Merge branch 'develop' into feature/mstdn-direct-api
[akkoma] / lib / pleroma / web / activity_pub / activity_pub.ex
index 5937ec88cf6e69189f1e8e22ea242b92ad2444f1..f07e26afd02dd9e475caf396acb39da3d3d2c614 100644 (file)
 defmodule Pleroma.Web.ActivityPub.ActivityPub do
-  alias Pleroma.Repo
-  alias Pleroma.{Activity, Object, Upload, User}
+  alias Pleroma.{Activity, Repo, Object, Upload, User, Notification}
+  alias Pleroma.Web.ActivityPub.{Transmogrifier, MRF}
+  alias Pleroma.Web.WebFinger
+  alias Pleroma.Web.Federator
+  alias Pleroma.Web.OStatus
   import Ecto.Query
+  import Pleroma.Web.ActivityPub.Utils
+  require Logger
 
-  def insert(map) when is_map(map) do
-    map = map
-    |> Map.put_new_lazy("id", &generate_activity_id/0)
-    |> Map.put_new_lazy("published", &make_date/0)
+  @httpoison Application.get_env(:pleroma, :httpoison)
 
-    map = if is_map(map["object"]) do
-      object = Map.put_new_lazy(map["object"], "id", &generate_object_id/0)
-      Repo.insert!(%Object{data: object})
-      Map.put(map, "object", object)
+  @instance Application.get_env(:pleroma, :instance)
+
+  def get_recipients(data) do
+    (data["to"] || []) ++ (data["cc"] || [])
+  end
+
+  defp check_actor_is_active(actor) do
+    if not is_nil(actor) do
+      with user <- User.get_cached_by_ap_id(actor),
+           nil <- user.info["deactivated"] do
+        :ok
+      else
+        _e -> :reject
+      end
     else
-      map
+      :ok
     end
+  end
 
-    Repo.insert(%Activity{data: map})
+  def insert(map, local \\ true) when is_map(map) do
+    with nil <- Activity.get_by_ap_id(map["id"]),
+         map <- lazy_put_activity_defaults(map),
+         :ok <- check_actor_is_active(map["actor"]),
+         {:ok, map} <- MRF.filter(map),
+         :ok <- insert_full_object(map) do
+      {:ok, activity} =
+        Repo.insert(%Activity{
+          data: map,
+          local: local,
+          actor: map["actor"],
+          recipients: get_recipients(map)
+        })
+
+      Notification.create_notifications(activity)
+      stream_out(activity)
+      {:ok, activity}
+    else
+      %Activity{} = activity -> {:ok, activity}
+      error -> {:error, error}
+    end
   end
 
-  def like(%User{ap_id: ap_id} = user, %Object{data: %{ "id" => id}} = object) do
-    cond do
-      # There's already a like here, so return the original activity.
-      ap_id in (object.data["likes"] || []) ->
-        query = from activity in Activity,
-          where: fragment("? @> ?", activity.data, ^%{actor: ap_id, object: id, type: "Like"})
+  def stream_out(activity) do
+    public = "https://www.w3.org/ns/activitystreams#Public"
+
+    if activity.data["type"] in ["Create", "Announce"] do
+      Pleroma.Web.Streamer.stream("user", activity)
+
+      if Enum.member?(activity.data["to"], public) do
+        Pleroma.Web.Streamer.stream("public", activity)
+
+        if activity.local do
+          Pleroma.Web.Streamer.stream("public:local", activity)
+        end
+      else
+        if !Enum.member?(activity.data["cc"] || [], public) &&
+             !Enum.member?(
+               activity.data["to"],
+               User.get_by_ap_id(activity.data["actor"]).follower_address
+             ),
+           do: Pleroma.Web.Streamer.stream("direct", activity)
+      end
+    end
+  end
 
-        activity = Repo.one(query)
-        {:ok, activity, object}
-      true ->
-        data = %{
-          "type" => "Like",
-          "actor" => ap_id,
-          "object" => id,
-          "to" => [User.ap_followers(user), object.data["actor"]]
-        }
+  def create(%{to: to, actor: actor, context: context, object: object} = params) do
+    additional = params[:additional] || %{}
+    # only accept false as false value
+    local = !(params[:local] == false)
+    published = params[:published]
+
+    with create_data <-
+           make_create_data(
+             %{to: to, actor: actor, published: published, context: context, object: object},
+             additional
+           ),
+         {:ok, activity} <- insert(create_data, local),
+         :ok <- maybe_federate(activity),
+         {:ok, _actor} <- User.increase_note_count(actor) do
+      {:ok, activity}
+    end
+  end
 
