14 files changed, 375 insertions, 167 deletions

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 73c6e4cbf..20f72e676 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -188,6 +188,22 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     end)
   end
 
+  def stream_out_participations(%Object{data: %{"context" => context}}, user) do
+    with %Conversation{} = conversation <- Conversation.get_for_ap_id(context),
+         conversation = Repo.preload(conversation, :participations),
+         last_activity_id =
+           fetch_latest_activity_id_for_context(conversation.ap_id, %{
+             "user" => user,
+             "blocking_user" => user
+           }) do
+      if last_activity_id do
+        stream_out_participations(conversation.participations)
+      end
+    end
+  end
+
+  def stream_out_participations(_, _), do: :noop
+
   def stream_out(activity) do
     public = "https://www.w3.org/ns/activitystreams#Public"
 
@@ -388,6 +404,19 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     end
   end
 
+  def delete(%User{ap_id: ap_id, follower_address: follower_address} = user) do
+    with data <- %{
+           "to" => [follower_address],
+           "type" => "Delete",
+           "actor" => ap_id,
+           "object" => %{"type" => "Person", "id" => ap_id}
+         },
+         {:ok, activity} <- insert(data, true, true),
+         :ok <- maybe_federate(activity) do
+      {:ok, user}
+    end
+  end
+
   def delete(%Object{data: %{"id" => id, "actor" => actor}} = object, local \\ true) do
     user = User.get_cached_by_ap_id(actor)
     to = (object.data["to"] || []) ++ (object.data["cc"] || [])
@@ -400,7 +429,8 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
            "to" => to,
            "deleted_activity_id" => activity && activity.id
          },
-         {:ok, activity} <- insert(data, local),
+         {:ok, activity} <- insert(data, local, false),
+         stream_out_participations(object, user),
          _ <- decrease_replies_count_if_reply(object),
          # Changing note count prior to enqueuing federation task in order to avoid
          # race conditions on updating user.info
diff --git a/lib/pleroma/web/activity_pub/activity_pub_controller.ex b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
index 0182bda46..cf5176201 100644
--- a/lib/pleroma/web/activity_pub/activity_pub_controller.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
@@ -31,9 +31,8 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
       conn
     else
       conn
-      |> put_status(404)
-      |> json(%{error: "not found"})
-      |> halt
+      |> render_error(:not_found, "not found")
+      |> halt()
     end
   end
 
@@ -190,7 +189,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
       Logger.info(inspect(conn.req_headers))
     end
 
-    json(conn, "error")
+    json(conn, dgettext("errors", "error"))
   end
 
   def relay(conn, _params) do
@@ -218,9 +217,15 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
       |> put_resp_header("content-type", "application/activity+json")
       |> json(UserView.render("inbox.json", %{user: user, max_id: params["max_id"]}))
     else
+      err =
+        dgettext("errors", "can't read inbox of %{nickname} as %{as_nickname}",
+          nickname: nickname,
+          as_nickname: user.nickname
+        )
+
       conn
       |> put_status(:forbidden)
-      |> json("can't read inbox of #{nickname} as #{user.nickname}")
+      |> json(err)
     end
   end
 
@@ -246,7 +251,7 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
          {:ok, delete} <- ActivityPub.delete(object) do
       {:ok, delete}
     else
-      _ -> {:error, "Can't delete object"}
+      _ -> {:error, dgettext("errors", "Can't delete object")}
     end
   end
 
@@ -255,12 +260,12 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
          {:ok, activity, _object} <- ActivityPub.like(user, object) do
       {:ok, activity}
     else
-      _ -> {:error, "Can't like object"}
+      _ -> {:error, dgettext("errors", "Can't like object")}
     end
   end
 
   def handle_user_activity(_, _) do
-    {:error, "Unhandled activity type"}
+    {:error, dgettext("errors", "Unhandled activity type")}
   end
 
   def update_outbox(
@@ -288,22 +293,28 @@ defmodule Pleroma.Web.ActivityPub.ActivityPubController do
           |> json(message)
       end
     else
+      err =
+        dgettext("errors", "can't update outbox of %{nickname} as %{as_nickname}",
+          nickname: nickname,
+          as_nickname: user.nickname
+        )
+
       conn
       |> put_status(:forbidden)
-      |> json("can't update outbox of #{nickname} as #{user.nickname}")
+      |> json(err)
     end
   end
 
   def errors(conn, {:error, :not_found}) do
     conn
-    |> put_status(404)
-    |> json("Not found")
+    |> put_status(:not_found)
+    |> json(dgettext("errors", "Not found"))
   end
 
   def errors(conn, _e) do
     conn
-    |> put_status(500)
-    |> json("error")
+    |> put_status(:internal_server_error)
+    |> json(dgettext("errors", "error"))
   end
 
