Redirecting To A Default Script File

How would you make it so anytime a file in a given directory is accessed, it automatically redirects you to a script file within the same directory (passing on the name of the file accessed).

In other words, if you went to:
my-site.com/some_folder/some_file.txt

You get forwarded to:
my-site.com/some_folder/some_script.php?file=some_file.txt