<?php
    $invaliduser = false;
    $invalidpass = false;
    $dupuser = false;
    $success=false;
    if($_SERVER['REQUEST_METHOD'] == 'POST') {
        if (!empty($_POST["username"]) && !empty($_POST["password"])) {
            $reg1 = '/^(([^<>()[\]\\\\.,;:\s@\"]+(\.[^<>()[\]\\\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/';
            $reg2 = '/^(?:[0-9]+[a-zA-Z]|[a-zA-Z]+[0-9])[A-Za-z0-9]*$/';
            include("database.php");
            $user = mysqli_real_escape_string($conn, $_POST["username"]);
            $pass = mysqli_real_escape_string($conn, $_POST["password"]);
            $invaliduser = !preg_match($reg1, $user);
            $invalidpass = !preg_match($reg2, $pass);
            if (!$invaliduser && !$invalidpass) {
                $pass=md5($pass);
                $result = mysqli_query($conn, "INSERT INTO `user`(`username`, `password`) VALUES (\"" . $user . "\",\"" . $pass . "\")");
                if ($result) {
                    $dupuser = false;
                    $success = true;
                } else {
                    if (mysqli_errno($conn) == 1062) {//duplicate user
                        $dupuser = true;
                    } else {
                        die("Errore generale nel database!");
                    }
                }
            }
        }
    }
?>