<?php

$servername = "localhost";
$username = "root";
$password = "root";
$DBName = "loginsystem";

$error;
if(strlen($error) < 2) echo $error;

if (isset($_POST["submit"])) {

	$user_firstname = $_POST["user_firstname"];
	$user_lastname = $_POST["user_lastname"];
	$user_email = $_POST["user_email"];
	$user_pwd = $_POST["user_pwd"];

	if(empty($user_firstname) || empty($user_lastname) || empty($user_email) || empty($user_pwd)) $error = "Chyba, zadana hodnota nesmie byt prazdna";
	elseif(!preg_match("/^[a-zA-z]*$/", $user_firstname) || !preg_match("/^[a-zA-z]*$/", $user_lastname)) $error = "Bol zadany neplatny znak";
	elseif(!filter_var($user_email, FILTER_VALIDATE_EMAIL)) $error = "Neplatny email";
	else{
		$conn = new mysqli($servername, $username, $password);

		if ($conn->connect_error) die("Chyba: " . $conn->connect_error);

		$sql = "SELECT * FROM users WHERE user_user_id='$user_id'";
		$result = mysqli_query($conn, $sql);

		if(mysqli_num_rows($result) > 0) $error = "Uzivatel uz existuje..."
		else{
			$ppod = [ 'cost' => 11, ];
            $hash = password_hash($user_pwd, PASSWORD_ARGON2I, $ppod);

			$sql = "INSERT INTO users (user_firstname, user_lastname, user_email, user_id, user_pwd) VALUES ($user_firstname, $user_lastname, $user_email, $user_id, $hash);";

			if($conn->query($sql)) error = "Uzivatel bol registrovany";
			else error = "Nastala chyba pri zapise do DB...";
		}
		$conn->close();
	}
}
?>