Cannot make register to work with reCAPTCHA2 - php

Question

I cannot make the register to work with recaptcha but it work normally without it
<?php
require_once("database.php");
$conn= pdo_con();
ini_set('SMTP','smtp.intnet.mu');
ini_set('smtp_port',25);
ini_set('sendmail_from','admin#example.co.uk');
if(!empty($_POST) || isset($_POST['regis_submit'])){
// Should the code be place here cause I already try it. //
$errors = array();
if (empty($_POST['firstname']) || empty($_POST['regis_username']) || empty($_POST['lastname']) || empty($_POST['inputEmail'])
|| empty($_POST['phone_num']) || empty($_POST["gender"]) || empty($_POST['regis_pass']) || empty($_POST["postal_address"])
|| empty($_POST["DateField"]) ){
$errors[] = 'Value(s) in the form missing, please fill them all out!';
exit();
} else if(!preg_match ('%^[A-Za-zÀàÂâÇçÉéÈèÊêËëÔôÙùÎîÏïÛûÜü\.\' \-]{2,15}$%', $_POST['firstname'])){
$errors['firstname'] = '<p><font color="red">Please enter your first name!</font></p>';
exit();
} else if ( etc...
}
else if (count($errors) > 0) {
foreach($errors as $error) {
echo $error;
}
} else {
$firstname = escape_data($_POST['firstname']);
$username = escape_data($_POST['regis_username']);
$lastname = escape_data($_POST['lastname']);
$email = escape_data($_POST['inputEmail']);
$telephone = escape_data($_POST['phone_num']);
$password = escape_data($_POST['regis_pass']);
$address = escape_data($_POST['postal_address']);
$gender = escape_data($_POST['gender']);
$date = escape_data($_POST['DateField']);
//check if user already exist
$exist = "";
$query = $heidisql->prepare("SELECT user_id as 'exist' FROM users WHERE user_username='$username' OR email_address='$email' ");
$query->execute();
while($userRow = $query->fetch(PDO::FETCH_ASSOC)) {
$exist = $userRow['exist'];
}
if(strlen($exist) > 0){
echo 'Account already exist!';
exit();
} else {
$sql = "";
$stmt = $heidisql->prepare($sql);
$token = bin2hex(random_bytes(20));
$hash = password_hash($password, PASSWORD_BCRYPT);
$stmt->execute(array ( ... ));
my email here
if (mail($to, $subject, $message, $headers)) { // Sending email // email_to, subject, body,email_from
echo 'Thank you for your registration. Check your email, and click on the link to activate your account ';
exit();
} else {
echo'Server failed to sent message, please try again later.';
exit();
}
}
} // END of else statement
exit();
}
debug($errors);
}
WHere exactly should I put the captcha code below into my code... I already try to put it on top but I get an error. Undefined $responseKey or something like that.
$secretKey = "xxxx";
$responseKey = $_POST['g-recaptcha-response'];
$userIP = $_SERVER['REMOTE_ADDR'];
$url = "https://www.google.com/recaptcha/api/siteverify";
$response = file_get_contents($url."?secret=".$secretKey."&response=".$responseKey."&remoteIP=".$userIP);
$data_response = json_decode($response);
if(isset($data_response->success) AND $data_response==true){
} else {
}
The and div are properly place into my form. I just cant pinpoint where the code should be placed exactly.