feat: prevent deletion of roles with assigned users

lib/mv_web/live/role_live/index.ex

@@ -62,25 +62,40 @@ defmodule MvWeb.RoleLive.Index do
   @impl true
   def handle_event("delete", %{"id" => id}, socket) do
     {:ok, role} = Authorization.get_role(id)
+    user_count = get_user_count(role, socket.assigns.user_counts)
 
-    case Authorization.destroy_role(role) do
-      :ok ->
-        updated_roles = Enum.reject(socket.assigns.roles, &(&1.id == id))
+    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
+         )
+       )}
+    else
+      case Authorization.destroy_role(role) do
+        :ok ->
+          updated_roles = Enum.reject(socket.assigns.roles, &(&1.id == id))
+          updated_counts = Map.delete(socket.assigns.user_counts, id)
 
-        {:noreply,
-         socket
-         |> assign(:roles, updated_roles)
-         |> put_flash(:info, gettext("Role deleted successfully"))}
+          {:noreply,
+           socket
+           |> assign(:roles, updated_roles)
+           |> assign(:user_counts, updated_counts)
+           |> put_flash(:info, gettext("Role deleted successfully"))}
 
-      {: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)
-         )}
+          {:noreply,
+           put_flash(
+             socket,
+             :error,
+             gettext("Failed to delete role: %{error}", error: error_message)
+           )}
+      end
     end
   end