vanity profile urls in php mvc not working - php

Question

I am making a social networking site where I have created my own PHP mvc but I am having problems in url rewriting. My mvc works this way.
If this is the domain www.example.com/manage/posts/11111 , manage is the class, post is the method in that class & 1111 is a parameter.
The problem is that I cannot create vanity profile urls since they will not work. I want each user to have vanity profile url ie www.example.com/username but this will search for a class named username.
Kindly advise me on how
a) I can achieve vanity profile urls such as www.example.com/username without adding anything such as www.example.com/users/username.
I know there a other PHP MVCs but I just want to use my own
This is my current htaccess code::
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)/?$ index.php?ref_url=$1 [NC,L,QSA]
</IfModule>

Answer 1

I don't know why all people try to build their own frameworks there are so many really good frameworks that have a look at security and many more. But ok i think your problem is your rewrite rule.
RewriteRule ^(.*)$ index.php?ref_url=$1 [NC,L,QSA]
Normally you should rewrite all your input to a given file and parse the url and call the controller you need. To get a better understanding take a look at the Symfony2 Routing component.
http://symfony.com/doc/current/components/routing/introduction.html

Answer 2

You should first create a router to route your urls to controllers/classes. I will prefer klein router or FastRoute for its simplicity.
After placing a router do what u want:
(Example)
$router=new Router;
$router->addroute("/[:username]",
function(){
//Bring UserAccount Details from DB using [:username]
}
);
$router->addroute("/manage/posts/[:id]",
function(){
//Get Post details using [:id]
}
$router->dispatch();
**NB:**This is only a basic representation of usage of a router