   defp set_requester_reachable(%Plug.Conn{} = conn, _) do
diff --git a/lib/pleroma/web/activity_pub/mrf/anti_link_spam_policy.ex b/lib/pleroma/web/activity_pub/mrf/anti_link_spam_policy.ex
new file mode 100644
index 000000000..2da3eac2f
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/mrf/anti_link_spam_policy.ex
@@ -0,0 +1,48 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.AntiLinkSpamPolicy do
+  alias Pleroma.User
+
+  require Logger
+
+  # has the user successfully posted before?
+  defp old_user?(%User{} = u) do
+    u.info.note_count > 0 || u.info.follower_count > 0
+  end
+
+  # does the post contain links?
+  defp contains_links?(%{"content" => content} = _object) do
+    content
+    |> Floki.filter_out("a.mention,a.hashtag,a[rel~=\"tag\"],a.zrl")
+    |> Floki.attribute("a", "href")
+    |> length() > 0
+  end
+
+  defp contains_links?(_), do: false
+
+  def filter(%{"type" => "Create", "actor" => actor, "object" => object} = message) do
+    with {:ok, %User{} = u} <- User.get_or_fetch_by_ap_id(actor),
+         {:contains_links, true} <- {:contains_links, contains_links?(object)},
+         {:old_user, true} <- {:old_user, old_user?(u)} do
+      {:ok, message}
+    else
+      {:contains_links, false} ->
+        {:ok, message}
+
+      {:old_user, false} ->
+        {:reject, nil}
+
+      {:error, _} ->
+        {:reject, nil}
+
+      e ->
+        Logger.warn("[MRF anti-link-spam] WTF: unhandled error #{inspect(e)}")
+        {:reject, nil}
+    end
+  end
+
+  # in all other cases, pass through
+  def filter(message), do: {:ok, message}
+end
diff --git a/lib/pleroma/web/activity_pub/mrf/ensure_re_prepended.ex b/lib/pleroma/web/activity_pub/mrf/ensure_re_prepended.ex
index 15d8514be..2d03df68a 100644
--- a/lib/pleroma/web/activity_pub/mrf/ensure_re_prepended.ex
+++ b/lib/pleroma/web/activity_pub/mrf/ensure_re_prepended.ex
@@ -9,8 +9,9 @@ defmodule Pleroma.Web.ActivityPub.MRF.EnsureRePrepended do
   @behaviour Pleroma.Web.ActivityPub.MRF
 
   @reply_prefix Regex.compile!("^re:[[:space:]]*", [:caseless])
+
   def filter_by_summary(
-        %{"summary" => parent_summary} = _parent,
+        %{data: %{"summary" => parent_summary}} = _in_reply_to,
         %{"summary" => child_summary} = child
       )
       when not is_nil(child_summary) and byte_size(child_summary) > 0 and
@@ -24,17 +25,13 @@ defmodule Pleroma.Web.ActivityPub.MRF.EnsureRePrepended do
     end
   end
 
-  def filter_by_summary(_parent, child), do: child
-
-  def filter(%{"type" => activity_type} = object) when activity_type == "Create" do
-    child = object["object"]
-    in_reply_to = Object.normalize(child["inReplyTo"])
+  def filter_by_summary(_in_reply_to, child), do: child
 
+  def filter(%{"type" => "Create", "object" => child_object} = object) do
     child =
-      if(in_reply_to,
-        do: filter_by_summary(in_reply_to.data, child),
-        else: child
-      )
+      child_object["inReplyTo"]
+      |> Object.normalize(child_object["inReplyTo"])
+      |> filter_by_summary(child_object)
 
     object = Map.put(object, "object", child)
 