-        {:ok, activity} = insert(data)
+  def accept(%{to: to, actor: actor, object: object} = params) do
+    # only accept false as false value
+    local = !(params[:local] == false)
 
-        likes = [ap_id | (object.data["likes"] || [])] |> Enum.uniq
+    with data <- %{"to" => to, "type" => "Accept", "actor" => actor, "object" => object},
+         {:ok, activity} <- insert(data, local),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity}
+    end
+  end
 
-        new_data = object.data
-        |> Map.put("like_count", length(likes))
-        |> Map.put("likes", likes)
+  def update(%{to: to, cc: cc, actor: actor, object: object} = params) do
+    # only accept false as false value
+    local = !(params[:local] == false)
+
+    with data <- %{
+           "to" => to,
+           "cc" => cc,
+           "type" => "Update",
+           "actor" => actor,
+           "object" => object
+         },
+         {:ok, activity} <- insert(data, local),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity}
+    end
+  end
 
-        changeset = Ecto.Changeset.change(object, data: new_data)
-        {:ok, object} = Repo.update(changeset)
+  # TODO: This is weird, maybe we shouldn't check here if we can make the activity.
+  def like(
+        %User{ap_id: ap_id} = user,
+        %Object{data: %{"id" => _}} = object,
+        activity_id \\ nil,
+        local \\ true
+      ) do
+    with nil <- get_existing_like(ap_id, object),
+         like_data <- make_like_data(user, object, activity_id),
+         {:ok, activity} <- insert(like_data, local),
+         {:ok, object} <- add_like_to_object(activity, object),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity, object}
+    else
+      %Activity{} = activity -> {:ok, activity, object}
+      error -> {:error, error}
+    end
+  end
 
-        update_object_in_activities(object)
+  def unlike(
+        %User{} = actor,
+        %Object{} = object,
+        activity_id \\ nil,
+        local \\ true
+      ) 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
+      _e -> {:ok, object}
+    end
+  end
 
-        {:ok, activity, object}
+  def announce(
+        %User{ap_id: _} = user,
+        %Object{data: %{"id" => _}} = object,
+        activity_id \\ nil,
+        local \\ true
+      ) do
+    with true <- is_public?(object),
+         announce_data <- make_announce_data(user, object, activity_id),
+         {:ok, activity} <- insert(announce_data, local),
+         {:ok, object} <- add_announce_to_object(activity, object),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity, object}
+    else
+      error -> {:error, error}
     end
   end
 
-  defp update_object_in_activities(%{data: %{"id" => id}} = object) do
-    # Update activities that already had this. Could be done in a seperate process.
-    relevant_activities = Activity.all_by_object_ap_id(id)
-    Enum.map(relevant_activities, fn (activity) ->
-      new_activity_data = activity.data |> Map.put("object", object.data)
-      changeset = Ecto.Changeset.change(activity, data: new_activity_data)
-      Repo.update(changeset)
-    end)
+  def unannounce(
+        %User{} = actor,
+        %Object{} = object,
+        activity_id \\ nil,
+        local \\ true
+      ) 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, announce_activity, object}
+    else
+      _e -> {:ok, object}
+    end
   end
 
-  def unlike(%User{ap_id: ap_id}, %Object{data: %{ "id" => id}} = object) do
-    query = from activity in Activity,
-      where: fragment("? @> ?", activity.data, ^%{actor: ap_id, object: id, type: "Like"})
+  def follow(follower, followed, activity_id \\ nil, local \\ true) do
+    with data <- make_follow_data(follower, followed, activity_id),
+         {:ok, activity} <- insert(data, local),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity}
+    end
+  end
 
-    activity = Repo.one(query)
+  def unfollow(follower, followed, local \\ true) do
+    with %Activity{} = follow_activity <- fetch_latest_follow(follower, followed),
+         unfollow_data <- make_unfollow_data(follower, followed, follow_activity),
+         {:ok, activity} <- insert(unfollow_data, local),
+         :ok,
+         maybe_federate(activity) do
+      {:ok, activity}
+    end
+  end
 
