defmodule UrbitEx do
  @moduledoc """
  Main API for the UrbitEx Package.
  Initializes the Urbit ship, logs in, opens an Eyre channel and starts an Server-side event pipeline.
  Start the connection with UrbitEx.start/2
  Subscribe to event streams with UrbitEx.subscribe.
  Once subscribed, Urbit server-side events will be sent as messages from the GenServer process to the current process.
  Set up your own logic to respond to events sent from Urbit inside UrbitEx.recv().
  """

  @doc """
    Starts the Urbit instance.

  ## Examples

      iex> {:ok, pid} = UrbitEx.start("http://localhost:8080", "sampel-dozzod-mirtyl-marzod")

  """
  def start(url, code) do
    {:ok, pid} = UrbitEx.Server.start_link(url: url, code: code)
    consume_feed(pid)
    {:ok, pid}
  end

  @doc """
  Sets the current process as consumer of the Urbit Ship's Eventstream.
  Every Urbit event will be sent from the Urbit GenServer to the current process.
  """
  defp consume_feed(pid) do
    GenServer.cast(pid, {:consume, self()})
  end

  @doc """
  Subscribes to event streams. Takes the pid of the connection (returned by UrbitExstart()),
  and a list of subscriptions. If it's a single subscription you want just wrap it in a list.
  """
  def subscribe(pid, subscriptions) do
    GenServer.cast(pid, {:subscribe, subscriptions})
  end

  def check_state(pid) do
    GenServer.call(pid, :get)
  end

  @doc """
    Starts a recursive loop that reacts to events received from your Urbit ship.
    Takes a single argument, a function that will process received messages.
    ## Examples

       ```
       function = fn
         %{"json" => json} -> IO.inspect(json)
         _message -> IO.inspect(:other_app)
       end
       UrbitEx.recv(function)
    ```

  """

  def recv(function) do
    receive do
      message ->
        function.(message)
    end

    recv(function)
  end

  @doc """
  Function provided for testing purposes. It will subscribe to the same event streams as the Landscape client does.
  Takes a url and `+code`.
  Returns the pid of the GenServer started.
  Check the state with check_state(pid) and you can browse all events received, etc.
  """

  def test(url, code) do
    {:ok, pid} = UrbitEx.start(url, code)
    s = landscape_subs()
    subscribe(pid, s)
    pid
  end

  defp landscape_subs() do
    [
      %{app: "metadata-store", path: "/all"},
      %{app: "invite-store", path: "/all"},
      %{app: "launch", path: "/all"},
      %{app: "weather", path: "/all"},
      %{app: "group-store", path: "/groups"},
      %{app: "contact-store", path: "/all"},
      %{app: "s3-store", path: "/all"},
      %{app: "graph-store", path: "/keys"},
      %{app: "hark-store", path: "/updates"},
      %{app: "hark-graph-hook", path: "/updates"},
      %{app: "hark-group-hook", path: "/updates"},
      %{app: "settings-store", path: "/all"},
      %{app: "group-view", path: "/all"},
      %{app: "contact-pull-hook", path: "/nacks"},
      %{app: "graph-store", path: "/updates"}
    ]
  end
end