defmodule PhaseDB.Server.Cowboy.WebsocketHandler do
  alias PhaseDB.Session
  alias PhaseDB.Server.Protocol

  require Logger

  @behaviour :cowboy_websocket_handler

  @moduledoc """
  Implements the Cowboy websocket handler protocol.
  """

  def init _transport, req, opts do
    init req, opts
  end

  def init req, opts do
    {:upgrade, :protocol, :cowboy_websocket, req, opts}
  end

  def upgrade req, env, _handler, handler_opts do
    :cowboy_websocket.upgrade req, env, __MODULE__, handler_opts
  end

  def websocket_init _transport, req, _ do
    case Session.create do
      {:ok, pid} ->
        send self, :send_init
        Process.monitor pid
        {:ok, req, %{session: pid}}
      e -> e
    end
  end

  def websocket_handle {:text, request}, req, %{session: pid}=state do
    {:reply, {:text, Protocol.handle(request, pid)}, req, state}
  end
  def websocket_info :send_init, req, state do
    {:reply, {:text, Protocol.init_message |> Poison.encode!}, req, state}
  end

  def websocket_info({:DOWN, _, :process, pid0, _}, req, %{session: pid1}=state) when pid0 == pid1 do
    send self, :shutdown
    {:reply, {:text, Protocol.error "Session disconnected"}, req, state}
  end

  def websocket_info({:DOWN, _, _, _, _}, req, state) do
    {:shutdown, req, state}
  end

  def websocket_info wat, req, state do
    IO.inspect wat
    {:shutdown, req, state}
  end

  def websocket_terminate _, _, %{session: pid} do
    Session.drop pid
    :ok
  end
end