Untitled

<?php
include("config.php");
session_start();

//Varijabla error za spremanje greske pilikom logina
$error = "";

//Ako je logovan tj. ako sesija jos uvijek postoji preusmjeri na panel
if (isset($_SESSION['login_user'])) {
    header("location:admin.php");
}

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    //Spremi unesene podatke iz polja
    $entered_username = mysqli_real_escape_string($db, $_POST['username']);
    $entered_password = mysqli_real_escape_string($db, $_POST['password']);

    //Provjeri bazu
    if (!$db) {
        printf("Konekcija s bazom ti je na postelji na UKCu odjel: %s\n", mysqli_connect_error());
        exit();
    } else {
        //Prepared statement da povuce podatke iz baze za uneseni username
        $stmt = $db->prepare("SELECT * FROM users WHERE username = ?");
        $stmt->bind_param('s', $entered_username);
        $stmt->execute();
        //Spremi podatke
        $stmt->bind_result($user_id, $username, $password, $firstname, $lastname, $role, $imagelink);
        $stmt->store_result();
    }

    //Provjeri da li postoji korisnik tj. samo jedan red kao rezultat
    if ($stmt->num_rows == 1) {
        //Fetchuj podatke
        if ($stmt->fetch()) {
            //Provjeri da li se uneseni pw poklapa sa Hashom iz baze tj. provjeri da li je pw tacan
            if (password_verify($entered_password, $password)) {
                //Provjera da li treba Rehash (ukoliko postoji noviji hash algoritam)
                if (password_needs_rehash($password, PASSWORD_DEFAULT)) {
                    //Ako postoji noviji Hash po php password default algoritmu update-uj ga u bazi
                    $newHash      = password_hash($entered_password, PASSWORD_DEFAULT);
                    $stmt_reahash = $db->prepare("INSERT INTO users (password) VALUES ('?') WHERE username = '?'");
                    $stmt_reahash->bind_param('ss', $newHash, $entered_username);
                    $stmt_reahash->execute();
                    $stmt_reahash->close();
                }
                //Nakon provjere ili eventualnog update-a stvori sesiju i preusmjeri korisnika na panel
                $_SESSION['login_user'] = $entered_username;
                header("location: admin.php");
            } else {
                $error = "Netačan password";
            }
        }
    } else {
        $error = "Korisnik ne postoji";
    }
    $stmt->close();
    $db->close();
}

?>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="description" content="OPIS">
    <meta name="author" content="Venan Osmic">

    <title>Store Management System - Login</title>

    <!-- Bootstrap core CSS -->
    <link href="dist/css/bootstrap.min.css" rel="stylesheet">

    <!-- Custom Styles -->
    <link href="dist/css/custom.css" rel="stylesheet">
    <!-- Custom JS -->
    <script src="dist/js/customJS.js"></script>
  </head>

  <body>

  <div class="login-page">
    <div class="form">
      <form class="login-form" action = "" method = "post">
        <p style="font-weight: bold; color:red;"> <?php
echo $error;
?> </p>
        <input type="text" placeholder="username" name="username"/>
        <input type="password" placeholder="password" name="password"/>
        <button type="submit"> Login </button>
      </form>
    </div>
  </div>


    <!-- Bootstrap core JavaScript
    ================================================== -->
    <!-- Placed at the end of the document so the pages load faster -->
    <script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
    <script>window.jQuery || document.write('<script src="../../assets/js/vendor/jquery.min.js"><\/script>')</script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
    <script src="dist/js/bootstrap.min.js"></script>
    <!-- IE10 viewport hack for Surface/desktop Windows 8 bug -->
    <script src="../../assets/js/ie10-viewport-bug-workaround.js"></script>
  </body>
</html>