X-Git-Url: http://git.squeep.com/?a=blobdiff_plain;f=lib%2Fpleroma%2Fweb%2Factivity_pub%2Ftransmogrifier.ex;h=4c27a5704890364f2b218f40ab2d03ea1e4083c8;hb=dfcfb184b10428af8d37492e64f271c0275fc2c9;hp=61631e1eaafb7ea8b3924cbc7868350d3f34959d;hpb=5da2355e715722f2f80a7587264a08d4281cb519;p=akkoma

diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index 61631e1ea..5864855b0 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -7,67 +7,215 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   alias Pleroma.Activity
   alias Pleroma.Repo
   alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.Web.ActivityPub.Utils
 
   import Ecto.Query
 
   require Logger
 
+  def get_actor(%{"actor" => actor}) when is_binary(actor) do
+    actor
+  end
+
+  def get_actor(%{"actor" => actor}) when is_list(actor) do
+    if is_binary(Enum.at(actor, 0)) do
+      Enum.at(actor, 0)
+    else
+      Enum.find(actor, fn %{"type" => type} -> type in ["Person", "Service", "Application"] end)
+      |> Map.get("id")
+    end
+  end
+
+  def get_actor(%{"actor" => %{"id" => id}}) when is_bitstring(id) do
+    id
+  end
+
+  def get_actor(%{"actor" => nil, "attributedTo" => actor}) when not is_nil(actor) do
+    get_actor(%{"actor" => actor})
+  end
+
+  @doc """
+  Checks that an imported AP object's actor matches the domain it came from.
+  """
+  def contain_origin(id, %{"actor" => nil}), do: :error
+
+  def contain_origin(id, %{"actor" => actor} = params) do
+    id_uri = URI.parse(id)
+    actor_uri = URI.parse(get_actor(params))
+
+    if id_uri.host == actor_uri.host do
+      :ok
+    else
+      :error
+    end
+  end
+
+  def contain_origin_from_id(id, %{"id" => nil}), do: :error
+
+  def contain_origin_from_id(id, %{"id" => other_id} = params) do
+    id_uri = URI.parse(id)
+    other_uri = URI.parse(other_id)
+
+    if id_uri.host == other_uri.host do
+      :ok
+    else
+      :error
+    end
+  end
+
   @doc """
   Modifies an incoming AP object (mastodon format) to our internal format.
   """
   def fix_object(object) do
     object
-    |> Map.put("actor", object["attributedTo"])
+    |> fix_actor
     |> fix_attachments
+    |> fix_url
     |> fix_context
     |> fix_in_reply_to
     |> fix_emoji
+    |> fix_tag
+    |> fix_content_map
+    |> fix_likes
+    |> fix_addressing
   end
 
-  def fix_in_reply_to(%{"inReplyTo" => in_reply_to_id} = object) when not is_nil(in_reply_to_id) do
-    case ActivityPub.fetch_object_from_id(in_reply_to_id) do
+  def fix_addressing_list(map, field) do
+    if is_binary(map[field]) do
+      map
+      |> Map.put(field, [map[field]])
+    else
+      map
+    end
+  end
+
+  def fix_addressing(map) do
+    map
+    |> fix_addressing_list("to")
+    |> fix_addressing_list("cc")
+    |> fix_addressing_list("bto")
+    |> fix_addressing_list("bcc")
+  end
+
+  def fix_actor(%{"attributedTo" => actor} = object) do
+    object
+    |> Map.put("actor", get_actor(%{"actor" => actor}))
+  end
+
+  def fix_likes(%{"likes" => likes} = object)
+      when is_bitstring(likes) do
+    # Check for standardisation
+    # This is what Peertube does
+    # curl -H 'Accept: application/activity+json' $likes | jq .totalItems
+    object
+    |> Map.put("likes", [])
+    |> Map.put("like_count", 0)
+  end
+
+  def fix_likes(object) do
+    object
+  end
+
+  def fix_in_reply_to(%{"inReplyTo" => in_reply_to} = object)
+      when not is_nil(in_reply_to) do
+    in_reply_to_id =
+      cond do
+        is_bitstring(in_reply_to) ->
+          in_reply_to
+
+        is_map(in_reply_to) && is_bitstring(in_reply_to["id"]) ->
+          in_reply_to["id"]
+
+        is_list(in_reply_to) && is_bitstring(Enum.at(in_reply_to, 0)) ->
+          Enum.at(in_reply_to, 0)
+
+        # Maybe I should output an error too?
+        true ->
+          ""
+      end
+
+    case fetch_obj_helper(in_reply_to_id) do
       {:ok, replied_object} ->
-        activity = Activity.get_create_activity_by_object_ap_id(replied_object.data["id"])
-        object
-        |> Map.put("inReplyTo", replied_object.data["id"])
-        |> Map.put("inReplyToAtomUri", object["inReplyToAtomUri"] || in_reply_to_id)
-        |> Map.put("inReplyToStatusId", activity.id)
-        |> Map.put("conversation", replied_object.data["context"] || object["conversation"])
-        |> Map.put("context", replied_object.data["context"] || object["conversation"])
+        with %Activity{} = activity <-
+               Activity.get_create_activity_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("inReplyToStatusId", activity.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 #{object["inReplyTo"]} #{inspect(e)}")
+        Logger.error("Couldn't fetch \"#{inspect(in_reply_to_id)}\", error: #{inspect(e)}")
         object
     end
   end
+
   def fix_in_reply_to(object), do: object
 
