ($this->default_folders as $folder)
-      {
-      $abs_name = $this->mod_mailbox($folder);
-      if (!in_array($abs_name, $a_folders))
-        $this->create_mailbox($folder, TRUE);
-      else if (!in_array($abs_name, $a_subscribed))
-        $this->subscribe($folder);
-      }
-    }
-
-
-
-  /* --------------------------------
-   *   internal caching methods
-   * --------------------------------*/
-
-  /**
-   * @access private
-   */
-  function set_caching($set)
-    {
-    if ($set && is_object($this->db))
-      $this->caching_enabled = TRUE;
-    else
-      $this->caching_enabled = FALSE;
-    }
-
-  /**
-   * @access private
-   */
-  function get_cache($key)
-    {
-    // read cache (if it was not read before)
-    if (!count($this->cache) && $this->caching_enabled)
-      {
-      return $this->_read_cache_record($key);
-      }
-    
-    return $this->cache[$key];
-    }
-
-  /**
-   * @access private
-   */
-  function update_cache($key, $data)
-    {
-    $this->cache[$key] = $data;
-    $this->cache_changed = TRUE;
-    $this->cache_changes[$key] = TRUE;
-    }
-
-  /**
-   * @access private
-   */
-  function write_cache()
-    {
-    if ($this->caching_enabled && $this->cache_changed)
-      {
-      foreach ($this->cache as $key => $data)
-        {
-        if ($this->cache_changes[$key])
-          $this->_write_cache_record($key, serialize($data));
+        // create default folders if they do not exist
+        foreach ($this->default_folders as $folder) {
+            if (!$this->folder_exists($folder)) {
+                $this->create_folder($folder, true);
+            }
+            else if (!$this->folder_exists($folder, true)) {
+                $this->subscribe($folder);
+            }
         }
-      }    
     }
 
-  /**
-   * @access private
-   */
-  function clear_cache($key=NULL)
+
+    /**
+     * Checks if folder exists and is subscribed
+     *
+     * @param string   $folder       Folder name
+     * @param boolean  $subscription Enable subscription checking
+     *
+     * @return boolean TRUE or FALSE
+     */
+    public function folder_exists($folder, $subscription=false)
     {
-    if (!$this->caching_enabled)
-      return;
-    
-    if ($key===NULL)
-      {
-      foreach ($this->cache as $key => $data)
-        $this->_clear_cache_record($key);
-
-      $this->cache = array();
-      $this->cache_changed = FALSE;
-      $this->cache_changes = array();
-      }
-    else
-      {
-      $this->_clear_cache_record($key);
-      $this->cache_changes[$key] = FALSE;
-      unset($this->cache[$key]);
-      }
-    }
-
-  /**
-   * @access private
-   */
-  private function _read_cache_record($key)
-    {
-    if ($this->db)
-      {
-      // get cached data from DB
-      $sql_result = $this->db->query(
-        "SELECT cache_id, data, cache_key
-         FROM ".get_table_name('cache')."
-         WHERE  user_id=?
-	 AND cache_key LIKE 'IMAP.%'",
-        $_SESSION['user_id']);
-
-      while ($sql_arr = $this->db->fetch_assoc($sql_result))
-        {
-	$sql_key = preg_replace('/^IMAP\./', '', $sql_arr['cache_key']);
-        $this->cache_keys[$sql_key] = $sql_arr['cache_id'];
-	if (!isset($this->cache[$sql_key]))
-	  $this->cache[$sql_key] = $sql_arr['data'] ? unserialize($sql_arr['data']) : FALSE;
-        }
-      }
-
-    return $this->cache[$key];
-    }
-
-  /**
-   * @access private
-   */
-  private function _write_cache_record($key, $data)
-    {
-    if (!$this->db)
-      return FALSE;
-
-    // update existing cache record
-    if ($this->cache_keys[$key])
-      {
-      $this->db->query(
-        "UPDATE ".get_table_name('cache')."
-         SET    created=". $this->db->now().", data=?
-         WHERE  user_id=?
-         AND    cache_key=?",
-        $data,
-        $_SESSION['user_id'],
-        'IMAP.'.$key);
-      }
-    // add new cache record
-    else
-      {
-      $this->db->query(
-        "INSERT INTO ".get_table_name('cache')."
-         (created, user_id, cache_key, data)
-         VALUES (".$this->db->now().", ?, ?, ?)",
-        $_SESSION['user_id'],
-        'IMAP.'.$key,
-        $data);
-
-      // get cache entry ID for this key
-      $sql_result = $this->db->query(
-        "SELECT cache_id
-         FROM ".get_table_name('cache')."
-         WHERE  user_id=?
-         AND    cache_key=?",
-        $_SESSION['user_id'],
-        'IMAP.'.$key);
-                                     
-        if ($sql_arr = $this->db->fetch_assoc($sql_result))
-          $this->cache_keys[$key] = $sql_arr['cache_id'];
-      }
-    }
-
-  /**
-   * @access private
-   */
-  private function _clear_cache_record($key)
-    {
-    $this->db->query(
-      "DELETE FROM ".get_table_name('cache')."
-       WHERE  user_id=?
-       AND    cache_key=?",
-      $_SESSION['user_id'],
-      'IMAP.'.$key);
-      
-    unset($this->cache_keys[$key]);
-    }
-
-
-
-  /* --------------------------------
-   *   message caching methods
-   * --------------------------------*/
-   
-
-  /**
-   * Checks if the cache is up-to-date
-   *
-   * @param string Mailbox name
-   * @param string Internal cache key
-   * @return int   Cache status: -3 = off, -2 = incomplete, -1 = dirty
-   */
-  private function check_cache_status($mailbox, $cache_key)
-  {
-    if (!$this->caching_enabled)
-      return -3;
-
-    $cache_index = $this->get_message_cache_index($cache_key);
-    $msg_count = $this->_messagecount($mailbox);
-    $cache_count = count($cache_index);
-
-    // empty mailbox
-    if (!$msg_count)
-      return $cache_count ? -2 : 1;
-
-    // @TODO: We've got one big performance problem in cache status checking method
-    // E.g. mailbox contains 1000 messages, in cache table we've got first 100
-    // of them. Now if we want to display only that 100 (which we've got)
-    // check_cache_status returns 'incomplete' and messages are fetched
-    // from IMAP instead of DB.
-
-    if ($cache_count==$msg_count) {
-      if ($this->skip_deleted) {
-	$h_index = iil_C_FetchHeaderIndex($this->conn, $mailbox, "1:*", 'UID', $this->skip_deleted);
-
-	if (sizeof($h_index) == $cache_count) {
-	  $cache_index = array_flip($cache_index);
-	  foreach ($h_index as $idx => $uid)
-            unset($cache_index[$uid]);
-
-	  if (empty($cache_index))
-	    return 1;
-	}
-	return -2;
-      } else {
-        // get UID of message with highest index
-        $uid = iil_C_ID2UID($this->conn, $mailbox, $msg_count);
-        $cache_uid = array_pop($cache_index);
-      
-        // uids of highest message matches -> cache seems OK
-        if ($cache_uid == $uid)
-          return 1;
-      }
-      // cache is dirty
-      return -1;
-    }
-    // if cache count differs less than 10% report as dirty
-    else if (abs($msg_count - $cache_count) < $msg_count/10)
-      return -1;
-    else
-      return -2;
-  }
-
-  /**
-   * @access private
-   */
-  private function get_message_cache($key, $from, $to, $sort_field, $sort_order)
-    {
-    $cache_key = "$key:$from:$to:$sort_field:$sort_order";
-    $db_header_fields = array('idx', 'uid', 'subject', 'from', 'to', 'cc', 'date', 'size');
-    
-    $config = rcmail::get_instance()->config;
-
-    // use idx sort for sorting by Date with index_sort=true or for unknown field
-    if (($sort_field == 'date' && $this->index_sort)
-      || !in_array($sort_field, $db_header_fields)) {
-      $sort_field = 'idx';
-      }
-    
-    if ($this->caching_enabled && !isset($this->cache[$cache_key]))
-      {
-      $this->cache[$cache_key] = array();
-      $sql_result = $this->db->limitquery(
-        "SELECT idx, uid, headers
-         FROM ".get_table_name('messages')."
