<?php

/*
 +-----------------------------------------------------------------------+
 | program/include/rcube.php                                             |
 |                                                                       |
 | This file is part of the Roundcube Webmail client                     |
 | Copyright (C) 2008-2012, 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:                                                              |
 |   Framework base class providing core functions and holding           |
 |   instances of all 'global' objects like db- and storage-connections  |
 +-----------------------------------------------------------------------+
 | Author: Thomas Bruederli <roundcube@gmail.com>                        |
 +-----------------------------------------------------------------------+
*/


/**
 * Base class of the Roundcube Framework
 * implemented as singleton
 *
 * @package Core
 */
class rcube
{
  const INIT_WITH_DB = 1;
  const INIT_WITH_PLUGINS = 2;

  /**
   * Singleton instace of rcube
   *
   * @var rcmail
   */
  static protected $instance;

  /**
   * Stores instance of rcube_config.
   *
   * @var rcube_config
   */
  public $config;

  /**
   * Instace of database class.
   *
   * @var rcube_pdo
   */
  public $db;

  /**
   * Instace of Memcache class.
   *
   * @var Memcache
   */
  public $memcache;

  /**
   * Instace of rcube_session class.
   *
   * @var rcube_session
   */
  public $session;

  /**
   * Instance of rcube_smtp class.
   *
   * @var rcube_smtp
   */
  public $smtp;

  /**
   * Instance of rcube_storage class.
   *
   * @var rcube_storage
   */
  public $storage;

  /**
   * Instance of rcube_output class.
   *
   * @var rcube_output
   */
  public $output;

  /**
   * Instance of rcube_plugin_api.
   *
   * @var rcube_plugin_api
   */
  public $plugins;


  /* private/protected vars */
  protected $texts;
  protected $caches = array();
  protected $shutdown_functions = array();
  protected $expunge_cache = false;


  /**
   * This implements the 'singleton' design pattern
   *
   * @return rcube The one and only instance
   */
  static function get_instance()
  {
    if (!self::$instance) {
      self::$instance = new rcube();
    }

    return self::$instance;
  }


  /**
   * Private constructor
   */
  protected function __construct()
  {
    // load configuration
    $this->config = new rcube_config();
    $this->plugins = new rcube_dummy_plugin_api;

    register_shutdown_function(array($this, 'shutdown'));
  }


  /**
   * Initial startup function
   */
  protected function init($mode = 0)
  {
    // initialize syslog
    if ($this->config->get('log_driver') == 'syslog') {
      $syslog_id = $this->config->get('syslog_id', 'roundcube');
      $syslog_facility = $this->config->get('syslog_facility', LOG_USER);
      openlog($syslog_id, LOG_ODELAY, $syslog_facility);
    }

    // connect to database
    if ($mode & self::INIT_WITH_DB) {
      $this->get_dbh();
    }

    // create plugin API and load plugins
    if ($mode & self::INIT_WITH_PLUGINS) {
      $this->plugins = rcube_plugin_api::get_instance();
    }
  }


  /**
   * Get the current database connection
   *
   * @return rcube_pdo  Database connection object
   */
  public function get_dbh()
  {
    if (!$this->db) {
      $config_all = $this->config->all();
      $this->db = rcube_db::factory($config_all['db_dsnw'], $config_all['db_dsnr'], $config_all['db_persistent']);
      $this->db->set_debug((bool)$config_all['sql_debug']);
    }

    return $this->db;
  }


  /**
   * Get global handle for memcache access
   *
   * @return object Memcache
   */
  public function get_memcache()
  {
    if (!isset($this->memcache)) {
      // no memcache support in PHP
      if (!class_exists('Memcache')) {
        $this->memcache = false;
        return false;
      }

      $this->memcache = new Memcache;
      $this->mc_available = 0;

