Codeigniter мультиязычность, смена языка по ссылке

application/config/routes.php

//route example: http://domain.tld/en/controller => http://domain.tld/controller
$route['(\w{2})/(.*)'] = '$2';
$route['(\w{2})'] = $route['default_controller'];

application/config/config.php

/*
|--------------------------------------------------------------------------
| Default Language
|--------------------------------------------------------------------------
|
| This determines which set of language files should be used. Make sure
| there is an available translation if you intend to use something other
| than english.
|
*/
$config['language'] = "spanish";

/* default language abbreviation */
$config['language_abbr'] = "es";

/* set available language abbreviations */
$config['lang_uri_abbr'] = array("es" => "spanish", "en" => "english", "ja" => "japanese");

/* hide the language segment (use cookie) */
$config['lang_ignore'] = TRUE;

application/core/MY_Lang.php

<?php (defined('BASEPATH')) OR exit('No direct script access allowed');
/**
* Language Identifier
* 
* Adds a language identifier prefix to all site_url links
* 
* @copyright     Copyright (c) 2011 Wiredesignz
* @version         0.29
* 
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* 
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* 
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
class MY_Lang extends CI_Lang
{
    function __construct() {

        global $URI, $CFG, $IN;

        $config =& $CFG->config;

        $index_page    = $config['index_page'];
        $lang_ignore   = $config['lang_ignore'];
        $default_abbr  = $config['language_abbr'];
        $lang_uri_abbr = $config['lang_uri_abbr'];

        /* get the language abbreviation from uri */
        $uri_abbr = $URI->segment(1);

        /* adjust the uri string leading slash */
        $URI->uri_string = preg_replace("|^\/?|", '/', $URI->uri_string);

        if ($lang_ignore) {

            if (isset($lang_uri_abbr[$uri_abbr])) {

                /* set the language_abbreviation cookie */
                $IN->set_cookie('user_lang', $uri_abbr, $config['sess_expiration']);

            } else {

                /* get the language_abbreviation from cookie */
                $lang_abbr = $IN->cookie($config['cookie_prefix'].'user_lang');

            }

            if (strlen($uri_abbr) == 2) {

                /* reset the uri identifier */
                $index_page .= empty($index_page) ? '' : '/';

                /* remove the invalid abbreviation */
                $URI->uri_string = preg_replace("|^\/?$uri_abbr\/?|", '', $URI->uri_string);

                /* redirect */
                header('Location: '.$config['base_url'].$index_page.$URI->uri_string);
                exit;
            }

        } else {

            /* set the language abbreviation */
            $lang_abbr = $uri_abbr;
        }

        /* check validity against config array */
        if (isset($lang_uri_abbr[$lang_abbr])) {

           /* reset uri segments and uri string */
           $URI->segment(array_shift($URI->segments));
           $URI->uri_string = preg_replace("|^\/?$lang_abbr|", '', $URI->uri_string);

           /* set config language values to match the user language */
           $config['language'] = $lang_uri_abbr[$lang_abbr];
           $config['language_abbr'] = $lang_abbr;

           /* if abbreviation is not ignored */
           if ( ! $lang_ignore) {

                   /* check and set the uri identifier */
                   $index_page .= empty($index_page) ? $lang_abbr : "/$lang_abbr";

                /* reset the index_page value */
                $config['index_page'] = $index_page;
           }

           /* set the language_abbreviation cookie */               
           $IN->set_cookie('user_lang', $lang_abbr, $config['sess_expiration']);

        } else {

            /* if abbreviation is not ignored */   
            if ( ! $lang_ignore) {                   

                   /* check and set the uri identifier to the default value */    
                $index_page .= empty($index_page) ? $default_abbr : "/$default_abbr";

                if (strlen($lang_abbr) == 2) {

                    /* remove invalid abbreviation */
                    $URI->uri_string = preg_replace("|^\/?$lang_abbr|", '', $URI->uri_string);
                }

                /* redirect */
                header('Location: '.$config['base_url'].$index_page.$URI->uri_string);
                exit;
            }

            /* set the language_abbreviation cookie */                
            $IN->set_cookie('user_lang', $default_abbr, $config['sess_expiration']);
        }

        log_message('debug', "Language_Identifier Class Initialized");
    }
}

/* translate helper */
function t($line) {
    global $LANG;
    return ($t = $LANG->line($line)) ? $t : $line;
}