-         WHERE  user_id=?
-         AND    cache_key=?
-         ORDER BY ".$this->db->quoteIdentifier($sort_field)." ".strtoupper($sort_order),
-        $from,
-        $to-$from,
-        $_SESSION['user_id'],
-        $key);
-
-      while ($sql_arr = $this->db->fetch_assoc($sql_result))
-        {
-        $uid = $sql_arr['uid'];
-        $this->cache[$cache_key][$uid] =  $this->db->decode(unserialize($sql_arr['headers']));
-
-        // featch headers if unserialize failed
-        if (empty($this->cache[$cache_key][$uid]))
-          $this->cache[$cache_key][$uid] = iil_C_FetchHeader($this->conn, preg_replace('/.msg$/', '', $key), $uid, true, $this->fetch_add_headers);
-        }
-      }
-
-    return $this->cache[$cache_key];
-    }
-
-  /**
-   * @access private
-   */
-  private function &get_cached_message($key, $uid)
-    {
-    $internal_key = '__single_msg';
-    
-    if ($this->caching_enabled && !isset($this->cache[$internal_key][$uid]))
-      {
-      $sql_result = $this->db->query(
-        "SELECT idx, headers, structure
-         FROM ".get_table_name('messages')."
-         WHERE  user_id=?
-         AND    cache_key=?
-         AND    uid=?",
-        $_SESSION['user_id'],
-        $key,
-        $uid);
-
-      if ($sql_arr = $this->db->fetch_assoc($sql_result))
-        {
-	$this->uid_id_map[preg_replace('/\.msg$/', '', $key)][$uid] = $sql_arr['idx'];
-        $this->cache[$internal_key][$uid] = $this->db->decode(unserialize($sql_arr['headers']));
-        if (is_object($this->cache[$internal_key][$uid]) && !empty($sql_arr['structure']))
-          $this->cache[$internal_key][$uid]->structure = $this->db->decode(unserialize($sql_arr['structure']));
-        }
-      }
-
-    return $this->cache[$internal_key][$uid];
-    }
-
-  /**
-   * @access private
-   */  
-  private function get_message_cache_index($key, $force=FALSE, $sort_field='idx', $sort_order='ASC')
-    {
-    static $sa_message_index = array();
-    
-    // empty key -> empty array
-    if (!$this->caching_enabled || empty($key))
-      return array();
-    
-    if (!empty($sa_message_index[$key]) && !$force)
-      return $sa_message_index[$key];
-
-    // use idx sort for sorting by Date with index_sort=true
-    if ($sort_field == 'date' && $this->index_sort)
-      $sort_field = 'idx';
-    
-    $sa_message_index[$key] = array();
-    $sql_result = $this->db->query(
-      "SELECT idx, uid
-       FROM ".get_table_name('messages')."
-       WHERE  user_id=?
-       AND    cache_key=?
-       ORDER BY ".$this->db->quote_identifier($sort_field)." ".$sort_order,
-      $_SESSION['user_id'],
-      $key);
-
-    while ($sql_arr = $this->db->fetch_assoc($sql_result))
-      $sa_message_index[$key][$sql_arr['idx']] = $sql_arr['uid'];
-      
-    return $sa_message_index[$key];
-    }
-
-  /**
-   * @access private
-   */
-  private function add_message_cache($key, $index, $headers, $struct=null, $force=false)
-    {
-    if (empty($key) || !is_object($headers) || empty($headers->uid))
-        return;
-
-    // add to internal (fast) cache
-    $this->cache['__single_msg'][$headers->uid] = clone $headers;
-    $this->cache['__single_msg'][$headers->uid]->structure = $struct;
-
-    // no further caching
-    if (!$this->caching_enabled)
-      return;
-    
-    // check for an existing record (probly headers are cached but structure not)
-    if (!$force) {
-      $sql_result = $this->db->query(
-        "SELECT message_id
-         FROM ".get_table_name('messages')."
-         WHERE  user_id=?
-         AND    cache_key=?
-         AND    uid=?",
-        $_SESSION['user_id'],
-        $key,
-        $headers->uid);
-      if ($sql_arr = $this->db->fetch_assoc($sql_result))
-        $message_id = $sql_arr['message_id'];
-      }
-
-    // update cache record
-    if ($message_id)
-      {
-      $this->db->query(
-        "UPDATE ".get_table_name('messages')."
-         SET   idx=?, headers=?, structure=?
-         WHERE message_id=?",
-        $index,
-        serialize($this->db->encode(clone $headers)),
-        is_object($struct) ? serialize($this->db->encode(clone $struct)) : NULL,
-        $message_id
-        );
-      }
-    else  // insert new record
-      {
-      $this->db->query(
-        "INSERT INTO ".get_table_name('messages')."
-         (user_id, del, cache_key, created, idx, uid, subject, ".$this->db->quoteIdentifier('from').", ".$this->db->quoteIdentifier('to').", cc, date, size, headers, structure)
-         VALUES (?, 0, ?, ".$this->db->now().", ?, ?, ?, ?, ?, ?, ".$this->db->fromunixtime($headers->timestamp).", ?, ?, ?)",
-        $_SESSION['user_id'],
-        $key,
-        $index,
-        $headers->uid,
-        (string)mb_substr($this->db->encode($this->decode_header($headers->subject, TRUE)), 0, 128),
-        (string)mb_substr($this->db->encode($this->decode_header($headers->from, TRUE)), 0, 128),
-        (string)mb_substr($this->db->encode($this->decode_header($headers->to, TRUE)), 0, 128),
-        (string)mb_substr($this->db->encode($this->decode_header($headers->cc, TRUE)), 0, 128),
-        (int)$headers->size,
-        serialize($this->db->encode(clone $headers)),
-        is_object($struct) ? serialize($this->db->encode(clone $struct)) : NULL
-        );
-      }
-    }
-    
-  /**
-   * @access private
-   */
-  private function remove_message_cache($key, $ids, $idx=false)
-    {
-    if (!$this->caching_enabled)
-      return;
-    
-    $this->db->query(
-      "DELETE FROM ".get_table_name('messages')."
-      WHERE user_id=?
-      AND cache_key=?
-      AND ".($idx ? "idx" : "uid")." IN (".$this->db->array2list($ids, 'integer').")",
-      $_SESSION['user_id'],
-      $key);
-    }
-
-  /**
-   * @access private
-   */
-  private function clear_message_cache($key, $start_index=1)
-    {
-    if (!$this->caching_enabled)
-      return;
-    
-    $this->db->query(
-      "DELETE FROM ".get_table_name('messages')."
-       WHERE user_id=?
-       AND cache_key=?
-       AND idx>=?",
-      $_SESSION['user_id'], $key, $start_index);
-    }
-
-  /**
-   * @access private
-   */
-  private function get_message_cache_index_min($key, $uids=NULL)
-    {
-    if (!$this->caching_enabled)
-      return;
-    
-    $sql_result = $this->db->query(
-      "SELECT MIN(idx) AS minidx
-      FROM ".get_table_name('messages')."
-      WHERE  user_id=?
-      AND    cache_key=?"
