fix visibility issues with multiple users

lib/memex/pipelines/steps.ex

@@ -21,11 +21,10 @@ defmodule Memex.Pipelines.Steps do
 
   """
   @spec list_steps(Pipeline.t(), User.t()) :: [Step.t()]
-  def list_steps(%{id: pipeline_id}, %{id: user_id}) do
+  def list_steps(%{id: pipeline_id}, %{id: user_id}) when user_id |> is_binary() do
     Repo.all(
       from s in Step,
         where: s.pipeline_id == ^pipeline_id,
-        where: s.user_id == ^user_id,
         order_by: s.position
     )
   end
@@ -62,8 +61,8 @@ defmodule Memex.Pipelines.Steps do
 
   """
   @spec get_step!(Step.id(), User.t()) :: Step.t()
-  def get_step!(id, %{id: user_id}) do
-    Repo.one!(from n in Step, where: n.id == ^id, where: n.user_id == ^user_id)
+  def get_step!(id, %{id: user_id}) when user_id |> is_binary() do
+    Repo.one!(from n in Step, where: n.id == ^id)
   end
 
   def get_step!(id, _invalid_user) do
@@ -119,22 +118,15 @@ defmodule Memex.Pipelines.Steps do
 
   ## Examples
 
-      iex> delete_step(%Step{user_id: 123}, %User{id: 123})
-      {:ok, %Step{}}
-
-      iex> delete_step(%Step{}, %User{role: :admin})
-      {:ok, %Step{}}
-
       iex> delete_step(%Step{}, %User{id: 123})
+      {:ok, %Step{}}
+
+      iex> delete_step(%Step{}, nil)
       {:error, %Ecto.Changeset{}}
 
   """
   @spec delete_step(Step.t(), User.t()) :: {:ok, Step.t()} | {:error, Step.changeset()}
-  def delete_step(%Step{user_id: user_id} = step, %{id: user_id}) do
-    delete_step(step)
-  end
-
-  def delete_step(%Step{} = step, %{role: :admin}) do
+  def delete_step(%Step{} = step, %{id: user_id}) when user_id |> is_binary() do
     delete_step(step)
   end
 
@@ -181,10 +173,11 @@ defmodule Memex.Pipelines.Steps do
   def reorder_step(%Step{position: 0} = step, :up, _user), do: {:error, step}
 
   def reorder_step(
-        %Step{position: position, pipeline_id: pipeline_id, user_id: user_id} = step,
+        %Step{position: position, pipeline_id: pipeline_id} = step,
         :up,
         %{id: user_id} = user
-      ) do
+      )
+      when user_id |> is_binary() do
     Multi.new()
     |> Multi.update_all(
       :reorder_steps,
@@ -207,10 +200,11 @@ defmodule Memex.Pipelines.Steps do
   end
 
   def reorder_step(
-        %Step{pipeline_id: pipeline_id, position: position, user_id: user_id} = step,
+        %Step{pipeline_id: pipeline_id, position: position} = step,
         :down,
         %{id: user_id} = user
-      ) do
+      )
+      when user_id |> is_binary() do
     Multi.new()
     |> Multi.one(
       :step_count,