CodeIgniter 2.1.0 Mutilingual

my_app.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

// Internationalization
// Default language: folder name
$config['language'] = 'es';
// Default language: abbreviation
$config['language_code'] = 'es';
// Available languages and its corresponding folders
// ISO 2 letter language codes http://reference.sitepoint.com/html/lang-codes
$config['language_code_expand'] = array('es' => 'es', 'eu' => 'eu');
// Language descriptions (useful for language switcher labeling on the front-end)
$config['language_code_name'] = array('es' => 'Español', 'eu' => 'Euskara');
// Non multilingual resources (discrete controllers or folders of controllers,
// that appear in the first segment of the URI)
$config['language_code_exclude'] = array('admin');
// Whether to negotiate the language if no language code is found in the URI
$config['language_negotiate'] = TRUE;
// Language persistence (uses cookies)
$config['language_persist'] = TRUE;
// Language persistence cookie name
$config['language_persist_cookie'] = 'lang';
// Language persistence cookie lifetime (seconds)
$config['language_persist_time'] = 60*60*24*365; //1 año

MY_Lang.php

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

// Adds support for language code in the first segment of the URI.
// It negotiates the language if no language is found in the URI.
// Negotiation priority: URI language code segment > Cookie ($_COOKIE) > User agent ($_SERVER['HTTP_ACCEPT_LANGUAGE']) > Fallback (Configuration)

class MY_Lang extends CI_Lang {

    /**
	 * Config class
	 *
	 * @var object
	 */
    public $config;
    /**
	 * URI class
	 *
	 * @var object
	 */
    public $uri;

    public function __construct()
    {
        parent::__construct();

        $this->config =& load_class('Config', 'core');
        $this->uri =& load_class('URI', 'core');

        // Needed for accessing the app configuration (my_app.php) in My_Lang()
        // Otherwise the configuration wouldn't be available until CI_Controller.php calls $this->load->initialize() and this one to _ci_autoloader()
        // CI_Lang.php is loaded on [220] and CI_Controller.php on [308] of CodeIgniter.php [CI 2.1.0].
        $this->config->load('my_app');

        // Temporary fix for CI 2.1.0 bug
        $this->fix_uri_string();

        // Is the requested resource multilingual?
        if($this->config->item('language_code_exclude') AND ! in_array(current($this->uri->segment_array()), $this->config->item('language_code_exclude')))
        {
            $this->config->set_item('is_multilingual', TRUE);

            // Get the language code specified in the URI
            $language_code = current($this->uri->segment_array());

            // URI language code validation
            if ($language_code AND array_key_exists($language_code, $this->config->item('language_code_expand')))
            {
                // Remove the language code from the $this->uri->segments array
                array_shift($this->uri->segments);
                // Remove "$language_code" from the start of the $this->uri->uri_string string
                $this->uri->_set_uri_string(substr($this->uri->uri_string(), strlen($language_code)));
                // Make the language globally available throughout the application
                $this->config->set_item('language_code', $language_code);
                // Language determined by URI, we don't need to negotiate the language
                $this->config->set_item('language_negotiate', FALSE);
            }
        }
        // The requested resource is not multilingual, we don't need to negotiate the language
        else
        {
            $this->config->set_item('is_multilingual', FALSE);
            $this->config->set_item('language_negotiate', FALSE);
        }

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

    public function init_language()
    {
        $CI =& get_instance();

        $CI->load->helper('cookie');

        // Is the resource multilingual?
        if ($CI->config->item('is_multilingual'))
        {
            // Do we need to negotiate the language?
            if ($CI->config->item('language_negotiate'))
            {
                $this->negotiate_language();
            }

            $this->set_language();
        }
    }

    protected function negotiate_language()
    {
        $CI =& get_instance();

        // Negotiation priority:
        // URI language code segment > Cookie ($_COOKIE) > User agent ($_SERVER['HTTP_ACCEPT_LANGUAGE']) > Fallback (Configuration)

        $language_code = FALSE;
        $languages = $CI->config->item('language_code_expand');

