<?php

if(isset($_GET['action'])){
    $action = $_GET['action'];
    $actions = array('login', 'sercure');
}else{
    $action = '';
    $actions = array('login', 'sercure');
}

if(!isset($action) || !in_array($action, $actions)){
    echo '<a href="index.php?action=login">Login</a>';
}else{
    if($action == 'login'){
        echo '<form method="post" action="">
                <input type="text" name ="username" /><br />
                <input type="password" name="password" /><br />
                <input type="submit" name="login" value="Login!" />
              </form>';
        if(isset($_POST['login'])){
            $username = $_POST['username'];
            $password = md5(sha1($_POST['password']));
            if($username == 'admin' && $password == md5(sha1('wezBB'))){
                $_SESSION['isLogged'] == 'true';
                header('Location: index.php?action=sercure');
                die;
            }
        }
    }
    if($action == 'sercure'){
        if($_SESSION['isLogged'] == 'true'){
            echo 'Logged In!';
        }
    }
}