Xenforo Authentication Script to get user groups

index.php

<?php
$servername = "";
$username = "";
$password = "";
$database = "";

// Create connection
$conn = new mysqli($servername, $username, $password, $database);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

function getUserGroup($id, $conn){
    $stmt = $conn->prepare("select user_group_id from xf_user_group_relation where user_id = ? and is_primary = 1");
    $stmt->bind_param('i', $id);
    $stmt->execute();
    $stmt->bind_result($groups);
    $stmt->store_result();
    $stmt->fetch();
    $stmt->close();
    return $groups;
}

function getUserPasswordHash($id, $conn)
{
    $stmt = $conn->prepare("select data from xf_user_authenticate where user_id = ?");
    $stmt->bind_param('i', $id);
    $stmt->execute();
    $stmt->bind_result($messhash);
    $stmt->store_result();
    $stmt->fetch();
    $password = substr($messhash, 22, -3);
    $stmt->close();
    return $password;
}

function getUserID($username, $conn){
    $stmt = $conn->prepare("select user_id from xf_user where username = ?");
    $stmt->bind_param('s', $username);
    $stmt->execute();
    $stmt->bind_result($userid);
    $stmt->store_result();
    $stmt->fetch();
    $stmt->close();
    return $userid;
}

function checkUserPasswordHash($hash, $password){
    if(strlen($hash) < 5){
        die("This user has not setup a password");
    }
    return password_verify($password, $hash);
}

$username = $_REQUEST['username'];
$password = $_REQUEST['password'];
if(!$username || !$password){
    die("All required parameters were not supplied");
}
$userid = getUserID($username, $conn);
$passwordHash = getUserPasswordHash($userid, $conn);
$correctPass = checkUserPasswordHash($passwordHash,$password);
if(!$correctPass){
    die("Credentials enterd do not match our records.");
}
echo getUserGroup($userid, $conn);