diff --git a/lib/pleroma/web/activity_pub/mrf/mediaproxy_warming_policy.ex b/lib/pleroma/web/activity_pub/mrf/mediaproxy_warming_policy.ex
new file mode 100644
index 000000000..01d21a299
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/mrf/mediaproxy_warming_policy.ex
@@ -0,0 +1,56 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.MediaProxyWarmingPolicy do
+  @moduledoc "Preloads any attachments in the MediaProxy cache by prefetching them"
+  @behaviour Pleroma.Web.ActivityPub.MRF
+
+  alias Pleroma.HTTP
+  alias Pleroma.Web.MediaProxy
+
+  require Logger
+
+  @hackney_options [
+    pool: :media,
+    recv_timeout: 10_000
+  ]
+
+  def perform(:prefetch, url) do
+    Logger.info("Prefetching #{inspect(url)}")
+
+    url
+    |> MediaProxy.url()
+    |> HTTP.get([], adapter: @hackney_options)
+  end
+
+  def perform(:preload, %{"object" => %{"attachment" => attachments}} = _message) do
+    Enum.each(attachments, fn
+      %{"url" => url} when is_list(url) ->
+        url
+        |> Enum.each(fn
+          %{"href" => href} ->
+            PleromaJobQueue.enqueue(:background, __MODULE__, [:prefetch, href])
+
+          x ->
+            Logger.debug("Unhandled attachment URL object #{inspect(x)}")
+        end)
+
+      x ->
+        Logger.debug("Unhandled attachment #{inspect(x)}")
+    end)
+  end
+
+  @impl true
+  def filter(
+        %{"type" => "Create", "object" => %{"attachment" => attachments} = _object} = message
+      )
+      when is_list(attachments) and length(attachments) > 0 do
+    PleromaJobQueue.enqueue(:background, __MODULE__, [:preload, message])
+
+    {:ok, message}
+  end
+
+  @impl true
+  def filter(message), do: {:ok, message}
+end
diff --git a/lib/pleroma/web/activity_pub/mrf/no_placeholder_text_policy.ex b/lib/pleroma/web/activity_pub/mrf/no_placeholder_text_policy.ex
index f30fee0d5..86a48bda5 100644
--- a/lib/pleroma/web/activity_pub/mrf/no_placeholder_text_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/no_placeholder_text_policy.ex
@@ -10,19 +10,11 @@ defmodule Pleroma.Web.ActivityPub.MRF.NoPlaceholderTextPolicy do
   def filter(
         %{
           "type" => "Create",
-          "object" => %{"content" => content, "attachment" => _attachment} = child_object
+          "object" => %{"content" => content, "attachment" => _} = _child_object
         } = object
       )
       when content in [".", "<p>.</p>"] do
-    child_object =
-      child_object
-      |> Map.put("content", "")
-
-    object =
-      object
-      |> Map.put("object", child_object)
-
-    {:ok, object}
+    {:ok, put_in(object, ["object", "content"], "")}
   end
 
   @impl true
diff --git a/lib/pleroma/web/activity_pub/mrf/normalize_markup.ex b/lib/pleroma/web/activity_pub/mrf/normalize_markup.ex
index 9c87c6963..c269d0f89 100644
--- a/lib/pleroma/web/activity_pub/mrf/normalize_markup.ex
+++ b/lib/pleroma/web/activity_pub/mrf/normalize_markup.ex
@@ -8,18 +8,14 @@ defmodule Pleroma.Web.ActivityPub.MRF.NormalizeMarkup do
 
   @behaviour Pleroma.Web.ActivityPub.MRF
 
-  def filter(%{"type" => activity_type} = object) when activity_type == "Create" do
+  def filter(%{"type" => "Create", "object" => child_object} = object) do
     scrub_policy = Pleroma.Config.get([:mrf_normalize_markup, :scrub_policy])
 
-    child = object["object"]
-
     content =
-      child["content"]
+      child_object["content"]
       |> HTML.filter_tags(scrub_policy)
 
-    child = Map.put(child, "content", content)
-
-    object = Map.put(object, "object", child)
+    object = put_in(object, ["object", "content"], content)
 
     {:ok, object}
   end
diff --git a/lib/pleroma/web/activity_pub/mrf/reject_non_public.ex b/lib/pleroma/web/activity_pub/mrf/reject_non_public.ex
index ea3df1b4d..da13fd7c7 100644
--- a/lib/pleroma/web/activity_pub/mrf/reject_non_public.ex
+++ b/lib/pleroma/web/activity_pub/mrf/reject_non_public.ex
@@ -3,46 +3,42 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.ActivityPub.MRF.RejectNonPublic do
-  alias Pleroma.User
   @moduledoc "Rejects non-public (followers-only, direct) activities"
+
+  alias Pleroma.Config
+  alias Pleroma.User
+
   @behaviour Pleroma.Web.ActivityPub.MRF
 
+  @public "https://www.w3.org/ns/activitystreams#Public"
+
   @impl true
   def filter(%{"type" => "Create"} = object) do
     user = User.get_cached_by_ap_id(object["actor"])
-    public = "https://www.w3.org/ns/activitystreams#Public"
 
     # Determine visibility
     visibility =
       cond do
-        public in object["to"] -> "public"
-        public in object["cc"] -> "unlisted"
+        @public in object["to"] -> "public"
+        @public in object["cc"] -> "unlisted"
         user.follower_address in object["to"] -> "followers"
         true -> "direct"
       end
 
-    policy = Pleroma.Config.get(:mrf_rejectnonpublic)
+    policy = Config.get(:mrf_rejectnonpublic)
+
+    cond do
+      visibility in ["public", "unlisted"] ->
+        {:ok, object}
 
-    case visibility do
-      "public" ->
+      visibility == "followers" and Keyword.get(policy, :allow_followersonly) ->
         {:ok, object}
 
-      "unlisted" ->
+      visibility == "direct" and Keyword.get(policy, :allow_direct) ->
         {:ok, object}
 