-      .(!empty($uids) ? " AND uid IN (".$this->db->array2list($uids, 'integer').")" : ''),
-      $_SESSION['user_id'],
-      $key);
-
-    if ($sql_arr = $this->db->fetch_assoc($sql_result))
-      return $sql_arr['minidx'];
-    else
-      return 0;  
-    }
-
-
-  /* --------------------------------
-   *   encoding/decoding methods
-   * --------------------------------*/
-
-  /**
-   * Split an address list into a structured array list
-   *
-   * @param string  Input string
-   * @param int     List only this number of addresses
-   * @param boolean Decode address strings
-   * @return array  Indexed list of addresses
-   */
-  function decode_address_list($input, $max=null, $decode=true)
-    {
-    $a = $this->_parse_address_list($input, $decode);
-    $out = array();
-    // Special chars as defined by RFC 822 need to in quoted string (or escaped).
-    $special_chars = '[\(\)\<\>\\\.\[\]@,;:"]';
-    
-    if (!is_array($a))
-      return $out;
-
-    $c = count($a);
-    $j = 0;
-
-    foreach ($a as $val)
-      {
-      $j++;
-      $address = $val['address'];
-      $name = preg_replace(array('/^[\'"]/', '/[\'"]$/'), '', trim($val['name']));
-      if ($name && $address && $name != $address)
-        $string = sprintf('%s <%s>', preg_match("/$special_chars/", $name) ? '"'.addcslashes($name, '"').'"' : $name, $address);
-      else if ($address)
-        $string = $address;
-      else if ($name)
-        $string = $name;
-      
-      $out[$j] = array('name' => $name,
-                       'mailto' => $address,
-                       'string' => $string);
-              
-      if ($max && $j==$max)
-        break;
-      }
-    
-    return $out;
-    }
-  
-  
-  /**
-   * Decode a Microsoft Outlook TNEF part (winmail.dat)
-   *
-   * @param object rcube_message_part Message part to decode
-   * @param string UID of the message
-   * @return array List of rcube_message_parts extracted from windmail.dat
-   */
-  function tnef_decode(&$part, $uid)
-  {
-    if (!isset($part->body))
-      $part->body = $this->get_message_part($uid, $part->mime_id, $part);
-
-    $pid = 0;
-    $tnef_parts = array();
-    $tnef_arr = tnef_decode($part->body);
-    foreach ($tnef_arr as $winatt) {
-      $tpart = new rcube_message_part;
-      $tpart->filename = $winatt["name"];
-      $tpart->encoding = 'stream';
-      $tpart->ctype_primary = $winatt["type0"];
-      $tpart->ctype_secondary = $winatt["type1"];
-      $tpart->mimetype = strtolower($winatt["type0"] . "/" . $winatt["type1"]);
-      $tpart->mime_id = "winmail." . $part->mime_id . ".$pid";
-      $tpart->size = $winatt["size"];
-      $tpart->body = $winatt['stream'];
-      
-      $tnef_parts[] = $tpart;
-      $pid++;
-    }
-
-    return $tnef_parts;
-  }
-
-
-  /**
-   * Decode a message header value
-   *
-   * @param string  Header value
-   * @param boolean Remove quotes if necessary
-   * @return string Decoded string
-   */
-  function decode_header($input, $remove_quotes=FALSE)
-    {
-    $str = rcube_imap::decode_mime_string((string)$input, $this->default_charset);
-    if ($str{0}=='"' && $remove_quotes)
-      $str = str_replace('"', '', $str);
-    
-    return $str;
-    }
-
-
-  /**
-   * Decode a mime-encoded string to internal charset
-   *
-   * @param string $input    Header value
-   * @param string $fallback Fallback charset if none specified
-   *
-   * @return string Decoded string
-   * @static
-   */
-  public static function decode_mime_string($input, $fallback=null)
-    {
-    // Initialize variable
-    $out = '';
-
-    // Iterate instead of recursing, this way if there are too many values we don't have stack overflows
-    // rfc: all line breaks or other characters not found 
-    // in the Base64 Alphabet must be ignored by decoding software
-    // delete all blanks between MIME-lines, differently we can 
-    // receive unnecessary blanks and broken utf-8 symbols
-    $input = preg_replace("/\?=\s+=\?/", '?==?', $input);
-
-    // Check if there is stuff to decode
-    if (strpos($input, '=?') !== false) {
-      // Loop through the string to decode all occurences of =? ?= into the variable $out 
-      while(($pos = strpos($input, '=?')) !== false) {
-        // Append everything that is before the text to be decoded
-        $out .= substr($input, 0, $pos);
-
-        // Get the location of the text to decode
-        $end_cs_pos = strpos($input, "?", $pos+2);
-        $end_en_pos = strpos($input, "?", $end_cs_pos+1);
-        $end_pos = strpos($input, "?=", $end_en_pos+1);
-
-        // Extract the encoded string
-        $encstr = substr($input, $pos+2, ($end_pos-$pos-2));
-        // Extract the remaining string
-        $input = substr($input, $end_pos+2);
-
-        // Decode the string fragement
-        $out .= rcube_imap::_decode_mime_string_part($encstr);
-      }
-
-      // Deocde the rest (if any)
-      if (strlen($input) != 0)
-         $out .= rcube_imap::decode_mime_string($input, $fallback);
-
-       // return the results
-      return $out;
-    }
-
-    // no encoding information, use fallback
-    return rcube_charset_convert($input, 
-      !empty($fallback) ? $fallback : rcmail::get_instance()->config->get('default_charset', 'ISO-8859-1'));
-    }
-
-
-  /**
-   * Decode a part of a mime-encoded string
-   *
-   * @access private
-   */
-  private function _decode_mime_string_part($str)
-    {
-    $a = explode('?', $str);
-    $count = count($a);
-
-    // should be in format "charset?encoding?base64_string"
-    if ($count >= 3)
-      {
-      for ($i=2; $i<$count; $i++)
-        $rest.=$a[$i];
-
-      if (($a[1]=="B")||($a[1]=="b"))
-        $rest = base64_decode($rest);
-      else if (($a[1]=="Q")||($a[1]=="q"))
-        {
-        $rest = str_replace("_", " ", $rest);
-        $rest = quoted_printable_decode($rest);
+        if ($folder == 'INBOX') {
+            return true;
         }
 
-      return rcube_charset_convert($rest, $a[0]);
-      }
-    else
-      return $str;    // we dont' know what to do with this  
-    }
+        $key  = $subscription ? 'subscribed' : 'existing';
 
-
-  /**
-   * Decode a mime part
-   *
-   * @param string Input string
-   * @param string Part encoding
-   * @return string Decoded string
-   */
-  function mime_decode($input, $encoding='7bit')
-    {
-    switch (strtolower($encoding))
-      {
-      case 'quoted-printable':
-        return quoted_printable_decode($input);
-        break;
-      
-      case 'base64':
-        return base64_decode($input);
-        break;
-
-      case 'x-uuencode':
-      case 'x-uue':
-      case 'uue':
-      case 'uuencode':
-        return convert_uudecode($input);
-        break;
-						      
-      case '7bit':
-      default:
-        return $input;
-      }
-    }
-
-
-  /**
-   * Convert body charset to RCMAIL_CHARSET according to the ctype_parameters
-   *
-   * @param string Part body to decode
-   * @param string Charset to convert from
-   * @return string Content converted to internal charset
-   */
-  function charset_decode($body, $ctype_param)
-    {
-    if (is_array($ctype_param) && !empty($ctype_param['charset']))
-      return rcube_charset_convert($body, $ctype_param['charset']);
-
-    // defaults to what is specified in the class header
-    return rcube_charset_convert($body,  $this->default_charset);
-    }
-
-
-  /**
-   * Translate UID to message ID
-   *
-   * @param int    Message UID
-   * @param string Mailbox name
-   * @return int   Message ID
-   */
-  function get_id($uid, $mbox_name=NULL) 
-    {
-      $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-      return $this->_uid2id($uid, $mailbox);
-    }
-
-
-  /**
-   * Translate message number to UID
-   *
-   * @param int    Message ID
-   * @param string Mailbox name
-   * @return int   Message UID
-   */
-  function get_uid($id,$mbox_name=NULL)
-    {
-      $mailbox = $mbox_name ? $this->mod_mailbox($mbox_name) : $this->mailbox;
-      return $this->_id2uid($id, $mailbox);
-    }
-
-
-  /**
-   * Modify folder name for input/output according to root dir and namespace
-   *
-   * @param string  Folder name
-   * @param string  Mode
-   * @return string Folder name
-   */
-  function mod_mailbox($mbox_name, $mode='in')
-    {
-    if ((!empty($this->root_ns) && $this->root_ns == $mbox_name) || $mbox_name == 'INBOX')
-      return $mbox_name;
-
-    if (!empty($this->root_dir)) {
-      if ($mode=='in')
-        $mbox_name = $this->root_dir.$this->delimiter.$mbox_name;
-      else if (!empty($mbox_name)) // $mode=='out'
-        $mbox_name = substr($mbox_name, strlen($this->root_dir)+1);
-      }
-    
-    return $mbox_name;
-    }
-
-
-  /* --------------------------------
-   *         private methods
-   * --------------------------------*/
-
-  /**
-   * Validate the given input and save to local properties
-   * @access private
-   */
-  private function _set_sort_order($sort_field, $sort_order)
-  {
-    if ($sort_field != null)
-      $this->sort_field = asciiwords($sort_field);
-    if ($sort_order != null)
-      $this->sort_order = strtoupper($sort_order) == 'DESC' ? 'DESC' : 'ASC';
-  }
-
-  /**
-   * Sort mailboxes first by default folders and then in alphabethical order
-   * @access private
-   */
-  private function _sort_mailbox_list($a_folders)
-    {
-    $a_out = $a_defaults = $folders = array();
-
-    $delimiter = $this->get_hierarchy_delimiter();
-
-    // find default folders and skip folders starting with '.'
