defmodule LSGWeb.IcecastSseController do
  use LSGWeb, :controller
  require Logger

  @ping_interval 20_000

  def sse(conn, _params) do
    conn
    |> put_resp_header("X-Accel-Buffering", "no")
    |> put_resp_header("content-type", "text/event-stream")
    |> send_chunked(200)
    |> subscribe
    |> send_sse_message("ping", "ping")
    |> send_sse_message("icecast", LSG.IcecastAgent.get)
    |> sse_loop
  end

  def subscribe(conn) do
    :timer.send_interval(@ping_interval, {:event, :ping})
    {:ok, _} = Registry.register(LSG.BroadcastRegistry, "icecast", [])
    conn
  end

  def sse_loop(conn) do
    {type, event} = receive do
      {:event, :ping} -> {"ping", "ping"}
      {:icecast, stats} -> {"icecast", stats}
    end

    conn
    |> send_sse_message(type, event)
    |> sse_loop()
  end

  defp send_sse_message(conn, type, data) do
    json = Jason.encode!(%{type => data})
    {:ok, conn} = chunk(conn, "event: #{type}\ndata: #{json}\n\n")
    conn
  end

end