Locale or language in URL

gistfile1.php

<?php
use Zend\EventManager\StaticEventManager;
use Zend\Mvc\MvcEvent;
use Locale;

$events = StaticEventManager::getInstance();
$events->attach('Zend\Mvc\Application', 'route', function(MvcEvent $event){
    $request       = $event->getRequest();
    $uri           = $request->uri();
    $baseUrlLength = strlen($request->getBaseUrl() ?: '');
    $path          = substr($uri->getPath(), $baseUrlLength);

    if (preg_match('(/(?P<language>[a-z]{2}))', $path, $match)) {
        // Well, you *should* validate the language and compose a real locale at
        // this point …
        Locale::setDefault($match['language']);

        // Update base URL for routing
        $event->getRouter()->setBaseUrl($request->getBaseUrl() . $match[0]);

        // Make sure that the request path after the base URL still contains at
        // least a slash so we do not confuse "home" routes
        if (strlen($path) === 3) {
            $url->setPath($uri->getPath() . '/');
        }
    }
}, PHP_INT_MAX);

// Following pseudo code for a view helper for the parts where you need to
// generate URLs to other languages (e.g. language switcher):
public function __invoke($name, array $params, array $options, $language)
{
    $router  = $this->getRouter();
    $baseUrl = $router->getBaseUrl();

    // Trim language from base URL if present
    if (preg_match('(/(?P<language>[a-z]{2})$)', $path, $match)) {
        $newBaseUrl = substr($baseUrl, 0, -3);
    } else {
        $newBaseUrl = $baseUrl;
    }

    // Append alternative language to the base URL
    if ($language !== 'en') {
        $newBaseUrl .= '/' . $language;
    }

    $router->setBaseUrl($newBaseUrl);

    $url = $router->assemble($name, $params, $options);

    // Reset base URL
    $router->setBaseUrl($baseUrl);

    return $url;
}