-    foreach ($a_folders as $i => $folder)
-      {
-      if ($folder{0}=='.')
-        continue;
-
-      if (($p = array_search($folder, $this->default_folders)) !== false && !$a_defaults[$p])
-        $a_defaults[$p] = $folder;
-      else
-        $folders[$folder] = mb_strtolower(rcube_charset_convert($folder, 'UTF7-IMAP'));
-      }
-
-    // sort folders and place defaults on the top
-    asort($folders, SORT_LOCALE_STRING);
-    ksort($a_defaults);
-    $folders = array_merge($a_defaults, array_keys($folders));
-
-    // finally we must rebuild the list to move 
-    // subfolders of default folders to their place...
-    // ...also do this for the rest of folders because
-    // asort() is not properly sorting case sensitive names
-    while (list($key, $folder) = each($folders)) {
-      // set the type of folder name variable (#1485527) 
-      $a_out[] = (string) $folder;
-      unset($folders[$key]);
-      $this->_rsort($folder, $delimiter, $folders, $a_out);	
-      }
-
-    return $a_out;
-    }
-
-
-  /**
-   * @access private
-   */
-  private function _rsort($folder, $delimiter, &$list, &$out)
-    {
-      while (list($key, $name) = each($list)) {
-	if (strpos($name, $folder.$delimiter) === 0) {
-	  // set the type of folder name variable (#1485527) 
-    	  $out[] = (string) $name;
-	  unset($list[$key]);
-	  $this->_rsort($name, $delimiter, $list, $out);
-	  }
-        }
-      reset($list);	
-    }
-
-
-  /**
-   * @access private
-   */
-  private function _uid2id($uid, $mbox_name=NULL)
-    {
-    if (!$mbox_name)
-      $mbox_name = $this->mailbox;
-      
-    if (!isset($this->uid_id_map[$mbox_name][$uid]))
-      $this->uid_id_map[$mbox_name][$uid] = iil_C_UID2ID($this->conn, $mbox_name, $uid);
-
-    return $this->uid_id_map[$mbox_name][$uid];
-    }
-
-  /**
-   * @access private
-   */
-  private function _id2uid($id, $mbox_name=NULL)
-    {
-    if (!$mbox_name)
-      $mbox_name = $this->mailbox;
-
-    if ($uid = array_search($id, (array)$this->uid_id_map[$mbox_name]))
-      return $uid;
-
-    $uid = iil_C_ID2UID($this->conn, $mbox_name, $id);
-    $this->uid_id_map[$mbox_name][$uid] = $id;
-    
-    return $uid;
-    }
-
-
-  /**
-   * Subscribe/unsubscribe a list of mailboxes and update local cache
-   * @access private
-   */
-  private function _change_subscription($a_mboxes, $mode)
-    {
-    $updated = FALSE;
-
-    if (is_array($a_mboxes))
-      foreach ($a_mboxes as $i => $mbox_name)
-        {
-        $mailbox = $this->mod_mailbox($mbox_name);
-        $a_mboxes[$i] = $mailbox;
-
-        if ($mode=='subscribe')
-          $updated = iil_C_Subscribe($this->conn, $mailbox);
-        else if ($mode=='unsubscribe')
-          $updated = iil_C_UnSubscribe($this->conn, $mailbox);
+        if (is_array($this->icache[$key]) && in_array($folder, $this->icache[$key])) {
+            return true;
         }
 
-    // get cached mailbox list
-    if ($updated)
-      {
-      $a_mailbox_cache = $this->get_cache('mailboxes');
-      if (!is_array($a_mailbox_cache))
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        if ($subscription) {
+            $a_folders = $this->conn->listSubscribed('', $folder);
+        }
+        else {
+            $a_folders = $this->conn->listMailboxes('', $folder);
+        }
+
+        if (is_array($a_folders) && in_array($folder, $a_folders)) {
+            $this->icache[$key][] = $folder;
+            return true;
+        }
+
+        return false;
+    }
+
+
+    /**
+     * Returns the namespace where the folder is in
+     *
+     * @param string $folder Folder name
+     *
+     * @return string One of 'personal', 'other' or 'shared'
+     */
+    public function folder_namespace($folder)
+    {
+        if ($folder == 'INBOX') {
+            return 'personal';
+        }
+
+        foreach ($this->namespace as $type => $namespace) {
+            if (is_array($namespace)) {
+                foreach ($namespace as $ns) {
+                    if ($len = strlen($ns[0])) {
+                        if (($len > 1 && $folder == substr($ns[0], 0, -1))
+                            || strpos($folder, $ns[0]) === 0
+                        ) {
+                            return $type;
+                        }
+                    }
+                }
+            }
+        }
+
+        return 'personal';
+    }
+
+
+    /**
+     * Modify folder name according to namespace.
+     * For output it removes prefix of the personal namespace if it's possible.
+     * For input it adds the prefix. Use it before creating a folder in root
+     * of the folders tree.