-    if activity do
-      # just delete for now...
-      {:ok, _activity} = Repo.delete(activity)
+  def delete(%Object{data: %{"id" => id, "actor" => actor}} = object, local \\ true) do
+    user = User.get_cached_by_ap_id(actor)
 
-      likes = (object.data["likes"] || []) |> List.delete(ap_id)
+    data = %{
+      "type" => "Delete",
+      "actor" => actor,
+      "object" => id,
+      "to" => [user.follower_address, "https://www.w3.org/ns/activitystreams#Public"]
+    }
 
-      new_data = object.data
-      |> Map.put("like_count", length(likes))
-      |> Map.put("likes", likes)
+    with Repo.delete(object),
+         Repo.delete_all(Activity.all_non_create_by_object_ap_id_q(id)),
+         {:ok, activity} <- insert(data, local),
+         :ok <- maybe_federate(activity),
+         {:ok, _actor} <- User.decrease_note_count(user) do
+      {:ok, activity}
+    end
+  end
 
-      changeset = Ecto.Changeset.change(object, data: new_data)
-      {:ok, object} = Repo.update(changeset)
+  def fetch_activities_for_context(context, opts \\ %{}) do
+    public = ["https://www.w3.org/ns/activitystreams#Public"]
 
-      update_object_in_activities(object)
+    recipients =
+      if opts["user"], do: [opts["user"].ap_id | opts["user"].following] ++ public, else: public
 
-      {:ok, object}
-    else
-      {:ok, object}
-    end
+    query = from(activity in Activity)
+
+    query =
+      query
+      |> restrict_blocked(opts)
+      |> restrict_recipients(recipients, opts["user"])
+
+    query =
+      from(
+        activity in query,
+        where:
+          fragment(
+            "?->>'type' = ? and ?->>'context' = ?",
+            activity.data,
+            "Create",
+            activity.data,
+            ^context
+          ),
+        order_by: [desc: :id]
+      )
+
+    Repo.all(query)
   end
 
-  def generate_activity_id do
-    generate_id("activities")
+  def fetch_public_activities(opts \\ %{}) do
+    q = fetch_activities_query(["https://www.w3.org/ns/activitystreams#Public"], opts)
+
+    q
+    |> restrict_unlisted()
+    |> Repo.all()
+    |> Enum.reverse()
   end
 
-  def generate_context_id do
-    generate_id("contexts")
+  @valid_visibilities ~w[direct unlisted public private]
+
+  defp restrict_visibility(query, %{visibility: "direct"}) do
+    public = "https://www.w3.org/ns/activitystreams#Public"
+
+    from(
+      activity in query,
+      join: sender in User,
+      on: sender.ap_id == activity.actor,
+      # Are non-direct statuses with no to/cc possible?
+      where:
+        fragment("not coalesce(data->'to' \\? ?, false)", ^public) and
+          fragment("not coalesce(data->'cc' \\? ?, false)", ^public) and
+          fragment("not coalesce(data->'to' \\? ?, false)", sender.follower_address)
+    )
   end
 
-  def generate_object_id do
-    generate_id("objects")
+  defp restrict_visibility(_query, %{visibility: visibility})
+       when visibility not in @valid_visibilities do
+    Logger.error("Could not restrict visibility to #{visibility}")
   end
 
-  def generate_id(type) do
-    "#{Pleroma.Web.base_url()}/#{type}/#{Ecto.UUID.generate}"
+  defp restrict_visibility(query, _visibility), do: query
+
+  def fetch_user_activities(user, reading_user, params \\ %{}) do
+    params =
+      params
+      |> Map.put("type", ["Create", "Announce"])
+      |> Map.put("actor_id", user.ap_id)
+      |> Map.put("whole_db", true)
+
+    recipients =
+      if reading_user do
+        ["https://www.w3.org/ns/activitystreams#Public"] ++
+          [reading_user.ap_id | reading_user.following]
+      else
+        ["https://www.w3.org/ns/activitystreams#Public"]
+      end
+
+    fetch_activities(recipients, params)
+    |> Enum.reverse()
   end
 
