defmodule MessageContext do
  @moduledoc """
    This module maintain the required settings to achieve communication with the message broker, it also provides default semantic settings
  """
  use GenServer
  require Logger
  @table_name :msg_ctx

  @default_values %{
    reply_exchange: "globalReply",
    direct_exchange: "directMessages",
    events_exchange: "domainEvents",
    connection_props: "amqp://guest:guest@localhost",
    connection_assignation: %{
      ReplyListener: ListenerConn,
      QueryListener: ListenerConn,
      CommandListener: ListenerConn,
      EventListener: ListenerConn,
      NotificationEventListener: ListenerConn,
      MessageExtractor: ListenerConn,
      MessageSender: SenderConn,
      ListenerController: SenderConn,
    },
    queries_reply: true,
    with_dlq_retry: false,
    retry_delay: 500,
    max_retries: 10,
    prefetch_count: 250,
  }

  def start_link(config = %AsyncConfig{}) do
    GenServer.start_link(__MODULE__, config, name: __MODULE__)
  end


  @impl
  def init(config = %AsyncConfig{}) do
    config
    |> put_default_values()
    |> put_route_info()
    |> save_in_ets()
    {:ok, nil}
  end

  def save_handlers_config(config = %HandlersConfig{}) do
    GenServer.call(__MODULE__, {:save_handlers_config, config})
  end

  defp put_route_info(config = %AsyncConfig{application_name: app_name}) do
    %AsyncConfig{
      config |
      reply_routing_key: NameGenerator.generate(),
      reply_queue: NameGenerator.generate(app_name, "reply"),
      query_queue: "#{app_name}.query",
      event_queue: "#{app_name}.subsEvents",
      notification_event_queue: NameGenerator.generate(app_name, "notification"),
      command_queue: "#{app_name}",
    }
  end

  defp put_default_values(config = %AsyncConfig{}) do
    @default_values
    |> Enum.reduce(config, fn {key, value}, conf -> put_if_nil(conf, key, value) end)
  end

  defp put_if_nil(map, key, value) do
    case Map.get(map, key) do
      nil -> Map.put(map, key, value)
      _ -> map
    end
  end

  defp save_in_ets(config) do
    :ets.new(@table_name, [:named_table, read_concurrency: true])
    :ets.insert(@table_name, {:conf, config})
  end

  def reply_queue_name(), do: config().reply_queue
  def query_queue_name(), do: config().query_queue
  def command_queue_name(), do: config().command_queue
  def event_queue_name(), do: config().event_queue
  def notification_event_queue_name(), do: config().notification_event_queue
  def reply_routing_key(), do: config().reply_routing_key
  def reply_exchange_name(), do: config().reply_exchange
  def direct_exchange_name(), do: config().direct_exchange
  def events_exchange_name(), do: config().events_exchange
  def with_dlq_retry(), do: config().with_dlq_retry
  def retry_delay(), do: config().retry_delay
  def max_retries(), do: config().max_retries
  def prefetch_count(), do: config().prefetch_count
  def application_name(), do: config().application_name

  def config() do
    [{:conf, config}] = :ets.lookup(@table_name, :conf)
    config
  end

  def handlers() do
    case :ets.lookup(@table_name, :handlers) do
      [{:handlers, config}] -> config
      [] -> []
    end
  end

  @impl true
  def handle_call({:save_handlers_config, config}, _from, state) do
    Logger.info "Saving handlers config!"
    true = :ets.insert(@table_name, {:handlers, config})
    {:reply, :ok, state}
  end

  def table() do
    :ets.tab2list(@table_name)
  end

end