openflow/actions: Improve readability of experimenter action codec

lib/openflow/actions/experimenter.ex

@@ -20,34 +20,54 @@ defmodule Openflow.Action.Experimenter do
 
   @spec pack_exp_header(binary()) :: binary()
   def pack_exp_header(exp_body) do
-    pad_length =
-      exp_body
-      |> Kernel.byte_size()
-      |> Kernel.+(4)
-      |> Openflow.Utils.padding(8)
+    pad_length = pad_length_of(exp_body)
 
-    length =
-      exp_body
-      |> byte_size()
-      |> Kernel.+(4)
-      |> Kernel.+(pad_length)
-
-    <<0xFFFF::16, length::16, exp_body::bytes, 0::size(pad_length)-unit(8)>>
+    <<
+      0xFFFF::16,
+      length_of(exp_body, pad_length)::16,
+      exp_body::bytes,
+      0::size(pad_length)-unit(8)
+    >>
   end
 
-  def read(<<0xFFFF::16, _length::16, exp_id::32, exp_type::16, data::bytes>>) do
-    case Openflow.Utils.get_enum(exp_id, :action_vendor) do
-      vendor_id when is_integer(vendor_id) ->
+  def read(<<
+        0xFFFF::16,
+        _length::16,
+        exp_id::32,
+        exp_type::16,
+        data::bytes
+      >>) do
+    exp_id
+    |> Openflow.Utils.get_enum(:action_vendor)
+    |> read(exp_id, exp_type, data)
+  end
+
+  ## private functions
+
+  defp read(vendor_id, exp_id, exp_type, <<data::bytes>>) when is_atom(vendor_id) do
+    case Openflow.Utils.get_enum(exp_type, vendor_id) do
+      codec when is_atom(codec) ->
+        codec.read(<<exp_id::32, exp_type::16, data::bytes>>)
+
+      exp_type when is_integer(exp_type) ->
         %Experimenter{exp_id: exp_id, data: <<exp_type::16, data::bytes>>}
-
-      vendor when is_atom(vendor) ->
-        case Openflow.Utils.get_enum(exp_type, vendor) do
-          codec when is_atom(codec) ->
-            codec.read(<<exp_id::32, exp_type::16, data::bytes>>)
-
-          exp_type when is_integer(exp_type) ->
-            %Experimenter{exp_id: exp_id, data: <<exp_type::16, data::bytes>>}
-        end
     end
   end
+
+  defp read(vendor_id, exp_id, exp_type, <<data::bytes>>) when is_integer(vendor_id),
+    do: %Experimenter{exp_id: exp_id, data: <<exp_type::16, data::bytes>>}
+
+  defp pad_length_of(<<exp_body::bytes>>) do
+    exp_body
+    |> Kernel.byte_size()
+    |> Kernel.+(4)
+    |> Openflow.Utils.padding(8)
+  end
+
+  defp length_of(<<exp_body::bytes>>, pad_length) do
+    exp_body
+    |> byte_size()
+    |> Kernel.+(4)
+    |> Kernel.+(pad_length)
+  end
 end