-      "followers" ->
-        with true <- Keyword.get(policy, :allow_followersonly) do
-          {:ok, object}
-        else
-          _e -> {:reject, nil}
-        end
-
-      "direct" ->
-        with true <- Keyword.get(policy, :allow_direct) do
-          {:ok, object}
-        else
-          _e -> {:reject, nil}
-        end
+      true ->
+        {:reject, nil}
     end
   end
 
diff --git a/lib/pleroma/web/activity_pub/mrf/tag_policy.ex b/lib/pleroma/web/activity_pub/mrf/tag_policy.ex
index 6683b8d8e..b42c4ed76 100644
--- a/lib/pleroma/web/activity_pub/mrf/tag_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/tag_policy.ex
@@ -19,12 +19,17 @@ defmodule Pleroma.Web.ActivityPub.MRF.TagPolicy do
      - `mrf_tag:disable-any-subscription`: Reject any follow requests
   """
 
+  @public "https://www.w3.org/ns/activitystreams#Public"
+
   defp get_tags(%User{tags: tags}) when is_list(tags), do: tags
   defp get_tags(_), do: []
 
   defp process_tag(
          "mrf_tag:media-force-nsfw",
-         %{"type" => "Create", "object" => %{"attachment" => child_attachment} = object} = message
+         %{
+           "type" => "Create",
+           "object" => %{"attachment" => child_attachment} = object
+         } = message
        )
        when length(child_attachment) > 0 do
     tags = (object["tag"] || []) ++ ["nsfw"]
@@ -41,7 +46,10 @@ defmodule Pleroma.Web.ActivityPub.MRF.TagPolicy do
 
   defp process_tag(
          "mrf_tag:media-strip",
-         %{"type" => "Create", "object" => %{"attachment" => child_attachment} = object} = message
+         %{
+           "type" => "Create",
+           "object" => %{"attachment" => child_attachment} = object
+         } = message
        )
        when length(child_attachment) > 0 do
     object = Map.delete(object, "attachment")
@@ -52,19 +60,22 @@ defmodule Pleroma.Web.ActivityPub.MRF.TagPolicy do
 
   defp process_tag(
          "mrf_tag:force-unlisted",
-         %{"type" => "Create", "to" => to, "cc" => cc, "actor" => actor} = message
+         %{
+           "type" => "Create",
+           "to" => to,
+           "cc" => cc,
+           "actor" => actor,
+           "object" => object
+         } = message
        ) do
     user = User.get_cached_by_ap_id(actor)
 
-    if Enum.member?(to, "https://www.w3.org/ns/activitystreams#Public") do
-      to =
-        List.delete(to, "https://www.w3.org/ns/activitystreams#Public") ++ [user.follower_address]
-
-      cc =
-        List.delete(cc, user.follower_address) ++ ["https://www.w3.org/ns/activitystreams#Public"]
+    if Enum.member?(to, @public) do
+      to = List.delete(to, @public) ++ [user.follower_address]
+      cc = List.delete(cc, user.follower_address) ++ [@public]
 
       object =
-        message["object"]
+        object
         |> Map.put("to", to)
         |> Map.put("cc", cc)
 
@@ -82,19 +93,22 @@ defmodule Pleroma.Web.ActivityPub.MRF.TagPolicy do
 
   defp process_tag(
          "mrf_tag:sandbox",
-         %{"type" => "Create", "to" => to, "cc" => cc, "actor" => actor} = message
+         %{
+           "type" => "Create",
+           "to" => to,
+           "cc" => cc,
+           "actor" => actor,
+           "object" => object
+         } = message
        ) do
     user = User.get_cached_by_ap_id(actor)
 
-    if Enum.member?(to, "https://www.w3.org/ns/activitystreams#Public") or
-         Enum.member?(cc, "https://www.w3.org/ns/activitystreams#Public") do
-      to =
-        List.delete(to, "https://www.w3.org/ns/activitystreams#Public") ++ [user.follower_address]
-
-      cc = List.delete(cc, "https://www.w3.org/ns/activitystreams#Public")
+    if Enum.member?(to, @public) or Enum.member?(cc, @public) do
+      to = List.delete(to, @public) ++ [user.follower_address]
+      cc = List.delete(cc, @public)
 
       object =
-        message["object"]
+        object
         |> Map.put("to", to)
         |> Map.put("cc", cc)
 
@@ -123,7 +137,8 @@ defmodule Pleroma.Web.ActivityPub.MRF.TagPolicy do
     end
   end
 
