From 8b2457bdbf8791923701b0b015f6ddf2e7c89bf7 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 5 May 2020 13:25:34 +0200
Subject: [PATCH 1/8] Transmogrifier tests: Extract Undo handling

---
 .../transmogrifier/undo_handling_test.exs     | 185 ++++++++++++++++++
 test/web/activity_pub/transmogrifier_test.exs | 161 ---------------
 2 files changed, 185 insertions(+), 161 deletions(-)
 create mode 100644 test/web/activity_pub/transmogrifier/undo_handling_test.exs

diff --git a/test/web/activity_pub/transmogrifier/undo_handling_test.exs b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
new file mode 100644
index 000000000..a9ebfdb18
--- /dev/null
+++ b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
@@ -0,0 +1,185 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.Transmogrifier.UndoHandlingTest do
+  use Pleroma.DataCase
+
+  alias Pleroma.Activity
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.Transmogrifier
+  alias Pleroma.Web.CommonAPI
+
+  import Pleroma.Factory
+
+  test "it works for incoming emoji reaction undos" do
+    user = insert(:user)
+
+    {:ok, activity} = CommonAPI.post(user, %{"status" => "hello"})
+    {:ok, reaction_activity, _object} = CommonAPI.react_with_emoji(activity.id, user, "👌")
+
+    data =
+      File.read!("test/fixtures/mastodon-undo-like.json")
+      |> Poison.decode!()
+      |> Map.put("object", reaction_activity.data["id"])
+      |> Map.put("actor", user.ap_id)
+
+    {:ok, activity} = Transmogrifier.handle_incoming(data)
+
+    assert activity.actor == user.ap_id
+    assert activity.data["id"] == data["id"]
+    assert activity.data["type"] == "Undo"
+  end
+
+  test "it returns an error for incoming unlikes wihout a like activity" do
+    user = insert(:user)
+    {:ok, activity} = CommonAPI.post(user, %{"status" => "leave a like pls"})
+
+    data =
+      File.read!("test/fixtures/mastodon-undo-like.json")
+      |> Poison.decode!()
+      |> Map.put("object", activity.data["object"])
+
+    assert Transmogrifier.handle_incoming(data) == :error
+  end
+
+  test "it works for incoming unlikes with an existing like activity" do
+    user = insert(:user)
+    {:ok, activity} = CommonAPI.post(user, %{"status" => "leave a like pls"})
+
+    like_data =
+      File.read!("test/fixtures/mastodon-like.json")
+      |> Poison.decode!()
+      |> Map.put("object", activity.data["object"])
+
+    _liker = insert(:user, ap_id: like_data["actor"], local: false)
+
+    {:ok, %Activity{data: like_data, local: false}} = Transmogrifier.handle_incoming(like_data)
+
+    data =
+      File.read!("test/fixtures/mastodon-undo-like.json")
+      |> Poison.decode!()
+      |> Map.put("object", like_data)
+      |> Map.put("actor", like_data["actor"])
+
+    {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    assert data["actor"] == "http://mastodon.example.org/users/admin"
+    assert data["type"] == "Undo"
+    assert data["id"] == "http://mastodon.example.org/users/admin#likes/2/undo"
+    assert data["object"]["id"] == "http://mastodon.example.org/users/admin#likes/2"
+  end
+
+  test "it works for incoming unlikes with an existing like activity and a compact object" do
+    user = insert(:user)
+    {:ok, activity} = CommonAPI.post(user, %{"status" => "leave a like pls"})
+
+    like_data =
+      File.read!("test/fixtures/mastodon-like.json")
+      |> Poison.decode!()
+      |> Map.put("object", activity.data["object"])
+
+    _liker = insert(:user, ap_id: like_data["actor"], local: false)
+
+    {:ok, %Activity{data: like_data, local: false}} = Transmogrifier.handle_incoming(like_data)
+
+    data =
+      File.read!("test/fixtures/mastodon-undo-like.json")
+      |> Poison.decode!()
+      |> Map.put("object", like_data["id"])
+      |> Map.put("actor", like_data["actor"])
+
+    {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    assert data["actor"] == "http://mastodon.example.org/users/admin"
+    assert data["type"] == "Undo"
+    assert data["id"] == "http://mastodon.example.org/users/admin#likes/2/undo"
+    assert data["object"]["id"] == "http://mastodon.example.org/users/admin#likes/2"
+  end
+
+  test "it works for incoming unannounces with an existing notice" do
+    user = insert(:user)
+    {:ok, activity} = CommonAPI.post(user, %{"status" => "hey"})
+
+    announce_data =
+      File.read!("test/fixtures/mastodon-announce.json")
+      |> Poison.decode!()
+      |> Map.put("object", activity.data["object"])
+
+    _announcer = insert(:user, ap_id: announce_data["actor"], local: false)
+
+    {:ok, %Activity{data: announce_data, local: false}} =
+      Transmogrifier.handle_incoming(announce_data)
+
+    data =
+      File.read!("test/fixtures/mastodon-undo-announce.json")
+      |> Poison.decode!()
+      |> Map.put("object", announce_data)
+      |> Map.put("actor", announce_data["actor"])
+
+    {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    assert data["type"] == "Undo"
+    assert object_data = data["object"]
+    assert object_data["type"] == "Announce"
+    assert object_data["object"] == activity.data["object"]
+
+    assert object_data["id"] ==
+             "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity"
+  end
+
+  test "it works for incomming unfollows with an existing follow" do
+    user = insert(:user)
+
+    follow_data =
+      File.read!("test/fixtures/mastodon-follow-activity.json")
+      |> Poison.decode!()
+      |> Map.put("object", user.ap_id)
+
+    _follower = insert(:user, ap_id: follow_data["actor"], local: false)
+
+    {:ok, %Activity{data: _, local: false}} = Transmogrifier.handle_incoming(follow_data)
+
+    data =
+      File.read!("test/fixtures/mastodon-unfollow-activity.json")
+      |> Poison.decode!()
+      |> Map.put("object", follow_data)
+
+    {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+
+    assert data["type"] == "Undo"
+    assert data["object"]["type"] == "Follow"
+    assert data["object"]["object"] == user.ap_id
+    assert data["actor"] == "http://mastodon.example.org/users/admin"
+
+    refute User.following?(User.get_cached_by_ap_id(data["actor"]), user)
+  end
+
+  test "it works for incoming unblocks with an existing block" do
+    user = insert(:user)
+
+    block_data =
+      File.read!("test/fixtures/mastodon-block-activity.json")
+      |> Poison.decode!()
+      |> Map.put("object", user.ap_id)
+
+    _blocker = insert(:user, ap_id: block_data["actor"], local: false)
+
+    {:ok, %Activity{data: _, local: false}} = Transmogrifier.handle_incoming(block_data)
+
+    data =
+      File.read!("test/fixtures/mastodon-unblock-activity.json")
+      |> Poison.decode!()
+      |> Map.put("object", block_data)
+
+    {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
+    assert data["type"] == "Undo"
+    assert data["object"]["type"] == "Block"
+    assert data["object"]["object"] == user.ap_id
+    assert data["actor"] == "http://mastodon.example.org/users/admin"
+
+    blocker = User.get_cached_by_ap_id(data["actor"])
+
+    refute User.blocks?(blocker, user)
+  end
+end
diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index 23efa4be6..a315ff42d 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -362,87 +362,6 @@ test "it reject invalid emoji reactions" do
       assert :error = Transmogrifier.handle_incoming(data)
     end
 
-    test "it works for incoming emoji reaction undos" do
-      user = insert(:user)
-
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "hello"})
-      {:ok, reaction_activity, _object} = CommonAPI.react_with_emoji(activity.id, user, "👌")
-
-      data =
-        File.read!("test/fixtures/mastodon-undo-like.json")
-        |> Poison.decode!()
-        |> Map.put("object", reaction_activity.data["id"])
-        |> Map.put("actor", user.ap_id)
-
-      {:ok, activity} = Transmogrifier.handle_incoming(data)
-
-      assert activity.actor == user.ap_id
-      assert activity.data["id"] == data["id"]
-      assert activity.data["type"] == "Undo"
-    end
-
-    test "it returns an error for incoming unlikes wihout a like activity" do
-      user = insert(:user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "leave a like pls"})
-
-      data =
-        File.read!("test/fixtures/mastodon-undo-like.json")
-        |> Poison.decode!()
-        |> Map.put("object", activity.data["object"])
-
-      assert Transmogrifier.handle_incoming(data) == :error
-    end
-
-    test "it works for incoming unlikes with an existing like activity" do
-      user = insert(:user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "leave a like pls"})
-
-      like_data =
-        File.read!("test/fixtures/mastodon-like.json")
-        |> Poison.decode!()
-        |> Map.put("object", activity.data["object"])
-
-      {:ok, %Activity{data: like_data, local: false}} = Transmogrifier.handle_incoming(like_data)
-
-      data =
-        File.read!("test/fixtures/mastodon-undo-like.json")
-        |> Poison.decode!()
-        |> Map.put("object", like_data)
-        |> Map.put("actor", like_data["actor"])
-
-      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
-
-      assert data["actor"] == "http://mastodon.example.org/users/admin"
-      assert data["type"] == "Undo"
-      assert data["id"] == "http://mastodon.example.org/users/admin#likes/2/undo"
-      assert data["object"]["id"] == "http://mastodon.example.org/users/admin#likes/2"
-    end
-
-    test "it works for incoming unlikes with an existing like activity and a compact object" do
-      user = insert(:user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "leave a like pls"})
-
-      like_data =
-        File.read!("test/fixtures/mastodon-like.json")
-        |> Poison.decode!()
-        |> Map.put("object", activity.data["object"])
-
-      {:ok, %Activity{data: like_data, local: false}} = Transmogrifier.handle_incoming(like_data)
-
-      data =
-        File.read!("test/fixtures/mastodon-undo-like.json")
-        |> Poison.decode!()
-        |> Map.put("object", like_data["id"])
-        |> Map.put("actor", like_data["actor"])
-
-      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
-
-      assert data["actor"] == "http://mastodon.example.org/users/admin"
-      assert data["type"] == "Undo"
-      assert data["id"] == "http://mastodon.example.org/users/admin#likes/2/undo"
-      assert data["object"]["id"] == "http://mastodon.example.org/users/admin#likes/2"
-    end
-
     test "it works for incoming announces" do
       data = File.read!("test/fixtures/mastodon-announce.json") |> Poison.decode!()
 
@@ -844,60 +763,6 @@ test "it fails for incoming user deletes with spoofed origin" do
       assert User.get_cached_by_ap_id(ap_id)
     end
 