        // Cookie
        // Is the language cookie set? Does it contain a valid language code?
        $language_cookie = get_cookie($CI->config->item('language_persist_cookie'));

        if($language_cookie AND array_key_exists($language_cookie, $languages))
        {
            $language_code = $language_cookie;
        }
        else
        {
            // User agent
            // No language code found in cookie. What about the user agent reported languages?
            $CI->load->library('user_agent');
            $agent_languages = $CI->agent->languages();

            foreach ($agent_languages as $language)
            {
                if (array_key_exists($language, $languages))
                {
                    $language_code = $language;
                    break;
                }
            }

            // Fallback
            // No language could be set based on user preferences. Let's use the default site language.
            if( ! $language_code)
            {
                $language_code = $CI->config->item('language_code');
            }
        }

        $CI->load->helper('url');

        // Redirect the user to the resolved language resulting from the negotiation
        redirect($language_code.'/'.$CI->uri->uri_string);
    }

    protected function set_language()
    {
        $CI =& get_instance();

        $languages = $CI->config->item('language_code_expand');
        $language_code = $CI->config->item('language_code');

        $CI->config->set_item('language', $languages[$language_code]);

        // Add the language code to the index_page config variable,
        // which is used by the site_url() method of Config.php
        // for dynamic URL generation
        $index_page = $CI->config->item('index_page');

        $index_page .= ($index_page)? '/'.$language_code : $language_code;

        $CI->config->set_item('index_page', $index_page);

        // Language choice persistence
        if ($CI->config->item('language_persist'))
        {
            $language_cookie = get_cookie($CI->config->item('language_persist_cookie'));

            if ($language_cookie != $language_code)
            {
                set_cookie($CI->config->item('language_persist_cookie'), $language_code, $CI->config->item('language_persist_time'));
            }
        }
    }

    protected function fix_uri_string()
    {
        // CodeIgniter 2.1.0 bug, $this->uri->uri_string format inconsistency
        // $this->uri->_fetch_uri_string() sets $uri_string  with or without a leading forward slash '/' depending on the detection method used
        // For example: _detect_uri() trims the leading slash, while the $_SERVER['PATH_INFO'] based method preserves it
        // Temporary Fix: remove any leading or trailing forward slash from $uri_string, as that is the intended behavior https://github.com/EllisLab/CodeIgniter/issues/9
        $this->uri->_set_uri_string(trim($this->uri->uri_string(), '/'));
    }
}

/* End of file MY_Lang.php */

MY_language_helper.php

<?php  if (!defined('BASEPATH')) exit('No direct script access allowed');

if ( ! function_exists('current_lang'))
{
    function current_lang($option = 'name')
    {
        $CI =& get_instance();

        switch ($option)
        {
            case 'code':
                return $CI->config->item('language_code');
            break;

            case 'name':
                $names = $CI->config->item('language_code_name');
                return $names[$CI->config->item('language_code')];
            break;

            case 'folder':
                return $CI->config->item('language');
            break;
        }
    }
}

if ( ! function_exists('l'))
{
    function l($line, $id = '')
    {
        echo lang($line, $id);
    }
}

if ( ! function_exists('switch_lang'))
{
    function switch_lang()
    {
        $languages = array();

        $CI =& get_instance();
        $index_page = $CI->config->item('index_page');
        $uri = $CI->uri->uri_string();

        $CI->config->set_item('index_page', substr($index_page, 0, -2));

        foreach (config_item('language_code_name') as $code => $name)
        {
            $languages[$code]['name'] = $name;
            $languages[$code]['url'] = site_url($code.$uri);
        }

        $CI->config->set_item('index_page', $index_page);

        return $languages;
    }
}

/* End of file MY_language_helper.php */

MY_url_helper.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');

/**
 * Create URL Title with support for accented characters
 *
 * Takes a "title" string as input and creates a
 * human-friendly URL string with either a dash
 * or an underscore as the word separator.
 *
 * All accented characters get transliterated
 * via the the convert_accented_characters() function
 * which relies on this mapping application/config/foreign_chars.php
 *
 * @access	public
 * @param	string	the string
 * @param	string	the separator: dash, or underscore
 * @return	string
 */
if ( ! function_exists('url_title_i18n'))
{
    function url_title_i18n($str, $separator = 'dash', $lowercase = FALSE)
    {
        $CI =& get_instance();
        $CI->load->helper('text');

        return url_title(convert_accented_characters($str), $separator, $lowercase);
    }
}

/* End of file MY_url_helper.php */