      // add alll configured hosts to pool
      $pconnect = $this->config->get('memcache_pconnect', true);
      foreach ($this->config->get('memcache_hosts', array()) as $host) {
        list($host, $port) = explode(':', $host);
        if (!$port) $port = 11211;
        $this->mc_available += intval($this->memcache->addServer($host, $port, $pconnect, 1, 1, 15, false, array($this, 'memcache_failure')));
      }

      // test connection and failover (will result in $this->mc_available == 0 on complete failure)
      $this->memcache->increment('__CONNECTIONTEST__', 1);  // NOP if key doesn't exist

      if (!$this->mc_available)
        $this->memcache = false;
    }

    return $this->memcache;
  }


  /**
   * Callback for memcache failure
   */
  public function memcache_failure($host, $port)
  {
    static $seen = array();

    // only report once
    if (!$seen["$host:$port"]++) {
      $this->mc_available--;
      self::raise_error(array('code' => 604, 'type' => 'db',
        'line' => __LINE__, 'file' => __FILE__,
        'message' => "Memcache failure on host $host:$port"),
        true, false);
    }
  }


  /**
   * Initialize and get cache object
   *
   * @param string $name   Cache identifier
   * @param string $type   Cache type ('db', 'apc' or 'memcache')
   * @param string $ttl    Expiration time for cache items
   * @param bool   $packed Enables/disables data serialization
   *
   * @return rcube_cache Cache object
   */
  public function get_cache($name, $type='db', $ttl=0, $packed=true)
  {
    if (!isset($this->caches[$name])) {
      $userid = $this->get_user_id();
      $this->caches[$name] = new rcube_cache($type, $userid, $name, $ttl, $packed);
    }

    return $this->caches[$name];
  }


  /**
   * Create SMTP object and connect to server
   *
   * @param boolean True if connection should be established
   */
  public function smtp_init($connect = false)
  {
    $this->smtp = new rcube_smtp();

    if ($connect)
      $this->smtp->connect();
  }


  /**
   * Initialize and get storage object
   *
   * @return rcube_storage Storage object
   */
  public function get_storage()
  {
    // already initialized
    if (!is_object($this->storage)) {
      $this->storage_init();
    }

    return $this->storage;
  }


  /**
   * Initialize storage object
   */
  public function storage_init()
  {
    // already initialized
    if (is_object($this->storage)) {
      return;
    }

    $driver = $this->config->get('storage_driver', 'imap');
    $driver_class = "rcube_{$driver}";

    if (!class_exists($driver_class)) {
      self::raise_error(array(
        'code' => 700, 'type' => 'php',
        'file' => __FILE__, 'line' => __LINE__,
        'message' => "Storage driver class ($driver) not found!"),
        true, true);
    }

    // Initialize storage object
    $this->storage = new $driver_class;

    // for backward compat. (deprecated, will be removed)
    $this->imap = $this->storage;

    // enable caching of mail data
    $storage_cache  = $this->config->get("{$driver}_cache");
    $messages_cache = $this->config->get('messages_cache');
    // for backward compatybility
    if ($storage_cache === null && $messages_cache === null && $this->config->get('enable_caching')) {
        $storage_cache  = 'db';
        $messages_cache = true;
    }

    if ($storage_cache)
        $this->storage->set_caching($storage_cache);
    if ($messages_cache)
        $this->storage->set_messages_caching(true);

    // set pagesize from config
    $pagesize = $this->config->get('mail_pagesize');
    if (!$pagesize) {
        $pagesize = $this->config->get('pagesize', 50);
    }
    $this->storage->set_pagesize($pagesize);

    // set class options
    $options = array(
      'auth_type'   => $this->config->get("{$driver}_auth_type", 'check'),
      'auth_cid'    => $this->config->get("{$driver}_auth_cid"),
      'auth_pw'     => $this->config->get("{$driver}_auth_pw"),
      'debug'       => (bool) $this->config->get("{$driver}_debug"),
      'force_caps'  => (bool) $this->config->get("{$driver}_force_caps"),
      'timeout'     => (int) $this->config->get("{$driver}_timeout"),
      'skip_deleted' => (bool) $this->config->get('skip_deleted'),
      'driver'      => $driver,
    );

    if (!empty($_SESSION['storage_host'])) {
      $options['host']     = $_SESSION['storage_host'];
      $options['user']     = $_SESSION['username'];
      $options['port']     = $_SESSION['storage_port'];
      $options['ssl']      = $_SESSION['storage_ssl'];
      $options['password'] = $this->decrypt($_SESSION['password']);
      $_SESSION[$driver.'_host'] = $_SESSION['storage_host'];
    }