   def fix_context(object) do
+    context = object["context"] || object["conversation"] || Utils.generate_context_id()
+
     object
-    |> Map.put("context", object["conversation"])
+    |> Map.put("context", context)
+    |> Map.put("conversation", context)
   end
 
-  def fix_attachments(object) do
-    attachments = (object["attachment"] || [])
-    |> Enum.map(fn (data) ->
-      url = [%{"type" => "Link", "mediaType" => data["mediaType"], "href" => data["url"]}]
-      Map.put(data, "url", url)
-    end)
+  def fix_attachments(%{"attachment" => attachment} = object) when is_list(attachment) do
+    attachments =
+      attachment
+      |> Enum.map(fn data ->
+        url = [%{"type" => "Link", "mediaType" => data["mediaType"], "href" => data["url"]}]
+        Map.put(data, "url", url)
+      end)
 
     object
     |> Map.put("attachment", attachments)
   end
 
-  def fix_emoji(object) do
-    tags = (object["tag"] || [])
-    emoji = tags |> Enum.filter(fn (data) -> data["type"] == "Emoji" and data["icon"] end)
-    emoji = emoji |> Enum.reduce(%{}, fn (data, mapping) ->
-      name = data["name"]
-      if String.starts_with?(name, ":") do
-        name = name |> String.slice(1..-2)
+  def fix_attachments(%{"attachment" => attachment} = object) when is_map(attachment) do
+    Map.put(object, "attachment", [attachment])
+    |> fix_attachments()
+  end
+
+  def fix_attachments(object), do: object
+
+  def fix_url(%{"url" => url} = object) when is_map(url) do
+    object
+    |> Map.put("url", url["href"])
+  end
+
+  def fix_url(%{"url" => url} = object) when is_list(url) do
+    first_element = Enum.at(url, 0)
+
+    url_string =
+      cond do
+        is_bitstring(first_element) -> first_element
+        is_map(first_element) -> first_element["href"] || ""
+        true -> ""
       end
 
-      mapping |> Map.put(name, data["icon"]["url"])
-    end)
+    object
+    |> Map.put("url", url_string)
+  end
+
+  def fix_url(object), do: object
+
+  def fix_emoji(%{"tag" => tags} = object) when is_list(tags) do
+    emoji = tags |> Enum.filter(fn data -> data["type"] == "Emoji" and data["icon"] end)
+
+    emoji =
+      emoji
+      |> Enum.reduce(%{}, fn data, mapping ->
+        name = String.trim(data["name"], ":")
+
+        mapping |> Map.put(name, data["icon"]["url"])
+      end)
 
     # we merge mastodon and pleroma emoji into a single mapping, to allow for both wire formats
     emoji = Map.merge(object["emoji"] || %{}, emoji)
@@ -76,10 +224,65 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     |> Map.put("emoji", emoji)
   end
 
