git.squeep.com Git - akkoma/blob - lib/pleroma/web/activity_pub/activity_pub.ex

   1 defmodule Pleroma.Web.ActivityPub.ActivityPub do
   2   alias Pleroma.{Activity, Repo, Object, Upload, User, Notification}
   3   alias Pleroma.Web.ActivityPub.{Transmogrifier, MRF}
   4   alias Pleroma.Web.WebFinger
   5   alias Pleroma.Web.Federator
   6   alias Pleroma.Web.OStatus
   7   import Ecto.Query
   8   import Pleroma.Web.ActivityPub.Utils
   9   require Logger
  10
  11   @httpoison Application.get_env(:pleroma, :httpoison)
  12
  13   @instance Application.get_env(:pleroma, :instance)
  14
  15   # For Announce activities, we filter the recipients based on following status for any actors
  16   # that match actual users.  See issue #164 for more information about why this is necessary.
  17   defp get_recipients(%{"type" => "Announce"} = data) do
  18     to = data["to"] || []
  19     cc = data["cc"] || []
  20     recipients = to ++ cc
  21     actor = User.get_cached_by_ap_id(data["actor"])
  22
  23     recipients
  24     |> Enum.filter(fn recipient ->
  25       case User.get_cached_by_ap_id(recipient) do
  26         nil ->
  27           true
  28
  29         user ->
  30           User.following?(user, actor)
  31       end
  32     end)
  33
  34     {recipients, to, cc}
  35   end
  36
  37   defp get_recipients(data) do
  38     to = data["to"] || []
  39     cc = data["cc"] || []
  40     recipients = to ++ cc
  41     {recipients, to, cc}
  42   end
  43
  44   defp check_actor_is_active(actor) do
  45     if not is_nil(actor) do
  46       with user <- User.get_cached_by_ap_id(actor),
  47            false <- !!user.info["deactivated"] do
  48         :ok
  49       else
  50         _e -> :reject
  51       end
  52     else
  53       :ok
  54     end
  55   end
  56
  57   def insert(map, local \\ true) when is_map(map) do
  58     with nil <- Activity.normalize(map),
  59          map <- lazy_put_activity_defaults(map),
  60          :ok <- check_actor_is_active(map["actor"]),
  61          {:ok, map} <- MRF.filter(map),
  62          :ok <- insert_full_object(map) do
  63       {recipients, _, _} = get_recipients(map)
  64
  65       {:ok, activity} =
  66         Repo.insert(%Activity{
  67           data: map,
  68           local: local,
  69           actor: map["actor"],
  70           recipients: recipients
  71         })
  72
  73       Notification.create_notifications(activity)
  74       stream_out(activity)
  75       {:ok, activity}
  76     else
  77       %Activity{} = activity -> {:ok, activity}
  78       error -> {:error, error}
  79     end
  80   end
  81
  82   def stream_out(activity) do
  83     public = "https://www.w3.org/ns/activitystreams#Public"
  84
  85     if activity.data["type"] in ["Create", "Announce"] do
  86       Pleroma.Web.Streamer.stream("user", activity)
  87       Pleroma.Web.Streamer.stream("list", activity)
  88
  89       if Enum.member?(activity.data["to"], public) do
  90         Pleroma.Web.Streamer.stream("public", activity)
  91
  92         if activity.local do
  93           Pleroma.Web.Streamer.stream("public:local", activity)
  94         end
  95
  96         activity.data["object"]
  97         |> Map.get("tag", [])
  98         |> Enum.filter(fn tag -> is_bitstring(tag) end)
  99         |> Enum.map(fn tag -> Pleroma.Web.Streamer.stream("hashtag:" <> tag, activity) end)
 100
 101         if activity.data["object"]["attachment"] != [] do
 102           Pleroma.Web.Streamer.stream("public:media", activity)
 103
 104           if activity.local do
 105             Pleroma.Web.Streamer.stream("public:local:media", activity)
 106           end
 107         end
 108       else
 109         if !Enum.member?(activity.data["cc"] || [], public) &&
 110              !Enum.member?(
 111                activity.data["to"],
 112                User.get_by_ap_id(activity.data["actor"]).follower_address
 113              ),
 114            do: Pleroma.Web.Streamer.stream("direct", activity)
 115       end
 116     end
 117   end
 118
 119   def create(%{to: to, actor: actor, context: context, object: object} = params) do
 120     additional = params[:additional] || %{}
 121     # only accept false as false value
 122     local = !(params[:local] == false)
 123     published = params[:published]
 124
 125     with create_data <-
 126            make_create_data(
 127              %{to: to, actor: actor, published: published, context: context, object: object},
 128              additional
 129            ),
 130          {:ok, activity} <- insert(create_data, local),
 131          :ok <- maybe_federate(activity),
 132          {:ok, _actor} <- User.increase_note_count(actor) do
 133       {:ok, activity}
 134     end
 135   end
 136
 137   def accept(%{to: to, actor: actor, object: object} = params) do
 138     # only accept false as false value
 139     local = !(params[:local] == false)
 140
 141     with data <- %{"to" => to, "type" => "Accept", "actor" => actor, "object" => object},
 142          {:ok, activity} <- insert(data, local),
 143          :ok <- maybe_federate(activity) do
 144       {:ok, activity}
 145     end
 146   end
 147
 148   def reject(%{to: to, actor: actor, object: object} = params) do
 149     # only accept false as false value
 150     local = !(params[:local] == false)
 151
 152     with data <- %{"to" => to, "type" => "Reject", "actor" => actor, "object" => object},
 153          {:ok, activity} <- insert(data, local),
 154          :ok <- maybe_federate(activity) do
 155       {:ok, activity}
 156     end
 157   end
 158
 159   def update(%{to: to, cc: cc, actor: actor, object: object} = params) do
 160     # only accept false as false value
 161     local = !(params[:local] == false)
 162
 163     with data <- %{
 164            "to" => to,
 165            "cc" => cc,
 166            "type" => "Update",
 167            "actor" => actor,
 168            "object" => object
 169          },
 170          {:ok, activity} <- insert(data, local),
 171          :ok <- maybe_federate(activity) do
 172       {:ok, activity}
 173     end
 174   end
 175
 176   # TODO: This is weird, maybe we shouldn't check here if we can make the activity.
