PHP Routing System - own MVC - php

Question

I am trying to develop my own MVC and i got to the point where a routing system is due.
I have used some examples from the internet and partially it works fine. Evan so, i think something is wrong and i will detail it right bellow.
My MVC has a frontend and a backend. The first question is : Do i need to load the same routing system for the frontend and the backend? Or do i need to have different routing systems? How would you choose?
In the frontend, whenever i am using the main menu to navigate i can go to home or contact page and the pages are displaying corectlly - and the browser url - looks fine : localhost/home or localhost/contact (without the php extension - which is the desired behaviour.)
In the backend section of my website - reaching it by using localhost/admin - of course the routing system from my front-end section has some rules for the admin, so when i am reaching the admin section the browser url is fine - showing http://localhost/admin/ and displays some login form. The Login Form uses post to send info to another page- login.php which runs the login system, and if successfull requires a page named home.php. The problem is after the successfull login - the browser url is http://localhost/admin/login.php !!! which IS NOT the desired behaviour because i am expecting in fact localhost/admin/home (without the php extension) . i have tried with a different routing system for the backend - but for some reason it's not taken in consideration and i have also tried to include the routing system after the succesfull login. I cannot find a good solution. I am surely missing something and i do not know why so please help me. This is how my routing system is looking.
<?php
// Include router class
include('Route.php');
// Add base route (startpage)
Route::add('/',function(){
require 'pages/home.php';
});
// Simple test route that simulates static html file
Route::add('/contact',function(){
require 'pages/contact.php';
});
// Post route example
Route::add('/contact-form',function(){
echo '<form method="post"><input type="text" name="test" /><input type="submit" value="send" /></form>';
},'get');
// Post route example
Route::add('/contact-form',function(){
echo 'Hey! The form has been sent:<br/>';
print_r($_POST);
},'post');
// Accept only numbers as parameter. Other characters will result in a 404 error
Route::add('/foo/([0-9]*)/bar',function($var1){
echo $var1.' is a great number!';
});
Route::run('/');
My router Class:
class Router
{
/**
* The request we're working with.
*
* #var string
*/
public $request;
/**
* The $routes array will contain our URI's and callbacks.
* #var array
*/
public $routes = [];
/**
* For this example, the constructor will be responsible
* for parsing the request.
*
* #param array $request
*/
public function __construct(array $request)
{
/**
* This is a very (VERY) simple example of parsing
* the request. We use the $_SERVER superglobal to
* grab the URI.
*/
$this->request = basename($request['REQUEST_URI']);
}
/**
* Add a route and callback to our $routes array.
*
* #param string $uri
* #param Callable $fn
*/
public function addRoute(string $uri, \Closure $fn) : void
{
$this->routes[$uri] = $fn;
}
/**
* Determine is the requested route exists in our
* routes array.
*
* #param string $uri
* #return boolean
*/
public function hasRoute(string $uri) : bool
{
return array_key_exists($uri, $this->routes);
}
/**
* Run the router.
*
* #return mixed
*/
public function run()
{
if($this->hasRoute($this->request)) {
$this->routes[$this->request]->call($this);
}
}
}
and my successfull login statement which redirect to home :
if ($login) {
require './pages/home.php';
} else {
echo 'ERROR';
}
my htaccess from the admin section folder :
DirectoryIndex index.php
FallbackResource /index.php
# enable apache rewrite engine
RewriteEngine on
# set your rewrite base
# Edit this in your init method too if you script lives in a subfolder
RewriteBase /admin
# Deliver the folder or file directly if it exists on the server
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# Push every request to index.php
RewriteRule ^(.*)$ index.php [QSA]