From 1fb383f368b861d7aea77770ba7be6e3dfe3468e Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Thu, 30 Apr 2020 15:42:30 +0200
Subject: [PATCH] DeleteValidator: Deleting a user is valid.

---
 lib/pleroma/web/activity_pub/builder.ex           | 15 +++++++++++++--
 .../object_validators/common_validations.ex       | 11 +++++++++++
 .../object_validators/delete_validator.ex         |  2 +-
 test/web/activity_pub/object_validator_test.exs   |  7 ++++++-
 4 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/builder.ex b/lib/pleroma/web/activity_pub/builder.ex
index 5cc46c3ea..1345a3a3e 100644
--- a/lib/pleroma/web/activity_pub/builder.ex
+++ b/lib/pleroma/web/activity_pub/builder.ex
@@ -12,9 +12,20 @@ defmodule Pleroma.Web.ActivityPub.Builder do
 
   @spec delete(User.t(), String.t()) :: {:ok, map(), keyword()}
   def delete(actor, object_id) do
-    object = Object.normalize(object_id)
+    object = Object.normalize(object_id, false)
 
-    to = (object.data["to"] || []) ++ (object.data["cc"] || [])
+    user = !object && User.get_cached_by_ap_id(object_id)
+
+    to =
+      case {object, user} do
+        {%Object{}, _} ->
+          # We are deleting an object, address everyone who was originally mentioned
+          (object.data["to"] || []) ++ (object.data["cc"] || [])
+
+        {_, %User{follower_address: follower_address}} ->
+          # We are deleting a user, address the followers of that user
+          [follower_address]
+      end
 
     {:ok,
      %{
diff --git a/lib/pleroma/web/activity_pub/object_validators/common_validations.ex b/lib/pleroma/web/activity_pub/object_validators/common_validations.ex
index e115d9526..d9a629a34 100644
--- a/lib/pleroma/web/activity_pub/object_validators/common_validations.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/common_validations.ex
@@ -49,4 +49,15 @@ def validate_object_presence(cng, field_name \\ :object) do
       end
     end)
   end
+
+  def validate_object_or_user_presence(cng, field_name \\ :object) do
+    cng
+    |> validate_change(field_name, fn field_name, object ->
+      if Object.get_cached_by_ap_id(object) || User.get_cached_by_ap_id(object) do
+        []
+      else
+        [{field_name, "can't find object"}]
+      end
+    end)
+  end
 end
diff --git a/lib/pleroma/web/activity_pub/object_validators/delete_validator.ex b/lib/pleroma/web/activity_pub/object_validators/delete_validator.ex
index 0eb31451c..fa1713b50 100644
--- a/lib/pleroma/web/activity_pub/object_validators/delete_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/delete_validator.ex
@@ -31,7 +31,7 @@ def validate_data(cng) do
     |> validate_required([:id, :type, :actor, :to, :cc, :object])
     |> validate_inclusion(:type, ["Delete"])
     |> validate_same_domain()
-    |> validate_object_presence()
+    |> validate_object_or_user_presence()
   end
 
   def validate_same_domain(cng) do
diff --git a/test/web/activity_pub/object_validator_test.exs b/test/web/activity_pub/object_validator_test.exs
index ab26d3501..83b21a9bc 100644
--- a/test/web/activity_pub/object_validator_test.exs
+++ b/test/web/activity_pub/object_validator_test.exs
@@ -15,14 +15,19 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidatorTest do
       {:ok, post_activity} = CommonAPI.post(user, %{"status" => "cancel me daddy"})
 
       {:ok, valid_post_delete, _} = Builder.delete(user, post_activity.data["object"])
+      {:ok, valid_user_delete, _} = Builder.delete(user, user.ap_id)
 
-      %{user: user, valid_post_delete: valid_post_delete}
+      %{user: user, valid_post_delete: valid_post_delete, valid_user_delete: valid_user_delete}
     end
 
     test "it is valid for a post deletion", %{valid_post_delete: valid_post_delete} do
       assert match?({:ok, _, _}, ObjectValidator.validate(valid_post_delete, []))
     end
 
+    test "it is valid for a user deletion", %{valid_user_delete: valid_user_delete} do
+      assert match?({:ok, _, _}, ObjectValidator.validate(valid_user_delete, []))
+    end
+
     test "it's invalid if the id is missing", %{valid_post_delete: valid_post_delete} do
       no_id =
         valid_post_delete