-  defp process_tag("mrf_tag:disable-any-subscription", %{"type" => "Follow"}), do: {:reject, nil}
+  defp process_tag("mrf_tag:disable-any-subscription", %{"type" => "Follow"}),
+    do: {:reject, nil}
 
   defp process_tag(_, message), do: {:ok, message}
 
diff --git a/lib/pleroma/web/activity_pub/mrf/user_allowlist.ex b/lib/pleroma/web/activity_pub/mrf/user_allowlist_policy.ex
index 47663414a..e35d2c422 100644
--- a/lib/pleroma/web/activity_pub/mrf/user_allowlist.ex
+++ b/lib/pleroma/web/activity_pub/mrf/user_allowlist_policy.ex
@@ -21,7 +21,12 @@ defmodule Pleroma.Web.ActivityPub.MRF.UserAllowListPolicy do
   @impl true
   def filter(%{"actor" => actor} = object) do
     actor_info = URI.parse(actor)
-    allow_list = Config.get([:mrf_user_allowlist, String.to_atom(actor_info.host)], [])
+
+    allow_list =
+      Config.get(
+        [:mrf_user_allowlist, String.to_atom(actor_info.host)],
+        []
+      )
 
     filter_by_list(object, allow_list)
   end
diff --git a/lib/pleroma/web/activity_pub/publisher.ex b/lib/pleroma/web/activity_pub/publisher.ex
index f376e5618..b7dc90caa 100644
--- a/lib/pleroma/web/activity_pub/publisher.ex
+++ b/lib/pleroma/web/activity_pub/publisher.ex
@@ -88,7 +88,7 @@ defmodule Pleroma.Web.ActivityPub.Publisher do
       true
     else
       inbox_info = URI.parse(inbox)
-      !Enum.member?(Pleroma.Config.get([:instance, :quarantined_instances], []), inbox_info.host)
+      !Enum.member?(Config.get([:instance, :quarantined_instances], []), inbox_info.host)
     end
   end
 
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index d22d24479..ad741122f 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -14,6 +14,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   alias Pleroma.Web.ActivityPub.ActivityPub
   alias Pleroma.Web.ActivityPub.Utils
   alias Pleroma.Web.ActivityPub.Visibility
+  alias Pleroma.Web.Federator
 
   import Ecto.Query
 
@@ -22,20 +23,20 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   @doc """
   Modifies an incoming AP object (mastodon format) to our internal format.
   """
-  def fix_object(object) do
+  def fix_object(object, options \\ []) do
     object
     |> fix_actor
     |> fix_url
     |> fix_attachments
     |> fix_context
-    |> fix_in_reply_to
+    |> fix_in_reply_to(options)
     |> fix_emoji
     |> fix_tag
     |> fix_content_map
     |> fix_likes
     |> fix_addressing
     |> fix_summary
-    |> fix_type
+    |> fix_type(options)
   end
 
   def fix_summary(%{"summary" => nil} = object) do
@@ -164,7 +165,9 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     object
   end
 
-  def fix_in_reply_to(%{"inReplyTo" => in_reply_to} = object)
+  def fix_in_reply_to(object, options \\ [])
+
+  def fix_in_reply_to(%{"inReplyTo" => in_reply_to} = object, options)
       when not is_nil(in_reply_to) do
     in_reply_to_id =
       cond do
@@ -182,28 +185,34 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
           ""
       end
 
-    case get_obj_helper(in_reply_to_id) do
-      {:ok, replied_object} ->
-        with %Activity{} = _activity <-
-               Activity.get_create_by_object_ap_id(replied_object.data["id"]) do
-          object
-          |> Map.put("inReplyTo", replied_object.data["id"])
-          |> Map.put("inReplyToAtomUri", object["inReplyToAtomUri"] || in_reply_to_id)
-          |> Map.put("conversation", replied_object.data["context"] || object["conversation"])
-          |> Map.put("context", replied_object.data["context"] || object["conversation"])
-        else
-          e ->
-            Logger.error("Couldn't fetch \"#{inspect(in_reply_to_id)}\", error: #{inspect(e)}")
+    object = Map.put(object, "inReplyToAtomUri", in_reply_to_id)
+
+    if Federator.allowed_incoming_reply_depth?(options[:depth]) do
+      case get_obj_helper(in_reply_to_id, options) do
+        {:ok, replied_object} ->
+          with %Activity{} = _activity <-
+                 Activity.get_create_by_object_ap_id(replied_object.data["id"]) do
             object
-        end
+            |> Map.put("inReplyTo", replied_object.data["id"])
+            |> Map.put("inReplyToAtomUri", object["inReplyToAtomUri"] || in_reply_to_id)
+            |> Map.put("conversation", replied_object.data["context"] || object["conversation"])
+            |> Map.put("context", replied_object.data["context"] || object["conversation"])
+          else
+            e ->
+              Logger.error("Couldn't fetch \"#{inspect(in_reply_to_id)}\", error: #{inspect(e)}")
+              object
+          end
 
-      e ->
-        Logger.error("Couldn't fetch \"#{inspect(in_reply_to_id)}\", error: #{inspect(e)}")
-        object
+        e ->
+          Logger.error("Couldn't fetch \"#{inspect(in_reply_to_id)}\", error: #{inspect(e)}")
+          object
+      end
+    else
+      object
     end
   end
 