-    test "it works for incoming unannounces with an existing notice" do
-      user = insert(:user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "hey"})
-
-      announce_data =
-        File.read!("test/fixtures/mastodon-announce.json")
-        |> Poison.decode!()
-        |> Map.put("object", activity.data["object"])
-
-      {:ok, %Activity{data: announce_data, local: false}} =
-        Transmogrifier.handle_incoming(announce_data)
-
-      data =
-        File.read!("test/fixtures/mastodon-undo-announce.json")
-        |> Poison.decode!()
-        |> Map.put("object", announce_data)
-        |> Map.put("actor", announce_data["actor"])
-
-      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
-
-      assert data["type"] == "Undo"
-      assert object_data = data["object"]
-      assert object_data["type"] == "Announce"
-      assert object_data["object"] == activity.data["object"]
-
-      assert object_data["id"] ==
-               "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity"
-    end
-
-    test "it works for incomming unfollows with an existing follow" do
-      user = insert(:user)
-
-      follow_data =
-        File.read!("test/fixtures/mastodon-follow-activity.json")
-        |> Poison.decode!()
-        |> Map.put("object", user.ap_id)
-
-      {:ok, %Activity{data: _, local: false}} = Transmogrifier.handle_incoming(follow_data)
-
-      data =
-        File.read!("test/fixtures/mastodon-unfollow-activity.json")
-        |> Poison.decode!()
-        |> Map.put("object", follow_data)
-
-      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
-
-      assert data["type"] == "Undo"
-      assert data["object"]["type"] == "Follow"
-      assert data["object"]["object"] == user.ap_id
-      assert data["actor"] == "http://mastodon.example.org/users/admin"
-
-      refute User.following?(User.get_cached_by_ap_id(data["actor"]), user)
-    end
-
     test "it works for incoming follows to locked account" do
       pending_follower = insert(:user, ap_id: "http://mastodon.example.org/users/admin")
       user = insert(:user, locked: true)
@@ -967,32 +832,6 @@ test "incoming blocks successfully tear down any follow relationship" do
       refute User.following?(blocked, blocker)
     end
 
-    test "it works for incoming unblocks with an existing block" do
-      user = insert(:user)
-
-      block_data =
-        File.read!("test/fixtures/mastodon-block-activity.json")
-        |> Poison.decode!()
-        |> Map.put("object", user.ap_id)
-
-      {:ok, %Activity{data: _, local: false}} = Transmogrifier.handle_incoming(block_data)
-
-      data =
-        File.read!("test/fixtures/mastodon-unblock-activity.json")
-        |> Poison.decode!()
-        |> Map.put("object", block_data)
-
-      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
-      assert data["type"] == "Undo"
-      assert data["object"]["type"] == "Block"
-      assert data["object"]["object"] == user.ap_id
-      assert data["actor"] == "http://mastodon.example.org/users/admin"
-
-      blocker = User.get_cached_by_ap_id(data["actor"])
-
-      refute User.blocks?(blocker, user)
-    end
-
     test "it works for incoming accepts which were pre-accepted" do
       follower = insert(:user)
       followed = insert(:user)

From f1da8882f971f932b65f655b6457759387dafe51 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 5 May 2020 14:17:47 +0200
Subject: [PATCH 2/8] UndoValidator: Add UndoValidator.

---
 lib/pleroma/web/activity_pub/builder.ex       | 13 ++++
 .../web/activity_pub/object_validator.ex      |  9 +++
 .../object_validators/common_validations.ex   |  3 +-
 .../object_validators/undo_validator.ex       | 62 +++++++++++++++++++
 .../activity_pub/object_validator_test.exs    | 41 ++++++++++++
 5 files changed, 127 insertions(+), 1 deletion(-)
 create mode 100644 lib/pleroma/web/activity_pub/object_validators/undo_validator.ex

diff --git a/lib/pleroma/web/activity_pub/builder.ex b/lib/pleroma/web/activity_pub/builder.ex
index 429a510b8..380d8f565 100644
--- a/lib/pleroma/web/activity_pub/builder.ex
+++ b/lib/pleroma/web/activity_pub/builder.ex
@@ -10,6 +10,19 @@ defmodule Pleroma.Web.ActivityPub.Builder do
   alias Pleroma.Web.ActivityPub.Utils
   alias Pleroma.Web.ActivityPub.Visibility
 
+  @spec undo(User.t(), Activity.t()) :: {:ok, map(), keyword()}
+  def undo(actor, object) do
+    {:ok,
+     %{
+       "id" => Utils.generate_activity_id(),
+       "actor" => actor.ap_id,
+       "type" => "Undo",
+       "object" => object.data["id"],
+       "to" => object.data["to"] || [],
+       "cc" => object.data["cc"] || []
+     }, []}
+  end
+
   @spec like(User.t(), Object.t()) :: {:ok, map(), keyword()}
   def like(actor, object) do
     object_actor = User.get_cached_by_ap_id(object.data["actor"])
diff --git a/lib/pleroma/web/activity_pub/object_validator.ex b/lib/pleroma/web/activity_pub/object_validator.ex
index dc4bce059..b6937d2e1 100644
--- a/lib/pleroma/web/activity_pub/object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validator.ex
@@ -12,10 +12,19 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
   alias Pleroma.Object
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.ObjectValidators.LikeValidator
+  alias Pleroma.Web.ActivityPub.ObjectValidators.UndoValidator
 
   @spec validate(map(), keyword()) :: {:ok, map(), keyword()} | {:error, any()}
   def validate(object, meta)
 
+  def validate(%{"type" => "Undo"} = object, meta) do
+    with {:ok, object} <-
+           object |> UndoValidator.cast_and_validate() |> Ecto.Changeset.apply_action(:insert) do
+      object = stringify_keys(object |> Map.from_struct())
+      {:ok, object, meta}
+    end
+  end
+
   def validate(%{"type" => "Like"} = object, meta) do
     with {:ok, object} <-
            object |> LikeValidator.cast_and_validate() |> Ecto.Changeset.apply_action(:insert) do
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 b479c3918..067ee4f9a 100644
--- a/lib/pleroma/web/activity_pub/object_validators/common_validations.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/common_validations.ex
@@ -5,6 +5,7 @@
 defmodule Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations do
   import Ecto.Changeset
 
+  alias Pleroma.Activity
   alias Pleroma.Object
   alias Pleroma.User
 
@@ -22,7 +23,7 @@ def validate_actor_presence(cng, field_name \\ :actor) do
   def validate_object_presence(cng, field_name \\ :object) do
     cng
     |> validate_change(field_name, fn field_name, object ->
-      if Object.get_cached_by_ap_id(object) do
+      if Object.get_cached_by_ap_id(object) || Activity.get_by_ap_id(object) do
         []
       else
         [{field_name, "can't find object"}]
diff --git a/lib/pleroma/web/activity_pub/object_validators/undo_validator.ex b/lib/pleroma/web/activity_pub/object_validators/undo_validator.ex
new file mode 100644
index 000000000..d0ba418e8
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/object_validators/undo_validator.ex
@@ -0,0 +1,62 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.UndoValidator do
+  use Ecto.Schema
+
+  alias Pleroma.Activity
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types
+
+  import Ecto.Changeset
+  import Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
+
+  @primary_key false
+
+  embedded_schema do
+    field(:id, Types.ObjectID, primary_key: true)
+    field(:type, :string)
+    field(:object, Types.ObjectID)
+    field(:actor, Types.ObjectID)
+    field(:to, {:array, :string}, default: [])
+    field(:cc, {:array, :string}, default: [])
+  end
+
+  def cast_and_validate(data) do
+    data
+    |> cast_data()
+    |> validate_data()
+  end
+
+  def cast_data(data) do
+    %__MODULE__{}
+    |> changeset(data)
+  end
+
+  def changeset(struct, data) do
+    struct
+    |> cast(data, __schema__(:fields))
+  end
+
+  def validate_data(data_cng) do
+    data_cng
+    |> validate_inclusion(:type, ["Undo"])
+    |> validate_required([:id, :type, :object, :actor, :to, :cc])
+    |> validate_actor_presence()
+    |> validate_object_presence()
+    |> validate_undo_rights()
+  end
+
+  def validate_undo_rights(cng) do
+    actor = get_field(cng, :actor)
+    object = get_field(cng, :object)
+
+    with %Activity{data: %{"actor" => object_actor}} <- Activity.get_by_ap_id(object),
+         true <- object_actor != actor do
+      cng
+      |> add_error(:actor, "not the same as object actor")
+    else
+      _ -> cng
+    end
+  end
+end
diff --git a/test/web/activity_pub/object_validator_test.exs b/test/web/activity_pub/object_validator_test.exs
index 93989e28a..8626e127e 100644
--- a/test/web/activity_pub/object_validator_test.exs
+++ b/test/web/activity_pub/object_validator_test.exs
@@ -1,6 +1,7 @@
 defmodule Pleroma.Web.ActivityPub.ObjectValidatorTest do
   use Pleroma.DataCase
 
+  alias Pleroma.Web.ActivityPub.Builder
   alias Pleroma.Web.ActivityPub.ObjectValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.LikeValidator
   alias Pleroma.Web.ActivityPub.Utils
@@ -8,6 +9,46 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidatorTest do
 
   import Pleroma.Factory
 
+  describe "Undos" do
+    setup do
+      user = insert(:user)
+      {:ok, post_activity} = CommonAPI.post(user, %{"status" => "uguu"})
+      {:ok, like} = CommonAPI.favorite(user, post_activity.id)
+      {:ok, valid_like_undo, []} = Builder.undo(user, like)
+
+      %{user: user, like: like, valid_like_undo: valid_like_undo}
+    end
+
+    test "it validates a basic like undo", %{valid_like_undo: valid_like_undo} do
+      assert {:ok, _, _} = ObjectValidator.validate(valid_like_undo, [])
+    end
+
+    test "it does not validate if the actor of the undo is not the actor of the object", %{
+      valid_like_undo: valid_like_undo
+    } do
+      other_user = insert(:user, ap_id: "https://gensokyo.2hu/users/raymoo")
+
+      bad_actor =
+        valid_like_undo
+        |> Map.put("actor", other_user.ap_id)
+
+      {:error, cng} = ObjectValidator.validate(bad_actor, [])
+
+      assert {:actor, {"not the same as object actor", []}} in cng.errors
+    end
+
+    test "it does not validate if the object is missing", %{valid_like_undo: valid_like_undo} do
+      missing_object =
+        valid_like_undo
+        |> Map.put("object", "https://gensokyo.2hu/objects/1")
+
+      {:error, cng} = ObjectValidator.validate(missing_object, [])
+
+      assert {:object, {"can't find object", []}} in cng.errors
+      assert length(cng.errors) == 1
+    end
+  end
+
   describe "likes" do
     setup do
       user = insert(:user)

From a3071f023166cb5364ce56e3666d5a77baa16434 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 5 May 2020 15:08:41 +0200
Subject: [PATCH 3/8] Undoing: Move undoing likes to the pipeline everywhere.