+     *
+     * @param string $folder Folder name
+     * @param string $mode    Mode name (out/in)
+     *
+     * @return string Folder name
+     */
+    public function mod_folder($folder, $mode = 'out')
+    {
+        if (!strlen($folder)) {
+            return $folder;
+        }
+
+        $prefix     = $this->namespace['prefix']; // see set_env()
+        $prefix_len = strlen($prefix);
+
+        if (!$prefix_len) {
+            return $folder;
+        }
+
+        // remove prefix for output
+        if ($mode == 'out') {
+            if (substr($folder, 0, $prefix_len) === $prefix) {
+                return substr($folder, $prefix_len);
+            }
+        }
+        // add prefix for input (e.g. folder creation)
+        else {
+            return $prefix . $folder;
+        }
+
+        return $folder;
+    }
+
+
+    /**
+     * Gets folder attributes from LIST response, e.g. \Noselect, \Noinferiors
+     *
+     * @param string $folder Folder name
+     * @param bool   $force   Set to True if attributes should be refreshed
+     *
+     * @return array Options list
+     */
+    public function folder_attributes($folder, $force=false)
+    {
+        // get attributes directly from LIST command
+        if (!empty($this->conn->data['LIST']) && is_array($this->conn->data['LIST'][$folder])) {
+            $opts = $this->conn->data['LIST'][$folder];
+        }
+        // get cached folder attributes
+        else if (!$force) {
+            $opts = $this->get_cache('mailboxes.attributes');
+            $opts = $opts[$folder];
+        }
+
+        if (!is_array($opts)) {
+            if (!$this->check_connection()) {
+                return array();
+            }
+
+            $this->conn->listMailboxes('', $folder);
+            $opts = $this->conn->data['LIST'][$folder];
+        }
+
+        return is_array($opts) ? $opts : array();
+    }
+
+
+    /**
+     * Gets connection (and current folder) data: UIDVALIDITY, EXISTS, RECENT,
+     * PERMANENTFLAGS, UIDNEXT, UNSEEN
+     *
+     * @param string $folder Folder name
+     *
+     * @return array Data
+     */
+    public function folder_data($folder)
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder !== null ? $this->folder : 'INBOX';
+        }
+
+        if ($this->conn->selected != $folder) {
+            if (!$this->check_connection()) {
+                return array();
+            }
+
+            if ($this->conn->select($folder)) {
+                $this->folder = $folder;
+            }
+            else {
+                return null;
+            }
+        }
+
+        $data = $this->conn->data;
+
+        // add (E)SEARCH result for ALL UNDELETED query
+        if (!empty($this->icache['undeleted_idx'])
+            && $this->icache['undeleted_idx']->get_parameters('MAILBOX') == $folder
+        ) {
+            $data['UNDELETED'] = $this->icache['undeleted_idx'];
+        }
+
+        return $data;
+    }
+
+
+    /**
+     * Returns extended information about the folder
+     *
+     * @param string $folder Folder name
+     *
+     * @return array Data
+     */
+    public function folder_info($folder)
+    {
+        if ($this->icache['options'] && $this->icache['options']['name'] == $folder) {
+            return $this->icache['options'];
+        }
+
+        $acl       = $this->get_capability('ACL');
+        $namespace = $this->get_namespace();
+        $options   = array();
+
+        // check if the folder is a namespace prefix
+        if (!empty($namespace)) {
+            $mbox = $folder . $this->delimiter;
+            foreach ($namespace as $ns) {
+                if (!empty($ns)) {
+                    foreach ($ns as $item) {
+                        if ($item[0] === $mbox) {
+                            $options['is_root'] = true;
+                            break 2;
+                        }
+                    }
+                }
+            }
+        }
+        // check if the folder is other user virtual-root
+        if (!$options['is_root'] && !empty($namespace) && !empty($namespace['other'])) {
+            $parts = explode($this->delimiter, $folder);
+            if (count($parts) == 2) {
+                $mbox = $parts[0] . $this->delimiter;
+                foreach ($namespace['other'] as $item) {
+                    if ($item[0] === $mbox) {
+                        $options['is_root'] = true;
+                        break;
+                    }
+                }
+            }
+        }
+
+        $options['name']       = $folder;
+        $options['attributes'] = $this->folder_attributes($folder, true);
+        $options['namespace']  = $this->folder_namespace($folder);
+        $options['rights']     = $acl && !$options['is_root'] ? (array)$this->my_rights($folder) : array();
+        $options['special']    = in_array($folder, $this->default_folders);
+
+        // Set 'noselect' and 'norename' flags
+        if (is_array($options['attributes'])) {
+            foreach ($options['attributes'] as $attrib) {
+                $attrib = strtolower($attrib);
+                if ($attrib == '\noselect' || $attrib == '\nonexistent') {
+                    $options['noselect'] = true;
+                }
+            }
+        }
+        else {
+            $options['noselect'] = true;
+        }
+
+        if (!empty($options['rights'])) {
+            $options['norename'] = !in_array('x', $options['rights']) && !in_array('d', $options['rights']);
+
+            if (!$options['noselect']) {
+                $options['noselect'] = !in_array('r', $options['rights']);
+            }
+        }
+        else {
+            $options['norename'] = $options['is_root'] || $options['namespace'] != 'personal';
+        }
+
+        $this->icache['options'] = $options;
+
+        return $options;
+    }
+
+
+    /**
+     * Synchronizes messages cache.
+     *
+     * @param string $folder Folder name
+     */
+    public function folder_sync($folder)
+    {
+        if ($mcache = $this->get_mcache_engine()) {
+            $mcache->synchronize($folder);
+        }
+    }
+
+
+    /**
+     * Get message header names for rcube_imap_generic::fetchHeader(s)
+     *
+     * @return string Space-separated list of header names
+     */
+    protected function get_fetch_headers()
+    {
+        if (!empty($this->options['fetch_headers'])) {
+            $headers = explode(' ', $this->options['fetch_headers']);
+            $headers = array_map('strtoupper', $headers);
+        }
+        else {
+            $headers = array();
+        }
+
+        if ($this->messages_caching || $this->options['all_headers']) {
+            $headers = array_merge($headers, $this->all_headers);
+        }
+
+        return implode(' ', array_unique($headers));
+    }
+
+
+    /* -----------------------------------------
+     *   ACL and METADATA/ANNOTATEMORE methods
+     * ----------------------------------------*/
+
+    /**
+     * Changes the ACL on the specified folder (SETACL)
+     *
+     * @param string $folder  Folder name
+     * @param string $user    User name
+     * @param string $acl     ACL string
+     *
+     * @return boolean True on success, False on failure
+     * @since 0.5-beta
+     */
+    public function set_acl($folder, $user, $acl)
+    {
+        if (!$this->get_capability('ACL')) {
+            return false;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        return $this->conn->setACL($folder, $user, $acl);
+    }
+
+
+    /**
+     * Removes any <identifier,rights> pair for the
+     * specified user from the ACL for the specified
+     * folder (DELETEACL)
+     *
+     * @param string $folder  Folder name
+     * @param string $user    User name
+     *
+     * @return boolean True on success, False on failure
+     * @since 0.5-beta
+     */
+    public function delete_acl($folder, $user)
+    {
+        if (!$this->get_capability('ACL')) {
+            return false;
+        }
+
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        return $this->conn->deleteACL($folder, $user);
+    }
+
+
+    /**
+     * Returns the access control list for folder (GETACL)
+     *
+     * @param string $folder Folder name
+     *
+     * @return array User-rights array on success, NULL on error
+     * @since 0.5-beta
+     */
+    public function get_acl($folder)
+    {
+        if (!$this->get_capability('ACL')) {
+            return null;
+        }
+
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        return $this->conn->getACL($folder);
+    }
+
+
+    /**
+     * Returns information about what rights can be granted to the
+     * user (identifier) in the ACL for the folder (LISTRIGHTS)
