nav.php

<nav class="navbar navbar-expand-md bg-dark navbar-dark">
    <!-- Brand -->
    <a class="navbar-brand" href="#">MK Movies</a>

    <!-- Toggler/collapsibe Button -->
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsibleNavbar">
        <span class="navbar-toggler-icon"></span>
    </button>
    <!-- Navbar links -->
    <div class="collapse navbar-collapse" id="collapsibleNavbar">
        <ul class="navbar-nav ml-auto">
            <?php if (isset($_SESSION["logged_in"])):  ?>

                <li class="nav-item">
                    <a class="nav-link" href="add-product.php">Add Product</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="add-customer.php">Add Customer</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="sales.php">Sales</a>
                </li>

                <?php if ( $_SESSION["admin"] == 1 ):  ?>

                    <li class="nav-item">
                        <a class="nav-link" href="sales-report.php">Reports</a>
                    </li>

                    <li class="nav-item">
                        <a class="nav-link" href="add-user.php">Add User</a>
                    </li>

                <?php endif; ?>


                <li class="nav-item dropdown">
                    <a class="nav-link dropdown-toggle" href="#" id="navbardrop" data-toggle="dropdown">
                        <?= $_SESSION["names"] ?>
                    </a>
                    <div class="dropdown-menu">
                        <a class="dropdown-item" href="logout.php">Sign Out</a>
                    </div>
                </li>
            <?php endif; ?>


            <?php if (! isset($_SESSION["logged_in"])):  ?>
                <li class="nav-item">
                    <a class="nav-link" href="#">Login</a>
                </li>
            <?php endif; ?>



        </ul>
    </div>
</nav>