ActivityPub: Handle clashing nicknames for the same ap id

If we get a new user (identified by ap_id) that would have the same
nickname as an existing user, give the existing user a nickname that
is prepended with the user id, as this will never clash.

This can happen when a user switches server software and that soft-
ware generates ap ids in a different way.

1 files changed, 25 insertions, 0 deletions

diff --git a/test/user_test.exs b/test/user_test.exs
index 9b66f3f51..7126bb539 100644
--- a/test/user_test.exs
+++ b/test/user_test.exs
@@ -597,6 +597,31 @@ defmodule Pleroma.UserTest do
       refute user.last_refreshed_at == orig_user.last_refreshed_at
     end
 
+    test "if nicknames clash, the old user gets a prefix with the old id to the nickname" do
+      a_week_ago = NaiveDateTime.add(NaiveDateTime.utc_now(), -604_800)
+
+      orig_user =
+        insert(
+          :user,
+          local: false,
+          nickname: "admin@mastodon.example.org",
+          ap_id: "http://mastodon.example.org/users/harinezumigari",
+          last_refreshed_at: a_week_ago
+        )
+
+      assert orig_user.last_refreshed_at == a_week_ago
+
+      {:ok, user} = User.get_or_fetch_by_ap_id("http://mastodon.example.org/users/admin")
+
+      assert user.inbox
+
+      refute user.id == orig_user.id
+
+      orig_user = User.get_by_id(orig_user.id)
+
+      assert orig_user.nickname == "#{orig_user.id}.admin@mastodon.example.org"
+    end
+
     @tag capture_log: true
     test "it returns the old user if stale, but unfetchable" do
       a_week_ago = NaiveDateTime.add(NaiveDateTime.utc_now(), -604_800)