+     *
+     * @param string $folder  Folder name
+     * @param string $user    User name
+     *
+     * @return array List of user rights
+     * @since 0.5-beta
+     */
+    public function list_rights($folder, $user)
+    {
+        if (!$this->get_capability('ACL')) {
+            return null;
+        }
+
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        return $this->conn->listRights($folder, $user);
+    }
+
+
+    /**
+     * Returns the set of rights that the current user has to
+     * folder (MYRIGHTS)
+     *
+     * @param string $folder Folder name
+     *
+     * @return array MYRIGHTS response on success, NULL on error
+     * @since 0.5-beta
+     */
+    public function my_rights($folder)
+    {
+        if (!$this->get_capability('ACL')) {
+            return null;
+        }
+
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        return $this->conn->myRights($folder);
+    }
+
+
+    /**
+     * Sets IMAP metadata/annotations (SETMETADATA/SETANNOTATION)
+     *
+     * @param string $folder  Folder name (empty for server metadata)
+     * @param array  $entries Entry-value array (use NULL value as NIL)
+     *
+     * @return boolean True on success, False on failure
+     * @since 0.5-beta
+     */
+    public function set_metadata($folder, $entries)
+    {
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        if ($this->get_capability('METADATA') ||
+            (!strlen($folder) && $this->get_capability('METADATA-SERVER'))
+        ) {
+            return $this->conn->setMetadata($folder, $entries);
+        }
+        else if ($this->get_capability('ANNOTATEMORE') || $this->get_capability('ANNOTATEMORE2')) {
+            foreach ((array)$entries as $entry => $value) {
+                list($ent, $attr) = $this->md2annotate($entry);
+                $entries[$entry] = array($ent, $attr, $value);
+            }
+            return $this->conn->setAnnotation($folder, $entries);
+        }
+
+        return false;
+    }
+
+
+    /**
+     * Unsets IMAP metadata/annotations (SETMETADATA/SETANNOTATION)
+     *
+     * @param string $folder  Folder name (empty for server metadata)
+     * @param array  $entries Entry names array
+     *
+     * @return boolean True on success, False on failure
+     * @since 0.5-beta
+     */
+    public function delete_metadata($folder, $entries)
+    {
+        if (!$this->check_connection()) {
+            return false;
+        }
+
+        if ($this->get_capability('METADATA') || 
+            (!strlen($folder) && $this->get_capability('METADATA-SERVER'))
+        ) {
+            return $this->conn->deleteMetadata($folder, $entries);
+        }
+        else if ($this->get_capability('ANNOTATEMORE') || $this->get_capability('ANNOTATEMORE2')) {
+            foreach ((array)$entries as $idx => $entry) {
+                list($ent, $attr) = $this->md2annotate($entry);
+                $entries[$idx] = array($ent, $attr, NULL);
+            }
+            return $this->conn->setAnnotation($folder, $entries);
+        }
+
+        return false;
+    }
+
+
+    /**
+     * Returns IMAP metadata/annotations (GETMETADATA/GETANNOTATION)
+     *
+     * @param string $folder  Folder name (empty for server metadata)
+     * @param array  $entries Entries
+     * @param array  $options Command options (with MAXSIZE and DEPTH keys)
+     *
+     * @return array Metadata entry-value hash array on success, NULL on error
+     * @since 0.5-beta
+     */
+    public function get_metadata($folder, $entries, $options=array())
+    {
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        if ($this->get_capability('METADATA') ||
+            (!strlen($folder) && $this->get_capability('METADATA-SERVER'))
+        ) {
+            return $this->conn->getMetadata($folder, $entries, $options);
+        }
+        else if ($this->get_capability('ANNOTATEMORE') || $this->get_capability('ANNOTATEMORE2')) {
+            $queries = array();
+            $res     = array();
+
+            // Convert entry names
+            foreach ((array)$entries as $entry) {
+                list($ent, $attr) = $this->md2annotate($entry);
+                $queries[$attr][] = $ent;
+            }
+
+            // @TODO: Honor MAXSIZE and DEPTH options
+            foreach ($queries as $attrib => $entry) {
+                if ($result = $this->conn->getAnnotation($folder, $entry, $attrib)) {
+                    $res = array_merge_recursive($res, $result);
+                }
+            }
+
+            return $res;
+        }
+
+        return null;
+    }
+
+
+    /**
+     * Converts the METADATA extension entry name into the correct
+     * entry-attrib names for older ANNOTATEMORE version.
+     *
+     * @param string $entry Entry name
+     *
+     * @return array Entry-attribute list, NULL if not supported (?)
+     */
+    protected function md2annotate($entry)
+    {
+        if (substr($entry, 0, 7) == '/shared') {
+            return array(substr($entry, 7), 'value.shared');
+        }
+        else if (substr($entry, 0, 8) == '/private') {
+            return array(substr($entry, 8), 'value.priv');
+        }
+
+        // @TODO: log error
+        return null;
+    }
+
+
+    /* --------------------------------
+     *   internal caching methods
+     * --------------------------------*/
+
+    /**
+     * Enable or disable indexes caching
+     *
+     * @param string $type Cache type (@see rcmail::get_cache)
+     */
+    public function set_caching($type)
+    {
+        if ($type) {
+            $this->caching = $type;
+        }
+        else {
+            if ($this->cache) {
+                $this->cache->close();
+            }
+            $this->cache   = null;
+            $this->caching = false;
+        }
+    }
+
+    /**
+     * Getter for IMAP cache object
+     */
+    protected function get_cache_engine()
+    {
+        if ($this->caching && !$this->cache) {
+            $rcmail = rcmail::get_instance();
+            $ttl = $rcmail->config->get('message_cache_lifetime', '10d');
+            $ttl = get_offset_time($ttl) - time();
+            $this->cache = $rcmail->get_cache('IMAP', $this->caching, $ttl);
+        }
+
+        return $this->cache;
+    }
+
+    /**
+     * Returns cached value
+     *
+     * @param string $key Cache key
+     *
+     * @return mixed
+     */
+    public function get_cache($key)
+    {
+        if ($cache = $this->get_cache_engine()) {
+            return $cache->get($key);
+        }
+    }
+
+    /**
+     * Update cache
+     *
+     * @param string $key  Cache key
+     * @param mixed  $data Data
+     */
+    public function update_cache($key, $data)
+    {
+        if ($cache = $this->get_cache_engine()) {
+            $cache->set($key, $data);
+        }
+    }
+
+    /**
+     * Clears the cache.
+     *
+     * @param string  $key         Cache key name or pattern
+     * @param boolean $prefix_mode Enable it to clear all keys starting
+     *                             with prefix specified in $key
+     */
+    public function clear_cache($key = null, $prefix_mode = false)
+    {
+        if ($cache = $this->get_cache_engine()) {
+            $cache->remove($key, $prefix_mode);
+        }
+    }
+
+    /**
+     * Delete outdated cache entries
+     */
+    public function expunge_cache()
+    {
+        if ($this->mcache) {
+            $ttl = rcmail::get_instance()->config->get('message_cache_lifetime', '10d');
+            $this->mcache->expunge($ttl);
+        }
+
+        if ($this->cache)
+            $this->cache->expunge();
+    }
+
+
+    /* --------------------------------
+     *   message caching methods
+     * --------------------------------*/
+
+    /**
+     * Enable or disable messages caching
+     *
+     * @param boolean $set Flag
+     */
+    public function set_messages_caching($set)
+    {
+        if ($set) {
+            $this->messages_caching = true;
+        }
+        else {
+            if ($this->mcache) {
+                $this->mcache->close();
+            }
+            $this->mcache = null;
+            $this->messages_caching = false;
+        }
+    }
+
+
+    /**
+     * Getter for messages cache object
+     */
+    protected function get_mcache_engine()
+    {
+        if ($this->messages_caching && !$this->mcache) {
+            $rcmail = rcmail::get_instance();
+            if ($dbh = $rcmail->get_dbh()) {
+                $this->mcache = new rcube_imap_cache(
+                    $dbh, $this, $rcmail->user->ID, $this->options['skip_deleted']);
+            }
+        }
+
+        return $this->mcache;
+    }
+
+
+    /**
+     * Clears the messages cache.