-  def fetch_public_activities(opts \\ %{}) do
-    public = ["https://www.w3.org/ns/activitystreams#Public"]
-    fetch_activities(public, opts)
+  defp restrict_since(query, %{"since_id" => since_id}) do
+    from(activity in query, where: activity.id > ^since_id)
   end
 
-  def fetch_activities(recipients, opts \\ %{}) do
-    since_id = opts["since_id"] || 0
+  defp restrict_since(query, _), do: query
 
-    query = from activity in Activity,
-      limit: 20,
-      order_by: [desc: :inserted_at]
+  defp restrict_tag(query, %{"tag" => tag}) do
+    from(
+      activity in query,
+      where: fragment("? <@ (? #> '{\"object\",\"tag\"}')", ^tag, activity.data)
+    )
+  end
 
-    query = Enum.reduce(recipients, query, fn (recipient, q) ->
-      map = %{ to: [recipient] }
-      from activity in q,
-      or_where: fragment(~s(? @> ?), activity.data, ^map)
-    end)
+  defp restrict_tag(query, _), do: query
 
-    query = from activity in query,
-      where: activity.id > ^since_id
+  defp restrict_recipients(query, [], _user), do: query
 
-    query = if opts["max_id"] do
-      from activity in query, where: activity.id < ^opts["max_id"]
-    else
-      query
-    end
+  defp restrict_recipients(query, recipients, nil) do
+    from(activity in query, where: fragment("? && ?", ^recipients, activity.recipients))
+  end
 
-    query = if opts["actor_id"] do
-      from activity in query,
-        where: fragment("? @> ?", activity.data, ^%{actor: opts["actor_id"]})
-    else
-      query
-    end
+  defp restrict_recipients(query, recipients, user) do
+    from(
+      activity in query,
+      where: fragment("? && ?", ^recipients, activity.recipients),
+      or_where: activity.actor == ^user.ap_id
+    )
+  end
 
-    Repo.all(query)
-    |> Enum.reverse
+  defp restrict_limit(query, %{"limit" => limit}) do
+    from(activity in query, limit: ^limit)
   end
 
-  def announce(%User{ap_id: ap_id} = user, %Object{data: %{"id" => id}} = object) do
-    data = %{
-      "type" => "Announce",
-      "actor" => ap_id,
-      "object" => id,
-      "to" => [User.ap_followers(user), object.data["actor"]]
-    }
+  defp restrict_limit(query, _), do: query
+
+  defp restrict_local(query, %{"local_only" => true}) do
+    from(activity in query, where: activity.local == true)
+  end
+
+  defp restrict_local(query, _), do: query
 
-    {:ok, activity} = insert(data)
+  defp restrict_max(query, %{"max_id" => max_id}) do
+    from(activity in query, where: activity.id < ^max_id)
+  end
 
-    announcements = [ap_id | (object.data["announcements"] || [])] |> Enum.uniq
+  defp restrict_max(query, _), do: query
 
-    new_data = object.data
-    |> Map.put("announcement_count", length(announcements))
-    |> Map.put("announcements", announcements)
+  defp restrict_actor(query, %{"actor_id" => actor_id}) do
+    from(activity in query, where: activity.actor == ^actor_id)
+  end
 
-    changeset = Ecto.Changeset.change(object, data: new_data)
-    {:ok, object} = Repo.update(changeset)
+  defp restrict_actor(query, _), do: query
 
-    update_object_in_activities(object)
+  defp restrict_type(query, %{"type" => type}) when is_binary(type) do
+    restrict_type(query, %{"type" => [type]})
+  end
 
-    {:ok, activity, object}
+  defp restrict_type(query, %{"type" => type}) do
+    from(activity in query, where: fragment("?->>'type' = ANY(?)", activity.data, ^type))
   end
 
-  def fetch_activities_for_context(context) do
-    query = from activity in Activity,
-      where: fragment("? @> ?", activity.data, ^%{ context: context })
-    Repo.all(query)
+  defp restrict_type(query, _), do: query
+
+  defp restrict_favorited_by(query, %{"favorited_by" => ap_id}) do
+    from(
+      activity in query,
+      where: fragment("? <@ (? #> '{\"object\",\"likes\"}')", ^ap_id, activity.data)
+    )
+  end
+
+  defp restrict_favorited_by(query, _), do: query
+
+  defp restrict_media(query, %{"only_media" => val}) when val == "true" or val == "1" do
+    from(
+      activity in query,
+      where: fragment("not (? #> '{\"object\",\"attachment\"}' = ?)", activity.data, ^[])
+    )
   end
 
