defmodule UrbitEx.API do
  alias UrbitEx.{Airlock, Actions}

  def init(url, code) do
    %UrbitEx.Session{
      url: url,
      code: code,
      channel: set_channel()
    }
  end

  @spec login(%{:code => any, :url => binary, optional(any) => any}) :: %{
          :code => any,
          :cookie => binary,
          :ship => binary | {integer, integer},
          :url => binary,
          optional(any) => any
        }
  def login(session) do
    endpoint = "/~/login"
    url = session.url <> endpoint
    body = "password=#{session.code}"
    {:ok, res} = Airlock.post(url, body)
    {_, cookiestring} = Enum.find(res.headers, fn x -> match?({"set-cookie", _}, x) end)
    [cookie | _] = cookiestring |> String.split(";")
    # ships don't take the '~'
    [ship] = Regex.run(~r/(?<=~)[a-z]+[^=]*/, cookie)

    session
    |> Map.put(:cookie, cookie)
    |> Map.put(:ship, ship)
  end

  defp set_channel do
    "/~/channel/#{System.os_time(:millisecond)}-#{
      :crypto.strong_rand_bytes(3) |> Base.encode16(case: :lower)
    }"
  end

  def open_channel(session) do
    body = Actions.poke(session.ship, "hood", "helm-hi", "Opening airlock")
    wrap_put(session, body)
    session
  end

  def start_sse(session) do
    {:ok, _res} = Airlock.sse(session.url, session.channel, session.cookie, session.last_sse)
    session
  end

  def logout(session) do
    body = %{id: increment_id(session), action: "delete"}
    wrap_put(session, body)
    session
  end

  ## subscriptions to be a Map %{app: foo, path: bar}
  def subscribe(session, subscription) do
    body = Actions.subscribe(session.ship, subscription.app, subscription.path)
    wrap_put(session, body)
    session
  end

  defp wrap_put(session, body) do
    session = session |> increment_id
    body = Map.put(body, :id, session.last_action)
    body = if need_ack?(session), do: [Actions.ack(session.last_sse) | [body]], else: [body]
    Airlock.put(session.url, session.channel, session.cookie, body)
  end

  defp increment_id(session) do
    Map.put(session, :last_action, session.last_action + 1)
  end

  defp need_ack?(session) do
    session.last_ack < session.last_sse
  end
end