+     *
+     * @param string $folder Folder name
+     * @param array  $uids    Optional message UIDs to remove from cache
+     */
+    protected function clear_message_cache($folder = null, $uids = null)
+    {
+        if ($mcache = $this->get_mcache_engine()) {
+            $mcache->clear($folder, $uids);
+        }
+    }
+
+
+    /* --------------------------------
+     *         protected methods
+     * --------------------------------*/
+
+    /**
+     * Validate the given input and save to local properties
+     *
+     * @param string $sort_field Sort column
+     * @param string $sort_order Sort order
+     */
+    protected function set_sort_order($sort_field, $sort_order)
+    {
+        if ($sort_field != null) {
+            $this->sort_field = asciiwords($sort_field);
+        }
+        if ($sort_order != null) {
+            $this->sort_order = strtoupper($sort_order) == 'DESC' ? 'DESC' : 'ASC';
+        }
+    }
+
+
+    /**
+     * Sort folders first by default folders and then in alphabethical order
+     *
+     * @param array $a_folders Folders list
+     */
+    protected function sort_folder_list($a_folders)
+    {
+        $a_out = $a_defaults = $folders = array();
+
+        $delimiter = $this->get_hierarchy_delimiter();
+
+        // find default folders and skip folders starting with '.'
+        foreach ($a_folders as $i => $folder) {
+            if ($folder[0] == '.') {
+                continue;
+            }
+
+            if (($p = array_search($folder, $this->default_folders)) !== false && !$a_defaults[$p]) {
+                $a_defaults[$p] = $folder;
+            }
+            else {
+                $folders[$folder] = rcube_charset_convert($folder, 'UTF7-IMAP');
+            }
+        }
+
+        // sort folders and place defaults on the top
+        asort($folders, SORT_LOCALE_STRING);
+        ksort($a_defaults);
+        $folders = array_merge($a_defaults, array_keys($folders));
+
+        // finally we must rebuild the list to move
+        // subfolders of default folders to their place...
+        // ...also do this for the rest of folders because
+        // asort() is not properly sorting case sensitive names
+        while (list($key, $folder) = each($folders)) {
+            // set the type of folder name variable (#1485527)
+            $a_out[] = (string) $folder;
+            unset($folders[$key]);
+            $this->rsort($folder, $delimiter, $folders, $a_out);
+        }
+
+        return $a_out;
+    }
+
+
+    /**
+     * Recursive method for sorting folders
+     */
+    protected function rsort($folder, $delimiter, &$list, &$out)
+    {
+        while (list($key, $name) = each($list)) {
+	        if (strpos($name, $folder.$delimiter) === 0) {
+	            // set the type of folder name variable (#1485527)
+    	        $out[] = (string) $name;
+	            unset($list[$key]);
+	            $this->rsort($name, $delimiter, $list, $out);
+	        }
+        }
+        reset($list);
+    }
+
+
+    /**
+     * Find UID of the specified message sequence ID
+     *
+     * @param int    $id       Message (sequence) ID
+     * @param string $folder   Folder name
+     *
+     * @return int Message UID
+     */
+    public function id2uid($id, $folder = null)
+    {
+        if (!strlen($folder)) {
+            $folder = $this->folder;
+        }
+
+        if ($uid = array_search($id, (array)$this->uid_id_map[$folder])) {
+            return $uid;
+        }
+
+        if (!$this->check_connection()) {
+            return null;
+        }
+
+        $uid = $this->conn->ID2UID($folder, $id);
+
+        $this->uid_id_map[$folder][$uid] = $id;
+
+        return $uid;
+    }
+
+
+    /**
+     * Subscribe/unsubscribe a list of folders and update local cache
+     */
+    protected function change_subscription($folders, $mode)
+    {
+        $updated = false;
+
+        if (!empty($folders)) {
+            if (!$this->check_connection()) {
+                return false;
+            }
+
+            foreach ((array)$folders as $i => $folder) {
+                $folders[$i] = $folder;
+
+                if ($mode == 'subscribe') {
+                    $updated = $this->conn->subscribe($folder);
+                }
+                else if ($mode == 'unsubscribe') {
+                    $updated = $this->conn->unsubscribe($folder);
+                }
+            }
+        }
+
+        // clear cached folders list(s)
+        if ($updated) {
+            $this->clear_cache('mailboxes', true);
+        }
+
         return $updated;
-
-      // modify cached list
-      if ($mode=='subscribe')
-        $a_mailbox_cache = array_merge($a_mailbox_cache, $a_mboxes);
-      else if ($mode=='unsubscribe')
-        $a_mailbox_cache = array_diff($a_mailbox_cache, $a_mboxes);
-
-      // write mailboxlist to cache
-      $this->update_cache('mailboxes', $this->_sort_mailbox_list($a_mailbox_cache));
-      }
-
-    return $updated;
     }
 
 
-  /**
-   * Increde/decrese messagecount for a specific mailbox
-   * @access private
-   */
-  private function _set_messagecount($mbox_name, $mode, $increment)
+    /**
+     * Increde/decrese messagecount for a specific folder
+     */
+    protected function set_messagecount($folder, $mode, $increment)
     {
-    $a_mailbox_cache = FALSE;
-    $mailbox = $mbox_name ? $mbox_name : $this->mailbox;
-    $mode = strtoupper($mode);
-
-    $a_mailbox_cache = $this->get_cache('messagecount');
-    
-    if (!is_array($a_mailbox_cache[$mailbox]) || !isset($a_mailbox_cache[$mailbox][$mode]) || !is_numeric($increment))
-      return FALSE;
-    
-    // add incremental value to messagecount
-    $a_mailbox_cache[$mailbox][$mode] += $increment;
-    
-    // there's something wrong, delete from cache
-    if ($a_mailbox_cache[$mailbox][$mode] < 0)
-      unset($a_mailbox_cache[$mailbox][$mode]);
-
-    // write back to cache
-    $this->update_cache('messagecount', $a_mailbox_cache);
-    
-    return TRUE;
-    }
-
-
-  /**
-   * Remove messagecount of a specific mailbox from cache
-   * @access private
-   */
-  private function _clear_messagecount($mbox_name='')
-    {
-    $a_mailbox_cache = FALSE;
-    $mailbox = $mbox_name ? $mbox_name : $this->mailbox;
-
-    $a_mailbox_cache = $this->get_cache('messagecount');
-
-    if (is_array($a_mailbox_cache[$mailbox]))
-      {
-      unset($a_mailbox_cache[$mailbox]);
-      $this->update_cache('messagecount', $a_mailbox_cache);
-      }
-    }
-
-
-  /**
-   * Split RFC822 header string into an associative array
-   * @access private
-   */
-  private function _parse_headers($headers)
-    {
-    $a_headers = array();
-    $headers = preg_replace('/\r?\n(\t| )+/', ' ', $headers);
-    $lines = explode("\n", $headers);
-    $c = count($lines);
-    for ($i=0; $i<$c; $i++)
-      {
-      if ($p = strpos($lines[$i], ': '))
-        {
-        $field = strtolower(substr($lines[$i], 0, $p));
-        $value = trim(substr($lines[$i], $p+1));
-        if (!empty($value))
-          $a_headers[$field] = $value;
+        if (!is_numeric($increment)) {
+            return false;
         }
-      }
-    
-    return $a_headers;
-    }
 
+        $mode = strtoupper($mode);
+        $a_folder_cache = $this->get_cache('messagecount');
 
-  /**
-   * @access private
-   */
-  private function _parse_address_list($str, $decode=true)
-    {
-    // remove any newlines and carriage returns before
-    $a = rcube_explode_quoted_string('[,;]', preg_replace( "/[\r\n]/", " ", $str));
-    $result = array();
-
-    foreach ($a as $key => $val)
-      {
-      $val = preg_replace("/([\"\w])</", "$1 <", $val);
-      $sub_a = rcube_explode_quoted_string(' ', $decode ? $this->decode_header($val) : $val);
-      $result[$key]['name'] = '';
-
-      foreach ($sub_a as $k => $v)
-        {
-	// use angle brackets in regexp to not handle names with @ sign
