#lang racket

(require racket-upnp)

(provide check-dlna-players)

(define running-sem (make-semaphore 1))
(define running #f)

(define (check-dlna-players gui)
  (let ((can-check (begin
                     (semaphore-wait running-sem)
                     (let ((rng running))
                       (if rng
                           (begin
                             (semaphore-post running-sem)
                             #f)
                           (begin
                             (set! running #t)
                             (semaphore-post running-sem)
                             #t))))))
    (if can-check
        (void
         (thread
          (λ ()
            (let ((r (query-media-renderers)))
              (let ((r* (map (λ (r)
                               (list (media-renderer-name r)
                                     r))
                             r)))
                (send gui set-dlna-renderers! r*)
                (semaphore-wait running-sem)
                (set! running #f)
                (semaphore-post running-sem)
                )))))
        (void
         (send gui dlna-query-busy))
        )
    )
  )