I've been trying to achieve this since about 1.5 hours now. I want to have the following transformations when requesting sites on my website:

homepage.com/                           => index.php
homepage.com/archive                    => index.php?archive
homepage.com/archive/site-01            => index.php?archive/site-01
homepage.com/files/css/main.css         => requestfile.php?css/main.css

The first three transformations can be done by using the following:

RewriteEngine   on
RewriteRule     ^/?$                    index.php
RewriteRule     ^/?(.*)$                index.php?$1

However, I'm stuck at the point where all requests to the files subdirectory should be redirected to requestfile.php. This is one of the tries I've done:

RewriteEngine   on
RewriteRule     ^/?$                    index.php
RewriteRule     ^/?files/(.+)$          requestfile.php?$1
RewriteRule     ^/?(.*)$                index.php?$1

But that does not work. I've also tried to put [L] after the third line, but that didn't help as I'm using this configuration in .htaccess and sub-requests will transform that URL again, etc. I fuzzed with the RewriteCond command but I couldn't get it to work.

How needs the configuration to look like to achieve what I desire?