+  def fix_emoji(%{"tag" => %{"type" => "Emoji"} = tag} = object) do
+    name = String.trim(tag["name"], ":")
+    emoji = %{name => tag["icon"]["url"]}
+
+    object
+    |> Map.put("emoji", emoji)
+  end
+
+  def fix_emoji(object), do: object
+
+  def fix_tag(%{"tag" => tag} = object) when is_list(tag) do
+    tags =
+      tag
+      |> Enum.filter(fn data -> data["type"] == "Hashtag" and data["name"] end)
+      |> Enum.map(fn data -> String.slice(data["name"], 1..-1) end)
+
+    combined = tag ++ tags
+
+    object
+    |> Map.put("tag", combined)
+  end
+
+  def fix_tag(%{"tag" => %{"type" => "Hashtag", "name" => hashtag} = tag} = object) do
+    combined = [tag, String.slice(hashtag, 1..-1)]
+
+    object
+    |> Map.put("tag", combined)
+  end
+
+  def fix_tag(object), do: object
+
+  # content map usually only has one language so this will do for now.
+  def fix_content_map(%{"contentMap" => content_map} = object) do
+    content_groups = Map.to_list(content_map)
+    {_, content} = Enum.at(content_groups, 0)
+
+    object
+    |> Map.put("content", content)
+  end
+
+  def fix_content_map(object), do: object
+
+  # disallow objects with bogus IDs
+  def handle_incoming(%{"id" => nil}), do: :error
+  def handle_incoming(%{"id" => ""}), 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
+
   # TODO: validate those with a Ecto scheme
   # - tags
   # - emoji
-  def handle_incoming(%{"type" => "Create", "object" => %{"type" => "Note"} = object} = data) do
+  def handle_incoming(%{"type" => "Create", "object" => %{"type" => objtype} = object} = data)
+      when objtype in ["Article", "Note", "Video", "Page"] do
+    actor = get_actor(data)
+
+    data =
+      Map.put(data, "actor", actor)
+      |> fix_addressing
+
     with nil <- Activity.get_create_activity_by_object_ap_id(object["id"]),
          %User{} = user <- User.get_or_fetch_by_ap_id(data["actor"]) do
       object = fix_object(data["object"])
@@ -91,13 +294,13 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
         context: object["conversation"],
         local: false,
         published: data["published"],
-        additional: Map.take(data, [
-              "cc",
-              "id"
-            ])
+        additional:
+          Map.take(data, [
+            "cc",
+            "id"
+          ])
       }
 
-
       ActivityPub.create(params)
     else
       %Activity{} = activity -> {:ok, activity}
@@ -105,52 +308,158 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     end
   end
 
-  def handle_incoming(%{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = data) do
+  def handle_incoming(
+        %{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = data
+      ) do
     with %User{local: true} = followed <- User.get_cached_by_ap_id(followed),
          %User{} = follower <- User.get_or_fetch_by_ap_id(follower),
          {:ok, activity} <- ActivityPub.follow(follower, followed, id, false) do
-      ActivityPub.accept(%{to: [follower.ap_id], actor: followed.ap_id, object: data, local: true})
-      User.follow(follower, followed)
+      if not User.locked?(followed) do
+        ActivityPub.accept(%{
+          to: [follower.ap_id],
+          actor: followed.ap_id,
+          object: data,
+          local: true
+        })
+
+        User.follow(follower, followed)
+      end
+
+      {:ok, activity}
+    else
+      _e -> :error
+    end
+  end
+
+  defp mastodon_follow_hack(%{"id" => id, "actor" => follower_id}, followed) do
+    with true <- id =~ "follows",
+         %User{local: true} = follower <- User.get_cached_by_ap_id(follower_id),
+         %Activity{} = activity <- Utils.fetch_latest_follow(follower, followed) do
+      {:ok, activity}
+    else
+      _ -> {:error, nil}
+    end
+  end
+
+  defp mastodon_follow_hack(_), do: {:error, nil}
+
+  defp get_follow_activity(follow_object, followed) do
+    with object_id when not is_nil(object_id) <- Utils.get_ap_id(follow_object),
+         {_, %Activity{} = activity} <- {:activity, Activity.get_by_ap_id(object_id)} do
+      {:ok, activity}
+    else
+      # Can't find the activity. This might a Mastodon 2.3 "Accept"
+      {:activity, nil} ->
+        mastodon_follow_hack(follow_object, followed)
+
+      _ ->
+        {:error, nil}
+    end
+  end
+
+  def handle_incoming(
+        %{"type" => "Accept", "object" => follow_object, "actor" => actor, "id" => id} = data
+      ) do
+    with actor <- get_actor(data),
+         %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"),
+         %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.ap_id,
+             object: follow_activity.data["id"],
+             local: false
+           }) do
+      if not User.following?(follower, followed) do
+        {:ok, follower} = User.follow(follower, followed)
+      end
+
       {:ok, activity}
     else
       _e -> :error
     end
   end
 
