small refactoring

[StefanHoutzager]

I just for fun refactored a couple of functions in avia/apps/admin_app/lib/admin_app/order/order.ex.
The get_rummage function contains a risky String.to_atom call (see https://hexdocs.pm/elixir/String.html#to_atom/1). I removed it. The rest of the changes could speak for itself (feel free to ask if you have questions). There is one order_list function now. I have no elixir editor from where I work, so maybe there are errors in the code.

  def order_list(order_state, sort_order) do
    orders =
      get_rummage(sort_order)
      |> query_orders(order_state)
      |> load_orders()
	  
    case order_state do
      "complete" ->  orders 
      _          ->  orders |> Enum.filter(fn order -> filter_order?(order.packages, order_state) end)
    end  
  end
  
  defp filter_order?(packages, "pending"), do: 
    Enum.member?(packages, "processing")
 
  defp filter_order?(packages, "unshipped"), do: 
    Enum.member?(packages, "ready")
	
  defp filter_order?(packages, "shipped"), do: 
    Enum.any?(packages, fn package ->
      package.state == "shipped" || package.state == "delivered"
    end)
  
  defp get_rummage(sort_order) do
    case sort_order do
      nil ->
        %{}

      "asc" ->
        %{
          sort: %{field: :inserted_at, order: :asc}
        }
      "desc" ->
        %{
          sort: %{field: :inserted_at, order: :desc}
        }		
    end
  end  
  
  defp query_orders(rummage, order_state) do
    {queryable, _rummage} = Order.rummage(rummage)

    case order_state do
      complete" -> from(p in queryable, where: p.state == "complete")
      _         -> from(p in queryable, where: p.state == "confirmed") 
    end
  end