    $options = $this->plugins->exec_hook("storage_init", $options);

    // for backward compat. (deprecated, to be removed)
    $options = $this->plugins->exec_hook("imap_init", $options);

    $this->storage->set_options($options);
    $this->set_storage_prop();
  }


  /**
   * Set storage parameters.
   * This must be done AFTER connecting to the server!
   */
  protected function set_storage_prop()
  {
    $storage = $this->get_storage();

    $storage->set_charset($this->config->get('default_charset', RCMAIL_CHARSET));

    if ($default_folders = $this->config->get('default_folders')) {
      $storage->set_default_folders($default_folders);
    }
    if (isset($_SESSION['mbox'])) {
      $storage->set_folder($_SESSION['mbox']);
    }
    if (isset($_SESSION['page'])) {
      $storage->set_page($_SESSION['page']);
    }
  }


    /**
     * Create session object and start the session.
     */
    public function session_init()
    {
        // session started (Installer?)
        if (session_id()) {
            return;
        }

        $sess_name   = $this->config->get('session_name');
        $sess_domain = $this->config->get('session_domain');
        $lifetime    = $this->config->get('session_lifetime', 0) * 60;

        // set session domain
        if ($sess_domain) {
            ini_set('session.cookie_domain', $sess_domain);
        }
        // set session garbage collecting time according to session_lifetime
        if ($lifetime) {
            ini_set('session.gc_maxlifetime', $lifetime * 2);
        }

        ini_set('session.cookie_secure', rcube_utils::https_check());
        ini_set('session.name', $sess_name ? $sess_name : 'roundcube_sessid');
        ini_set('session.use_cookies', 1);
        ini_set('session.use_only_cookies', 1);
        ini_set('session.serialize_handler', 'php');

        // use database for storing session data
        $this->session = new rcube_session($this->get_dbh(), $this->config);

        $this->session->register_gc_handler(array($this, 'temp_gc'));
        $this->session->register_gc_handler(array($this, 'cache_gc'));

        // start PHP session (if not in CLI mode)
        if ($_SERVER['REMOTE_ADDR']) {
            session_start();
        }
    }


    /**
     * Configure session object internals
     */
    public function session_configure()
    {
        if (!$this->session) {
            return;
        }

        $lifetime   = $this->config->get('session_lifetime', 0) * 60;
        $keep_alive = $this->config->get('keep_alive');

        // set keep-alive/check-recent interval
        if ($keep_alive) {
            // be sure that it's less than session lifetime
            if ($lifetime) {
                $keep_alive = min($keep_alive, $lifetime - 30);
            }
            $keep_alive = max(60, $keep_alive);
            $this->session->set_keep_alive($keep_alive);
        }

        $this->session->set_secret($this->config->get('des_key') . dirname($_SERVER['SCRIPT_NAME']));
        $this->session->set_ip_check($this->config->get('ip_check'));
    }


    /**
     * Garbage collector function for temp files.
     * Remove temp files older than two days
     */
    public function temp_gc()
    {
        $tmp = unslashify($this->config->get('temp_dir'));
        $expire = time() - 172800;  // expire in 48 hours

        if ($tmp && ($dir = opendir($tmp))) {
            while (($fname = readdir($dir)) !== false) {
                if ($fname{0} == '.') {
                    continue;
                }

                if (filemtime($tmp.'/'.$fname) < $expire) {
                    @unlink($tmp.'/'.$fname);
                }
            }

            closedir($dir);
        }
    }


    /**
     * Garbage collector for cache entries.
     * Set flag to expunge caches on shutdown
     */
    public function cache_gc()
    {
        // because this gc function is called before storage is initialized,
        // we just set a flag to expunge storage cache on shutdown.
        $this->expunge_cache = true;
    }


