untested, now pending follows

lib/vonbraun/ecto/schema/actor.ex

@@ -18,9 +18,9 @@ defmodule Vonbraun.Ecto.Schema.Actor do
   @type t :: %__MODULE__{
           muted: boolean(),
           blocked: DateTime.t(),
-          follows_me_state: String.t(),
+          follows_me_state: String.t() | nil,
           follows_me_ts: DateTime.t(),
-          following_state: String.t(),
+          following_state: String.t() | nil,
           following_ts: String.t()
         }
 
@@ -92,4 +92,38 @@ defmodule Vonbraun.Ecto.Schema.Actor do
         end
     end
   end
+
+  @spec mark_pending_follow(String.t(), nil | String.t(), keyword()) ::
+          {:ok, __MODULE__.t()} | {:error, any()}
+  @spec mark_pending_follow(String.t(), nil | String.t()) ::
+          {:error, any()} | {:ok, __MODULE__.t()}
+  def mark_pending_follow(id, new_state, options \\ [])
+      when is_binary(id) and new_state in [nil, "accepted", "pending", "rejected"] do
+    with {:actor,
+          {:ok, actor = %{:blocked => blocked?, :following_state => existing_following_state}}} <-
+           {:actor, maybe_insert(id)} do
+      valid_set_pending? = existing_following_state == nil && new_state == "pending"
+
+      valid_set_response? =
+        existing_following_state == "pending" && new_state in ["accepted", "pending"]
+
+      force? = Keyword.get(options, :force, false)
+
+      cond do
+        # You NEED to unblock manually first.
+        blocked? ->
+          {:error, :blocked}
+
+        force? || valid_set_pending? || valid_set_response? ->
+          changeset(actor, %{following_state: new_state, following_ts: DateTime.now!("Etc/UTC")})
+          |> Repo.update()
+
+        true ->
+          {:error, :invalid_state}
+      end
+    else
+      {:actor, {:error, error}} ->
+        {:error, error}
+    end
+  end
 end