Nginx Joomla Internationalization URL rewriting - joomla

Question

I'm using Joomla in combination with Nginx, and I'm currently trying to achieve some URL rewriting for a website that has several langages supported (italian, french, chinese, and deutch)
The urls have the country code after the domain name, like so :
http://www.example.com/fr/test/test.html
or
http://www.example.com/de/test/test.html
I'm looking to rewrite the urls so the country code is part of the subdomain :
so
http://www.example.com/fr/test/test.html
becomes
http://fr.example.com/test/test.html
Is there a way to achieve this with Nginx or should I look into a third party extension for Joomla (not my favorite choice).
Thanks !!
Update :
I wasn't clear enough : I wanted the redirection from the rewrited URL to be transparent. Here is what I came up with, thanks to VBart help :
server {
server_name ~^(?<lang>.+)\.example\.com$;
location / {
rewrite /(.*)$ /$lang/$1 break;
proxy_pass http://www.example.com;
proxy_redirect http://www.example.com http://$lang.example.com/$request_uri;
}
}
Now, is there a way for Nginx to modify links on the fly in the served content ? ie: I want all the link in the generated page to look like http://fr... instead of http://.../fr/... ?

Answer 1

server {
server_name ~^(?<lang>.+)\.example\.com$;
...
}
server {
server_name www.example.com;
rewrite ^/(?<lang>[a-z]+)(?<rest>.+)$ http://$lang.example.com$rest? permanent;
}
opposite example:
server {
server_name ~^(?<lang>.+)\.example\.com$;
return 301 http://www.example.com/$lang$request_uri;
}
server {
server_name www.example.com;
...
}