  /**
   * Get localized text in the desired language
   *
   * @param mixed   $attrib  Named parameters array or label name
   * @param string  $domain  Label domain (plugin) name
   *
   * @return string Localized text
   */
  public function gettext($attrib, $domain=null)
  {
    // load localization files if not done yet
    if (empty($this->texts))
      $this->load_language();

    // extract attributes
    if (is_string($attrib))
      $attrib = array('name' => $attrib);

    $name = $attrib['name'] ? $attrib['name'] : '';

    // attrib contain text values: use them from now
    if (($setval = $attrib[strtolower($_SESSION['language'])]) || ($setval = $attrib['en_us']))
        $this->texts[$name] = $setval;

    // check for text with domain
    if ($domain && ($text = $this->texts[$domain.'.'.$name]))
      ;
    // text does not exist
    else if (!($text = $this->texts[$name])) {
      return "[$name]";
    }

    // replace vars in text
    if (is_array($attrib['vars'])) {
      foreach ($attrib['vars'] as $var_key => $var_value)
        $text = str_replace($var_key[0]!='$' ? '$'.$var_key : $var_key, $var_value, $text);
    }

    // format output
    if (($attrib['uppercase'] && strtolower($attrib['uppercase']=='first')) || $attrib['ucfirst'])
      return ucfirst($text);
    else if ($attrib['uppercase'])
      return mb_strtoupper($text);
    else if ($attrib['lowercase'])
      return mb_strtolower($text);

    return strtr($text, array('\n' => "\n"));
  }


  /**
   * Check if the given text label exists
   *
   * @param string  $name       Label name
   * @param string  $domain     Label domain (plugin) name or '*' for all domains
   * @param string  $ref_domain Sets domain name if label is found
   *
   * @return boolean True if text exists (either in the current language or in en_US)
   */
  public function text_exists($name, $domain = null, &$ref_domain = null)
  {
    // load localization files if not done yet
    if (empty($this->texts))
      $this->load_language();

    if (isset($this->texts[$name])) {
        $ref_domain = '';
        return true;
    }

    // any of loaded domains (plugins)
    if ($domain == '*') {
      foreach ($this->plugins->loaded_plugins() as $domain)
        if (isset($this->texts[$domain.'.'.$name])) {
          $ref_domain = $domain;
          return true;
        }
    }
    // specified domain
    else if ($domain) {
      $ref_domain = $domain;
      return isset($this->texts[$domain.'.'.$name]);
    }

    return false;
  }

  /**
   * Load a localization package
   *
   * @param string Language ID
   */
  public function load_language($lang = null, $add = array())
  {
    $lang = $this->language_prop(($lang ? $lang : $_SESSION['language']));

    // load localized texts
    if (empty($this->texts) || $lang != $_SESSION['language']) {
      $this->texts = array();

      // handle empty lines after closing PHP tag in localization files
      ob_start();

      // get english labels (these should be complete)
      @include(INSTALL_PATH . 'program/localization/en_US/labels.inc');
      @include(INSTALL_PATH . 'program/localization/en_US/messages.inc');

      if (is_array($labels))
        $this->texts = $labels;
      if (is_array($messages))
        $this->texts = array_merge($this->texts, $messages);

      // include user language files
      if ($lang != 'en' && $lang != 'en_US' && is_dir(INSTALL_PATH . 'program/localization/' . $lang)) {
        include_once(INSTALL_PATH . 'program/localization/' . $lang . '/labels.inc');
        include_once(INSTALL_PATH . 'program/localization/' . $lang . '/messages.inc');

        if (is_array($labels))
          $this->texts = array_merge($this->texts, $labels);
        if (is_array($messages))
          $this->texts = array_merge($this->texts, $messages);
      }

      ob_end_clean();