-  def fetch_latest_follow(%User{ap_id: follower_id},
-                          %User{ap_id: followed_id}) do
-    query = from activity in Activity,
-      where: fragment("? @> ?", activity.data, ^%{type: "Follow", actor: follower_id,
-                                                  object: followed_id}),
-      order_by: [desc: :inserted_at],
-      limit: 1
-    Repo.one(query)
+  defp restrict_media(query, _), do: query
+
+  # Only search through last 100_000 activities by default
+  defp restrict_recent(query, %{"whole_db" => true}), do: query
+
+  defp restrict_recent(query, _) do
+    since = (Repo.aggregate(Activity, :max, :id) || 0) - 100_000
+
+    from(activity in query, where: activity.id > ^since)
+  end
+
+  defp restrict_blocked(query, %{"blocking_user" => %User{info: info}}) do
+    blocks = info["blocks"] || []
+
+    from(
+      activity in query,
+      where: fragment("not (? = ANY(?))", activity.actor, ^blocks),
+      where: fragment("not (?->'to' \\?| ?)", activity.data, ^blocks)
+    )
+  end
+
+  defp restrict_blocked(query, _), do: query
+
+  defp restrict_unlisted(query) do
+    from(
+      activity in query,
+      where:
+        fragment(
+          "not (coalesce(?->'cc', '{}'::jsonb) \\?| ?)",
+          activity.data,
+          ^["https://www.w3.org/ns/activitystreams#Public"]
+        )
+    )
+  end
+
+  def fetch_activities_query(recipients, opts \\ %{}) do
+    base_query =
+      from(
+        activity in Activity,
+        limit: 20,
+        order_by: [fragment("? desc nulls last", activity.id)]
+      )
+
+    base_query
+    |> restrict_recipients(recipients, opts["user"])
+    |> restrict_tag(opts)
+    |> restrict_since(opts)
+    |> restrict_local(opts)
+    |> restrict_limit(opts)
+    |> restrict_max(opts)
+    |> restrict_actor(opts)
+    |> restrict_type(opts)
+    |> restrict_favorited_by(opts)
+    |> restrict_recent(opts)
+    |> restrict_blocked(opts)
+    |> restrict_media(opts)
+    |> restrict_visibility(opts)
+  end
+
+  def fetch_activities(recipients, opts \\ %{}) do
+    fetch_activities_query(recipients, opts)
+    |> Repo.all()
+    |> Enum.reverse()
   end
 
   def upload(file) do
@@ -189,7 +461,170 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     Repo.insert(%Object{data: data})
   end
 
