refactor(elixir): hierarchical refactor

to extract common code patterns from
category/storage location systems

lib/components_elixir/inventory/category.ex

@@ -5,6 +5,7 @@ defmodule ComponentsElixir.Inventory.Category do
   Categories can be hierarchical with parent-child relationships.
   """
   use Ecto.Schema
+  use ComponentsElixir.Inventory.HierarchicalSchema
   import Ecto.Changeset
 
   alias ComponentsElixir.Inventory.{Category, Component}
@@ -34,11 +35,20 @@ defmodule ComponentsElixir.Inventory.Category do
   @doc """
   Returns the full path of the category including parent names.
   """
-  def full_path(%Category{parent: nil} = category), do: category.name
-  def full_path(%Category{parent: %Category{} = parent} = category) do
-    "#{full_path(parent)} > #{category.name}"
-  end
-  def full_path(%Category{parent: %Ecto.Association.NotLoaded{}} = category) do
-    category.name
+  @impl true
+  def full_path(%Category{} = category) do
+    Hierarchical.full_path(category, &(&1.parent), path_separator())
   end
+
+  @impl true
+  def parent(%Category{parent: parent}), do: parent
+
+  @impl true
+  def children(%Category{children: children}), do: children
+
+  @impl true
+  def path_separator(), do: " > "
+
+  @impl true
+  def entity_type(), do: :category
 end