-  def handle_incoming(%{"type" => "Like", "object" => object_id, "actor" => actor, "id" => id} = data) do
-    with %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, object} <- get_obj_helper(object_id) || ActivityPub.fetch_object_from_id(object_id),
-         {:ok, activity, object} <- ActivityPub.like(actor, object, id, false) do
+  def handle_incoming(
+        %{"type" => "Reject", "object" => follow_object, "actor" => actor, "id" => id} = data
+      ) do
+    with actor <- get_actor(data),
+         %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"),
+         %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.ap_id,
+             object: follow_activity.data["id"],
+             local: false
+           }) do
+      User.unfollow(follower, followed)
+
       {:ok, activity}
     else
       _e -> :error
     end
   end
 
-  def handle_incoming(%{"type" => "Announce", "object" => object_id, "actor" => actor, "id" => id} = data) do
-    with %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, object} <- get_obj_helper(object_id) || ActivityPub.fetch_object_from_id(object_id),
-         {:ok, activity, object} <- ActivityPub.announce(actor, object, id, false) do
+  def handle_incoming(
+        %{"type" => "Like", "object" => object_id, "actor" => actor, "id" => id} = data
+      ) do
+    with actor <- get_actor(data),
+         %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
+         {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+         {:ok, activity, _object} <- ActivityPub.like(actor, object, id, false) do
       {:ok, activity}
     else
       _e -> :error
     end
   end
 
-  def handle_incoming(%{"type" => "Update", "object" => %{"type" => "Person"} = object, "actor" => actor_id} = data) do
+  def handle_incoming(
+        %{"type" => "Announce", "object" => object_id, "actor" => actor, "id" => id} = data
+      ) do
+    with actor <- get_actor(data),
+         %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
+         {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+         {:ok, activity, _object} <- ActivityPub.announce(actor, object, id, false) do
+      {:ok, activity}
+    else
+      _e -> :error
+    end
+  end
+
+  def handle_incoming(
+        %{"type" => "Update", "object" => %{"type" => object_type} = object, "actor" => actor_id} =
+          data
+      )
+      when object_type in ["Person", "Application", "Service", "Organization"] do
     with %User{ap_id: ^actor_id} = actor <- User.get_by_ap_id(object["id"]) do
       {:ok, new_user_data} = ActivityPub.user_data_from_user_object(object)
 
       banner = new_user_data[:info]["banner"]
-      update_data = new_user_data
-      |> Map.take([:name, :bio, :avatar])
-      |> Map.put(:info, Map.merge(actor.info, %{"banner" => banner}))
+      locked = new_user_data[:info]["locked"] || false
+
+      update_data =
+        new_user_data
+        |> Map.take([:name, :bio, :avatar])
+        |> Map.put(:info, Map.merge(actor.info, %{"banner" => banner, "locked" => locked}))
 
       actor
       |> User.upgrade_changeset(update_data)
       |> User.update_and_set_cache()
 
-      ActivityPub.update(%{local: false, to: data["to"] || [], cc: data["cc"] || [], object: object, actor: actor_id})
+      ActivityPub.update(%{
+        local: false,
+        to: data["to"] || [],
+        cc: data["cc"] || [],
+        object: object,
+        actor: actor_id
+      })
     else
       e ->
         Logger.error(e)
@@ -158,29 +467,122 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     end
   end
 
