parent id can be omitted in case prev id is set

lib/radiator/outline.ex

@@ -93,12 +93,12 @@ defmodule Radiator.Outline do
         |> where_parent_node_equals(parent_node_id)
         |> Repo.one()
 
-      with parent_node <- NodeRepository.get_node_if(parent_node_id),
-           prev_node <- NodeRepository.get_node_if(prev_node_id),
+      with prev_node <- NodeRepository.get_node_if(prev_node_id),
+           parent_node <- find_parent_node(prev_node, parent_node_id),
            true <- parent_and_prev_consistent?(parent_node, prev_node),
-           {:ok, node} <- NodeRepository.create_node(attrs),
-           {:ok, _node_to_move} <- move_node_if(next_node, parent_node_id, node.uuid),
-           {:ok, node} <- move_node_if(node, parent_node_id, prev_node_id) do
+           true <- episode_valid?(episode_id, parent_node, prev_node),
+           {:ok, node} <- NodeRepository.create_node(set_parent_id_if(attrs, parent_node)),
+           {:ok, _node_to_move} <- move_node_if(next_node, parent_node_id, node.uuid) do
         %NodeRepoResult{node: node, next_id: get_node_id(next_node)}
       else
         false ->
@@ -111,6 +111,25 @@ defmodule Radiator.Outline do
     end)
   end
 
+  defp episode_valid?(episode_id, %Node{episode_id: episode_id}, %Node{episode_id: episode_id}),
+    do: true
+
+  defp episode_valid?(episode_id, %Node{episode_id: episode_id}, nil), do: true
+  defp episode_valid?(episode_id, nil, %Node{episode_id: episode_id}), do: true
+  defp episode_valid?(_episode_id, nil, nil), do: true
+  defp episode_valid?(_episode_id, _parent_node, _prev_node), do: false
+
+  defp set_parent_id_if(attrs, nil), do: attrs
+  defp set_parent_id_if(attrs, %Node{uuid: uuid}), do: Map.put_new(attrs, "parent_id", uuid)
+
+  defp find_parent_node(%Node{parent_id: parent_id}, nil) do
+    NodeRepository.get_node_if(parent_id)
+  end
+
+  defp find_parent_node(_, parent_id) do
+    NodeRepository.get_node_if(parent_id)
+  end
+
   @doc """
   Moves a node to another parent.
 

test/radiator/outline_test.exs

@@ -5,6 +5,7 @@ defmodule Radiator.OutlineTest do
   alias Radiator.Outline
   alias Radiator.Outline.Node
   alias Radiator.Outline.NodeRepository
+  alias Radiator.Podcast
   alias Radiator.PodcastFixtures
 
   import Radiator.OutlineFixtures
@@ -186,6 +187,20 @@ defmodule Radiator.OutlineTest do
       assert new_node.prev_id == nested_node_1.uuid
     end
 
+    test "if prev_id has been given the parent_id can be omitted", %{
+      node_3: node_3,
+      nested_node_1: nested_node_1
+    } do
+      node_attrs = %{
+        "content" => "new node",
+        "episode_id" => node_3.episode_id,
+        "prev_id" => nested_node_1.uuid
+      }
+
+      {:ok, %{node: new_node}} = Outline.insert_node(node_attrs)
+      assert new_node.parent_id == node_3.uuid
+    end
+
     test "all nodes in same level are correctly connected", %{
       node_3: node_3,
       nested_node_1: nested_node_1,
@@ -289,15 +304,18 @@ defmodule Radiator.OutlineTest do
     end
 
     test "in case of error no node gets inserted", %{
+      episode: episode,
       parent_node: parent_node,
       nested_node_1: nested_node_1
     } do
       count_nodes = NodeRepository.count_nodes_by_episode(parent_node.episode_id)
 
+      {:ok, another_episode} =
+        Podcast.create_episode(%{title: "current episode", show_id: episode.show_id, number: 23})
+
       node_attrs = %{
         "content" => "new node",
-        "episode_id" => parent_node.episode_id,
-        "parent_id" => parent_node.uuid,
+        "episode_id" => another_episode.id,
         "prev_id" => nested_node_1.uuid
       }
 

test/support/data_case.ex

@@ -177,6 +177,7 @@ defmodule Radiator.DataCase do
     assert nested_node_2.prev_id == nested_node_1.uuid
 
     %{
+      episode: episode,
       node_1: node_1,
       node_2: node_2,
       node_3: node_3,