net.cljs

(ns example.net
  (:require [goog.net.WebSocket]
            [goog.events :refer (listen)]
            [cljs.core.async :as async :refer (chan <! >! put! close)]
            [cljs.core.async.impl.protocols :as proto])
  (:require-macros [cljs.core.async.macros :refer (go)]))

(defn ws
  "WebSocket as a core.async channel
  returns a channel which delivers the ws chan then closes"
  [url]
  (let [socket (new goog.net.WebSocket)
        [read write opener] (repeatedly 3 chan)
        ws-chan (reify 
                  proto/ReadPort
                  (take! [_ fn-handler]
                    (proto/take! read fn-handler))
                  proto/WritePort
                  (put! [_ val fn-handler]
                    (proto/put! write val fn-handler))
                  proto/Channel
                  (close! [_]
                    (do (proto/close! read)
                        (proto/close! write)
                        (.close socket))))]
    (go 
      (while true (.send socket (<! write))))
    (listen socket goog.net.WebSocket.EventType.MESSAGE
      (fn [evt] (put! read (.-message evt))))
    (listen socket goog.net.WebSocket.EventType.OPENED
      (fn [evt] (go (>! opener ws-chan) (close! opener))
    (.open socket url)
    opener))

(comment ;; example usage

(go 
  (let [ws-chan (<! (ws "ws://localhost:8080/ws"))]
    (>! ws-chan "Hello, remote server!")
    (js/console.log (<! ws-chan))))
  
)