      $_SESSION['language'] = $lang;
    }

    // append additional texts (from plugin)
    if (is_array($add) && !empty($add))
      $this->texts += $add;
  }


  /**
   * Check the given string and return a valid language code
   *
   * @param string Language code
   * @return string Valid language code
   */
  protected function language_prop($lang)
  {
    static $rcube_languages, $rcube_language_aliases;

    // user HTTP_ACCEPT_LANGUAGE if no language is specified
    if (empty($lang) || $lang == 'auto') {
       $accept_langs = explode(',', $_SERVER['HTTP_ACCEPT_LANGUAGE']);
       $lang = str_replace('-', '_', $accept_langs[0]);
     }

    if (empty($rcube_languages)) {
      @include(INSTALL_PATH . 'program/localization/index.inc');
    }

    // check if we have an alias for that language
    if (!isset($rcube_languages[$lang]) && isset($rcube_language_aliases[$lang])) {
      $lang = $rcube_language_aliases[$lang];
    }
    // try the first two chars
    else if (!isset($rcube_languages[$lang])) {
      $short = substr($lang, 0, 2);

      // check if we have an alias for the short language code
      if (!isset($rcube_languages[$short]) && isset($rcube_language_aliases[$short])) {
        $lang = $rcube_language_aliases[$short];
      }
      // expand 'nn' to 'nn_NN'
      else if (!isset($rcube_languages[$short])) {
        $lang = $short.'_'.strtoupper($short);
      }
    }

    if (!isset($rcube_languages[$lang]) || !is_dir(INSTALL_PATH . 'program/localization/' . $lang)) {
      $lang = 'en_US';
    }

    return $lang;
  }


  /**
   * Read directory program/localization and return a list of available languages
   *
   * @return array List of available localizations
   */
  public function list_languages()
  {
    static $sa_languages = array();

    if (!sizeof($sa_languages)) {
      @include(INSTALL_PATH . 'program/localization/index.inc');

      if ($dh = @opendir(INSTALL_PATH . 'program/localization')) {
        while (($name = readdir($dh)) !== false) {
          if ($name[0] == '.' || !is_dir(INSTALL_PATH . 'program/localization/' . $name))
            continue;

          if ($label = $rcube_languages[$name])
            $sa_languages[$name] = $label;
        }
        closedir($dh);
      }
    }

    return $sa_languages;
  }


  /**
   * Encrypt using 3DES
   *
   * @param string $clear clear text input
   * @param string $key encryption key to retrieve from the configuration, defaults to 'des_key'
   * @param boolean $base64 whether or not to base64_encode() the result before returning
   *
   * @return string encrypted text
   */
  public function encrypt($clear, $key = 'des_key', $base64 = true)
  {
    if (!$clear)
      return '';

    /*-
     * Add a single canary byte to the end of the clear text, which
     * will help find out how much of padding will need to be removed
     * upon decryption; see http://php.net/mcrypt_generic#68082
     */
    $clear = pack("a*H2", $clear, "80");

    if (function_exists('mcrypt_module_open') &&
        ($td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_CBC, ""))) {
      $iv = $this->create_iv(mcrypt_enc_get_iv_size($td));
      mcrypt_generic_init($td, $this->config->get_crypto_key($key), $iv);
      $cipher = $iv . mcrypt_generic($td, $clear);
      mcrypt_generic_deinit($td);
      mcrypt_module_close($td);
    }
    else {
      @include_once 'des.inc';

      if (function_exists('des')) {
        $des_iv_size = 8;
        $iv = $this->create_iv($des_iv_size);
        $cipher = $iv . des($this->config->get_crypto_key($key), $clear, 1, 1, $iv);
      }
      else {
        self::raise_error(array(
          'code' => 500, 'type' => 'php',
          'file' => __FILE__, 'line' => __LINE__,
          'message' => "Could not perform encryption; make sure Mcrypt is installed or lib/des.inc is available"
        ), true, true);
      }
    }

    return $base64 ? base64_encode($cipher) : $cipher;
  }

  /**
   * Decrypt 3DES-encrypted string
   *
   * @param string $cipher encrypted text
   * @param string $key encryption key to retrieve from the configuration, defaults to 'des_key'
   * @param boolean $base64 whether or not input is base64-encoded
   *
   * @return string decrypted text
   */
  public function decrypt($cipher, $key = 'des_key', $base64 = true)
  {
    if (!$cipher)
      return '';

