Regex match url without file extension - regex

Question

I would like some help matching the following urls.
/settings => /settings.php
/657_46hallo => /657_46hallo.php
/users/create => /users.php/create
/contact/create/user => /contact.php/create/user
/view/info.php => /view.php/info.php
/view/readme - now.txt => /view.php/readme - now.txt
/ => [NO MATCH]
/filename.php => /unknown.php
/filename.php/users/create => /unknown.php
if the first part after the domain name is a filename ending with ".php"
(see last 2 examples) It should redirect to /unknown.php
I think I need 2 regular expressions
1st should be almost something like: ^/([a-zA-Z0-9_]+)(/)?(.*)?$
2nd to catch the direct filename "/filename.php" or "/filename.php/create/user"
so I can redirect to unknown.php
The 1st regular expression that I got almost works for the first part.
==============================================
request url: http://domain.com/user/create
regex: ^/([a-zA-Z0-9_]+)(/)?(.*)?$
replace http://domain.com/$1.php$2$3
makes: http://domain.com/user.php/create
Problem is it also matches http://domain.com/user.php/create
If someone could help me with both regular expressions that would be great.

Answer 1

If you want to match those .php cases you can try this:
^\/([a-zA-Z0-9_]+)(\/)?(.*)?$
See here on Regexr
If you want to avoid those cases try this:
^/([a-zA-Z0-9_]+)(?!\.php)(?:(/)(.*)|)$
See here on Regexr
The (?!\.php) is a negative look ahead that ensures that there is no .php at this place.

Answer 2

When all you have is a hammer...
While this probably could be solved with a regexp, it is probably the wrong tool for the job, unless you have constraints that MANDATE the use of regexps.
Split the string using '/' as the delimiter, see whether the first component ends with '.php'; if so, reject it, otherwise append '.php' to the first component and join the components back using '/'.