$subdomain="amestrov";
    $client_id="LworutTiRfoYZLpbE4B9aQ";
    $client_secret="pn2bgiu2l5B-qHIx6NAPdiNDOxlKXndDZJRoRXfpDYw1kmqNLp8LYk341sy3VxPQtHvndpbdf6wRAqJ3ztvG8g";
    $redirect_uri="http%3A%2F%2Fclients.neuralab.net%2Fclient-area%2F";
  $url='https://'.$subdomain.'.harvestapp.com/oauth2/authorize?client_id='.$client_id.'&redirect_uri='.$redirect_uri.'&state=optional-csrf-token&response_type=code';
  if(!isset($_GET['code'])){
        wp_redirect($url);
        exit;
    }
    else{
        $code=$_GET['code'];
        $pp=array(
            'code'          => $code,
            'client_id'     => $client_id,
            'client_secret' => $client_secret,
            'redirect_uri'  => $redirect_uri,
            'grant_type'    => 'authorization_code'
        );
        $ppp = json_encode($pp);
        echo $ppp;
        $post_data="code=".$code."&client_id=".$client_id."&client_secret=".$client_secret."&redirect_uri=".$redirect_uri."&grant_type=authorization_code";
        $headers = array(
        "Content-type:application/x-www-form-urlencoded",
    );
//  $post_data="grant_type=password&username=alenmestrov@gmail.com&password=399ae0c91";
        $ch=curl_init();
        curl_setopt($ch, CURLOPT_URL,"https://".$subdomain.".harvestapp.com/oauth2/token");
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $ppp);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
        $server_output = curl_exec($ch);
        curl_close($ch);