IMPOSSIBLE de se connecter à un site via cURL en POST

<?php
/* Connexion au site */


class ccurl{
 private $ch = null;
 private $url_connect = 'https://www.x/welcome.php';
 private $url_datas = 'https://www.x/messages.php';
 private $username = 'Project1';
 private $password = 'azertyuiop123';
 private $cookies_file = __DIR__.'\cookies.txt';
 
 function __construct(){
   $this->ch = curl_init();
   $this->connect();
   
 }
 
 private function connect(){
    $timeout = 1000;
   //Initialise une nouvelle connexion
    curl_setopt($this->ch, CURLOPT_URL, $this->url_connect);
    curl_setopt($this->ch, CURLOPT_FRESH_CONNECT, true);
    curl_setopt($this->ch, CURLOPT_TIMEOUT, $timeout);
    curl_setopt($this->ch, CURLOPT_CONNECTTIMEOUT, $timeout);
    curl_setopt($this->ch, CURLOPT_FOLLOWLOCATION, true);
    curl_setopt($this->ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($this->ch, CURLOPT_SSL_VERIFYPEER, 0); 
    curl_setopt($this->ch, CURLOPT_SSL_VERIFYHOST, 0);
    curl_setopt($this->ch, CURLOPT_NOBODY, true);
 
    //Initialise les cookies
    curl_setopt($this->ch, CURLOPT_COOKIESESSION, true);
 
    // Saisie des paramètres de connexion
    curl_setopt($this->ch, CURLOPT_POST, true);
    curl_setopt($this->ch, CURLOPT_POSTFIELDS, array(
        'username' => $this->username,
        'password' => $this->password,
        'x' => 0,
        'y' => 0
    ));
    // Sauvgarde de la session dans un cookie
    curl_setopt($this->ch, CURLOPT_COOKIEJAR, $this->cookies_file);
    // Lecture du cookie enregistré
    curl_setopt($this->ch, CURLOPT_COOKIEFILE, $this->cookies_file);
    $res = curl_exec($this->ch);
    if($res==false){
      echo 'Erreur lors de la connexion : ' . curl_error($ch);
      exit();
    }
  }
  
  public function getDatas(){
    curl_setopt($this->ch, CURLOPT_URL, $this->url_datas);
    curl_setopt($this->ch, CURLOPT_POST, false);
    curl_setopt($this->ch, CURLOPT_POSTFIELDS, "");
    $res = curl_exec($this->ch);
 
    if($res==false){
      echo 'Erreur lors de la connexion : ' . curl_error($ch);
      exit();
    }else{
      return $res;
    }
  }
  
  public function close(){
    curl_close($this->ch);
  }
}

//et pour l'utiliser :
$oCurl = new ccurl();
$datas = $oCurl->getDatas();
$oCurl->close();
print_r($datas);
 
?>