Hide Form Div Using PHP if Statment - php

Question

Trying to make a login form become hidden once a successful login has happened within the form, so that the form cannot be seen by the user once they are logged in, but I still need a success message to be displayed when a successful login has happened.
I have the form and the login sorted and it displayed a success message when a successful login has been made but I cant hide the form upon successful login.
i have an if statement set up using isset but that's as far as I got I don't know what needs to go inside the if statement for me to hide the form.
This is the PHP code for my login page -
<?php
require('includes/application_top.php');
$page_title='Login!';
if (isset($_POST['action'])) {
$username_input = $_POST['username'];
$password_input = $_POST['password'];
$login_ok = login($username_input, $password_input);
}
require('includes/site_header.php');
?>
<style>
<?php
require('css/login.css');
?>
</style>
<br>
<br>
<br>
<?php
if (isset($login_ok)) {
?>
<div class="row">
<div class="col-sm-12">
<?php
if ( ! $login_ok) {
?>
<div class="alert alert-danger">
<p>Your credentials were invalid</p>
</div>
<?php
} else {
?>
<div class="alert alert-success">
<p>Login successful</p>
</div>
<?php
}
?>
</div>
</div>
<?php
}
?>
<!-- This is the if statement I mention -->
<?php
if !isset($login_okay){
?>
<div class="wrapper dafswInDown" hidden>
}
?>
<div class="wrapper fadeInDown">
<div id="formContent">
<!-- Icon -->
<div class="fadeIn first">
<br>
<img src="images/Head1.jpg" style="height: 40%; width: 60%;" id="icon" alt="User Icon" />
<br>
<h3> Login! </h3>
</div>
<br>
<!-- Login Form -->
<form id="login_form" action="login_page.php" method="post">
<input type="text" class="fadeIn second" id="username" name="username" placeholder="Username" value="<?= isset($_POST['username']) ? htmlspecialchars($_POST['username']) : '' ?>" maxlength="100" />
<input type="password" class="form-control" id="password" name="password" placeholder="Password" value="" />
<input type="submit" class="fadeIn fourth" name="action" value="Login"/>
</form>
<!-- Remind Passowrd -->
<div id="formFooter">
<a class="underlineHover" href="#">Forgot Password?</a>
</div>
</div>
</div>
<?php
require('includes/application_bottom.php');
require('includes/site_footer.php');
?>

Answer 1

There are a number of different ways you can approach this problem, but i think the best way to do this is with a session variable. Make your login function create a session variable that will follow the logged in user around throughout the website, then its just a matter of checking for the value and either displaying or hiding the form based on that. Here is a simplified example:
<?php function login($username_input=false, $password_input=false){
// Do all your verification here
// If logged in then:
session_start();
$_SESSION["user"] = true;
}
// Then on the form side just do this:
if(!$_SESSION["user"]){ ?>
FORM HERE
<?php } ?>