How to automatically redirect to a store view based on the browser language

[el machine]

I'm trying to automatically redirect people to a store view based on their browser language.

Situation: 5 store views (en, de, it, fr, nl) Magento 1.9.1

I used this piece of code in index.php:

require_once 'app/Mage.php';
/* Determine correct language store based on browser */
function getStoreForLanguage()
{
if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
    foreach (explode(",", strtolower($_SERVER['HTTP_ACCEPT_LANGUAGE'])) as $accept) {
        if (preg_match("!([a-z-]+)(;q=([0-9.]+))?!", trim($accept), $found)) {            $langs[] = $found[1];            $quality[] = (isset($found[3]) ? (float) $found[3] : 1.0);
        }
    }
    // Order the codes by quality    array_multisort($quality, SORT_NUMERIC, SORT_DESC, $langs);
    // get list of stores and use the store code for the key    $stores = Mage::app()->getStores(false, true);
    // iterate through languages found in the accept-language header
    foreach ($langs as $lang) {        $lang = substr($lang,0,2);
        if (isset($stores[$lang]) && $stores[$lang]->getIsActive()) return $stores[$lang];
    }
}
return Mage::app()->getStore();
}
/* Auto redirect to language store view if request is for root */
if ($_SERVER['REQUEST_URI'] === '/') {    header('Location: '.getStoreForLanguage()->getBaseUrl());
    exit;
}

#Varien_Profiler::enable();

#Mage::setIsDeveloperMode(true);

#ini_set('display_errors', 1);umask(0);
Mage::run(); 

It seems like the browser wants to redirect because if i type in: domain.com it goes for a second to domain.com/nl but after a second an error appears:

"There has been an error processing your request. Exception printing is disabled by default for security reasons."

If i look at the error in the log file i see this:

a:4:{i:0;s:53:"Mage registry key "application_params" already exists";i:1;s:349:"#0 /var/www/webroot/ROOT/app/Mage.php(223): Mage::throwException('Mage registry k...')
#1 /var/www/webroot/ROOT/app/code/core/Mage/Core/Model/App.php(338): Mage::register('application_par...', Array)
#2 /var/www/webroot/ROOT/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#3 /var/www/webroot/ROOT/index.php(129): Mage::run('', 'store')
#4 {main}";s:3:"url";s:4:"/nl/";s:11:"script_name";s:10:"/index.php";}

[iweb_smartie]

Is that the entire index.php?

[el machine]

No the entire index.php without the previous code for redirecting looks like this:

<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magentocommerce.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category   Mage
 * @package    Mage
 * @copyright  Copyright (c) 2008 Irubin Consulting Inc. DBA Varien (http://www.varien.com)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

if (version_compare(phpversion(), '5.3.0', '<')===true) {
    echo  '<div style="font:12px/1.35em arial, helvetica, sans-serif;">
<div style="margin:0 0 25px 0; border-bottom:1px solid #ccc;">
<h3 style="margin:0; font-size:1.7em; font-weight:normal; text-transform:none; text-align:left; color:#2f2f2f;">
Whoops, it looks like you have an invalid PHP version.</h3></div><p>Magento supports PHP 5.3.0 or newer.
<a href="http://www.magentocommerce.com/install" target="">Find out</a> how to install</a>
 Magento using PHP-CGI as a work-around.</p></div>';
    exit;
}

/**
 * Error reporting
 */
error_reporting(E_ALL | E_STRICT);

/**
 * Compilation includes configuration file
 */
define('MAGENTO_ROOT', getcwd());

$compilerConfig = MAGENTO_ROOT . '/includes/config.php';
if (file_exists($compilerConfig)) {
    include $compilerConfig;
}

$mageFilename = MAGENTO_ROOT . '/app/Mage.php';
$maintenanceFile = 'maintenance.flag';

if (!file_exists($mageFilename)) {
    if (is_dir('downloader')) {
        header("Location: downloader");
    } else {
        echo $mageFilename." was not found";
    }
    exit;
}

if (file_exists($maintenanceFile)) {
    include_once dirname(__FILE__) . '/errors/503.php';
    exit;
}

require_once $mageFilename;

#Varien_Profiler::enable();

if (isset($_SERVER['MAGE_IS_DEVELOPER_MODE'])) {
    Mage::setIsDeveloperMode(true);
}

#ini_set('display_errors', 1);

umask(0);

/* Store or website code */
$mageRunCode = isset($_SERVER['MAGE_RUN_CODE']) ? $_SERVER['MAGE_RUN_CODE'] : '';

/* Run store or run website */
$mageRunType = isset($_SERVER['MAGE_RUN_TYPE']) ? $_SERVER['MAGE_RUN_TYPE'] : 'store';

Mage::run($mageRunCode, $mageRunType);

Thanks for your quick response!

