;; Doesn't currently work. I'm unable to join the multicast group to listen for messages.
(defpackage :cl-mdns/publisher
  (:use :cl
	:cl-mdns/packet)
  (:local-nicknames (:nb :nibbles)
                    (:f :fsocket)))
(in-package :cl-mdns/publisher)

(defvar *mdns-address* #(224 0 0 251))
(defvar *mdns-port* 5353)

; TODO: Bring cl-arrows lib so I can thread expressions
(defun parse-query-body-message (lst)
  "Parses the body of message.
The rest of the packet (meaning the tail) is ignored."
  (labels ((parse-rec (acc rem-lst)
	     (destructuring-bind (cnt &rest msg) rem-lst
	       (if (or (null cnt) (zerop cnt))
		   acc
		   (parse-rec
		    (concatenate 'list acc (list (coerce (map 'list #'code-char (subseq msg 0 cnt)) 'string)))
		    (nthcdr cnt msg))))))
    (parse-rec nil lst)))

(defun parse-query (query)
  "Parses question/query and returns domain name.
Completely ignores header and tail of packet for now."
  (let ((message (subseq query 12)))
    (format nil "~{~A~^.~}"
     (parse-query-body-message message))))

(defun publish ()
  (f:with-poll (pc)
    (f:with-socket (sock :datagram)
      (let ((addr (f:make-sockaddr-in :addr *mdns-address* :port *mdns-port*))
            (laddr (f:make-sockaddr-in :port *mdns-port*))
            (buffer (make-array 512 :element-type '(unsigned-byte 8))))

        ;; Prepare multicast socket
        (setf (f:socket-option sock :socket :reuseaddr) t)
        (f:socket-bind sock laddr)
        (f:multicast-join sock addr)

        ;; Register for polling - we don't want to waste compute time on active listening
        (f:poll-register pc (make-instance 'f:pollfd :fd sock :events (f:poll-events :pollin)))
        (loop
          (f:doevents (pollfd event) (f:poll pc)
            (case event
             (:pollin
              (multiple-value-bind (count saddr) (f:socket-recvfrom sock buffer)
                (format t "Recieved ~A from ~A, buffer: ~A" count saddr (subseq buffer 0 count))))
             )))))))