<?php
// define the pages
$dir "./Pages";
$options scandir($dirSCANDIR_SORT_DESCENDING);

// check if no page has been selected
if (!isset($_POST['DATA_page']))
    
$_POST['DATA_page'] = $options[0];

// check if the page exists in the array
if (!in_array($_POST['DATA_page'], $options))
    
$_POST['DATA_page'] = $options[0];

$filename 'Pages/' $_POST['DATA_page'];

// save 
if (isset($_POST['BUTTON_save'])) {

    if (
file_exists($filename)) {
        
// save code to file
        
file_put_contents($filename$_POST['DATA_code']);
    }
}
?>

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="main">
        <form action="index.php?page=cms" id="form" method="POST">
            <label for="DATA_page">page</label>
            <select name="DATA_page" onchange="document.getElementById('form').submit();">
                <?php
                $files 
scandir("./Pages"SCANDIR_SORT_DESCENDING);
                foreach (
$files as $file) {
                    if (
$file != "." && $file != "" && $file != "..") {
                        
?>
                        <option <?php if($_POST["DATA_page"] == $file) echo "selected='selected'" ?>><?= $file ?></option>
                        <?php
                    
}
                }
                
?>
            </select>
            <input type="submit" value="Edit">
        </form>
    </div>
    <div id="editarea">
        <form action="index.php?page=cms" method="POST">
            <?php
            
// check if the file exists
            
if (file_exists($filename)) {
                
$code file_get_contents($filename);
                
?>
                <textarea name="DATA_code"><?= $code ?></textarea>
                <button type="submit" name="BUTTON_save">Save</button>
                <?php
            
} else
                echo 
"Sorry, the file $page does not exist on the server.";
            
?>
        </form>
    </div>
</body>

</html>