-  # TODO: Make secure.
-  def handle_incoming(%{"type" => "Delete", "object" => object_id, "actor" => actor, "id" => id} = data) do
-    object_id = case object_id do
-                  %{"id" => id} -> id
-                  id -> id
-                end
-    with %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
-         {:ok, object} <- get_obj_helper(object_id) || ActivityPub.fetch_object_from_id(object_id),
+  # TODO: We presently assume that any actor on the same origin domain as the object being
+  # deleted has the rights to delete that object.  A better way to validate whether or not
+  # the object should be deleted is to refetch the object URI, which should return either
+  # 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
+      ) do
+    object_id = Utils.get_ap_id(object_id)
+
+    with actor <- get_actor(data),
+         %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
+         {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+         :ok <- contain_origin(actor.ap_id, object.data),
          {:ok, activity} <- ActivityPub.delete(object, false) do
       {:ok, activity}
+    else
+      _e -> :error
+    end
+  end
+
+  def handle_incoming(
+        %{
+          "type" => "Undo",
+          "object" => %{"type" => "Announce", "object" => object_id},
+          "actor" => actor,
+          "id" => id
+        } = data
+      ) do
+    with actor <- get_actor(data),
+         %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
+         {:ok, object} <- get_obj_helper(object_id) || fetch_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",
+          "object" => %{"type" => "Follow", "object" => followed},
+          "actor" => follower,
+          "id" => id
+        } = _data
+      ) do
+    with %User{local: true} = followed <- User.get_cached_by_ap_id(followed),
+         %User{} = follower <- User.get_or_fetch_by_ap_id(follower),
+         {:ok, activity} <- ActivityPub.unfollow(follower, followed, id, false) do
+      User.unfollow(follower, followed)
+      {:ok, activity}
+    else
+      e -> :error
+    end
+  end
+
+  def handle_incoming(
+        %{
+          "type" => "Undo",
+          "object" => %{"type" => "Block", "object" => blocked},
+          "actor" => blocker,
+          "id" => id
+        } = _data
+      ) do
+    with true <- Pleroma.Config.get([:activitypub, :accept_blocks]),
+         %User{local: true} = blocked <- User.get_cached_by_ap_id(blocked),
+         %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
+      ) do
+    with true <- Pleroma.Config.get([:activitypub, :accept_blocks]),
+         %User{local: true} = blocked = User.get_cached_by_ap_id(blocked),
+         %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
 
-  # TODO
-  # Accept
-  # Undo
+  def handle_incoming(
+        %{
+          "type" => "Undo",
+          "object" => %{"type" => "Like", "object" => object_id},
+          "actor" => actor,
+          "id" => id
+        } = data
+      ) do
+    with actor <- get_actor(data),
+         %User{} = actor <- User.get_or_fetch_by_ap_id(actor),
+         {:ok, object} <- get_obj_helper(object_id) || fetch_obj_helper(object_id),
+         {:ok, activity, _, _} <- ActivityPub.unlike(actor, object, id, false) do
+      {:ok, activity}
+    else
+      _e -> :error
+    end
+  end
 
   def handle_incoming(_), do: :error
 
+  def fetch_obj_helper(id) when is_bitstring(id), do: ActivityPub.fetch_object_from_id(id)
+  def fetch_obj_helper(obj) when is_map(obj), do: ActivityPub.fetch_object_from_id(obj["id"])
+
   def get_obj_helper(id) do
-    if object = Object.get_by_ap_id(id), do: {:ok, object}, else: nil
+    if object = Object.normalize(id), do: {:ok, object}, else: nil
   end
 
   def set_reply_to_uri(%{"inReplyTo" => inReplyTo} = object) do
@@ -191,6 +593,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
       _e -> object
     end
   end
+
   def set_reply_to_uri(obj), do: obj
 
   # Prepares the object of an outgoing create activity.
@@ -204,40 +607,87 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     |> prepare_attachments
     |> set_conversation
     |> set_reply_to_uri
+    |> strip_internal_fields
+    |> strip_internal_tags
   end
 
-  @doc
-  """
-  internal -> Mastodon
-  """
+  #  @doc
+  #  """
+  #  internal -> Mastodon
+  #  """
+
   def prepare_outgoing(%{"type" => "Create", "object" => %{"type" => "Note"} = object} = data) do
-    object = object
-    |> prepare_object
-    data = data
-    |> Map.put("object", object)
-    |> Map.put("@context", "https://www.w3.org/ns/activitystreams")
+    object =
+      object
+      |> prepare_object
+
+    data =
+      data
+      |> Map.put("object", object)
+      |> Map.merge(Utils.make_json_ld_header())
 
