;; -*- Mode: Irken -*-

;; will need two CVs eventually.  the obvious one for read,
;;  but if/when we honor window sizes, we will need a CV for write.

(define (make-channel c2s-id s2c-id winsz maxpkt session-handler channel-write)

  (let ((read-cv (cv/make))
        (write-cv (cv/make))
        (rqueue (queue/make))
        (wqueue (queue/make)))

    (define (recv data)
      (queue/add! rqueue data)
      (read-cv.wake-one)
      )

    (define (read)
      (when (= rqueue.len 0)
        (read-cv.wait))
      (let ((pieces (list:nil)))
        (while (> rqueue.len 0)
          (when-maybe piece (queue/pop! rqueue)
            (push! pieces piece)))
        (string-concat (reverse pieces))
        ))

    ;; (define (write data)
    ;;   (queue/add! wqueue data)
    ;;   (write-cv.wake_one))

    (define (write data)
      (channel-write c2s-id data))

    (poller/fork (lambda () (session-handler read write)))

    { c2s-id = c2s-id
      s2c-id = s2c-id
      winsz = winsz
      maxpkt = maxpkt
      recv = recv }

    ))

(define (make-channel-manager)
  (let ((map (tree/empty))
        (counter 0))

    (define (next-id)
      (let ((r counter))
        (inc! counter)
        r))

    (define (new c2s-chan winsz maxpkt session-handler write)
      (let ((chan-id (next-id))
            (chan (make-channel c2s-chan chan-id winsz maxpkt session-handler write)))
        (tree/insert! map int-cmp chan-id chan)
        chan
        ))

    (define (close c2s-id s2c-id)
      (tree/delete! map int-cmp s2c-id))

    (define (lookup s2c-id)
      (tree/member map int-cmp s2c-id))

    { new = new
      lookup = lookup
      close = close }

    ))