defmodule File.Only.Logger.App do
  use Application
  use PersistConfig

  alias File.Only.Logger.Log

  @logger_config get_env(:logger)
  @handler_config hd(@logger_config)
  # :debug_handler...
  @handler_id elem(@handler_config, 1)

  @spec start(Application.start_type(), term) :: {:ok, pid}
  def start(_start_type, _start_args = :ok) do
    add_handlers(:file_only_logger, @handler_id in :logger.get_handler_ids())
    {:ok, self()}
  end

  ## Private functions

  # Add debug, info, warning and error handlers...
  # Returns :ok or {:error, term} where term would likely be:
  # {:bad_config, {:handler, {:file_only_logger, {:already_exist, _id}}}}
  @spec add_handlers(Application.app(), boolean) :: :ok
  defp add_handlers(app, _handlers_already_exist? = false) do
    case Logger.add_handlers(app) do
      :ok -> :ok
      {:error, reason} -> :ok = Log.error(:handlers, {reason, app, __ENV__})
    end
  end

  defp add_handlers(_app, _) do
    :ok
  end
end