This is my first working with wordpress rest api. Here I get a token in the header and a user-id from the url. By checking them I make a response which show the audio list from the uploads folder.

Rest Api in wordpress

add_action('rest_api_init',function(){
    register_rest_route('uploads','/audios/',array(
        'methods'=>'GET',
        'callback'=>'meditation_upload_file_auth',
    ));
});
function meditation_upload_file_auth(WP_REST_Request $request) {
    $user_id = isset($_GET['userid'])?(int)$_GET['userid']:'';
    $user_data = get_user_by('ID',$user_id);
    $token = $request->get_header('token');
    // $token = $attribues['args']['token'][0];
    if(empty($token)) {
        return new WP_Error( 'empty_token', 'Empty Token', array( 'status' => 404 ) );
     }
     if($token !='meditationpeggyapp'){
         return new WP_Error( 'invalid_token', 'Invalid Token', array( 'status' => 404 ) );
     }
    if(empty($user_id)) {
        return new WP_Error( 'empty_userID', 'Empty Userid', array( 'status' => 404 ) );
    }
    if($user_data ==false) {
        return new WP_Error( 'invalid_userID', 'Invalid Userid', array( 'status' => 404 ) );
    }else {
        $upload_dir = wp_upload_dir();

        if($dir=opendir($upload_dir['basedir'].'/audios')) {

        $modules = array();
        while(false!==($file=readdir($dir))) {

            if($file!="." && $file!='..') {
                $modules[] = $file;
            }
        }
        closedir($dir);
        sort($modules);
        $response = array();

        foreach($modules as $module) {
        $count = 0;
            $purchased_products = array();
            $purchased_products['module_title'] = $module;
            $listed_audios = glob($upload_dir['basedir'].'/audios/'.$module.'/*');
            $count = 1;
            foreach($listed_audios as $single_audio){

                $purchased_products['products'][] = array(
                    'title'=>'audio '.$count,
                    'url'=> str_replace("/home/admin/web/meditationwithpeggygaines.com/public_html/wp-content/",$upload_dir['baseurl'].'/',$single_audio),
                );
                $count++;
            }
            $response[] = $purchased_products;
        }

        $json = array();
        $json['success'] = true;
        $json['message'] = 'Product fetch successful';
        $json['purchased_products'] = $response;
        $message = new WP_REST_Response($json, 200); // data => array of returned data
        return $message;

        }
    }


}