-  defp make_date do
-    DateTime.utc_now() |> DateTime.to_iso8601
+  def user_data_from_user_object(data) do
+    avatar =
+      data["icon"]["url"] &&
+        %{
+          "type" => "Image",
+          "url" => [%{"href" => data["icon"]["url"]}]
+        }
+
+    banner =
+      data["image"]["url"] &&
+        %{
+          "type" => "Image",
+          "url" => [%{"href" => data["image"]["url"]}]
+        }
+
+    data = Transmogrifier.maybe_fix_user_object(data)
+
+    user_data = %{
+      ap_id: data["id"],
+      info: %{
+        "ap_enabled" => true,
+        "source_data" => data,
+        "banner" => banner
+      },
+      avatar: avatar,
+      nickname: "#{data["preferredUsername"]}@#{URI.parse(data["id"]).host}",
+      name: data["name"],
+      follower_address: data["followers"],
+      bio: data["summary"]
+    }
+
+    {:ok, user_data}
+  end
+
+  def fetch_and_prepare_user_from_ap_id(ap_id) do
+    with {:ok, %{status_code: 200, body: body}} <-
+           @httpoison.get(ap_id, Accept: "application/activity+json"),
+         {:ok, data} <- Jason.decode(body) do
+      user_data_from_user_object(data)
+    else
+      e -> Logger.error("Could not decode user at fetch #{ap_id}, #{inspect(e)}")
+    end
+  end
+
+  def make_user_from_ap_id(ap_id) do
+    if _user = User.get_by_ap_id(ap_id) do
+      Transmogrifier.upgrade_user_from_ap_id(ap_id)
+    else
+      with {:ok, data} <- fetch_and_prepare_user_from_ap_id(ap_id) do
+        User.insert_or_update_user(data)
+      else
+        e -> {:error, e}
+      end
+    end
+  end
+
+  def make_user_from_nickname(nickname) do
+    with {:ok, %{"ap_id" => ap_id}} when not is_nil(ap_id) <- WebFinger.finger(nickname) do
+      make_user_from_ap_id(ap_id)
+    else
+      _e -> {:error, "No AP id in WebFinger"}
+    end
+  end
+
+  def publish(actor, activity) do
+    followers =
+      if actor.follower_address in activity.recipients do
+        {:ok, followers} = User.get_followers(actor)
+        followers |> Enum.filter(&(!&1.local))
+      else
+        []
+      end
+
+    remote_inboxes =
+      (Pleroma.Web.Salmon.remote_users(activity) ++ followers)
+      |> Enum.filter(fn user -> User.ap_enabled?(user) end)
+      |> Enum.map(fn %{info: %{"source_data" => data}} ->
+        (data["endpoints"] && data["endpoints"]["sharedInbox"]) || data["inbox"]
+      end)
+      |> Enum.uniq()
+
+    {:ok, data} = Transmogrifier.prepare_outgoing(activity.data)
+    json = Jason.encode!(data)
+
+    Enum.each(remote_inboxes, fn inbox ->
+      Federator.enqueue(:publish_single_ap, %{
+        inbox: inbox,
+        json: json,
+        actor: actor,
+        id: activity.data["id"]
+      })
+    end)
+  end
+
+  def publish_one(%{inbox: inbox, json: json, actor: actor, id: id}) do
+    Logger.info("Federating #{id} to #{inbox}")
+    host = URI.parse(inbox).host
+
+    signature =
+      Pleroma.Web.HTTPSignatures.sign(actor, %{host: host, "content-length": byte_size(json)})
+
+    @httpoison.post(
+      inbox,
+      json,
+      [{"Content-Type", "application/activity+json"}, {"signature", signature}],
+      hackney: [pool: :default]
+    )
+  end
+
+  # TODO:
+  # This will create a Create activity, which we need internally at the moment.
+  def fetch_object_from_id(id) do
+    if object = Object.get_cached_by_ap_id(id) do
+      {:ok, object}
+    else
+      Logger.info("Fetching #{id} via AP")
+
+      with true <- String.starts_with?(id, "http"),
+           {:ok, %{body: body, status_code: code}} when code in 200..299 <-
+             @httpoison.get(
+               id,
+               [Accept: "application/activity+json"],
+               follow_redirect: true,
+               timeout: 10000,
+               recv_timeout: 20000
+             ),
+           {:ok, data} <- Jason.decode(body),
+           nil <- Object.get_by_ap_id(data["id"]),
+           params <- %{
+             "type" => "Create",
+             "to" => data["to"],
+             "cc" => data["cc"],
+             "actor" => data["attributedTo"],
+             "object" => data
+           },
+           {:ok, activity} <- Transmogrifier.handle_incoming(params) do
+        {:ok, Object.get_by_ap_id(activity.data["object"]["id"])}
+      else
+        object = %Object{} ->
+          {:ok, object}
+
+        _e ->
+          Logger.info("Couldn't get object via AP, trying out OStatus fetching...")
+
+          case OStatus.fetch_activity_from_url(id) do
+            {:ok, [activity | _]} -> {:ok, Object.get_by_ap_id(activity.data["object"]["id"])}
+            e -> e
+          end
+      end
+    end
+  end
+
+  def is_public?(activity) do
+    "https://www.w3.org/ns/activitystreams#Public" in (activity.data["to"] ++
+                                                         (activity.data["cc"] || []))
+  end
+
+  def visible_for_user?(activity, nil) do
+    is_public?(activity)
+  end
+
+  def visible_for_user?(activity, user) do
+    x = [user.ap_id | user.following]
+    y = activity.data["to"] ++ (activity.data["cc"] || [])
+    visible_for_user?(activity, nil) || Enum.any?(x, &(&1 in y))
   end
 end