Auto-promo bot PHP side

<?php
$group_id         = $_GET['groupId'];
$new_role_set_id  = $_GET['newRoleSetId'];
$target_user_id   = $_GET['targetUserId'];


$login_user       = 'username=YOURBOTUSERNAME&password=YOURBOTPASSWORD';
$file_path_rs     = 'rs.txt';
$file_path_token  = 'token.txt';
$current_rs       = file_get_contents($file_path_rs);
$current_token    = file_get_contents($file_path_token);


function getRS()
{
    global $login_user, $file_path_rs;

    $get_cookies = curl_init('https://www.roblox.com/newlogin');
    curl_setopt_array($get_cookies,
        array(
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_HEADER => true,
            CURLOPT_POST => true,
            // CURLOPT_HTTPHEADER => array("Content-Length: " . strlen($login_user)),
            CURLOPT_POSTFIELDS => $login_user
        )
    );

    $rs = (preg_match('/(\.ROBLOSECURITY=.*?);/', curl_exec($get_cookies), $matches) ? $matches[1] : '');
    file_put_contents($file_path_rs, $rs, true);
    curl_close($get_cookies);

    return $rs;
}


function changeRank($rs, $token)
{
    global $group_id, $new_role_set_id, $target_user_id, $file_path_token;

    $promote_user = curl_init("http://www.roblox.com/groups/api/change-member-rank?groupId=$group_id&newRoleSetId=$new_role_set_id&targetUserId=$target_user_id");
    curl_setopt_array($promote_user,
        array(
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_POST => true,
            CURLOPT_HEADER => true,
            CURLOPT_HTTPHEADER => array("Cookie: $rs", "X-CSRF-TOKEN: $token")
        )
    );

    $resp = curl_exec($promote_user);
    $resp_header_size = curl_getinfo($promote_user, CURLINFO_HEADER_SIZE);
    $resp_header = substr($resp, 0, $resp_header_size);
    $resp_body = substr($resp, $resp_header_size);

    if (preg_match('/GuestData/', $resp_header)) {

        $resp_body = changeRank( getRS(), $token );
    } else if (preg_match('/Token Validation Failed/', $resp_header)) {

        $new_token = (preg_match('/X-CSRF-TOKEN: (\S+)/', $resp_header, $matches) ? $matches[1] : '');
        file_put_contents($file_path_token, $new_token, true);
        $resp_body = changeRank( $rs, $new_token );
    }

    curl_close($promote_user);

    return $resp_body;
}


echo changeRank($current_rs, $current_token);