    $cipher = $base64 ? base64_decode($cipher) : $cipher;

    if (function_exists('mcrypt_module_open') &&
        ($td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_CBC, ""))) {
      $iv_size = mcrypt_enc_get_iv_size($td);
      $iv = substr($cipher, 0, $iv_size);

      // session corruption? (#1485970)
      if (strlen($iv) < $iv_size)
        return '';

      $cipher = substr($cipher, $iv_size);
      mcrypt_generic_init($td, $this->config->get_crypto_key($key), $iv);
      $clear = mdecrypt_generic($td, $cipher);
      mcrypt_generic_deinit($td);
      mcrypt_module_close($td);
    }
    else {
      @include_once 'des.inc';

      if (function_exists('des')) {
        $des_iv_size = 8;
        $iv = substr($cipher, 0, $des_iv_size);
        $cipher = substr($cipher, $des_iv_size);
        $clear = des($this->config->get_crypto_key($key), $cipher, 0, 1, $iv);
      }
      else {
        self::raise_error(array(
          'code' => 500, 'type' => 'php',
          'file' => __FILE__, 'line' => __LINE__,
          'message' => "Could not perform decryption; make sure Mcrypt is installed or lib/des.inc is available"
        ), true, true);
      }
    }

    /*-
     * Trim PHP's padding and the canary byte; see note in
     * rcube::encrypt() and http://php.net/mcrypt_generic#68082
     */
    $clear = substr(rtrim($clear, "\0"), 0, -1);

    return $clear;
  }

  /**
   * Generates encryption initialization vector (IV)
   *
   * @param int Vector size
   * @return string Vector string
   */
  private function create_iv($size)
  {
    // mcrypt_create_iv() can be slow when system lacks entrophy
    // we'll generate IV vector manually
    $iv = '';
    for ($i = 0; $i < $size; $i++)
        $iv .= chr(mt_rand(0, 255));
    return $iv;
  }


  /**
   * Build a valid URL to this instance of Roundcube
   *
   * @param mixed Either a string with the action or url parameters as key-value pairs
   * @return string Valid application URL
   */
  public function url($p)
  {
      // STUB: should be overloaded by the application
      return '';
  }


  /**
   * Function to be executed in script shutdown
   * Registered with register_shutdown_function()
   */
  public function shutdown()
  {
    foreach ($this->shutdown_functions as $function)
      call_user_func($function);

    if (is_object($this->smtp))
      $this->smtp->disconnect();

    foreach ($this->caches as $cache) {
        if (is_object($cache))
            $cache->close();
    }

    if (is_object($this->storage)) {
      if ($this->expunge_cache)
        $this->storage->expunge_cache();
      $this->storage->close();
    }
  }


  /**
   * Registers shutdown function to be executed on shutdown.
   * The functions will be executed before destroying any
   * objects like smtp, imap, session, etc.
   *
   * @param callback Function callback
   */
  public function add_shutdown_function($function)
  {
    $this->shutdown_functions[] = $function;
  }


  /**
   * Construct shell command, execute it and return output as string.
   * Keywords {keyword} are replaced with arguments
   *
   * @param $cmd Format string with {keywords} to be replaced
   * @param $values (zero, one or more arrays can be passed)
   * @return output of command. shell errors not detectable
   */
  public static function exec(/* $cmd, $values1 = array(), ... */)
  {
    $args = func_get_args();
    $cmd = array_shift($args);
    $values = $replacements = array();

