Exercise about abstract and final classes in OOP

HighWay.php

<?php

abstract class HighWay
{
    protected array $currentVehicles;
    
    protected int $nbLane;
    
    protected int $maxSpeed;
    
    /**
     * Get the value of currentVehicles
     *
     * @return  array
     */
    public function getCurrentVehicles()
    {
        return $this->currentVehicles;
    }
    
    /**
     * Set the value of currentVehicles
     *
     * @param  array  $currentVehicles
     *
     * @return  self
     */
    public function setCurrentVehicles(array $currentVehicles)
    {
        $this->currentVehicles = $currentVehicles;
        
        return $this;
    }
    
    /**
     * Get the value of nbLane
     *
     * @return  int
     */
    public function getNbLane()
    {
        return $this->nbLane;
    }
    
    /**
     * Set the value of nbLane
     *
     * @param  int  $nbLane
     *
     * @return  self
     */
    public function setNbLane(int $nbLane)
    {
        $this->nbLane = $nbLane;
        
        return $this;
    }
    
    /**
     * Get the value of maxSpeed
     *
     * @return  int
     */
    public function getMaxSpeed()
    {
        return $this->maxSpeed;
    }
    
    /**
     * Set the value of maxSpeed
     *
     * @param  int  $maxSpeed
     *
     * @return  self
     */
    public function setMaxSpeed(int $maxSpeed)
    {
        $this->maxSpeed = $maxSpeed;
        
        return $this;
    }

    abstract public function addVehicle(Vehicle $vehicle) : void;
}

index.php

<?php
require_once '../src/Bicycle.php';
require_once '../src/Car.php';
require_once '../src/Truck.php';
require_once '../src/MotorWay.php';
require_once '../src/PedestrianWay.php';
require_once '../src/ResidentialWay.php';

$bicycle = new Bicycle('blue', 1, 'human energy');
echo $bicycle->forward();
// var_dump($bicycle);


$car = new Car('green', 4, 'electric');
echo $car->forward();
var_dump($car);
var_dump(Car::ALLOWED_ENERGIES);

// Showing the steps of the truck's filling
$truck = new Truck('red', 2, 50);
// echo "<strong> The truck is </strong>" . $truck->filling();

// Getting the departure, currentspeed of the truck
$truck2 = new Truck('black', 3, 40);
// echo "<strong> The second truck starts... </strong>" . $truck2->forward() . "</br>" . $truck2->getCurrentSpeed() ."'s the current speed... </br>" . $truck2->brake();

// Creating a new electric car with Car type
$electricCar = new Car('green', 4, 'electric');
// var_dump($electricCar);

// Creating a new bikecar with Bicycle type
$bTwin = new Bicycle('orange', 2, 'human');

// Creating a new Motorway called Vinci
$vinciAutoroute = new MotorWay();
var_dump($vinciAutoroute);

// Adding a new vehicle with a $bTwin bicycle type to our Motorway
$vinciAutoroute->addVehicle($bTwin);
var_dump($vinciAutoroute);

// Adding a new vehicle on $VinciAutoroute
$vinciAutoroute->addVehicle($electricCar);
var_dump($vinciAutoroute);

// Creating a new Residentialway called $residentialSquare
$residentialSquare = new ResidentialWay();
$residentialSquare->addVehicle($truck2);
var_dump($residentialSquare);

// Creating a new Pedestrianway called $pedestrianSquare
$pedestrianSquare = new PedestrianWay();
// Adding a new vehicle with a $bTwin bicycle type to our Pedestrianway
$pedestrianSquare->addVehicle($bTwin);
var_dump($pedestrianSquare);

// Adding a new vehicle with an $electricCar type to our Pedestrianway
$pedestrianSquare->addVehicle($electricCar);
var_dump($pedestrianSquare);

MotorWay.php

<?php

require_once 'Highway.php';


final class MotorWay extends HighWay
{
    public function __construct()
    {
        $this->nbLane = 4;
        $this->maxSpeed = 130;
    }

    public function addVehicle(Vehicle $vehicle) : void
    {
        if (is_a($vehicle, 'Car')) {
            $this->currentVehicles[] = $vehicle;
        } else {
            echo "<strong> Ce véhicule n'est pas une voiture! </strong>";
        }
    }
}

PedestrianWay.php

<?php

require_once 'Highway.php';

final class PedestrianWay extends HighWay
{
    public function __construct()
    {
        $this->nbLane = 1;
        $this->maxSpeed = 10;
    }
    public function addVehicle(Vehicle $vehicle) : void
    {
        if (is_a($vehicle, 'Bicycle') || is_a($vehicle, 'Skate')) {
            $this->currentVehicles[] = $vehicle;
        } else {
            echo "<strong> Ce véhicule n'est pas un vélo ou un skate! </strong>";
        }
    }
}

ResidentialWay.php

<?php

require_once 'Highway.php';

final class ResidentialWay extends HighWay
{
    public function __construct()
    {
        $this->nbLane = 2;
        $this->maxSpeed = 50;
    }
    
    public function addVehicle(Vehicle $vehicle) : void
    {
        $this->currentVehicles[] = $vehicle;
    }
}