-  def fix_in_reply_to(object), do: object
+  def fix_in_reply_to(object, _options), do: object
 
   def fix_context(object) do
     context = object["context"] || object["conversation"] || Utils.generate_context_id()
@@ -336,17 +345,22 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
   def fix_content_map(object), do: object
 
-  def fix_type(%{"inReplyTo" => reply_id} = object) when is_binary(reply_id) do
-    reply = Object.normalize(reply_id)
+  def fix_type(object, options \\ [])
 
-    if reply.data["type"] == "Question" and object["name"] do
+  def fix_type(%{"inReplyTo" => reply_id} = object, options) when is_binary(reply_id) do
+    reply =
+      if Federator.allowed_incoming_reply_depth?(options[:depth]) do
+        Object.normalize(reply_id, true)
+      end
+
+    if reply && (reply.data["type"] == "Question" and object["name"]) do
       Map.put(object, "type", "Answer")
     else
       object
     end
   end
 
-  def fix_type(object), do: object
+  def fix_type(object, _), do: object
 
   defp mastodon_follow_hack(%{"id" => id, "actor" => follower_id}, followed) do
     with true <- id =~ "follows",
@@ -374,9 +388,11 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     end
   end
 
+  def handle_incoming(data, options \\ [])
+
   # Flag objects are placed ahead of the ID check because Mastodon 2.8 and earlier send them
   # with nil ID.
-  def handle_incoming(%{"type" => "Flag", "object" => objects, "actor" => actor} = data) do
+  def handle_incoming(%{"type" => "Flag", "object" => objects, "actor" => actor} = data, _options) do
     with context <- data["context"] || Utils.generate_context_id(),
          content <- data["content"] || "",
          %User{} = actor <- User.get_cached_by_ap_id(actor),
@@ -409,15 +425,19 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   # disallow objects with bogus IDs
-  def handle_incoming(%{"id" => nil}), do: :error
-  def handle_incoming(%{"id" => ""}), do: :error
+  def handle_incoming(%{"id" => nil}, _options), do: :error
+  def handle_incoming(%{"id" => ""}, _options), do: :error
   # length of https:// = 8, should validate better, but good enough for now.
-  def handle_incoming(%{"id" => id}) when not (is_binary(id) and length(id) > 8), do: :error
+  def handle_incoming(%{"id" => id}, _options) when not (is_binary(id) and length(id) > 8),
+    do: :error
 
   # TODO: validate those with a Ecto scheme
   # - tags
   # - emoji
-  def handle_incoming(%{"type" => "Create", "object" => %{"type" => objtype} = object} = data)
+  def handle_incoming(
+        %{"type" => "Create", "object" => %{"type" => objtype} = object} = data,
+        options
+      )
       when objtype in ["Article", "Note", "Video", "Page", "Question", "Answer"] do
     actor = Containment.get_actor(data)
 
@@ -427,7 +447,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
     with nil <- Activity.get_create_by_object_ap_id(object["id"]),
          {:ok, %User{} = user} <- User.get_or_fetch_by_ap_id(data["actor"]) do
-      object = fix_object(data["object"])
+      options = Keyword.put(options, :depth, (options[:depth] || 0) + 1)
+      object = fix_object(data["object"], options)
 
       params = %{
         to: data["to"],
@@ -452,16 +473,19 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def handle_incoming(
-        %{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = data
+        %{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = data,
+        _options
       ) do
     with %User{local: true} = followed <- User.get_cached_by_ap_id(followed),
          {:ok, %User{} = follower} <- User.get_or_fetch_by_ap_id(follower),
          {:ok, activity} <- ActivityPub.follow(follower, followed, id, false) do
       with deny_follow_blocked <- Pleroma.Config.get([:user, :deny_follow_blocked]),
-           {:user_blocked, false} <-
+           {_, false} <-
              {:user_blocked, User.blocks?(followed, follower) && deny_follow_blocked},
-           {:user_locked, false} <- {:user_locked, User.locked?(followed)},
-           {:follow, {:ok, follower}} <- {:follow, User.follow(follower, followed)} do
+           {_, false} <- {:user_locked, User.locked?(followed)},
+           {_, {:ok, follower}} <- {:follow, User.follow(follower, followed)},
+           {_, {:ok, _}} <-
+             {:follow_state_update, Utils.update_follow_state_for_all(activity, "accept")} do
         ActivityPub.accept(%{
           to: [follower.ap_id],
           actor: followed,
@@ -470,7 +494,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
         })
       else
         {:user_blocked, true} ->
-          {:ok, _} = Utils.update_follow_state(activity, "reject")
+          {:ok, _} = Utils.update_follow_state_for_all(activity, "reject")
 
           ActivityPub.reject(%{
             to: [follower.ap_id],
@@ -480,7 +504,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
           })
 