[iweb_smartie]

No worries

Can you post your entire index.php WITH your modifications in. It looks like it is running the mage app twice.

[el machine]

<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magentocommerce.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magentocommerce.com for more information.
 *
 * @category   Mage
 * @package    Mage
 * @copyright  Copyright (c) 2008 Irubin Consulting Inc. DBA Varien (http://www.varien.com)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

if (version_compare(phpversion(), '5.3.0', '<')===true) {
    echo  '<div style="font:12px/1.35em arial, helvetica, sans-serif;">
<div style="margin:0 0 25px 0; border-bottom:1px solid #ccc;">
<h3 style="margin:0; font-size:1.7em; font-weight:normal; text-transform:none; text-align:left; color:#2f2f2f;">
Whoops, it looks like you have an invalid PHP version.</h3></div><p>Magento supports PHP 5.3.0 or newer.
<a href="http://www.magentocommerce.com/install" target="">Find out</a> how to install</a>
 Magento using PHP-CGI as a work-around.</p></div>';
    exit;
}

require_once 'app/Mage.php';
/* Determine correct language store based on browser */
function getStoreForLanguage()
{
if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
    foreach (explode(",", strtolower($_SERVER['HTTP_ACCEPT_LANGUAGE'])) as $accept) {
        if (preg_match("!([a-z-]+)(;q=([0-9.]+))?!", trim($accept), $found)) {            $langs[] = $found[1];            $quality[] = (isset($found[3]) ? (float) $found[3] : 1.0);
        }
    }
    // Order the codes by quality    array_multisort($quality, SORT_NUMERIC, SORT_DESC, $langs);
    // get list of stores and use the store code for the key    $stores = Mage::app()->getStores(false, true);
    // iterate through languages found in the accept-language header
    foreach ($langs as $lang) {        $lang = substr($lang,0,2);
        if (isset($stores[$lang]) && $stores[$lang]->getIsActive()) return $stores[$lang];
    }
}
return Mage::app()->getStore();
}
/* Auto redirect to language store view if request is for root */
if ($_SERVER['REQUEST_URI'] === '/') {    header('Location: '.getStoreForLanguage()->getBaseUrl());
    exit;
}

#Varien_Profiler::enable();

#Mage::setIsDeveloperMode(true);

#ini_set('display_errors', 1);umask(0);
Mage::run(); 


/**
 * Error reporting
 */
error_reporting(E_ALL | E_STRICT);

/**
 * Compilation includes configuration file
 */
define('MAGENTO_ROOT', getcwd());

$compilerConfig = MAGENTO_ROOT . '/includes/config.php';
if (file_exists($compilerConfig)) {
    include $compilerConfig;
}

$mageFilename = MAGENTO_ROOT . '/app/Mage.php';
$maintenanceFile = 'maintenance.flag';

if (!file_exists($mageFilename)) {
    if (is_dir('downloader')) {
        header("Location: downloader");
    } else {
        echo $mageFilename." was not found";
    }
    exit;
}

if (file_exists($maintenanceFile)) {
    include_once dirname(__FILE__) . '/errors/503.php';
    exit;
}

require_once $mageFilename;

#Varien_Profiler::enable();

if (isset($_SERVER['MAGE_IS_DEVELOPER_MODE'])) {
    Mage::setIsDeveloperMode(true);
}

#ini_set('display_errors', 1);

umask(0);

/* Store or website code */
$mageRunCode = isset($_SERVER['MAGE_RUN_CODE']) ? $_SERVER['MAGE_RUN_CODE'] : '';

/* Run store or run website */
$mageRunType = isset($_SERVER['MAGE_RUN_TYPE']) ? $_SERVER['MAGE_RUN_TYPE'] : 'store';

Mage::run($mageRunCode, $mageRunType);

[iweb_smartie]

Get rid of the following from half way down your file

Mage::run();

 I would also actually remove 

require_once 'app/Mage.php';

 from the top of the file and then move your if check to underneath

require_once $mageFilename;

[el machine]

Well i'm not getting any errors anymore So that's a start haha

But problem is now that i'm not getting sent to the right store view based on browser language. Just goes to the default store view

[iweb_smartie]

To be perfectly honest this is not how i would have done this. Instead i would have set up a module with an observer that checked the url. The main issue i can see though here is that in your function you have nothing that populares the $stores var, if it even gets that far.

Debugging by yourself required