File login.php of Package mddb

<?php
include 'db_connect.php';

// Odbieranie danych w formacie JSON
$data = json_decode(file_get_contents("php://input"), true);

$username = $data["username"];
$stage = $data["stage"];
$response = array();

if ($stage == "username") {
    $sql = "SELECT * FROM users WHERE username='$username'";
    $result = $conn->query($sql);
    if ($result->num_rows > 0) {
        $response["status"] = "success";
    } else {
        $response["status"] = "error";
        $response["message"] = "Nieprawidłowa nazwa użytkownika.";
    }
} elseif ($stage == "password") {
    $password_hash = hash('sha256', $data["password"]);
    $sql = "SELECT * FROM users WHERE username='$username' AND password_hash='$password_hash'";
    $result = $conn->query($sql);
    if ($result->num_rows > 0) {
        $response["status"] = "success";
    } else {
        $response["status"] = "error";
        $response["message"] = "Nieprawidłowe hasło.";
    }
} elseif ($stage == "security") {
    $security_phrase_hash = hash('sha256', $data["securityPhrase"]);
    $sql = "SELECT * FROM users WHERE username='$username' AND security_phrase_hash='$security_phrase_hash'";
    $result = $conn->query($sql);
    if ($result->num_rows > 0) {
        $response["status"] = "success";
    } else {
        $response["status"] = "error";
        $response["message"] = "Nieprawidłowa fraza bezpieczeństwa.";
    }
}


echo json_encode($response);
$conn->close();
?>