         {:follow, {:error, _}} ->
-          {:ok, _} = Utils.update_follow_state(activity, "reject")
+          {:ok, _} = Utils.update_follow_state_for_all(activity, "reject")
 
           ActivityPub.reject(%{
             to: [follower.ap_id],
@@ -501,38 +525,35 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def handle_incoming(
-        %{"type" => "Accept", "object" => follow_object, "actor" => _actor, "id" => _id} = data
+        %{"type" => "Accept", "object" => follow_object, "actor" => _actor, "id" => _id} = data,
+        _options
       ) do
     with actor <- Containment.get_actor(data),
          {:ok, %User{} = followed} <- User.get_or_fetch_by_ap_id(actor),
          {:ok, follow_activity} <- get_follow_activity(follow_object, followed),
-         {:ok, follow_activity} <- Utils.update_follow_state(follow_activity, "accept"),
+         {:ok, follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "accept"),
          %User{local: true} = follower <- User.get_cached_by_ap_id(follow_activity.data["actor"]),
-         {:ok, activity} <-
-           ActivityPub.accept(%{
-             to: follow_activity.data["to"],
-             type: "Accept",
-             actor: followed,
-             object: follow_activity.data["id"],
-             local: false
-           }) do
-      if not User.following?(follower, followed) do
-        {:ok, _follower} = User.follow(follower, followed)
-      end
-
-      {:ok, activity}
+         {:ok, _follower} = User.follow(follower, followed) do
+      ActivityPub.accept(%{
+        to: follow_activity.data["to"],
+        type: "Accept",
+        actor: followed,
+        object: follow_activity.data["id"],
+        local: false
+      })
     else
       _e -> :error
     end
   end
 
   def handle_incoming(
-        %{"type" => "Reject", "object" => follow_object, "actor" => _actor, "id" => _id} = data
+        %{"type" => "Reject", "object" => follow_object, "actor" => _actor, "id" => _id} = data,
+        _options
       ) do
     with actor <- Containment.get_actor(data),
          {:ok, %User{} = followed} <- User.get_or_fetch_by_ap_id(actor),
          {:ok, follow_activity} <- get_follow_activity(follow_object, followed),
-         {:ok, follow_activity} <- Utils.update_follow_state(follow_activity, "reject"),
+         {:ok, follow_activity} <- Utils.update_follow_state_for_all(follow_activity, "reject"),
          %User{local: true} = follower <- User.get_cached_by_ap_id(follow_activity.data["actor"]),
          {:ok, activity} <-
            ActivityPub.reject(%{
@@ -551,7 +572,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def handle_incoming(
-        %{"type" => "Like", "object" => object_id, "actor" => _actor, "id" => id} = data
+        %{"type" => "Like", "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),
@@ -564,7 +586,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def handle_incoming(
-        %{"type" => "Announce", "object" => object_id, "actor" => _actor, "id" => id} = data
+        %{"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),
@@ -579,7 +602,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
   def handle_incoming(
         %{"type" => "Update", "object" => %{"type" => object_type} = object, "actor" => actor_id} =
-          data
+          data,
+        _options
       )
       when object_type in ["Person", "Application", "Service", "Organization"] do
     with %User{ap_id: ^actor_id} = actor <- User.get_cached_by_ap_id(object["id"]) do
@@ -617,7 +641,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   # an error or a tombstone.  This would allow us to verify that a deletion actually took
   # place.
   def handle_incoming(
-        %{"type" => "Delete", "object" => object_id, "actor" => _actor, "id" => _id} = data
+        %{"type" => "Delete", "object" => object_id, "actor" => actor, "id" => _id} = data,
+        _options
       ) do
     object_id = Utils.get_ap_id(object_id)
 
@@ -628,7 +653,30 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
          {:ok, activity} <- ActivityPub.delete(object, false) do
       {:ok, activity}
     else
-      _e -> :error
+      nil ->
+        case User.get_cached_by_ap_id(object_id) do
+          %User{ap_id: ^actor} = user ->
+            {:ok, followers} = User.get_followers(user)
+
+            Enum.each(followers, fn follower ->
+              User.unfollow(follower, user)
+            end)
+
+            {:ok, friends} = User.get_friends(user)
+
+            Enum.each(friends, fn followed ->
+              User.unfollow(user, followed)
+            end)
+
+            User.invalidate_cache(user)
+            Repo.delete(user)
+
+          nil ->
+            :error
+        end
+
+      _e ->
+        :error
     end
   end
 