---
 lib/pleroma/user.ex                           | 12 ++--
 lib/pleroma/web/activity_pub/activity_pub.ex  | 23 -------
 lib/pleroma/web/activity_pub/side_effects.ex  | 19 ++++++
 .../web/activity_pub/transmogrifier.ex        | 11 +---
 lib/pleroma/web/common_api/common_api.ex      |  9 ++-
 .../controllers/status_controller.ex          |  6 +-
 test/notification_test.exs                    |  2 +-
 test/web/activity_pub/activity_pub_test.exs   | 60 -------------------
 test/web/activity_pub/side_effects_test.exs   | 29 +++++++++
 .../transmogrifier/undo_handling_test.exs     |  9 ++-
 10 files changed, 75 insertions(+), 105 deletions(-)

diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index 99358ddaf..0136ba119 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -29,7 +29,9 @@ defmodule Pleroma.User do
   alias Pleroma.UserRelationship
   alias Pleroma.Web
   alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.Web.ActivityPub.Builder
   alias Pleroma.Web.ActivityPub.ObjectValidators.Types
+  alias Pleroma.Web.ActivityPub.Pipeline
   alias Pleroma.Web.ActivityPub.Utils
   alias Pleroma.Web.CommonAPI
   alias Pleroma.Web.CommonAPI.Utils, as: CommonUtils
@@ -1553,11 +1555,13 @@ defp delete_activity(%{data: %{"type" => "Create"}} = activity) do
   end
 
   defp delete_activity(%{data: %{"type" => "Like"}} = activity) do
-    object = Object.normalize(activity)
+    actor =
+      activity.actor
+      |> get_cached_by_ap_id()
 
-    activity.actor
-    |> get_cached_by_ap_id()
-    |> ActivityPub.unlike(object)
+    {:ok, undo, _} = Builder.undo(actor, activity)
+
+    Pipeline.common_pipeline(undo, local: true)
   end
 
   defp delete_activity(%{data: %{"type" => "Announce"}} = activity) do
diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 1c21d78af..daad4d751 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -398,29 +398,6 @@ defp do_unreact_with_emoji(user, reaction_id, options) do
     end
   end
 
-  @spec unlike(User.t(), Object.t(), String.t() | nil, boolean()) ::
-          {:ok, Activity.t(), Activity.t(), Object.t()} | {:ok, Object.t()} | {:error, any()}
-  def unlike(%User{} = actor, %Object{} = object, activity_id \\ nil, local \\ true) do
-    with {:ok, result} <-
-           Repo.transaction(fn -> do_unlike(actor, object, activity_id, local) end) do
-      result
-    end
-  end
-
-  defp do_unlike(actor, object, activity_id, local) do
-    with %Activity{} = like_activity <- get_existing_like(actor.ap_id, object),
-         unlike_data <- make_unlike_data(actor, like_activity, activity_id),
-         {:ok, unlike_activity} <- insert(unlike_data, local),
-         {:ok, _activity} <- Repo.delete(like_activity),
-         {:ok, object} <- remove_like_from_object(like_activity, object),
-         :ok <- maybe_federate(unlike_activity) do
-      {:ok, unlike_activity, like_activity, object}
-    else
-      nil -> {:ok, object}
-      {:error, error} -> Repo.rollback(error)
-    end
-  end
-
   @spec announce(User.t(), Object.t(), String.t() | nil, boolean(), boolean()) ::
           {:ok, Activity.t(), Object.t()} | {:error, any()}
   def announce(
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index 6a8f1af96..8ed91e257 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -5,8 +5,10 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   liked object, a `Follow` activity will add the user to the follower
   collection, and so on.
   """
+  alias Pleroma.Activity
   alias Pleroma.Notification
   alias Pleroma.Object
+  alias Pleroma.Repo
   alias Pleroma.Web.ActivityPub.Utils
 
   def handle(object, meta \\ [])
@@ -23,8 +25,25 @@ def handle(%{data: %{"type" => "Like"}} = object, meta) do
     {:ok, object, meta}
   end
 
+  def handle(%{data: %{"type" => "Undo", "object" => undone_object}} = object, meta) do
+    with undone_object <- Activity.get_by_ap_id(undone_object),
+         :ok <- handle_undoing(undone_object) do
+      {:ok, object, meta}
+    end
+  end
+
   # Nothing to do
   def handle(object, meta) do
     {:ok, object, meta}
   end
+
+  def handle_undoing(%{data: %{"type" => "Like"}} = object) do
+    with %Object{} = liked_object <- Object.get_by_ap_id(object.data["object"]),
+         {:ok, _} <- Utils.remove_like_from_object(object, liked_object),
+         {:ok, _} <- Repo.delete(object) do
+      :ok
+    end
+  end
+
+  def handle_undoing(object), do: {:error, ["don't know how to handle", object]}
 end
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 581e7040b..a60b27bea 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -865,19 +865,12 @@ def handle_incoming(
   def handle_incoming(
         %{
           "type" => "Undo",
-          "object" => %{"type" => "Like", "object" => object_id},
-          "actor" => _actor,
-          "id" => id
+          "object" => %{"type" => "Like"}
         } = data,
         _options
       ) do
-    with actor <- Containment.get_actor(data),
-         {:ok, %User{} = actor} <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, object} <- get_obj_helper(object_id),
-         {:ok, activity, _, _} <- ActivityPub.unlike(actor, object, id, false) do
+    with {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
       {:ok, activity}
-    else
-      _e -> :error
     end
   end
 
diff --git a/lib/pleroma/web/common_api/common_api.ex b/lib/pleroma/web/common_api/common_api.ex
index f9db97d24..a670ea5bc 100644
--- a/lib/pleroma/web/common_api/common_api.ex
+++ b/lib/pleroma/web/common_api/common_api.ex
@@ -166,9 +166,12 @@ def favorite_helper(user, id) do
 
   def unfavorite(id, user) do
     with {_, %Activity{data: %{"type" => "Create"}} = activity} <-
-           {:find_activity, Activity.get_by_id(id)} do
-      object = Object.normalize(activity)
-      ActivityPub.unlike(user, object)
+           {:find_activity, Activity.get_by_id(id)},
+         %Object{} = note <- Object.normalize(activity, false),
+         %Activity{} = like <- Utils.get_existing_like(user.ap_id, note),
+         {:ok, undo, _} <- Builder.undo(user, like),
+         {:ok, activity, _} <- Pipeline.common_pipeline(undo, local: false) do
+      {:ok, activity}
     else
       {:find_activity, _} -> {:error, :not_found}
       _ -> {:error, dgettext("errors", "Could not unfavorite")}
diff --git a/lib/pleroma/web/mastodon_api/controllers/status_controller.ex b/lib/pleroma/web/mastodon_api/controllers/status_controller.ex
index 9eea2e9eb..2a5eac9d9 100644
--- a/lib/pleroma/web/mastodon_api/controllers/status_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/status_controller.ex
@@ -222,9 +222,9 @@ def favourite(%{assigns: %{user: user}} = conn, %{"id" => activity_id}) do
   end
 
   @doc "POST /api/v1/statuses/:id/unfavourite"
-  def unfavourite(%{assigns: %{user: user}} = conn, %{"id" => ap_id_or_id}) do
-    with {:ok, _, _, %{data: %{"id" => id}}} <- CommonAPI.unfavorite(ap_id_or_id, user),
-         %Activity{} = activity <- Activity.get_create_by_object_ap_id(id) do
+  def unfavourite(%{assigns: %{user: user}} = conn, %{"id" => activity_id}) do
+    with {:ok, _unfav} <- CommonAPI.unfavorite(activity_id, user),
+         %Activity{} = activity <- Activity.get_by_id(activity_id) do
       try_render(conn, "show.json", activity: activity, for: user, as: :activity)
     end
   end
diff --git a/test/notification_test.exs b/test/notification_test.exs
index 601a6c0ca..7d5b82993 100644
--- a/test/notification_test.exs
+++ b/test/notification_test.exs
@@ -724,7 +724,7 @@ test "liking an activity results in 1 notification, then 0 if the activity is un
 
       assert length(Notification.for_user(user)) == 1
 
-      {:ok, _, _, _} = CommonAPI.unfavorite(activity.id, other_user)
+      {:ok, _} = CommonAPI.unfavorite(activity.id, other_user)
 
       assert Enum.empty?(Notification.for_user(user))
     end
diff --git a/test/web/activity_pub/activity_pub_test.exs b/test/web/activity_pub/activity_pub_test.exs
index 84ead93bb..797af66a0 100644
--- a/test/web/activity_pub/activity_pub_test.exs
+++ b/test/web/activity_pub/activity_pub_test.exs
@@ -995,66 +995,6 @@ test "reverts emoji unreact on error" do
     end
   end
 
-  describe "unliking" do
-    test_with_mock "sends an activity to federation", Federator, [:passthrough], [] do
-      Config.put([:instance, :federating], true)
-
-      note_activity = insert(:note_activity)
-      object = Object.normalize(note_activity)
-      user = insert(:user)
-
-      {:ok, object} = ActivityPub.unlike(user, object)
-      refute called(Federator.publish())
-
-      {:ok, _like_activity} = CommonAPI.favorite(user, note_activity.id)
-      object = Object.get_by_id(object.id)
-      assert object.data["like_count"] == 1
-
-      {:ok, unlike_activity, _, object} = ActivityPub.unlike(user, object)
-      assert object.data["like_count"] == 0
-
-      assert called(Federator.publish(unlike_activity))
-    end
-
-    test "reverts unliking on error" do
-      note_activity = insert(:note_activity)
-      user = insert(:user)
-
-      {:ok, like_activity} = CommonAPI.favorite(user, note_activity.id)
-      object = Object.normalize(note_activity)
-      assert object.data["like_count"] == 1
-
-      with_mock(Utils, [:passthrough], maybe_federate: fn _ -> {:error, :reverted} end) do
-        assert {:error, :reverted} = ActivityPub.unlike(user, object)
-      end
-
-      assert Object.get_by_ap_id(object.data["id"]) == object
-      assert object.data["like_count"] == 1
-      assert Activity.get_by_id(like_activity.id)
-    end
-
-    test "unliking a previously liked object" do
-      note_activity = insert(:note_activity)
-      object = Object.normalize(note_activity)
-      user = insert(:user)
-
-      # Unliking something that hasn't been liked does nothing
-      {:ok, object} = ActivityPub.unlike(user, object)
-      assert object.data["like_count"] == 0
-
-      {:ok, like_activity} = CommonAPI.favorite(user, note_activity.id)
-
-      object = Object.get_by_id(object.id)
-      assert object.data["like_count"] == 1
-
-      {:ok, unlike_activity, _, object} = ActivityPub.unlike(user, object)
-      assert object.data["like_count"] == 0
-
-      assert Activity.get_by_id(like_activity.id) == nil
-      assert note_activity.actor in unlike_activity.recipients
-    end
-  end
-
   describe "announcing an object" do
     test "adds an announce activity to the db" do
       note_activity = insert(:note_activity)
diff --git a/test/web/activity_pub/side_effects_test.exs b/test/web/activity_pub/side_effects_test.exs
index 0b6b55156..61ef72742 100644
--- a/test/web/activity_pub/side_effects_test.exs
+++ b/test/web/activity_pub/side_effects_test.exs
@@ -5,6 +5,7 @@
 defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
   use Pleroma.DataCase
 
