PHP Sign-up Form Issues with Validation and Insertion - php

Question

I'm looking to create a sign-up page for a large-scale website which means I'm using a lot more layers of validation then I would normally do, given this should be common practice but in this particular case more than any other situation it is imperative.
I've already written most of the code required and formatted it in an order which I believed wouldn't lead to any undefined variable errors, however, upon form submission it doesn't create a new SQL row and doesn't return any errors under the error handling areas of the form validation. In all fairness, the error handling is quite simple at this point and is not a final version, just what I put in place to help me debug and troubleshoot any issues which should arise.
Here's the PHP code, and the snippet of the piss-poor error handling that is supposed to output an error message if an error occurs, to re-state, this error handling isn't final.
$conn = mysqli_connect('localhost', 'root2', '123', 'db');
$signupConditionsMet = "0";
if (isset($_POST["email"]) && isset($_POST["username"]) && isset($_POST["password"]) && isset($_POST["passwordCheck"]) && isset($_POST["birthdate"])) {
$signupConditionsMet = "1";
$birthGood = true;
$passGood = false;
$nameGood = false;
$emailGood = false;
}
$usernameSearch = $conn->prepare("SELECT * FROM users WHERE username = ?");
$userInsertion = $conn->prepare("INSERT INTO users (username, passwd, birthdate, email) VALUES (?,?,?,?)");
$nameErr = $emailErr = $passErr = $birthErr = "";
$name = $email = $pass = $birth = "";
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$name = $_POST["username"];
$email = $_POST["email"];
$pass = $_POST["password"];
$birthdate = $_POST["birthdate"];
$passCheck = $_POST["passwordCheck"];
}
if ($signupConditionsMet === "1"){
function test_input($name) {
if (!preg_match("/^[a-z\d_]{2,15}$/i",$name)) {
$nameErr = "Only letters and white space allowed";
} else {
$nameGood = true;
return $name;
echo "did name ez";
}
}
function test_input2($email){
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
$emailErr = "Invalid email format";
} else {
$emailGood = true;
return $email;
echo "did email ez";
}
}
function test_input3($password){
if (!preg_match("/^[a-z\d_]{2,15}$/",$pass)) {
$passErr = "Invalid password format";
} else if (!preg_match("/^[a-z\d_]{2,15}$/",$passCheck)){
$passErr = "Invalid password check format";
} else if ($_POST["password"] !== $_POST["passwordCheck"]){
$passErr = "Passwords do not match";
} else {
$passwd2 = AES_ENCRYPT($_POST["password"], 'mysecretstring');
$passwdGood = true;
return $passwd2;
echo "did pass ez";
}
}
}
if (($signupConditionsMet === "1") && ($birthGood === true) && ($nameGood === true) && ($passwdGood === true) && ($emailGood === true)) {
if ($usernameSearch->execute(array($_POST['username']))) {
while ($row = $usernameSearch->fetch()) {
if (!empty($row['id'])) {
$creationError = "This username is already taken";
} else {
$userInsertion->bindParam(1, $name);
$userInsertion->bindParam(2, $passwd2);
$userInsertion->bindParam(3, $birthdate);
$userInsertion->bindParam(4, $email);
$userInsertion->execute();
header('Location: userlanding.php');
}
}
}
}
/* PHP inside the HTML to output errors */
<?php if ($signupConditionsMet === "1") { echo "all inputs received"; echo $_SERVER["REQUEST_METHOD"];} else { echo "drats, they weren't all there"; echo $name; echo $email; echo $birthdate; echo $pass; echo $passCheck;}?>
<?php if ($passErr) { echo $passErr;} else if ($nameErr) { echo $nameErr;} else if ($emailErr) { echo $emailErr;} else if ($birthErr) { echo $birthErr;} ?>
Disregarding the previously admitted terrible error handling, I can't seem to wrap my head around why it doesn't work in its current form. It returns (from the client-side reporting) that all inputs were received and there isn't any fatal errors thrown from running the PHP code. In addition, the second client-side code which prints any errors doesn't print anything either, implying that all functions operated correctly, however, the echos at the bottom of the input tests don't echo the strings they've been assigned, implying those didn't work, but there was no errors. Hmm. Perhaps I'm missing something blatantly obvious regarding my syntax but I don't see why it wouldn't work. Any help would be appreciated.