    // merge values into one array
    foreach ($args as $arg)
      $values += (array)$arg;

    preg_match_all('/({(-?)([a-z]\w*)})/', $cmd, $matches, PREG_SET_ORDER);
    foreach ($matches as $tags) {
      list(, $tag, $option, $key) = $tags;
      $parts = array();

      if ($option) {
        foreach ((array)$values["-$key"] as $key => $value) {
          if ($value === true || $value === false || $value === null)
            $parts[] = $value ? $key : "";
          else foreach ((array)$value as $val)
            $parts[] = "$key " . escapeshellarg($val);
        }
      }
      else {
        foreach ((array)$values[$key] as $value)
          $parts[] = escapeshellarg($value);
      }

      $replacements[$tag] = join(" ", $parts);
    }

    // use strtr behaviour of going through source string once
    $cmd = strtr($cmd, $replacements);

    return (string)shell_exec($cmd);
  }


    /**
     * Print or write debug messages
     *
     * @param mixed Debug message or data
     */
    public static function console()
    {
        $args = func_get_args();

        if (class_exists('rcube', false)) {
            $rcube = self::get_instance();
            $plugin = $rcube->plugins->exec_hook('console', array('args' => $args));
            if ($plugin['abort']) {
                return;
            }
           $args = $plugin['args'];
        }

        $msg = array();
        foreach ($args as $arg) {
            $msg[] = !is_string($arg) ? var_export($arg, true) : $arg;
        }

        self::write_log('console', join(";\n", $msg));
    }


    /**
     * Append a line to a logfile in the logs directory.
     * Date will be added automatically to the line.
     *
     * @param $name name of log file
     * @param line Line to append
     */
    public static function write_log($name, $line)
    {
        if (!is_string($line)) {
            $line = var_export($line, true);
        }

        $date_format = self::$instance ? self::$instance->config->get('log_date_format') : null;
        $log_driver  = self::$instance ? self::$instance->config->get('log_driver') : null;

        if (empty($date_format)) {
            $date_format = 'd-M-Y H:i:s O';
        }

        $date = date($date_format);

        // trigger logging hook
        if (is_object(self::$instance) && is_object(self::$instance->plugins)) {
            $log  = self::$instance->plugins->exec_hook('write_log', array('name' => $name, 'date' => $date, 'line' => $line));
            $name = $log['name'];
            $line = $log['line'];
            $date = $log['date'];
            if ($log['abort'])
                return true;
        }

        if ($log_driver == 'syslog') {
            $prio = $name == 'errors' ? LOG_ERR : LOG_INFO;
            syslog($prio, $line);
            return true;
        }

        // log_driver == 'file' is assumed here

        $line = sprintf("[%s]: %s\n", $date, $line);
        $log_dir  = self::$instance ? self::$instance->config->get('log_dir') : null;

        if (empty($log_dir)) {
            $log_dir = INSTALL_PATH . 'logs';
        }

        // try to open specific log file for writing
        $logfile = $log_dir.'/'.$name;

        if ($fp = @fopen($logfile, 'a')) {
            fwrite($fp, $line);
            fflush($fp);
            fclose($fp);
            return true;
        }

        trigger_error("Error writing to log file $logfile; Please check permissions", E_USER_WARNING);
        return false;
    }


    /**
     * Throw system error (and show error page).
     *
     * @param array Named parameters
     *      - code:    Error code (required)
     *      - type:    Error type [php|db|imap|javascript] (required)
     *      - message: Error message
     *      - file:    File where error occured
     *      - line:    Line where error occured
     * @param boolean True to log the error
     * @param boolean Terminate script execution
     */
    public static function raise_error($arg = array(), $log = false, $terminate = false)
    {
        // handle PHP exceptions
        if (is_object($arg) && is_a($arg, 'Exception')) {
            $err = array(
                'type' => 'php',
                'code' => $arg->getCode(),
                'line' => $arg->getLine(),
                'file' => $arg->getFile(),
                'message' => $arg->getMessage(),
            );
            $arg = $err;
        }

