Router class

Here is an implementation of the Router class at blog/core/Router.php:

<?php

class Router {

    private $routes = [];

    function setRoutes(Array $routes) {
        $this->routes = $routes;
    }

    function getFilename(string $url) {
        foreach($this->routes as $route => $file) {
            if(strpos($url, $route) !== false){
                return $file;
            }
        }
    }
}

Router has two methods, Router::setRoutes(Array $routes) and Router::getFilename(). setRoutes() is taking an array of routes and storing it. Then, the getFilename() method is responsible for deciding which file to serve against which URL. We are not comparing the whole URL but we are using strpos() that checks if the string in $route exists in $url and, if it exists, it returns the appropriate filename.