RewriteEngine On
RewriteBase /
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /index\.php\ HTTP/
RewriteRule ^index\.php$ / [R=301,L]
RewriteCond %{REQUEST_URI} !^/get_download_url\.php$
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^/]+)\.php(\?[^\s]+)?\s
RewriteCond %1 !^index$
RewriteRule ^([^/]+)\.php$ /$1 [R=301,L,QSA]
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]