        // installer
        if (class_exists('rcube_install', false)) {
            $rci = rcube_install::get_instance();
            $rci->raise_error($arg);
            return;
        }

        if (($log || $terminate) && $arg['type'] && $arg['message']) {
            $arg['fatal'] = $terminate;
            self::log_bug($arg);
        }

        // display error page and terminate script
        if ($terminate && is_object(self::$instance->output)) {
            self::$instance->output->raise_error($arg['code'], $arg['message']);
        }
    }


    /**
     * Report error according to configured debug_level
     *
     * @param array Named parameters
     * @see self::raise_error()
     */
    public static function log_bug($arg_arr)
    {
        $program = strtoupper($arg_arr['type']);
        $level   = self::get_instance()->config->get('debug_level');

        // disable errors for ajax requests, write to log instead (#1487831)
        if (($level & 4) && !empty($_REQUEST['_remote'])) {
            $level = ($level ^ 4) | 1;
        }

        // write error to local log file
        if (($level & 1) || !empty($arg_arr['fatal'])) {
            if ($_SERVER['REQUEST_METHOD'] == 'POST') {
                $post_query = '?_task='.urlencode($_POST['_task']).'&_action='.urlencode($_POST['_action']);
            }
            else {
                $post_query = '';
            }

            $log_entry = sprintf("%s Error: %s%s (%s %s)",
                $program,
                $arg_arr['message'],
                $arg_arr['file'] ? sprintf(' in %s on line %d', $arg_arr['file'], $arg_arr['line']) : '',
                $_SERVER['REQUEST_METHOD'],
                $_SERVER['REQUEST_URI'] . $post_query);

            if (!self::write_log('errors', $log_entry)) {
                // send error to PHPs error handler if write_log didn't succeed
                trigger_error($arg_arr['message']);
            }
        }

        // report the bug to the global bug reporting system
        if ($level & 2) {
            // TODO: Send error via HTTP
        }

        // show error if debug_mode is on
        if ($level & 4) {
            print "<b>$program Error";

            if (!empty($arg_arr['file']) && !empty($arg_arr['line'])) {
                print " in $arg_arr[file] ($arg_arr[line])";
            }

            print ':</b>&nbsp;';
            print nl2br($arg_arr['message']);
            print '<br />';
            flush();
        }
    }


    /**
     * Returns current time (with microseconds).
     *
     * @return float Current time in seconds since the Unix
     */
    public static function timer()
    {
        return microtime(true);
    }


    /**
     * Logs time difference according to provided timer
     *
     * @param float  $timer  Timer (self::timer() result)
     * @param string $label  Log line prefix
     * @param string $dest   Log file name
     *
     * @see self::timer()
     */
    public static function print_timer($timer, $label = 'Timer', $dest = 'console')
    {
        static $print_count = 0;

        $print_count++;
        $now  = self::timer();
        $diff = $now - $timer;

        if (empty($label)) {
            $label = 'Timer '.$print_count;
        }

        self::write_log($dest, sprintf("%s: %0.4f sec", $label, $diff));
    }


    /**
     * Getter for logged user ID.
     *
     * @return mixed User identifier
     */
    public function get_user_id()
    {
        if (is_object($this->user)) {
            return $this->user->ID;
        }
        else if (isset($_SESSION['user_id'])) {
            return $_SESSION['user_id'];
        }

        return null;
    }


    /**
     * Getter for logged user name.
     *
     * @return string User name
     */
    public function get_user_name()
    {
        if (is_object($this->user)) {
            return $this->user->get_username();
        }

        return null;
    }
}


/**
 * Lightweight plugin API class serving as a dummy if plugins are not enabled
 *
 * @package Core
 */
class rcube_dummy_plugin_api
{
    /**
     * Triggers a plugin hook.
     * @see rcube_plugin_api::exec_hook()
     */
    public function exec_hook($hook, $args = array())
    {
        return $args;
    }
}