@@ -638,7 +686,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
           "object" => %{"type" => "Announce", "object" => object_id},
           "actor" => _actor,
           "id" => id
-        } = data
+        } = data,
+        _options
       ) do
     with actor <- Containment.get_actor(data),
          {:ok, %User{} = actor} <- User.get_or_fetch_by_ap_id(actor),
@@ -656,7 +705,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
           "object" => %{"type" => "Follow", "object" => followed},
           "actor" => follower,
           "id" => id
-        } = _data
+        } = _data,
+        _options
       ) do
     with %User{local: true} = followed <- User.get_cached_by_ap_id(followed),
          {:ok, %User{} = follower} <- User.get_or_fetch_by_ap_id(follower),
@@ -674,7 +724,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
           "object" => %{"type" => "Block", "object" => blocked},
           "actor" => blocker,
           "id" => id
-        } = _data
+        } = _data,
+        _options
       ) do
     with true <- Pleroma.Config.get([:activitypub, :accept_blocks]),
          %User{local: true} = blocked <- User.get_cached_by_ap_id(blocked),
@@ -688,7 +739,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def handle_incoming(
-        %{"type" => "Block", "object" => blocked, "actor" => blocker, "id" => id} = _data
+        %{"type" => "Block", "object" => blocked, "actor" => blocker, "id" => id} = _data,
+        _options
       ) do
     with true <- Pleroma.Config.get([:activitypub, :accept_blocks]),
          %User{local: true} = blocked = User.get_cached_by_ap_id(blocked),
@@ -708,7 +760,8 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
           "object" => %{"type" => "Like", "object" => object_id},
           "actor" => _actor,
           "id" => id
-        } = data
+        } = data,
+        _options
       ) do
     with actor <- Containment.get_actor(data),
          {:ok, %User{} = actor} <- User.get_or_fetch_by_ap_id(actor),
@@ -720,10 +773,10 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     end
   end
 
-  def handle_incoming(_), do: :error
+  def handle_incoming(_, _), do: :error
 
-  def get_obj_helper(id) do
-    if object = Object.normalize(id), do: {:ok, object}, else: nil
+  def get_obj_helper(id, options \\ []) do
+    if object = Object.normalize(id, true, options), do: {:ok, object}, else: nil
   end
 
   def set_reply_to_uri(%{"inReplyTo" => in_reply_to} = object) when is_binary(in_reply_to) do
diff --git a/lib/pleroma/web/activity_pub/utils.ex b/lib/pleroma/web/activity_pub/utils.ex
index faae7e747..4288ea4c8 100644
--- a/lib/pleroma/web/activity_pub/utils.ex
+++ b/lib/pleroma/web/activity_pub/utils.ex
@@ -151,16 +151,18 @@ defmodule Pleroma.Web.ActivityPub.Utils do
 
   def create_context(context) do
     context = context || generate_id("contexts")
-    changeset = Object.context_mapping(context)
 
-    case Repo.insert(changeset) do
-      {:ok, object} ->
-        object
+    # Ecto has problems accessing the constraint inside the jsonb,
+    # so we explicitly check for the existed object before insert
+    object = Object.get_cached_by_ap_id(context)
 
-      # This should be solved by an upsert, but it seems ecto
-      # has problems accessing the constraint inside the jsonb.
-      {:error, _} ->
-        Object.get_cached_by_ap_id(context)
+    with true <- is_nil(object),
+         changeset <- Object.context_mapping(context),
+         {:ok, inserted_object} <- Repo.insert(changeset) do
+      inserted_object
+    else
+      _ ->
+        object
     end
   end
 
@@ -168,14 +170,17 @@ defmodule Pleroma.Web.ActivityPub.Utils do
   Enqueues an activity for federation if it's local
   """
   def maybe_federate(%Activity{local: true} = activity) do
-    priority =
-      case activity.data["type"] do
-        "Delete" -> 10
-        "Create" -> 1
-        _ -> 5
-      end
+    if Pleroma.Config.get!([:instance, :federating]) do
+      priority =
+        case activity.data["type"] do
+          "Delete" -> 10
+          "Create" -> 1
+          _ -> 5
+        end
+
+      Pleroma.Web.Federator.publish(activity, priority)
+    end
 
-    Pleroma.Web.Federator.publish(activity, priority)
     :ok
   end
 
@@ -376,8 +381,8 @@ defmodule Pleroma.Web.ActivityPub.Utils do
   @doc """
   Updates a follow activity's state (for locked accounts).
   """
-  def update_follow_state(
-        %Activity{data: %{"actor" => actor, "object" => object, "state" => "pending"}} = activity,
+  def update_follow_state_for_all(
+        %Activity{data: %{"actor" => actor, "object" => object}} = activity,
         state
       ) do
     try do
diff --git a/lib/pleroma/web/activity_pub/visibility.ex b/lib/pleroma/web/activity_pub/visibility.ex
index 8965e3253..9908a2e75 100644
--- a/lib/pleroma/web/activity_pub/visibility.ex
+++ b/lib/pleroma/web/activity_pub/visibility.ex
@@ -1,3 +1,7 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
 defmodule Pleroma.Web.ActivityPub.Visibility do
   alias Pleroma.Activity
   alias Pleroma.Object