+  alias Pleroma.Activity
   alias Pleroma.Notification
   alias Pleroma.Object
   alias Pleroma.Repo
@@ -15,6 +16,34 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
 
   import Pleroma.Factory
 
+  describe "Undo objects" do
+    setup do
+      poster = insert(:user)
+      user = insert(:user)
+      {:ok, post} = CommonAPI.post(poster, %{"status" => "hey"})
+      {:ok, like} = CommonAPI.favorite(user, post.id)
+
+      {:ok, undo_data, _meta} = Builder.undo(user, like)
+      {:ok, like_undo, _meta} = ActivityPub.persist(undo_data, local: true)
+
+      %{like_undo: like_undo, post: post, like: like}
+    end
+
+    test "a like undo removes the like from the object", %{like_undo: like_undo, post: post} do
+      {:ok, _like_undo, _} = SideEffects.handle(like_undo)
+
+      object = Object.get_by_ap_id(post.data["object"])
+
+      assert object.data["like_count"] == 0
+      assert object.data["likes"] == []
+    end
+
+    test "deletes the original like", %{like_undo: like_undo, like: like} do
+      {:ok, _like_undo, _} = SideEffects.handle(like_undo)
+      refute Activity.get_by_id(like.id)
+    end
+  end
+
   describe "like objects" do
     setup do
       poster = insert(:user)
diff --git a/test/web/activity_pub/transmogrifier/undo_handling_test.exs b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
index a9ebfdb18..bf2a6bc5b 100644
--- a/test/web/activity_pub/transmogrifier/undo_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
@@ -6,6 +6,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier.UndoHandlingTest do
   use Pleroma.DataCase
 
   alias Pleroma.Activity
+  alias Pleroma.Object
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.Transmogrifier
   alias Pleroma.Web.CommonAPI
@@ -67,7 +68,11 @@ test "it works for incoming unlikes with an existing like activity" do
     assert data["actor"] == "http://mastodon.example.org/users/admin"
     assert data["type"] == "Undo"
     assert data["id"] == "http://mastodon.example.org/users/admin#likes/2/undo"
-    assert data["object"]["id"] == "http://mastodon.example.org/users/admin#likes/2"
+    assert data["object"] == "http://mastodon.example.org/users/admin#likes/2"
+
+    note = Object.get_by_ap_id(like_data["object"])
+    assert note.data["like_count"] == 0
+    assert note.data["likes"] == []
   end
 
   test "it works for incoming unlikes with an existing like activity and a compact object" do
@@ -94,7 +99,7 @@ test "it works for incoming unlikes with an existing like activity and a compact
     assert data["actor"] == "http://mastodon.example.org/users/admin"
     assert data["type"] == "Undo"
     assert data["id"] == "http://mastodon.example.org/users/admin#likes/2/undo"
-    assert data["object"]["id"] == "http://mastodon.example.org/users/admin#likes/2"
+    assert data["object"] == "http://mastodon.example.org/users/admin#likes/2"
   end
 
   test "it works for incoming unannounces with an existing notice" do

From b34debe61540cf845ccf4ac93066e45a1d9c8f85 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 5 May 2020 16:17:09 +0200
Subject: [PATCH 4/8] Undoing: Move undoing reactions to the pipeline
 everywhere.

---
 lib/pleroma/web/activity_pub/activity_pub.ex  | 25 ---------
 lib/pleroma/web/activity_pub/side_effects.ex  |  8 +++
 .../web/activity_pub/transmogrifier.ex        | 27 +--------
 lib/pleroma/web/common_api/common_api.ex      |  8 ++-
 .../controllers/pleroma_api_controller.ex     |  3 +-
 test/web/activity_pub/activity_pub_test.exs   | 56 -------------------
 test/web/activity_pub/side_effects_test.exs   | 30 +++++++++-
 test/web/common_api/common_api_test.exs       |  3 +-
 .../pleroma_api_controller_test.exs           | 10 +++-
 9 files changed, 57 insertions(+), 113 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index daad4d751..c94af3b5f 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -373,31 +373,6 @@ defp do_react_with_emoji(user, object, emoji, options) do
     end
   end
 
-  @spec unreact_with_emoji(User.t(), String.t(), keyword()) ::
-          {:ok, Activity.t(), Object.t()} | {:error, any()}
-  def unreact_with_emoji(user, reaction_id, options \\ []) do
-    with {:ok, result} <-
-           Repo.transaction(fn -> do_unreact_with_emoji(user, reaction_id, options) end) do
-      result
-    end
-  end
-
-  defp do_unreact_with_emoji(user, reaction_id, options) do
-    with local <- Keyword.get(options, :local, true),
-         activity_id <- Keyword.get(options, :activity_id, nil),
-         user_ap_id <- user.ap_id,
-         %Activity{actor: ^user_ap_id} = reaction_activity <- Activity.get_by_ap_id(reaction_id),
-         object <- Object.normalize(reaction_activity),
-         unreact_data <- make_undo_data(user, reaction_activity, activity_id),
-         {:ok, activity} <- insert(unreact_data, local),
-         {:ok, object} <- remove_emoji_reaction_from_object(reaction_activity, object),
-         :ok <- maybe_federate(activity) do
-      {:ok, activity, object}
-    else
-      {:error, error} -> Repo.rollback(error)
-    end
-  end
-
   @spec announce(User.t(), Object.t(), String.t() | nil, boolean(), boolean()) ::
           {:ok, Activity.t(), Object.t()} | {:error, any()}
   def announce(
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index 8ed91e257..d58df9394 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -45,5 +45,13 @@ def handle_undoing(%{data: %{"type" => "Like"}} = object) do
     end
   end
 
+  def handle_undoing(%{data: %{"type" => "EmojiReact"}} = object) do
+    with %Object{} = reacted_object <- Object.get_by_ap_id(object.data["object"]),
+         {:ok, _} <- Utils.remove_emoji_reaction_from_object(object, reacted_object),
+         {:ok, _} <- Repo.delete(object) do
+      :ok
+    end
+  end
+
   def handle_undoing(object), do: {:error, ["don't know how to handle", object]}
 end
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index a60b27bea..94849b5f5 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -806,28 +806,6 @@ def handle_incoming(
     end
   end
 
-  def handle_incoming(
-        %{
-          "type" => "Undo",
-          "object" => %{"type" => "EmojiReact", "id" => reaction_activity_id},
-          "actor" => _actor,
-          "id" => id
-        } = data,
-        _options
-      ) do
-    with actor <- Containment.get_actor(data),
-         {:ok, %User{} = actor} <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, activity, _} <-
-           ActivityPub.unreact_with_emoji(actor, reaction_activity_id,
-             activity_id: id,
-             local: false
-           ) do
-      {:ok, activity}
-    else
-      _e -> :error
-    end
-  end
-
   def handle_incoming(
         %{
           "type" => "Undo",
@@ -865,10 +843,11 @@ def handle_incoming(
   def handle_incoming(
         %{
           "type" => "Undo",
-          "object" => %{"type" => "Like"}
+          "object" => %{"type" => type}
         } = data,
         _options
-      ) do
+      )
+      when type in ["Like", "EmojiReact"] do
     with {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
       {:ok, activity}
     end
diff --git a/lib/pleroma/web/common_api/common_api.ex b/lib/pleroma/web/common_api/common_api.ex
index a670ea5bc..067ac875e 100644
--- a/lib/pleroma/web/common_api/common_api.ex
+++ b/lib/pleroma/web/common_api/common_api.ex
@@ -170,7 +170,7 @@ def unfavorite(id, user) do
          %Object{} = note <- Object.normalize(activity, false),
          %Activity{} = like <- Utils.get_existing_like(user.ap_id, note),
          {:ok, undo, _} <- Builder.undo(user, like),
-         {:ok, activity, _} <- Pipeline.common_pipeline(undo, local: false) do
+         {:ok, activity, _} <- Pipeline.common_pipeline(undo, local: true) do
       {:ok, activity}
     else
       {:find_activity, _} -> {:error, :not_found}
@@ -189,8 +189,10 @@ def react_with_emoji(id, user, emoji) do
   end
 
   def unreact_with_emoji(id, user, emoji) do
-    with %Activity{} = reaction_activity <- Utils.get_latest_reaction(id, user, emoji) do
-      ActivityPub.unreact_with_emoji(user, reaction_activity.data["id"])
+    with %Activity{} = reaction_activity <- Utils.get_latest_reaction(id, user, emoji),
+         {:ok, undo, _} <- Builder.undo(user, reaction_activity),
+         {:ok, activity, _} <- Pipeline.common_pipeline(undo, local: true) do
+      {:ok, activity}
     else
       _ ->
         {:error, dgettext("errors", "Could not remove reaction emoji")}
diff --git a/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex b/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
index 1bdb3aa4d..4aa5c1dd8 100644
--- a/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
+++ b/lib/pleroma/web/pleroma_api/controllers/pleroma_api_controller.ex
@@ -98,7 +98,8 @@ def unreact_with_emoji(%{assigns: %{user: user}} = conn, %{
         "id" => activity_id,
         "emoji" => emoji
       }) do
-    with {:ok, _activity, _object} <- CommonAPI.unreact_with_emoji(activity_id, user, emoji),
+    with {:ok, _activity} <-
+           CommonAPI.unreact_with_emoji(activity_id, user, emoji),
          activity <- Activity.get_by_id(activity_id) do
       conn
       |> put_view(StatusView)
diff --git a/test/web/activity_pub/activity_pub_test.exs b/test/web/activity_pub/activity_pub_test.exs
index 797af66a0..cb2d41f0b 100644
--- a/test/web/activity_pub/activity_pub_test.exs
+++ b/test/web/activity_pub/activity_pub_test.exs
@@ -939,62 +939,6 @@ test "reverts emoji reaction on error" do
     end
   end
 
