function checkInstallation()
{
    if (!file_exists('configuration/db.php')) {
        doAlert('Configuration file missing!\\nHave you done the setup procedure?');
        if (file_exists('setup.php')) {
            header('Location:setup.php');
        } else {
            doAlert('Your installation is compromised!\\nPlease, restart setup or contact support');
        }
    } else {
        return true;
    }
}
<?php

require_once '../configuration/db.php';
require_once '../configuration/ClassUser.php';
require_once '../function/funcs.php';
session_start();
checkLogin();
$user = new User();
setupUser($user);
if (checkUserAdminOrSuperUser($user)) {
    echo "\n    <html>\n    <head>\n    <title>OpenTroubleTicketing | Edit Categories</title>\n    <meta charset='utf-8'>\n    <meta name='viewport' content='width=device-width, initial-scale=1'>\n    <link rel='icon' href='icon/icon.png'/>\n    <link rel='stylesheet' href='../style/bootstrap.min.css'>\n    <link rel='stylesheet' href='cpanelCategoryStyle.css'>\n    <link rel='stylesheet' href='../style/defaultStyle.css'>\n    <script src='../js/jquery.min.js'></script>\n    <script src='../js/bootstrap.min.js'></script>\n    <script src='cpanelCategoryScript.js'></script>\n    <script src='../js/defaultScript.js'></script>\n    </head>\n    <body>";
    if (!isset($_GET['catNameQuery'])) {
        echo "\n    \n    <div id='addCategory' class='container'>\n      <h2 id='showCatMenu' class='entry'>Add a new category</h2>\n      <div class='container' id='newCat'>\n        <form role='form'>\n        <div class='form-group'>\n                  <label for='catName'>Enter the category's name</label>\n                  <input type='text' class='form-control' id='catName' size='10'>    \n        </div>\n        <div class='form-group'>\n                  <label for='catDesc'>Enter the category's description</label>\n                  <textarea row='4' cols='4' class='form-control' id='catDesc' size='500'></textarea>   \n        </div>\n        <div class='form-group'>\n                  <input type='button' value='INSERT' class='btn btn-warning btn-sm' id='insertCat'>\n        </div>\n        </form>\n      </div>  \n    </div>\n    <div id='showCategories' class='container'>\n     <h2 id='showAllCats' class='entry'>Show all categories</h2>\n      <div class='container' id='catTable'></div>\n    </div>\n    </body>\n    </html>\n    ";
    } else {
        $catNameEdit = $_GET['catNameQuery'];
        $connection = new mysqli(HOST, USER, PSW, DB);
        $query = "SELECT description FROM category WHERE name='" . $catNameEdit . "'";
        $exec = $connection->query($query);
        $res = $exec->fetch_assoc();
        echo "\n      <div id='editCategory' class='container'>\n        <form role='form'>\n        <div class='form-group'>\n                  <label for='catName'>Edit name:</label>\n                  <input type='text' class='form-control' id='catName' size='10' value='" . $catNameEdit . "'>\n                  <input type='text' id='originalCatName' class='hidden' value='" . $catNameEdit . "'>\n        </div>\n        <div class='form-group'>\n                  <label for='catDesc'>Edit description:</label>\n                  <textarea row='4' cols='4' class='form-control' id='catDesc' size='500'>" . $res['description'] . "</textarea>\n                  <textarea row='4' cols='4' class='hidden' id='originalCatDesc' size='500'>" . $res['description'] . "</textarea>   \n        </div>\n        <div class='form-group'>\n                  <input type='button' value='EDIT' class='btn btn-warning btn-sm' id='editCat'>\n                  <input type='button' value='DELETE' class='btn btn-danger btn-sm' id='deleteCat'>\n                  <button class='btn btn-info btn-sm' id='close'>CLOSE</button>\n        </div>\n        </form>\n       </div>  \n      </div>\n        ";
        $connection->close();
    }
} else {
    echo doAlert('You don\'t have the rights to do this');
}
      <span class="icon-bar"></span>
    </button>
    <a class="navbar-brand" href="#"><?php 
echo getBoardName();
?>
</a>
  </div>
  <?php 
if (!checkFirstSetup()) {
    echo "\n  <!-- Collect the nav links, forms, and other content for toggling -->\n  <div class='collapse navbar-collapse navbar-ex1-collapse'>\n    <ul class='nav navbar-nav'>\n      <li class='dropdown'>\n        <a href='#' class='dropdown-toggle' data-toggle='dropdown'>New..<b class='caret'></b></a>\n        <ul class='dropdown-menu'>\n            <li><a href='#' id='tktNew'>Ticket</a></li>\n            ";
    if ($user->getPosition() == 'admin' || $user->getPosition() == 'superuser') {
        echo "\n            <li><a href='#' id='customerNew'>Customer</a></li>\n            <li><a href='#' id='assetNew'>Asset</a></li>";
    }
    echo "      \n        </ul>\n      </li>\n      <li class='dropdown'>\n        <a href='#' class='dropdown-toggle' data-toggle='dropdown'>List Custom<b class='caret'></b></a>\n        <ul class='dropdown-menu'>\n          <li><a href='#'>list</a></li>\n          <li><a href='#'>something</a></li>\n          <li><a href='#'>custom</a></li>\n          <li><a href='#'>TO DO</a></li>\n        </ul>\n      </li>\n    </ul>\n    <form class='navbar-form navbar-left' role='search'>\n      <div class='form-group'>\n        <input type='text' class='form-control' data-toggle='tooltip' data-placement='bottom' title='You can use any parameter to search a ticket' id='ticketField' placeholder='Search Ticket'>\n      </div>\n      <button type='submit' id='searchTicket' class='btn btn-default'>Go</button>\n    </form>\n    <form class='navbar-form navbar-left' role='search'>\n      <div class='form-group'>\n        <input type='text' class='form-control' data-toggle='tooltip' data-placement='bottom' title='You can use any parameter to search a customer' id='customerField' placeholder='Search Customer'>\n      </div>\n      <button type='submit' id='searchCustomer' class='btn btn-default'>Go</button>\n    </form>\n     <form class='navbar-form navbar-left' role='search'>\n      <div class='form-group'>\n        <input type='text' class='form-control'data-toggle='tooltip' data-placement='bottom' title='You can use any parameter to search an asset' id='assetField' placeholder='Search Asset'>\n      </div>\n      <button type='submit' id='searchAsset' class='btn btn-default'>Go</button>\n    </form>\n    ";
} else {
    doAlert('An admin must complete the first setup procedure.\\nUse the control panel on the right!');
}
?>
    <ul class='nav navbar-nav navbar-right'>
    <?php 
if ($user->getPosition() == 'admin' || $user->getPosition() == 'superuser') {
    echo "   \n             <li><a href='#cpanel' id='cpanelButton'>Control Panel</a></li>";
}
?>
    <li class='dropdown'>
    <a href='#' class='dropdown-toggle' data-toggle='dropdown'><?php 
echo $user->getName() . " " . $user->getSurname() . "";
?>
 <b class='caret'></b></a>
    <ul class='dropdown-menu'>
    <li><a href='#'>Send a message</a></li>