Codeigniter - How to view files content from a different directory

Question

I'm quite new with Codeigniter. I managed to create a list displaying the files located in different folder with the below link:

https://mywebsite/index.php/report/generateList

However, when I click on the link links generated, it shows the 404 Page Not Found error.

The folder in question, is in a completely different location(not within Codeigniter directory). So I was wondering if anyone can shed some light on how I can create the link to view the content of the files when I click on it?

Here is my code:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Report extends CI_Controller {

        public function index()
        {
                echo 'Hello!';
        }

        public function generateList()
        {

                $directory = "/apps/text_files/";

                if (is_dir($directory))
                {
                        if ($opendirectory = opendir($directory))
                        {
                                while (($file = readdir($opendirectory)) !== false)
                                {
                                        echo "<a href='$directory" . "$file'>$file</a>"."<br>";
                                }
                        closedir($opendirectory);
                        }
                }
        }
}

Thank you in advance!