-  describe "unreacting to an object" do
-    test_with_mock "sends an activity to federation", Federator, [:passthrough], [] do
-      Config.put([:instance, :federating], true)
-      user = insert(:user)
-      reactor = insert(:user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "YASSSS queen slay"})
-      assert object = Object.normalize(activity)
-
-      {:ok, reaction_activity, _object} = ActivityPub.react_with_emoji(reactor, object, "🔥")
-
-      assert called(Federator.publish(reaction_activity))
-
-      {:ok, unreaction_activity, _object} =
-        ActivityPub.unreact_with_emoji(reactor, reaction_activity.data["id"])
-
-      assert called(Federator.publish(unreaction_activity))
-    end
-
-    test "adds an undo activity to the db" do
-      user = insert(:user)
-      reactor = insert(:user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "YASSSS queen slay"})
-      assert object = Object.normalize(activity)
-
-      {:ok, reaction_activity, _object} = ActivityPub.react_with_emoji(reactor, object, "🔥")
-
-      {:ok, unreaction_activity, _object} =
-        ActivityPub.unreact_with_emoji(reactor, reaction_activity.data["id"])
-
-      assert unreaction_activity.actor == reactor.ap_id
-      assert unreaction_activity.data["object"] == reaction_activity.data["id"]
-
-      object = Object.get_by_ap_id(object.data["id"])
-      assert object.data["reaction_count"] == 0
-      assert object.data["reactions"] == []
-    end
-
-    test "reverts emoji unreact on error" do
-      [user, reactor] = insert_list(2, :user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "Status"})
-      object = Object.normalize(activity)
-
-      {:ok, reaction_activity, _object} = ActivityPub.react_with_emoji(reactor, object, "😀")
-
-      with_mock(Utils, [:passthrough], maybe_federate: fn _ -> {:error, :reverted} end) do
-        assert {:error, :reverted} =
-                 ActivityPub.unreact_with_emoji(reactor, reaction_activity.data["id"])
-      end
-
-      object = Object.get_by_ap_id(object.data["id"])
-
-      assert object.data["reaction_count"] == 1
-      assert object.data["reactions"] == [["😀", [reactor.ap_id]]]
-    end
-  end
-
   describe "announcing an object" do
     test "adds an announce activity to the db" do
       note_activity = insert(:note_activity)
diff --git a/test/web/activity_pub/side_effects_test.exs b/test/web/activity_pub/side_effects_test.exs
index 61ef72742..abcfdfa2f 100644
--- a/test/web/activity_pub/side_effects_test.exs
+++ b/test/web/activity_pub/side_effects_test.exs
@@ -23,10 +23,38 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
       {:ok, post} = CommonAPI.post(poster, %{"status" => "hey"})
       {:ok, like} = CommonAPI.favorite(user, post.id)
 
+      {:ok, reaction, _} = CommonAPI.react_with_emoji(post.id, user, "👍")
+
       {:ok, undo_data, _meta} = Builder.undo(user, like)
       {:ok, like_undo, _meta} = ActivityPub.persist(undo_data, local: true)
 
-      %{like_undo: like_undo, post: post, like: like}
+      {:ok, undo_data, _meta} = Builder.undo(user, reaction)
+      {:ok, reaction_undo, _meta} = ActivityPub.persist(undo_data, local: true)
+
+      %{
+        like_undo: like_undo,
+        post: post,
+        like: like,
+        reaction_undo: reaction_undo,
+        reaction: reaction
+      }
+    end
+
+    test "a reaction undo removes the reaction from the object", %{
+      reaction_undo: reaction_undo,
+      post: post
+    } do
+      {:ok, _reaction_undo, _} = SideEffects.handle(reaction_undo)
+
+      object = Object.get_by_ap_id(post.data["object"])
+
+      assert object.data["reaction_count"] == 0
+      assert object.data["reactions"] == []
+    end
+
+    test "deletes the original reaction", %{reaction_undo: reaction_undo, reaction: reaction} do
+      {:ok, _reaction_undo, _} = SideEffects.handle(reaction_undo)
+      refute Activity.get_by_id(reaction.id)
     end
 
     test "a like undo removes the like from the object", %{like_undo: like_undo, post: post} do
diff --git a/test/web/common_api/common_api_test.exs b/test/web/common_api/common_api_test.exs
index bc0c1a791..0664b7f90 100644
--- a/test/web/common_api/common_api_test.exs
+++ b/test/web/common_api/common_api_test.exs
@@ -295,10 +295,11 @@ test "unreacting to a status with an emoji" do
       {:ok, activity} = CommonAPI.post(other_user, %{"status" => "cofe"})
       {:ok, reaction, _} = CommonAPI.react_with_emoji(activity.id, user, "👍")
 
-      {:ok, unreaction, _} = CommonAPI.unreact_with_emoji(activity.id, user, "👍")
+      {:ok, unreaction} = CommonAPI.unreact_with_emoji(activity.id, user, "👍")
 
       assert unreaction.data["type"] == "Undo"
       assert unreaction.data["object"] == reaction.data["id"]
+      assert unreaction.local
     end
 
     test "repeating a status" do
diff --git a/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs b/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs
index 61a1689b9..299dbad41 100644
--- a/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs
+++ b/test/web/pleroma_api/controllers/pleroma_api_controller_test.exs
@@ -3,12 +3,14 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.PleromaAPI.PleromaAPIControllerTest do
+  use Oban.Testing, repo: Pleroma.Repo
   use Pleroma.Web.ConnCase
 
   alias Pleroma.Conversation.Participation
   alias Pleroma.Notification
   alias Pleroma.Object
   alias Pleroma.Repo
+  alias Pleroma.Tests.ObanHelpers
   alias Pleroma.User
   alias Pleroma.Web.CommonAPI
 
@@ -41,7 +43,9 @@ test "DELETE /api/v1/pleroma/statuses/:id/reactions/:emoji", %{conn: conn} do
     other_user = insert(:user)
 
     {:ok, activity} = CommonAPI.post(user, %{"status" => "#cofe"})
-    {:ok, activity, _object} = CommonAPI.react_with_emoji(activity.id, other_user, "☕")
+    {:ok, _reaction, _object} = CommonAPI.react_with_emoji(activity.id, other_user, "☕")
+
+    ObanHelpers.perform_all()
 
     result =
       conn
@@ -52,7 +56,9 @@ test "DELETE /api/v1/pleroma/statuses/:id/reactions/:emoji", %{conn: conn} do
     assert %{"id" => id} = json_response(result, 200)
     assert to_string(activity.id) == id
 
-    object = Object.normalize(activity)
+    ObanHelpers.perform_all()
+
+    object = Object.get_by_ap_id(activity.data["object"])
 
     assert object.data["reaction_count"] == 0
   end

From a3bb2e5474ee068bf375b24df8906e51654c9699 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 5 May 2020 16:42:34 +0200
Subject: [PATCH 5/8] Undoing: Move undoing announcements to the pipeline
 everywhere.

---
 lib/pleroma/user.ex                           | 10 +---
 lib/pleroma/web/activity_pub/activity_pub.ex  | 28 -----------
 lib/pleroma/web/activity_pub/side_effects.ex  |  8 ++++
 .../web/activity_pub/transmogrifier.ex        | 21 +--------
 lib/pleroma/web/common_api/common_api.ex      |  9 ++--
 .../controllers/status_controller.ex          |  6 +--
 test/notification_test.exs                    |  2 +-
 test/web/activity_pub/activity_pub_test.exs   | 46 -------------------
 test/web/activity_pub/side_effects_test.exs   | 26 ++++++++++-
 .../transmogrifier/undo_handling_test.exs     |  5 +-
 10 files changed, 45 insertions(+), 116 deletions(-)

diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index 0136ba119..aa675a521 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -1554,7 +1554,7 @@ defp delete_activity(%{data: %{"type" => "Create"}} = activity) do
     |> ActivityPub.delete()
   end
 
-  defp delete_activity(%{data: %{"type" => "Like"}} = activity) do
+  defp delete_activity(%{data: %{"type" => type}} = activity) when type in ["Like", "Announce"] do
     actor =
       activity.actor
       |> get_cached_by_ap_id()
@@ -1564,14 +1564,6 @@ defp delete_activity(%{data: %{"type" => "Like"}} = activity) do
     Pipeline.common_pipeline(undo, local: true)
   end
 
-  defp delete_activity(%{data: %{"type" => "Announce"}} = activity) do
-    object = Object.normalize(activity)
-
-    activity.actor
-    |> get_cached_by_ap_id()
-    |> ActivityPub.unannounce(object)
-  end
-
   defp delete_activity(_activity), do: "Doing nothing"
 
   def html_filter_policy(%User{no_rich_text: true}) do
diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index c94af3b5f..be3d72c82 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -402,34 +402,6 @@ defp do_announce(user, object, activity_id, local, public) do
     end
   end
 
-  @spec unannounce(User.t(), Object.t(), String.t() | nil, boolean()) ::
-          {:ok, Activity.t(), Object.t()} | {:ok, Object.t()} | {:error, any()}
-  def unannounce(
-        %User{} = actor,
-        %Object{} = object,
-        activity_id \\ nil,
-        local \\ true
-      ) do
-    with {:ok, result} <-
-           Repo.transaction(fn -> do_unannounce(actor, object, activity_id, local) end) do
-      result
-    end
-  end
-
-  defp do_unannounce(actor, object, activity_id, local) do
-    with %Activity{} = announce_activity <- get_existing_announce(actor.ap_id, object),
-         unannounce_data <- make_unannounce_data(actor, announce_activity, activity_id),
-         {:ok, unannounce_activity} <- insert(unannounce_data, local),
-         :ok <- maybe_federate(unannounce_activity),
-         {:ok, _activity} <- Repo.delete(announce_activity),
-         {:ok, object} <- remove_announce_from_object(announce_activity, object) do
-      {:ok, unannounce_activity, object}
-    else
-      nil -> {:ok, object}
-      {:error, error} -> Repo.rollback(error)
-    end
-  end
-
   @spec follow(User.t(), User.t(), String.t() | nil, boolean()) ::
           {:ok, Activity.t()} | {:error, any()}
   def follow(follower, followed, activity_id \\ nil, local \\ true) do
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index d58df9394..146d30ac1 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -53,5 +53,13 @@ def handle_undoing(%{data: %{"type" => "EmojiReact"}} = object) do
     end
   end
 
+  def handle_undoing(%{data: %{"type" => "Announce"}} = object) do
+    with %Object{} = liked_object <- Object.get_by_ap_id(object.data["object"]),
+         {:ok, _} <- Utils.remove_announce_from_object(object, liked_object),
+         {:ok, _} <- Repo.delete(object) do
+      :ok
+    end
+  end
+
   def handle_undoing(object), do: {:error, ["don't know how to handle", object]}
 end
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 94849b5f5..afa171448 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -768,25 +768,6 @@ def handle_incoming(
     end
   end
 
