refactor: reduce nesting depth in RoleLive handle_event functions

lib/mv_web/live/role_live/show.ex

@@ -19,65 +19,127 @@ defmodule MvWeb.RoleLive.Show do
   @impl true
   def mount(%{"id" => id}, _session, socket) do
     # Ensure current_user has role loaded for authorization checks
-    socket =
-      if socket.assigns[:current_user] do
-        user = socket.assigns.current_user
+    socket = ensure_user_role_loaded(socket)
 
-        user_with_role =
-          case Map.get(user, :role) do
-            %Ash.NotLoaded{} -> Ash.load!(user, :role, domain: Mv.Accounts)
-            nil -> Ash.load!(user, :role, domain: Mv.Accounts)
-            role when not is_nil(role) -> user
-          end
+    try do
+      case Ash.get(
+             Mv.Authorization.Role,
+             id,
+             domain: Mv.Authorization,
+             actor: socket.assigns[:current_user]
+           ) do
+        {:ok, role} ->
+          user_count = load_user_count(role)
 
-        assign(socket, :current_user, user_with_role)
-      else
-        socket
+          {:ok,
+           socket
+           |> assign(:page_title, gettext("Show Role"))
+           |> assign(:role, role)
+           |> assign(:user_count, user_count)}
+
+        {:error, %Ash.Error.Invalid{errors: [%Ash.Error.Query.NotFound{} | _]}} ->
+          {:ok,
+           socket
+           |> put_flash(:error, gettext("Role not found."))
+           |> redirect(to: ~p"/admin/roles")}
+
+        {:error, error} ->
+          raise error
       end
+    rescue
+      e in [Ash.Error.Invalid] ->
+        case e do
+          %Ash.Error.Invalid{errors: [%Ash.Error.Query.NotFound{} | _]} ->
+            {:ok,
+             socket
+             |> put_flash(:error, gettext("Role not found."))
+             |> redirect(to: ~p"/admin/roles")}
 
-    role = Ash.get!(Mv.Authorization.Role, id, domain: Mv.Authorization)
-    user_count = load_user_count(role)
-
-    {:ok,
-     socket
-     |> assign(:page_title, gettext("Show Role"))
-     |> assign(:role, role)
-     |> assign(:user_count, user_count)}
+          _ ->
+            reraise e, __STACKTRACE__
+        end
+    end
   end
 
   @impl true
   def handle_event("delete", %{"id" => id}, socket) do
-    {:ok, role} = Mv.Authorization.get_role(id)
-    user_count = socket.assigns.user_count
+    case Mv.Authorization.get_role(id, actor: socket.assigns.current_user) do
+      {:ok, role} ->
+        handle_delete_role(role, socket)
 
-    if user_count > 0 do
-      {:noreply,
-       put_flash(
-         socket,
-         :error,
-         gettext(
-           "Cannot delete role. %{count} user(s) are still assigned to this role. Please assign them to another role first.",
-           count: user_count
+      {:error, %Ash.Error.Query.NotFound{}} ->
+        {:noreply,
+         put_flash(
+           socket,
+           :error,
+           gettext("Role not found.")
          )
-       )}
-    else
-      case Mv.Authorization.destroy_role(role) do
-        :ok ->
-          {:noreply,
-           socket
-           |> put_flash(:info, gettext("Role deleted successfully."))
-           |> push_navigate(to: ~p"/admin/roles")}
+         |> push_navigate(to: ~p"/admin/roles")}
 
-        {:error, error} ->
-          error_message = format_error(error)
+      {:error, error} ->
+        error_message = format_error(error)
 
-          {:noreply,
-           put_flash(
-             socket,
-             :error,
-             gettext("Failed to delete role: %{error}", error: error_message)
-           )}
-      end
+        {:noreply,
+         put_flash(
+           socket,
+           :error,
+           gettext("Failed to delete role: %{error}", error: error_message)
+         )}
+    end
+  end
+
+  defp handle_delete_role(role, socket) do
+    cond do
+      role.is_system_role ->
+        {:noreply,
+         put_flash(
+           socket,
+           :error,
+           gettext("System roles cannot be deleted.")
+         )}
+
+      recalculate_user_count(role) > 0 ->
+        user_count = recalculate_user_count(role)
+
+        {:noreply,
+         put_flash(
+           socket,
+           :error,
+           gettext(
+             "Cannot delete role. %{count} user(s) are still assigned to this role. Please assign them to another role first.",
+             count: user_count
+           )
+         )}
+
+      true ->
+        perform_role_deletion(role, socket)
+    end
+  end
+
+  defp perform_role_deletion(role, socket) do
+    case Mv.Authorization.destroy_role(role, actor: socket.assigns.current_user) do
+      :ok ->
+        {:noreply,
+         socket
+         |> put_flash(:info, gettext("Role deleted successfully."))
+         |> push_navigate(to: ~p"/admin/roles")}
+
+      {:error, error} ->
+        error_message = format_error(error)
+
+        {:noreply,
+         put_flash(
+           socket,
+           :error,
+           gettext("Failed to delete role: %{error}", error: error_message)
+         )}
+    end
+  end
+
+  defp recalculate_user_count(role) do
+    case Ash.count(Accounts.User |> Ash.Query.filter(role_id == ^role.id)) do
+      {:ok, count} -> count
+      _ -> 0
     end
   end
 
@@ -151,6 +213,31 @@ defmodule MvWeb.RoleLive.Show do
   defp format_error(error) when is_binary(error), do: error
   defp format_error(_error), do: gettext("An error occurred")
 
+  defp ensure_user_role_loaded(socket) do
+    if socket.assigns[:current_user] do
+      user = socket.assigns.current_user
+      user_with_role = load_user_role(user)
+      assign(socket, :current_user, user_with_role)
+    else
+      socket
+    end
+  end
+
+  defp load_user_role(user) do
+    case Map.get(user, :role) do
+      %Ash.NotLoaded{} -> load_role_safely(user)
+      nil -> load_role_safely(user)
+      _role -> user
+    end
+  end
+
+  defp load_role_safely(user) do
+    case Ash.load(user, :role, domain: Mv.Accounts) do
+      {:ok, loaded_user} -> loaded_user
+      {:error, _} -> user
+    end
+  end
+
   defp permission_set_badge_class("own_data"), do: "badge badge-neutral badge-sm"
   defp permission_set_badge_class("read_only"), do: "badge badge-info badge-sm"
   defp permission_set_badge_class("normal_user"), do: "badge badge-success badge-sm"