Mod Rewrite to remove language from url in Concrete5 cms - .htaccess

Question

I'm totally stumped. Hope you can help. I just spent a month redeveloping our website in Concrete5 version 7.3.1, latest version, and I'm ready to launch. It's a multi-lingual site and our SEO guy recommended not to include the language in the URL for the default language (English) as it would change our homepage from domain.com/ to domain.com/en/, and our old site default language was in the base directory.
Concrete5 doesn't support this so basically I'm hoping to accomplish this with some .htaccess trickery, but am getting no where.
Concrete5 urls are domain.com/index.php/en/path/to/page, so all pages are fed off index.php. There is a rewrite rule as follows to hide the index.php from the user and make the urls pretty.
#RewriteCond %{REQUEST_FILENAME} !-f
#RewriteCond %{REQUEST_FILENAME}/index.html !-f
#RewriteCond %{REQUEST_FILENAME}/index.php !-f
#RewriteRule . index.php
I want to further add a way to add the /en/ for the server side from a url which doesn't include it. i.e.
RewriteRule ^/index.php/(.*) ^/index.php/en/$1 [L]
So I can then strip the en from the urls and the system will still work.
I've tried putting this before concrete's rewrite (without index.php), after, and multiple different combinations, but keep getting a 401 error and it's hard to diagnose the problem as it's not so easy to see the generated url.
Any help would be much appreciated as I've got to figure this out before launch.

Answer 1

With this recently added event in the new 5.7.4 version that is to come out sometime soon, we're able to do some interesting things with the request. One thing we can do is ensure the page at that path doesn't exist, then rewrite the request to make it look to concrete5 that the request is actually coming in to /en.
\Events::addListener('on_before_dispatch', function() {
$request = \Request::getInstance();
$page = \Page::getByPath($request->getPath()); // Get the real requested page
if ($page->isError()) { // If it doesn't exist
$path = new \Concrete\Core\Url\Components\Path($request->getPath());
$path = $path->prepend('en'); // prepend "/en" to the path, ex: "/path/to" becomes "/en/path/to"
$page = Page::getByPath($path);
if (!$page->isError) { // Make sure that this page actually exists
// This may not work, you might need to replace the actual \Request instance.
$request->setCurrentPage($page); // Set it to the requested page.
}
}
});
I really suggest that you do not do this. As described in my comments on the question, you'll run into really weird cases that will cause SEO issues and general routing issues in your site.
Edit: concrete5 version 8 includes HTTP middleware, which is a better solution to this problem.