I have the code below but I want to write the file under a dynamically created folder from date. So it should look like this date/filename.txt

```
   <?php
    if(isset($_POST['field1']) && isset($_POST['field2'])) {
        $data = $_POST['field1'] . '-' . $_POST['field2'] . "\n";
        $filename = date('YmdHis').".txt";
        if (!file_exists($filename)) {
            $fh = fopen($filename, 'w') or die("Can't create file");
        }
        $ret = file_put_contents($filename, $data, FILE_APPEND | LOCK_EX);
        if($ret === false) {
            die('There was an error writing this file');
        }
        else {
            echo "$ret bytes written to file";
        }
    }
    else {
       die('no post data to process');
    }
    ?>

```