defmodule PubSub do

  def broadcast(channel, topic, payload) do
    {:ok, client} = Exredis.start_link
    payload = payload |> Map.put(:topic, topic)
    client |> Exredis.Api.publish channel, Poison.encode!(payload)
  end

  def subscribe(channel, module) do
    sup = spawn_link fn -> accept_messages(module) end
    {:ok, client_sub} = Exredis.Sub.start_link
    pid = Kernel.self
    client_sub |> Exredis.Sub.subscribe channel, fn(msg) ->
      send pid, msg
    end
    receive do
      msg ->
        accept_messages(module)
    end
    {:ok, sup}
  end

  def accept_messages(module) do
    receive do
      {:message, channel, payload, pid} ->
        payload = SyproPubSub.parse_payload(payload)
        module.process_payload(payload["topic"], payload)
        accept_messages(module)
      msg ->
        accept_messages(module)
    end
  end

  def parse_payload(payload) do
    Poison.Parser.parse!(payload)
  end

end