-  def handle_incoming(
-        %{
-          "type" => "Undo",
-          "object" => %{"type" => "Announce", "object" => object_id},
-          "actor" => _actor,
-          "id" => id
-        } = data,
-        _options
-      ) do
-    with actor <- Containment.get_actor(data),
-         {:ok, %User{} = actor} <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, object} <- get_obj_helper(object_id),
-         {:ok, activity, _} <- ActivityPub.unannounce(actor, object, id, false) do
-      {:ok, activity}
-    else
-      _e -> :error
-    end
-  end
-
   def handle_incoming(
         %{
           "type" => "Undo",
@@ -847,7 +828,7 @@ def handle_incoming(
         } = data,
         _options
       )
-      when type in ["Like", "EmojiReact"] do
+      when type in ["Like", "EmojiReact", "Announce"] do
     with {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
       {:ok, activity}
     end
diff --git a/lib/pleroma/web/common_api/common_api.ex b/lib/pleroma/web/common_api/common_api.ex
index 067ac875e..fc8246871 100644
--- a/lib/pleroma/web/common_api/common_api.ex
+++ b/lib/pleroma/web/common_api/common_api.ex
@@ -107,9 +107,12 @@ def repeat(id, user, params \\ %{}) do
 
   def unrepeat(id, user) do
     with {_, %Activity{data: %{"type" => "Create"}} = activity} <-
-           {:find_activity, Activity.get_by_id(id)} do
-      object = Object.normalize(activity)
-      ActivityPub.unannounce(user, object)
+           {:find_activity, Activity.get_by_id(id)},
+         %Object{} = note <- Object.normalize(activity, false),
+         %Activity{} = announce <- Utils.get_existing_announce(user.ap_id, note),
+         {:ok, undo, _} <- Builder.undo(user, announce),
+         {:ok, activity, _} <- Pipeline.common_pipeline(undo, local: true) do
+      {:ok, activity}
     else
       {:find_activity, _} -> {:error, :not_found}
       _ -> {:error, dgettext("errors", "Could not unrepeat")}
diff --git a/lib/pleroma/web/mastodon_api/controllers/status_controller.ex b/lib/pleroma/web/mastodon_api/controllers/status_controller.ex
index 2a5eac9d9..12e3ba15e 100644
--- a/lib/pleroma/web/mastodon_api/controllers/status_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/status_controller.ex
@@ -206,9 +206,9 @@ def reblog(%{assigns: %{user: user}} = conn, %{"id" => ap_id_or_id} = params) do
   end
 
   @doc "POST /api/v1/statuses/:id/unreblog"
-  def unreblog(%{assigns: %{user: user}} = conn, %{"id" => ap_id_or_id}) do
-    with {:ok, _unannounce, %{data: %{"id" => id}}} <- CommonAPI.unrepeat(ap_id_or_id, user),
-         %Activity{} = activity <- Activity.get_create_by_object_ap_id_with_object(id) do
+  def unreblog(%{assigns: %{user: user}} = conn, %{"id" => activity_id}) do
+    with {:ok, _unannounce} <- CommonAPI.unrepeat(activity_id, user),
+         %Activity{} = activity <- Activity.get_by_id(activity_id) do
       try_render(conn, "show.json", %{activity: activity, for: user, as: :activity})
     end
   end
diff --git a/test/notification_test.exs b/test/notification_test.exs
index 7d5b82993..09714f4c5 100644
--- a/test/notification_test.exs
+++ b/test/notification_test.exs
@@ -758,7 +758,7 @@ test "repeating an activity results in 1 notification, then 0 if the activity is
 
       assert length(Notification.for_user(user)) == 1
 
-      {:ok, _, _} = CommonAPI.unrepeat(activity.id, other_user)
+      {:ok, _} = CommonAPI.unrepeat(activity.id, other_user)
 
       assert Enum.empty?(Notification.for_user(user))
     end
diff --git a/test/web/activity_pub/activity_pub_test.exs b/test/web/activity_pub/activity_pub_test.exs
index cb2d41f0b..2c3d354f2 100644
--- a/test/web/activity_pub/activity_pub_test.exs
+++ b/test/web/activity_pub/activity_pub_test.exs
@@ -1008,52 +1008,6 @@ test "does not add an announce activity to the db if the announcer is not the au
     end
   end
 
-  describe "unannouncing an object" do
-    test "unannouncing a previously announced object" do
-      note_activity = insert(:note_activity)
-      object = Object.normalize(note_activity)
-      user = insert(:user)
-
-      # Unannouncing an object that is not announced does nothing
-      {:ok, object} = ActivityPub.unannounce(user, object)
-      refute object.data["announcement_count"]
-
-      {:ok, announce_activity, object} = ActivityPub.announce(user, object)
-      assert object.data["announcement_count"] == 1
-
-      {:ok, unannounce_activity, object} = ActivityPub.unannounce(user, object)
-      assert object.data["announcement_count"] == 0
-
-      assert unannounce_activity.data["to"] == [
-               User.ap_followers(user),
-               object.data["actor"]
-             ]
-
-      assert unannounce_activity.data["type"] == "Undo"
-      assert unannounce_activity.data["object"] == announce_activity.data
-      assert unannounce_activity.data["actor"] == user.ap_id
-      assert unannounce_activity.data["context"] == announce_activity.data["context"]
-
-      assert Activity.get_by_id(announce_activity.id) == nil
-    end
-
-    test "reverts unannouncing on error" do
-      note_activity = insert(:note_activity)
-      object = Object.normalize(note_activity)
-      user = insert(:user)
-
-      {:ok, _announce_activity, object} = ActivityPub.announce(user, object)
-      assert object.data["announcement_count"] == 1
-
-      with_mock(Utils, [:passthrough], maybe_federate: fn _ -> {:error, :reverted} end) do
-        assert {:error, :reverted} = ActivityPub.unannounce(user, object)
-      end
-
-      object = Object.get_by_ap_id(object.data["id"])
-      assert object.data["announcement_count"] == 1
-    end
-  end
-
   describe "uploading files" do
     test "copies the file to the configured folder" do
       file = %Plug.Upload{
diff --git a/test/web/activity_pub/side_effects_test.exs b/test/web/activity_pub/side_effects_test.exs
index abcfdfa2f..00241320b 100644
--- a/test/web/activity_pub/side_effects_test.exs
+++ b/test/web/activity_pub/side_effects_test.exs
@@ -22,8 +22,8 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
       user = insert(:user)
       {:ok, post} = CommonAPI.post(poster, %{"status" => "hey"})
       {:ok, like} = CommonAPI.favorite(user, post.id)
-
       {:ok, reaction, _} = CommonAPI.react_with_emoji(post.id, user, "👍")
+      {:ok, announce, _} = CommonAPI.repeat(post.id, user)
 
       {:ok, undo_data, _meta} = Builder.undo(user, like)
       {:ok, like_undo, _meta} = ActivityPub.persist(undo_data, local: true)
@@ -31,15 +31,37 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
       {:ok, undo_data, _meta} = Builder.undo(user, reaction)
       {:ok, reaction_undo, _meta} = ActivityPub.persist(undo_data, local: true)
 
+      {:ok, undo_data, _meta} = Builder.undo(user, announce)
+      {:ok, announce_undo, _meta} = ActivityPub.persist(undo_data, local: true)
+
       %{
         like_undo: like_undo,
         post: post,
         like: like,
         reaction_undo: reaction_undo,
-        reaction: reaction
+        reaction: reaction,
+        announce_undo: announce_undo,
+        announce: announce
       }
     end
 
+    test "an announce undo removes the announce from the object", %{
+      announce_undo: announce_undo,
+      post: post
+    } do
+      {:ok, _announce_undo, _} = SideEffects.handle(announce_undo)
+
+      object = Object.get_by_ap_id(post.data["object"])
+
+      assert object.data["announcement_count"] == 0
+      assert object.data["announcements"] == []
+    end
+
+    test "deletes the original announce", %{announce_undo: announce_undo, announce: announce} do
+      {:ok, _announce_undo, _} = SideEffects.handle(announce_undo)
+      refute Activity.get_by_id(announce.id)
+    end
+
     test "a reaction undo removes the reaction from the object", %{
       reaction_undo: reaction_undo,
       post: post
diff --git a/test/web/activity_pub/transmogrifier/undo_handling_test.exs b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
index bf2a6bc5b..281cf5b0d 100644
--- a/test/web/activity_pub/transmogrifier/undo_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
@@ -125,11 +125,8 @@ test "it works for incoming unannounces with an existing notice" do
     {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
 
     assert data["type"] == "Undo"
-    assert object_data = data["object"]
-    assert object_data["type"] == "Announce"
-    assert object_data["object"] == activity.data["object"]
 
-    assert object_data["id"] ==
+    assert data["object"] ==
              "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity"
   end
 

From 92caae592338a3ca307686e7644f2de18bb57ce5 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Tue, 5 May 2020 18:00:37 +0200
Subject: [PATCH 6/8] Undoing: Move undoing blocks to the pipeline everywhere.

---
 lib/pleroma/web/activity_pub/activity_pub.ex  | 21 --------
 lib/pleroma/web/activity_pub/side_effects.ex  | 12 +++++
 .../web/activity_pub/transmogrifier.ex        | 51 ++++++-------------
 lib/pleroma/web/activity_pub/utils.ex         | 49 ------------------
 lib/pleroma/web/common_api/common_api.ex      |  8 +++
 .../controllers/account_controller.ex         |  3 +-
 test/web/activity_pub/activity_pub_test.exs   | 34 +------------
 test/web/activity_pub/side_effects_test.exs   | 25 ++++++++-
 .../transmogrifier/undo_handling_test.exs     |  4 +-
 test/web/activity_pub/utils_test.exs          | 28 ----------
 10 files changed, 63 insertions(+), 172 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index be3d72c82..78e8c0cbe 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -532,27 +532,6 @@ defp do_block(blocker, blocked, activity_id, local) do
     end
   end
 
-  @spec unblock(User.t(), User.t(), String.t() | nil, boolean()) ::
-          {:ok, Activity.t()} | {:error, any()} | nil
-  def unblock(blocker, blocked, activity_id \\ nil, local \\ true) do
-    with {:ok, result} <-
-           Repo.transaction(fn -> do_unblock(blocker, blocked, activity_id, local) end) do
-      result
-    end
-  end
-
-  defp do_unblock(blocker, blocked, activity_id, local) do
-    with %Activity{} = block_activity <- fetch_latest_block(blocker, blocked),
-         unblock_data <- make_unblock_data(blocker, blocked, block_activity, activity_id),
-         {:ok, activity} <- insert(unblock_data, local),
-         :ok <- maybe_federate(activity) do
-      {:ok, activity}
-    else
-      nil -> nil
-      {:error, error} -> Repo.rollback(error)
-    end
-  end
-
   @spec flag(map()) :: {:ok, Activity.t()} | {:error, any()}
   def flag(
         %{
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index 146d30ac1..3fad6e4d8 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -9,6 +9,7 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   alias Pleroma.Notification
   alias Pleroma.Object
   alias Pleroma.Repo
+  alias Pleroma.User
   alias Pleroma.Web.ActivityPub.Utils
 
   def handle(object, meta \\ [])
@@ -61,5 +62,16 @@ def handle_undoing(%{data: %{"type" => "Announce"}} = object) do
     end
   end
 
+  def handle_undoing(
+        %{data: %{"type" => "Block", "actor" => blocker, "object" => blocked}} = object
+      ) do
+    with %User{} = blocker <- User.get_cached_by_ap_id(blocker),
+         %User{} = blocked <- User.get_cached_by_ap_id(blocked),
+         {:ok, _} <- User.unblock(blocker, blocked),
+         {:ok, _} <- Repo.delete(object) do
+      :ok
+    end
+  end
+
   def handle_undoing(object), do: {:error, ["don't know how to handle", object]}
 end
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index afa171448..65ae643ed 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -787,40 +787,6 @@ def handle_incoming(
     end
   end
 
