Mod Rewrite Sub Directory To Subdomain

i'd like to use a code similar to the one below, to rewrite a sub directory to a subdomain. www.domain.com/aoa/info/ to info.domain.com and then error 301 if someone goes to www.domain.com/aoa/info/ directly


# rewrite foo subdomain requests to foo subdirectory
rewriteCond %{HTTP_HOST} ^foo.example.com
rewriteCond %{REQUEST_URI} !^/foo/
rewriteRule (.*) /foo/$1 [L]
#
# Prevent direct client access to foo subdirectory
rewriteCond %{THE_REQUEST} ^[A-Z]{3,9} /foo [NC]
rewriteRule ^foo(.+) [url]