     {:ok, data}
   end
 
-  def prepare_outgoing(%{"type" => type} = data) do
-    data = data
-    |> maybe_fix_object_url
-    |> Map.put("@context", "https://www.w3.org/ns/activitystreams")
+  # Mastodon Accept/Reject requires a non-normalized object containing the actor URIs,
+  # because of course it does.
+  def prepare_outgoing(%{"type" => "Accept"} = data) do
+    with follow_activity <- Activity.normalize(data["object"]) do
+      object = %{
+        "actor" => follow_activity.actor,
+        "object" => follow_activity.data["object"],
+        "id" => follow_activity.data["id"],
+        "type" => "Follow"
+      }
+
+      data =
+        data
+        |> Map.put("object", object)
+        |> Map.merge(Utils.make_json_ld_header())
+
+      {:ok, data}
+    end
+  end
+
+  def prepare_outgoing(%{"type" => "Reject"} = data) do
+    with follow_activity <- Activity.normalize(data["object"]) do
+      object = %{
+        "actor" => follow_activity.actor,
+        "object" => follow_activity.data["object"],
+        "id" => follow_activity.data["id"],
+        "type" => "Follow"
+      }
+
+      data =
+        data
+        |> Map.put("object", object)
+        |> Map.merge(Utils.make_json_ld_header())
+
+      {:ok, data}
+    end
+  end
+
+  def prepare_outgoing(%{"type" => _type} = data) do
+    data =
+      data
+      |> maybe_fix_object_url
+      |> Map.merge(Utils.make_json_ld_header())
 
     {:ok, data}
   end
 
   def maybe_fix_object_url(data) do
     if is_binary(data["object"]) and not String.starts_with?(data["object"], "http") do
-      case ActivityPub.fetch_object_from_id(data["object"]) do
+      case fetch_obj_helper(data["object"]) do
         {:ok, relative_object} ->
           if relative_object.data["external_url"] do
-            data = data
-            |> Map.put("object", relative_object.data["external_url"])
+            _data =
+              data
+              |> Map.put("object", relative_object.data["external_url"])
           else
             data
           end
+
         e ->
           Logger.error("Couldn't fetch #{data["object"]} #{inspect(e)}")
           data
@@ -248,19 +698,27 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def add_hashtags(object) do
-    tags = (object["tag"] || [])
-    |> Enum.map fn (tag) -> %{"href" => Pleroma.Web.Endpoint.url() <> "/tags/#{tag}", "name" => "##{tag}", "type" => "Hashtag"} end
+    tags =
+      (object["tag"] || [])
+      |> Enum.map(fn tag ->
+        %{
+          "href" => Pleroma.Web.Endpoint.url() <> "/tags/#{tag}",
+          "name" => "##{tag}",
+          "type" => "Hashtag"
+        }
+      end)
 
     object
     |> Map.put("tag", tags)
   end
 
   def add_mention_tags(object) do
-    recipients = object["to"] ++ (object["cc"] || [])
-    mentions = recipients
-    |> Enum.map(fn (ap_id) -> User.get_cached_by_ap_id(ap_id) end)
-    |> Enum.filter(&(&1))
-    |> Enum.map(fn(user) -> %{"type" => "Mention", "href" => user.ap_id, "name" => "@#{user.nickname}"} end)
+    mentions =
+      object
+      |> Utils.get_notified_from_object()
+      |> Enum.map(fn user ->
+        %{"type" => "Mention", "href" => user.ap_id, "name" => "@#{user.nickname}"}
+      end)
 
     tags = object["tag"] || []
 
@@ -272,13 +730,18 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   def add_emoji_tags(object) do
     tags = object["tag"] || []
     emoji = object["emoji"] || []
-    out = emoji |> Enum.map(fn {name, url} ->
-      %{"icon" => %{"url" => url, "type" => "Image"},
-        "name" => ":" <> name <> ":",
-        "type" => "Emoji",
-        "updated" => "1970-01-01T00:00:00Z",
-        "id" => url}
-    end)
+
+    out =
+      emoji
+      |> Enum.map(fn {name, url} ->
+        %{
+          "icon" => %{"url" => url, "type" => "Image"},
+          "name" => ":" <> name <> ":",
+          "type" => "Emoji",
+          "updated" => "1970-01-01T00:00:00Z",
+          "id" => url
+        }
+      end)
 
     object
     |> Map.put("tag", tags ++ out)
@@ -301,21 +764,60 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
   end
 