-  def handle_incoming(
-        %{
-          "type" => "Undo",
-          "object" => %{"type" => "Block", "object" => blocked},
-          "actor" => blocker,
-          "id" => id
-        } = _data,
-        _options
-      ) do
-    with %User{local: true} = blocked <- User.get_cached_by_ap_id(blocked),
-         {:ok, %User{} = blocker} <- User.get_or_fetch_by_ap_id(blocker),
-         {:ok, activity} <- ActivityPub.unblock(blocker, blocked, id, false) do
-      User.unblock(blocker, blocked)
-      {:ok, activity}
-    else
-      _e -> :error
-    end
-  end
-
-  def handle_incoming(
-        %{"type" => "Block", "object" => blocked, "actor" => blocker, "id" => id} = _data,
-        _options
-      ) do
-    with %User{local: true} = blocked = User.get_cached_by_ap_id(blocked),
-         {:ok, %User{} = blocker} = User.get_or_fetch_by_ap_id(blocker),
-         {:ok, activity} <- ActivityPub.block(blocker, blocked, id, false) do
-      User.unfollow(blocker, blocked)
-      User.block(blocker, blocked)
-      {:ok, activity}
-    else
-      _e -> :error
-    end
-  end
-
   def handle_incoming(
         %{
           "type" => "Undo",
@@ -828,7 +794,7 @@ def handle_incoming(
         } = data,
         _options
       )
-      when type in ["Like", "EmojiReact", "Announce"] do
+      when type in ["Like", "EmojiReact", "Announce", "Block"] do
     with {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
       {:ok, activity}
     end
@@ -852,6 +818,21 @@ def handle_incoming(
     end
   end
 
+  def handle_incoming(
+        %{"type" => "Block", "object" => blocked, "actor" => blocker, "id" => id} = _data,
+        _options
+      ) do
+    with %User{local: true} = blocked = User.get_cached_by_ap_id(blocked),
+         {:ok, %User{} = blocker} = User.get_or_fetch_by_ap_id(blocker),
+         {:ok, activity} <- ActivityPub.block(blocker, blocked, id, false) do
+      User.unfollow(blocker, blocked)
+      User.block(blocker, blocked)
+      {:ok, activity}
+    else
+      _e -> :error
+    end
+  end
+
   def handle_incoming(
         %{
           "type" => "Move",
diff --git a/lib/pleroma/web/activity_pub/utils.ex b/lib/pleroma/web/activity_pub/utils.ex
index 2d685ecc0..95fb382f0 100644
--- a/lib/pleroma/web/activity_pub/utils.ex
+++ b/lib/pleroma/web/activity_pub/utils.ex
@@ -562,45 +562,6 @@ def make_announce_data(
     |> maybe_put("id", activity_id)
   end
 
-  @doc """
-  Make unannounce activity data for the given actor and object
-  """
-  def make_unannounce_data(
-        %User{ap_id: ap_id} = user,
-        %Activity{data: %{"context" => context, "object" => object}} = activity,
-        activity_id
-      ) do
-    object = Object.normalize(object)
-
-    %{
-      "type" => "Undo",
-      "actor" => ap_id,
-      "object" => activity.data,
-      "to" => [user.follower_address, object.data["actor"]],
-      "cc" => [Pleroma.Constants.as_public()],
-      "context" => context
-    }
-    |> maybe_put("id", activity_id)
-  end
-
-  def make_unlike_data(
-        %User{ap_id: ap_id} = user,
-        %Activity{data: %{"context" => context, "object" => object}} = activity,
-        activity_id
-      ) do
-    object = Object.normalize(object)
-
-    %{
-      "type" => "Undo",
-      "actor" => ap_id,
-      "object" => activity.data,
-      "to" => [user.follower_address, object.data["actor"]],
-      "cc" => [Pleroma.Constants.as_public()],
-      "context" => context
-    }
-    |> maybe_put("id", activity_id)
-  end
-
   def make_undo_data(
         %User{ap_id: actor, follower_address: follower_address},
         %Activity{
@@ -688,16 +649,6 @@ def make_block_data(blocker, blocked, activity_id) do
     |> maybe_put("id", activity_id)
   end
 
-  def make_unblock_data(blocker, blocked, block_activity, activity_id) do
-    %{
-      "type" => "Undo",
-      "actor" => blocker.ap_id,
-      "to" => [blocked.ap_id],
-      "object" => block_activity.data
-    }
-    |> maybe_put("id", activity_id)
-  end
-
   #### Create-related helpers
 
   def make_create_data(params, additional) do
diff --git a/lib/pleroma/web/common_api/common_api.ex b/lib/pleroma/web/common_api/common_api.ex
index fc8246871..2a1eb7f37 100644
--- a/lib/pleroma/web/common_api/common_api.ex
+++ b/lib/pleroma/web/common_api/common_api.ex
@@ -24,6 +24,14 @@ defmodule Pleroma.Web.CommonAPI do
   require Pleroma.Constants
   require Logger
 
+  def unblock(blocker, blocked) do
+    with %Activity{} = block <- Utils.fetch_latest_block(blocker, blocked),
+         {:ok, unblock_data, _} <- Builder.undo(blocker, block),
+         {:ok, unblock, _} <- Pipeline.common_pipeline(unblock_data, local: true) do
+      {:ok, unblock}
+    end
+  end
+
   def follow(follower, followed) do
     timeout = Pleroma.Config.get([:activitypub, :follow_handshake_timeout])
 
diff --git a/lib/pleroma/web/mastodon_api/controllers/account_controller.ex b/lib/pleroma/web/mastodon_api/controllers/account_controller.ex
index 61b0e2f63..2b208ddab 100644
--- a/lib/pleroma/web/mastodon_api/controllers/account_controller.ex
+++ b/lib/pleroma/web/mastodon_api/controllers/account_controller.ex
@@ -356,8 +356,7 @@ def block(%{assigns: %{user: blocker, account: blocked}} = conn, _params) do
 
   @doc "POST /api/v1/accounts/:id/unblock"
   def unblock(%{assigns: %{user: blocker, account: blocked}} = conn, _params) do
-    with {:ok, _user_block} <- User.unblock(blocker, blocked),
-         {:ok, _activity} <- ActivityPub.unblock(blocker, blocked) do
+    with {:ok, _activity} <- CommonAPI.unblock(blocker, blocked) do
       render(conn, "relationship.json", user: blocker, target: blocked)
     else
       {:error, message} -> json_response(conn, :forbidden, %{error: message})
diff --git a/test/web/activity_pub/activity_pub_test.exs b/test/web/activity_pub/activity_pub_test.exs
index 2c3d354f2..7824095c7 100644
--- a/test/web/activity_pub/activity_pub_test.exs
+++ b/test/web/activity_pub/activity_pub_test.exs
@@ -1114,7 +1114,7 @@ test "creates an undo activity for a pending follow request" do
     end
   end
 
-  describe "blocking / unblocking" do
+  describe "blocking" do
     test "reverts block activity on error" do
       [blocker, blocked] = insert_list(2, :user)
 
@@ -1136,38 +1136,6 @@ test "creates a block activity" do
       assert activity.data["actor"] == blocker.ap_id
       assert activity.data["object"] == blocked.ap_id
     end
-
-    test "reverts unblock activity on error" do
-      [blocker, blocked] = insert_list(2, :user)
-      {:ok, block_activity} = ActivityPub.block(blocker, blocked)
-
-      with_mock(Utils, [:passthrough], maybe_federate: fn _ -> {:error, :reverted} end) do
-        assert {:error, :reverted} = ActivityPub.unblock(blocker, blocked)
-      end
-
-      assert block_activity.data["type"] == "Block"
-      assert block_activity.data["actor"] == blocker.ap_id
-
-      assert Repo.aggregate(Activity, :count, :id) == 1
-      assert Repo.aggregate(Object, :count, :id) == 1
-    end
-
-    test "creates an undo activity for the last block" do
-      blocker = insert(:user)
-      blocked = insert(:user)
-
-      {:ok, block_activity} = ActivityPub.block(blocker, blocked)
-      {:ok, activity} = ActivityPub.unblock(blocker, blocked)
-
-      assert activity.data["type"] == "Undo"
-      assert activity.data["actor"] == blocker.ap_id
-
-      embedded_object = activity.data["object"]
-      assert is_map(embedded_object)
-      assert embedded_object["type"] == "Block"
-      assert embedded_object["object"] == blocked.ap_id
-      assert embedded_object["id"] == block_activity.data["id"]
-    end
   end
 
   describe "deletion" do
diff --git a/test/web/activity_pub/side_effects_test.exs b/test/web/activity_pub/side_effects_test.exs
index 00241320b..f41a7f3c1 100644
--- a/test/web/activity_pub/side_effects_test.exs
+++ b/test/web/activity_pub/side_effects_test.exs
@@ -9,6 +9,7 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
   alias Pleroma.Notification
   alias Pleroma.Object
   alias Pleroma.Repo
+  alias Pleroma.User
   alias Pleroma.Web.ActivityPub.ActivityPub
   alias Pleroma.Web.ActivityPub.Builder
   alias Pleroma.Web.ActivityPub.SideEffects
@@ -24,6 +25,8 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
       {:ok, like} = CommonAPI.favorite(user, post.id)
       {:ok, reaction, _} = CommonAPI.react_with_emoji(post.id, user, "👍")
       {:ok, announce, _} = CommonAPI.repeat(post.id, user)
+      {:ok, block} = ActivityPub.block(user, poster)
+      User.block(user, poster)
 
       {:ok, undo_data, _meta} = Builder.undo(user, like)
       {:ok, like_undo, _meta} = ActivityPub.persist(undo_data, local: true)
@@ -34,6 +37,9 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
       {:ok, undo_data, _meta} = Builder.undo(user, announce)
       {:ok, announce_undo, _meta} = ActivityPub.persist(undo_data, local: true)
 
+      {:ok, undo_data, _meta} = Builder.undo(user, block)
+      {:ok, block_undo, _meta} = ActivityPub.persist(undo_data, local: true)
+
       %{
         like_undo: like_undo,
         post: post,
@@ -41,10 +47,27 @@ defmodule Pleroma.Web.ActivityPub.SideEffectsTest do
         reaction_undo: reaction_undo,
         reaction: reaction,
         announce_undo: announce_undo,
-        announce: announce
+        announce: announce,
+        block_undo: block_undo,
+        block: block,
+        poster: poster,
+        user: user
       }
     end
 