-        if (preg_match('/^<\S+@\S+>$/', $v))
-          $result[$key]['address'] = trim($v, '<>');
-        else
-          $result[$key]['name'] .= (empty($result[$key]['name'])?'':' ').str_replace("\"",'',stripslashes($v));
+        if (!is_array($a_folder_cache[$folder]) || !isset($a_folder_cache[$folder][$mode])) {
+            return false;
         }
-        
-      if (empty($result[$key]['name']))
-        $result[$key]['name'] = $result[$key]['address'];        
-      elseif (empty($result[$key]['address']))
-        $result[$key]['address'] = $result[$key]['name'];
-      }
-    
-    return $result;
+
+        // add incremental value to messagecount
+        $a_folder_cache[$folder][$mode] += $increment;
+
+        // there's something wrong, delete from cache
+        if ($a_folder_cache[$folder][$mode] < 0) {
+            unset($a_folder_cache[$folder][$mode]);
+        }
+
+        // write back to cache
+        $this->update_cache('messagecount', $a_folder_cache);
+
+        return true;
     }
 
-}  // end class rcube_imap
+
+    /**
+     * Remove messagecount of a specific folder from cache
+     */
+    protected function clear_messagecount($folder, $mode=null)
+    {
+        $a_folder_cache = $this->get_cache('messagecount');
+
+        if (is_array($a_folder_cache[$folder])) {
+            if ($mode) {
+                unset($a_folder_cache[$folder][$mode]);
+            }
+            else {
+                unset($a_folder_cache[$folder]);
+            }
+            $this->update_cache('messagecount', $a_folder_cache);
+        }
+    }
 
 
-/**
- * Class representing a message part
- *
- * @package Mail
- */
-class rcube_message_part
-{
-  var $mime_id = '';
-  var $ctype_primary = 'text';
-  var $ctype_secondary = 'plain';
-  var $mimetype = 'text/plain';
-  var $disposition = '';
-  var $filename = '';
-  var $encoding = '8bit';
-  var $charset = '';
-  var $size = 0;
-  var $headers = array();
-  var $d_parameters = array();
-  var $ctype_parameters = array();
-
-  function __clone()
-  {
-    if (isset($this->parts))
-      foreach ($this->parts as $idx => $part)
-        if (is_object($part))
-	  $this->parts[$idx] = clone $part;
-  }				
-}
+    /**
+     * This is our own debug handler for the IMAP connection
+     * @access public
+     */
+    public function debug_handler(&$imap, $message)
+    {
+        write_log('imap', $message);
+    }
 
 
-/**
- * Class for sorting an array of iilBasicHeader objects in a predetermined order.
- *
- * @package Mail
- * @author Eric Stadtherr
- */
-class rcube_header_sorter
-{
-   var $sequence_numbers = array();
-   
-   /**
-    * Set the predetermined sort order.
-    *
-    * @param array Numerically indexed array of IMAP message sequence numbers
-    */
-   function set_sequence_numbers($seqnums)
-   {
-      $this->sequence_numbers = array_flip($seqnums);
-   }
- 
-   /**
-    * Sort the array of header objects
-    *
-    * @param array Array of iilBasicHeader objects indexed by UID
-    */
-   function sort_headers(&$headers)
-   {
-      /*
-       * uksort would work if the keys were the sequence number, but unfortunately
-       * the keys are the UIDs.  We'll use uasort instead and dereference the value
-       * to get the sequence number (in the "id" field).
-       * 
-       * uksort($headers, array($this, "compare_seqnums")); 
-       */
-       uasort($headers, array($this, "compare_seqnums"));
-   }
- 
-   /**
-    * Sort method called by uasort()
-    */
-   function compare_seqnums($a, $b)
-   {
-      // First get the sequence number from the header object (the 'id' field).
-      $seqa = $a->id;
-      $seqb = $b->id;
-      
-      // then find each sequence number in my ordered list
-      $posa = isset($this->sequence_numbers[$seqa]) ? intval($this->sequence_numbers[$seqa]) : -1;
-      $posb = isset($this->sequence_numbers[$seqb]) ? intval($this->sequence_numbers[$seqb]) : -1;
-      
-      // return the relative position as the comparison value
-      return $posa - $posb;
-   }
+    /**
+     * Deprecated methods (to be removed)
+     */
+
+    public function decode_address_list($input, $max = null, $decode = true, $fallback = null)
+    {
+        return rcube_mime::decode_address_list($input, $max, $decode, $fallback);
+    }
+
+    public function decode_header($input, $fallback = null)
+    {
+        return rcube_mime::decode_mime_string((string)$input, $fallback);
+    }
+
+    public static function decode_mime_string($input, $fallback = null)
+    {
+        return rcube_mime::decode_mime_string($input, $fallback);
+    }
+
+    public function mime_decode($input, $encoding = '7bit')
+    {
+        return rcube_mime::decode($input, $encoding);
+    }
+
+    public static function explode_header_string($separator, $str, $remove_comments = false)
+    {
+        return rcube_mime::explode_header_string($separator, $str, $remove_comments);
+    }
+
+    public function select_mailbox($mailbox)
+    {
+        // do nothing
+    }
+
+    public function set_mailbox($folder)
+    {
+        $this->set_folder($folder);
+    }
+
+    public function get_mailbox_name()
+    {
+        return $this->get_folder();
+    }
+
+    public function list_headers($folder='', $page=NULL, $sort_field=NULL, $sort_order=NULL, $slice=0)
+    {
+        return $this->list_messages($folder, $page, $sort_field, $sort_order, $slice);
+    }
+
+    public function mailbox_status($folder = null)
+    {
+        return $this->folder_status($folder);
+    }
+
+    public function message_index($folder = '', $sort_field = NULL, $sort_order = NULL)
+    {
+        return $this->index($folder, $sort_field, $sort_order);
+    }
+
+    public function message_index_direct($folder, $sort_field = null, $sort_order = null, $skip_cache = true)
+    {
+        return $this->index_direct($folder, $sort_field, $sort_order, $skip_cache);
+    }
+
+    public function list_mailboxes($root='', $name='*', $filter=null, $rights=null, $skip_sort=false)
+    {
+        return $this->list_folders_subscribed($root, $name, $filter, $rights, $skip_sort);
+    }
+
+    public function list_unsubscribed($root='', $name='*', $filter=null, $rights=null, $skip_sort=false)
+    {
+        return $this->list_folders($root, $name, $filter, $rights, $skip_sort);
+    }
+
+    public function get_mailbox_size($folder)
+    {
+        return $this->folder_size($folder);
+    }
+
+    public function create_mailbox($folder, $subscribe=false)
+    {
+        return $this->create_folder($folder, $subscribe);
+    }
+
+    public function rename_mailbox($folder, $new_name)
+    {
+        return $this->rename_folder($folder, $new_name);
+    }
+
+    function delete_mailbox($folder)
+    {
+        return $this->delete_folder($folder);
+    }
+
+    public function mailbox_exists($folder, $subscription=false)
+    {
+        return $this->folder_exists($folder, $subscription);
+    }
+
+    public function mailbox_namespace($folder)
+    {
+        return $this->folder_namespace($folder);
+    }
+
+    public function mod_mailbox($folder, $mode = 'out')
+    {
+        return $this->mod_folder($folder, $mode);
+    }
+
+    public function mailbox_attributes($folder, $force=false)
+    {
+        return $this->folder_attributes($folder, $force);
+    }
+
+    public function mailbox_data($folder)
+    {
+        return $this->folder_data($folder);
+    }
+
+    public function mailbox_info($folder)
+    {
+        return $this->folder_info($folder);
+    }
+
+    public function mailbox_sync($folder)
+    {
+        return $this->folder_sync($folder);
+    }
+
+    public function expunge($folder='', $clear_cache=true)
+    {
+        return $this->expunge_folder($folder, $clear_cache);
+    }
+
 }

--
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