(defn start-command-loop
  [{:keys [cmd-ch process] :as prev-state}]
  (if (and cmd-ch process)
    (do (log/warn "already started")
        prev-state)
    (do
      (log/info "starting liquidsoap command loop")
      (let [cmd-ch (async/chan (async/sliding-buffer 1000))
            liq-state (atom {})]
        (future  (loop []
                   (let [{:keys [cmd data]} (async/<!! cmd-ch)]
                     (swap! liq-state  #(try
                                          (case  cmd
                                            :start (if (process-live? %) %
                                                       (start! data))
                                            :stop (stop-liq! %)
                                            :quit {})
                                          (catch Throwable e
                                            (log/warn e))))
                     (when-not (= :quit cmd) (recur))))
                 (log/debug "exiting command loop"))
        {:cmd-ch cmd-ch
         :liq-state liq-state}))))