Add Webfinger

lib/nulla_web/controllers/webfinger_controller.ex

@@ -0,0 +1,34 @@
+defmodule NullaWeb.WebfingerController do
+  use NullaWeb, :controller
+  alias Nulla.Repo
+  alias Nulla.ActivityPub
+  alias Nulla.Models.User
+  alias Nulla.Models.InstanceSettings
+
+  def show(conn, %{"resource" => resource}) do
+    case Regex.run(~r/^acct:([^@]+)@(.+)$/, resource) do
+      [_, username, domain] ->
+        case User.get_user_by_username(username) do
+          nil ->
+            conn
+            |> put_status(:not_found)
+            |> json(%{error: "Not Found"})
+
+          user ->
+            instance_settings = InstanceSettings.get_instance_settings!()
+
+            if domain == instance_settings.domain do
+              json(conn, ActivityPub.webfinger(domain, username, resource))
+            else
+              conn
+              |> put_status(:not_found)
+              |> json(%{error: "Not Found"})
+            end
+        end
+      _ ->
+        conn
+        |> put_status(:bad_request)
+        |> json(%{error: "Bad Request"})
+    end
+  end
+end