RewriteEngine on 
RewriteCond %{THE_REQUEST} \s/+(.*)\.php(.*)\sHTTP.*$ [NC]
RewriteRule ^ /%1%2%3 [R=302,L,NE]
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule !.*\.php$ %{REQUEST_FILENAME}.php [QSA,L]
RewriteRule \.(md|json|xml|pdf|txt|log)$ - [F]