defmodule SomethingErlang.Grover do
  use GenServer

  require Logger

  def mount(user, thread_id) do
    DynamicSupervisor.start_child(
      SomethingErlang.Supervisor.Grovers,
      {__MODULE__, [self(), user, thread_id]}
    )
  end

  def get_thread!(thread_id, page_number) do
    GenServer.call(via(self()), {:show_thread, thread_id, page_number})
  end

  def start_link([lv_pid, user, thread_id]) do
    GenServer.start_link(
      __MODULE__,
      [lv_pid, user, thread_id],
      name: via(lv_pid))
  end

  @impl true
  def init([pid, user, thread_id]) do
    %{bbuserid: userid, bbpassword: userhash} = user
    initial_state = %{
      lv_pid: pid,
      thread_id: thread_id,
      page_number: 1,
      user: %{id: userid, hash: userhash}
    }

    Logger.debug "init #{userid} #{thread_id}"
    Process.monitor(pid)
    {:ok, initial_state}
  end

  @impl true
  def handle_call({:show_thread, thread_id, page_number}, _from, state) do
    thread = AwfulApi.parsed_thread(thread_id, page_number, state.user)
    {:reply, thread, %{state | page_number: page_number}}
  end

  @impl true
  def handle_info({:DOWN, _ref, :process, _object, reason}, state) do
    Logger.debug "received :DOWN from: #{inspect(state.lv_pid)} reason: #{inspect(reason)}"
    case reason do
      {:shutdown, _} -> {:stop, :normal, state}
      :killed -> {:stop, :normal, state}
      _ -> {:noreply, state}
    end
  end

  defp via(lv_pid),
    do: {:via, Registry, {SomethingErlang.Registry.Grovers, lv_pid}}
end