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<?php
session_start();

$form = <<<HTML
<form method="post" action="">
    <input type="text" name="username" value="Username" onfocus="this.value=''"><br>
    <input type="password" name="password" value="Password" onfocus="this.value=''"><br>
    <input type="submit" value="log ind">
</form>
HTML;

if(isset($_POST['username']) && !empty($_POST['password'])) {
    $_SESSION['username'] == "" ? $username = $_POST['username'] : $username = $_SESSION['username'];
    $_SESSION['password'] == "" ? $password = $_POST['password'] : $password = $_SESSION['password'];
    $login_query = mysql_query("SELECT * FROM `users` WHERE `username` = '{$username}' AND `password` = '{$password}'") or die(mysql_error());
    if(mysql_num_rows($login_query) != 0) {
        $_SESSION['username'] = $username;
        $_SESSION['password'] = $password;
        $_SESSION['logged_in'] = 1;
    } else {
        echo "Fejl ved log ind. Forkert brugernavn eller password<br>";
        echo $form;
    }
} else {
    if($_SESSION['logged_in'] != 1)
        echo $form;
    else
        include('admin_ui.php');
}

?>