facebook style user profile URL using htaccess - php

Question

Hi everyone i need help about htaccess. I am trying to make a facebook style profile url like : https://www.example.com/azzo
So the user_profile.php is in the pages folder. Now user profile link is this http://www.example.com/pages/user_profile?username=azzo So i want to cut the pages file name from the url. What should i do to use my url like facebook (https://www.example.com/azzo) .
I am using the following htaccess
Options +FollowSymLinks -MultiViews
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_METHOD} !POST
RewriteCond %{THE_REQUEST} \s/+(.+?)\.php[\s?] [NC]
RewriteRule ^ /%1 [R=302,NE,L]
RewriteCond %{REQUEST_METHOD} !POST
RewriteCond %{THE_REQUEST} /index\.php [NC]
RewriteRule ^(.*)index\.php$ /$1 [L,R=302,NC,NE]
RewriteCond %{REQUEST_FILENAME} -d [OR]
RewriteCond %{REQUEST_FILENAME} -f
RewriteRule ^ - [L]
RewriteRule ^group/([\w-]+)/?$ pages/group.php?group_username=$1 [L,QSA]
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^(.+?)/?$ $1.php [L]
RewriteRule ^(.+?)/?$ index.php?pages=$1 [L,QSA]
What should i do to change the url like this:
http://www.example.com/pages/user_profile?username=azzo
to this
https://www.example.com/azzo
I have tryed the following rule:
RewriteRule (?:^|/)([\w-]+)/?$ pages/user_profile.php?username=$1 [L,QSA]
after the
RewriteRule ^(.+?)/?$ index.php?pages=$1 [L,QSA]
but i get blank page.