.htaccess - htaccess: php language variable on index page -

i'm trying clean urls extensions , php language variables:

test.com/en/ => test.com/?lang=en

test.com/ro/page/ => test.com/page.php?lang=ro

here .htaccess:

adddefaultcharset utf-8  options +followsymlinks -multiviews rewriteengine on rewritebase /  rewritecond %{request_filename} -f  [or] rewritecond %{request_filename} -d rewriterule .* - [l] rewriterule ^([^/]+)/([^.]+)\.php  /$2.php?lang=$1 [l,nc,qsa]  rewritecond %{request_filename} !-f rewriterule ^([^/]+)/$ $1.php rewriterule ^([^/]+)/([^/]+)/$ /$1/$2.php rewritecond %{request_filename} !-f rewritecond %{request_filename} !-d rewritecond %{request_uri} !(\.[a-za-z0-9]{1,5}|/)$ rewriterule (.*)$ /$1/ [r=301,l] 

while transforms test.com/ro/page => test.com/page.php?lang=ro , test.com/ro/index => test.com/index.php?lang=ro

i cannot transform index page test.com/en/ => test.com/?lang=en

can guys please me achieve this?

right under rule:

rewriterule ^([^/]+)/([^.]+)\.php  /$2.php?lang=$1 [l,nc,qsa] 

try adding rule:

rewriterule ^([^/]{2})/?$ /?lang=$1 [l,nc,qsa]