+    test "deletes the original block", %{block_undo: block_undo, block: block} do
+      {:ok, _block_undo, _} = SideEffects.handle(block_undo)
+      refute Activity.get_by_id(block.id)
+    end
+
+    test "unblocks the blocked user", %{block_undo: block_undo, block: block} do
+      blocker = User.get_by_ap_id(block.data["actor"])
+      blocked = User.get_by_ap_id(block.data["object"])
+
+      {:ok, _block_undo, _} = SideEffects.handle(block_undo)
+      refute User.blocks?(blocker, blocked)
+    end
+
     test "an announce undo removes the announce from the object", %{
       announce_undo: announce_undo,
       post: post
diff --git a/test/web/activity_pub/transmogrifier/undo_handling_test.exs b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
index 281cf5b0d..6f5e61ac3 100644
--- a/test/web/activity_pub/transmogrifier/undo_handling_test.exs
+++ b/test/web/activity_pub/transmogrifier/undo_handling_test.exs
@@ -176,9 +176,7 @@ test "it works for incoming unblocks with an existing block" do
 
     {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
     assert data["type"] == "Undo"
-    assert data["object"]["type"] == "Block"
-    assert data["object"]["object"] == user.ap_id
-    assert data["actor"] == "http://mastodon.example.org/users/admin"
+    assert data["object"] == block_data["id"]
 
     blocker = User.get_cached_by_ap_id(data["actor"])
 
diff --git a/test/web/activity_pub/utils_test.exs b/test/web/activity_pub/utils_test.exs
index b0bfed917..b8d811c73 100644
--- a/test/web/activity_pub/utils_test.exs
+++ b/test/web/activity_pub/utils_test.exs
@@ -102,34 +102,6 @@ test "works with an object has tags as map" do
     end
   end
 
-  describe "make_unlike_data/3" do
-    test "returns data for unlike activity" do
-      user = insert(:user)
-      like_activity = insert(:like_activity, data_attrs: %{"context" => "test context"})
-
-      object = Object.normalize(like_activity.data["object"])
-
-      assert Utils.make_unlike_data(user, like_activity, nil) == %{
-               "type" => "Undo",
-               "actor" => user.ap_id,
-               "object" => like_activity.data,
-               "to" => [user.follower_address, object.data["actor"]],
-               "cc" => [Pleroma.Constants.as_public()],
-               "context" => like_activity.data["context"]
-             }
-
-      assert Utils.make_unlike_data(user, like_activity, "9mJEZK0tky1w2xD2vY") == %{
-               "type" => "Undo",
-               "actor" => user.ap_id,
-               "object" => like_activity.data,
-               "to" => [user.follower_address, object.data["actor"]],
-               "cc" => [Pleroma.Constants.as_public()],
-               "context" => like_activity.data["context"],
-               "id" => "9mJEZK0tky1w2xD2vY"
-             }
-    end
-  end
-
   describe "make_like_data" do
     setup do
       user = insert(:user)

From 788b7e7bbd2732e2af72adad1a660cf363486c6b Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Thu, 7 May 2020 14:52:37 +0200
Subject: [PATCH 7/8] Merge fixes.

---
 lib/pleroma/user.ex                           |  13 +--
 .../web/activity_pub/object_validator.ex      |   6 +-
 .../object_validators/common_validations.ex   |   2 +-
 .../activity_pub/object_validator_test.exs    |   1 -
 test/web/activity_pub/transmogrifier_test.exs | 107 ------------------
 5 files changed, 10 insertions(+), 119 deletions(-)

diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index 921bdd93a..2a6a23fec 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -1557,16 +1557,13 @@ def delete_user_activities(%User{ap_id: ap_id} = user) do
   defp delete_activity(%{data: %{"type" => "Create", "object" => object}}, user) do
     {:ok, delete_data, _} = Builder.delete(user, object)
 
-    Pipeline.common_pipeline(delete_data, local: true)
+    Pipeline.common_pipeline(delete_data, local: user.local)
   end
 
-  defp delete_activity(%{data: %{"type" => type}} = activity) when type in ["Like", "Announce"] do
-    actor =
-      activity.actor
-      |> get_cached_by_ap_id()
-
-    {:ok, undo, _} = Builder.undo(actor, activity)
-    Pipeline.common_pipeline(undo, local: true)
+  defp delete_activity(%{data: %{"type" => type}} = activity, user)
+       when type in ["Like", "Announce"] do
+    {:ok, undo, _} = Builder.undo(user, activity)
+    Pipeline.common_pipeline(undo, local: user.local)
   end
 
   defp delete_activity(_activity, _user), do: "Doing nothing"
diff --git a/lib/pleroma/web/activity_pub/object_validator.ex b/lib/pleroma/web/activity_pub/object_validator.ex
index 8e043287d..1f0431b36 100644
--- a/lib/pleroma/web/activity_pub/object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validator.ex
@@ -21,8 +21,10 @@ def validate(object, meta)
 
   def validate(%{"type" => "Undo"} = object, meta) do
     with {:ok, object} <-
-           object |> UndoValidator.cast_and_validate() |> Ecto.Changeset.apply_action(:insert) do
-      object = stringify_keys(object |> Map.from_struct())
+           object
+           |> UndoValidator.cast_and_validate()
+           |> Ecto.Changeset.apply_action(:insert) do
+      object = stringify_keys(object)
       {:ok, object, meta}
     end
   end
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 2ada9f09e..aeef31945 100644
--- a/lib/pleroma/web/activity_pub/object_validators/common_validations.ex
+++ b/lib/pleroma/web/activity_pub/object_validators/common_validations.ex
@@ -48,7 +48,7 @@ def validate_object_presence(cng, options \\ []) do
 
     cng
     |> validate_change(field_name, fn field_name, object_id ->
-      object = Object.get_cached_by_ap_id(object_id) || Activity.get_by_ap_id(object)
+      object = Object.get_cached_by_ap_id(object_id) || Activity.get_by_ap_id(object_id)
 
       cond do
         !object ->
diff --git a/test/web/activity_pub/object_validator_test.exs b/test/web/activity_pub/object_validator_test.exs
index 4d90a0cf3..174be5ec6 100644
--- a/test/web/activity_pub/object_validator_test.exs
+++ b/test/web/activity_pub/object_validator_test.exs
@@ -107,7 +107,6 @@ test "it's invalid if the object doesn't exist", %{valid_post_delete: valid_post
       {:error, cng} = ObjectValidator.validate(missing_object, [])
 
       assert {:object, {"can't find object", []}} in cng.errors
-      assert length(cng.errors) == 1
     end
 
     test "it's invalid if the actor of the object and the actor of delete are from different domains",
diff --git a/test/web/activity_pub/transmogrifier_test.exs b/test/web/activity_pub/transmogrifier_test.exs
index ae5d3bf92..4fd6c8b00 100644
--- a/test/web/activity_pub/transmogrifier_test.exs
+++ b/test/web/activity_pub/transmogrifier_test.exs
@@ -685,113 +685,6 @@ test "it works for incoming update activities which lock the account" do
       assert user.locked == true
     end
 
-    test "it works for incoming deletes" do
-      activity = insert(:note_activity)
-      deleting_user = insert(:user)
-
-      data =
-        File.read!("test/fixtures/mastodon-delete.json")
-        |> Poison.decode!()
-
-      object =
-        data["object"]
-        |> Map.put("id", activity.data["object"])
-
-      data =
-        data
-        |> Map.put("object", object)
-        |> Map.put("actor", deleting_user.ap_id)
-
-      {:ok, %Activity{actor: actor, local: false, data: %{"id" => id}}} =
-        Transmogrifier.handle_incoming(data)
-
-      assert id == data["id"]
-      refute Activity.get_by_id(activity.id)
-      assert actor == deleting_user.ap_id
-    end
-
-    test "it fails for incoming deletes with spoofed origin" do
-      activity = insert(:note_activity)
-
-      data =
-        File.read!("test/fixtures/mastodon-delete.json")
-        |> Poison.decode!()
-
-      object =
-        data["object"]
-        |> Map.put("id", activity.data["object"])
-
-      data =
-        data
-        |> Map.put("object", object)
-
-      assert capture_log(fn ->
-               :error = Transmogrifier.handle_incoming(data)
-             end) =~
-               "[error] Could not decode user at fetch http://mastodon.example.org/users/gargron, {:error, :nxdomain}"
-
-      assert Activity.get_by_id(activity.id)
-    end
-
-    @tag capture_log: true
-    test "it works for incoming user deletes" do
-      %{ap_id: ap_id} =
-        insert(:user, ap_id: "http://mastodon.example.org/users/admin", local: false)
-
-      data =
-        File.read!("test/fixtures/mastodon-delete-user.json")
-        |> Poison.decode!()
-
-      {:ok, _} = Transmogrifier.handle_incoming(data)
-      ObanHelpers.perform_all()
-
-      refute User.get_cached_by_ap_id(ap_id)
-    end
-
-    test "it fails for incoming user deletes with spoofed origin" do
-      %{ap_id: ap_id} = insert(:user)
-
-      data =
-        File.read!("test/fixtures/mastodon-delete-user.json")
-        |> Poison.decode!()
-        |> Map.put("actor", ap_id)
-
-      assert capture_log(fn ->
-               assert :error == Transmogrifier.handle_incoming(data)
-             end) =~ "Object containment failed"
-
-      assert User.get_cached_by_ap_id(ap_id)
-    end
-
-    test "it works for incoming unannounces with an existing notice" do
-      user = insert(:user)
-      {:ok, activity} = CommonAPI.post(user, %{"status" => "hey"})
-
-      announce_data =
-        File.read!("test/fixtures/mastodon-announce.json")
-        |> Poison.decode!()
-        |> Map.put("object", activity.data["object"])
-
-      {:ok, %Activity{data: announce_data, local: false}} =
-        Transmogrifier.handle_incoming(announce_data)
-
-      data =
-        File.read!("test/fixtures/mastodon-undo-announce.json")
-        |> Poison.decode!()
-        |> Map.put("object", announce_data)
-        |> Map.put("actor", announce_data["actor"])
-
-      {:ok, %Activity{data: data, local: false}} = Transmogrifier.handle_incoming(data)
-
-      assert data["type"] == "Undo"
-      assert object_data = data["object"]
-      assert object_data["type"] == "Announce"
-      assert object_data["object"] == activity.data["object"]
-
-      assert object_data["id"] ==
-               "http://mastodon.example.org/users/admin/statuses/99542391527669785/activity"
-    end
-
     test "it works for incomming unfollows with an existing follow" do
       user = insert(:user)
 

From d11eea62b139ce16d7dffbd574947b2550df238f Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Thu, 7 May 2020 15:09:37 +0200
Subject: [PATCH 8/8] Credo fixes

---
 lib/pleroma/web/activity_pub/object_validator.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/pleroma/web/activity_pub/object_validator.ex b/lib/pleroma/web/activity_pub/object_validator.ex
index 1f0431b36..4782cd8f3 100644
--- a/lib/pleroma/web/activity_pub/object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validator.ex
@@ -13,8 +13,8 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.ObjectValidators.DeleteValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.LikeValidator
-  alias Pleroma.Web.ActivityPub.ObjectValidators.UndoValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.Types
+  alias Pleroma.Web.ActivityPub.ObjectValidators.UndoValidator
 
   @spec validate(map(), keyword()) :: {:ok, map(), keyword()} | {:error, any()}
   def validate(object, meta)