   def prepare_attachments(object) do
-    attachments = (object["attachment"] || [])
-    |> Enum.map(fn (data) ->
-      [%{"mediaType" => media_type, "href" => href} | _] = data["url"]
-      %{"url" => href, "mediaType" => media_type, "name" => data["name"], "type" => "Document"}
-    end)
+    attachments =
+      (object["attachment"] || [])
+      |> Enum.map(fn data ->
+        [%{"mediaType" => media_type, "href" => href} | _] = data["url"]
+        %{"url" => href, "mediaType" => media_type, "name" => data["name"], "type" => "Document"}
+      end)
 
     object
     |> Map.put("attachment", attachments)
   end
 
+  defp strip_internal_fields(object) do
+    object
+    |> Map.drop([
+      "likes",
+      "like_count",
+      "announcements",
+      "announcement_count",
+      "emoji",
+      "context_id"
+    ])
+  end
+
+  defp strip_internal_tags(%{"tag" => tags} = object) do
+    tags =
+      tags
+      |> Enum.filter(fn x -> is_map(x) end)
+
+    object
+    |> Map.put("tag", tags)
+  end
+
+  defp strip_internal_tags(object), do: object
+
   defp user_upgrade_task(user) do
     old_follower_address = User.ap_followers(user)
-    q  = from u in User,
-    where: ^old_follower_address in u.following,
-    update: [set: [following: fragment("array_replace(?,?,?)", u.following, ^old_follower_address, ^user.follower_address)]]
+
+    q =
+      from(
+        u in User,
+        where: ^old_follower_address in u.following,
+        update: [
+          set: [
+            following:
+              fragment(
+                "array_replace(?,?,?)",
+                u.following,
+                ^old_follower_address,
+                ^user.follower_address
+              )
+          ]
+        ]
+      )
+
     Repo.update_all(q, [])
 
     maybe_retire_websub(user.ap_id)
@@ -323,22 +825,40 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
     # Only do this for recent activties, don't go through the whole db.
     # Only look at the last 1000 activities.
     since = (Repo.aggregate(Activity, :max, :id) || 0) - 1_000
-    q  = from a in Activity,
-    where: ^old_follower_address in a.recipients,
-    where: a.id > ^since,
-    update: [set: [recipients: fragment("array_replace(?,?,?)", a.recipients, ^old_follower_address, ^user.follower_address)]]
+
+    q =
+      from(
+        a in Activity,
+        where: ^old_follower_address in a.recipients,
+        where: a.id > ^since,
+        update: [
+          set: [
+            recipients:
+              fragment(
+                "array_replace(?,?,?)",
+                a.recipients,
+                ^old_follower_address,
+                ^user.follower_address
+              )
+          ]
+        ]
+      )
+
     Repo.update_all(q, [])
   end
 
   def upgrade_user_from_ap_id(ap_id, async \\ true) do
     with %User{local: false} = user <- User.get_by_ap_id(ap_id),
          {:ok, data} <- ActivityPub.fetch_and_prepare_user_from_ap_id(ap_id) do
-      data = data
-      |> Map.put(:info, Map.merge(user.info, data[:info]))
+      data =
+        data
+        |> Map.put(:info, Map.merge(user.info, data[:info]))
 
       already_ap = User.ap_enabled?(user)
-      {:ok, user} = User.upgrade_changeset(user, data)
-      |> Repo.update()
+
+      {:ok, user} =
+        User.upgrade_changeset(user, data)
+        |> Repo.update()
 
       if !already_ap do
         # This could potentially take a long time, do it in the background
@@ -359,10 +879,27 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
   def maybe_retire_websub(ap_id) do
     # some sanity checks
-    if is_binary(ap_id) && (String.length(ap_id) > 8) do
-      q = from ws in Pleroma.Web.Websub.WebsubClientSubscription,
-        where: fragment("? like ?", ws.topic, ^"#{ap_id}%")
+    if is_binary(ap_id) && String.length(ap_id) > 8 do
+      q =
+        from(
+          ws in Pleroma.Web.Websub.WebsubClientSubscription,
+          where: fragment("? like ?", ws.topic, ^"#{ap_id}%")
+        )
+
       Repo.delete_all(q)
     end
   end
+
+  def maybe_fix_user_url(data) do
+    if is_map(data["url"]) do
+      Map.put(data, "url", data["url"]["href"])
+    else
+      data
+    end
+  end
+
+  def maybe_fix_user_object(data) do
+    data
+    |> maybe_fix_user_url
+  end
 end