dbus

defmodule Dbus.PubSub do
  require Logger
  alias Dbus.Redis, as: R
  alias Dbus.Db, as: DB
  alias Dbus.Common, as: C
  alias Dbus.Queue, as: Q

  def pub(topic, msg) do
    R.q!(["RPUSH", DB.topic_id(topic), msg |> C.serialize])
    R.q!(["INCR", DB.total_id(topic)])
    Logger.debug("Sent #{topic}: #{msg |> inspect}")
  end

  def sub(topic, my_fn) do
    _sub(topic, my_fn, Q.pop(topic))
    Logger.debug("Subscribing to #{topic}.")
  end

  defp _sub(topic, my_fn, nil) do
    Logger.debug("Subscriber to #{topic} sleeping 5 seconds awaiting message.")
    :timer.sleep(5*1000)
    sub(topic, my_fn)
  end

  defp _sub(topic, my_fn, msg) do
    E.run(topic, my_fn, msg)
    sub(topic, my_fn)
  end
end