 177   def like(
 178         %User{ap_id: ap_id} = user,
 179         %Object{data: %{"id" => _}} = object,
 180         activity_id \\ nil,
 181         local \\ true
 182       ) do
 183     with nil <- get_existing_like(ap_id, object),
 184          like_data <- make_like_data(user, object, activity_id),
 185          {:ok, activity} <- insert(like_data, local),
 186          {:ok, object} <- add_like_to_object(activity, object),
 187          :ok <- maybe_federate(activity) do
 188       {:ok, activity, object}
 189     else
 190       %Activity{} = activity -> {:ok, activity, object}
 191       error -> {:error, error}
 192     end
 193   end
 194
 195   def unlike(
 196         %User{} = actor,
 197         %Object{} = object,
 198         activity_id \\ nil,
 199         local \\ true
 200       ) do
 201     with %Activity{} = like_activity <- get_existing_like(actor.ap_id, object),
 202          unlike_data <- make_unlike_data(actor, like_activity, activity_id),
 203          {:ok, unlike_activity} <- insert(unlike_data, local),
 204          {:ok, _activity} <- Repo.delete(like_activity),
 205          {:ok, object} <- remove_like_from_object(like_activity, object),
 206          :ok <- maybe_federate(unlike_activity) do
 207       {:ok, unlike_activity, like_activity, object}
 208     else
 209       _e -> {:ok, object}
 210     end
 211   end
 212
 213   def announce(
 214         %User{ap_id: _} = user,
 215         %Object{data: %{"id" => _}} = object,
 216         activity_id \\ nil,
 217         local \\ true
 218       ) do
 219     with true <- is_public?(object),
 220          announce_data <- make_announce_data(user, object, activity_id),
 221          {:ok, activity} <- insert(announce_data, local),
 222          {:ok, object} <- add_announce_to_object(activity, object),
 223          :ok <- maybe_federate(activity) do
 224       {:ok, activity, object}
 225     else
 226       error -> {:error, error}
 227     end
 228   end
 229
 230   def unannounce(
 231         %User{} = actor,
 232         %Object{} = object,
 233         activity_id \\ nil,
 234         local \\ true
 235       ) do
 236     with %Activity{} = announce_activity <- get_existing_announce(actor.ap_id, object),
 237          unannounce_data <- make_unannounce_data(actor, announce_activity, activity_id),
 238          {:ok, unannounce_activity} <- insert(unannounce_data, local),
 239          :ok <- maybe_federate(unannounce_activity),
 240          {:ok, _activity} <- Repo.delete(announce_activity),
 241          {:ok, object} <- remove_announce_from_object(announce_activity, object) do
 242       {:ok, unannounce_activity, object}
 243     else
 244       _e -> {:ok, object}
 245     end
 246   end
 247
 248   def follow(follower, followed, activity_id \\ nil, local \\ true) do
 249     with data <- make_follow_data(follower, followed, activity_id),
 250          {:ok, activity} <- insert(data, local),
 251          :ok <- maybe_federate(activity) do
 252       {:ok, activity}
 253     end
 254   end
 255
 256   def unfollow(follower, followed, activity_id \\ nil, local \\ true) do
 257     with %Activity{} = follow_activity <- fetch_latest_follow(follower, followed),
 258          {:ok, follow_activity} <- update_follow_state(follow_activity, "cancelled"),
 259          unfollow_data <- make_unfollow_data(follower, followed, follow_activity, activity_id),
 260          {:ok, activity} <- insert(unfollow_data, local),
 261          :ok <- maybe_federate(activity) do
 262       {:ok, activity}
 263     end
 264   end
 265
 266   def delete(%Object{data: %{"id" => id, "actor" => actor}} = object, local \\ true) do
 267     user = User.get_cached_by_ap_id(actor)
 268
 269     data = %{
 270       "type" => "Delete",
 271       "actor" => actor,
 272       "object" => id,
 273       "to" => [user.follower_address, "https://www.w3.org/ns/activitystreams#Public"]
 274     }
 275
 276     with Object.delete(object),
 277          {:ok, activity} <- insert(data, local),
 278          :ok <- maybe_federate(activity),
 279          {:ok, _actor} <- User.decrease_note_count(user) do
 280       {:ok, activity}
 281     end
 282   end
 283
 284   def block(blocker, blocked, activity_id \\ nil, local \\ true) do
 285     ap_config = Application.get_env(:pleroma, :activitypub)
 286     unfollow_blocked = Keyword.get(ap_config, :unfollow_blocked)
 287     outgoing_blocks = Keyword.get(ap_config, :outgoing_blocks)
 288
 289     with true <- unfollow_blocked do
 290       follow_activity = fetch_latest_follow(blocker, blocked)
 291
 292       if follow_activity do
 293         unfollow(blocker, blocked, nil, local)
 294       end
 295     end
 296
 297     with true <- outgoing_blocks,
 298          block_data <- make_block_data(blocker, blocked, activity_id),
 299          {:ok, activity} <- insert(block_data, local),
 300          :ok <- maybe_federate(activity) do
 301       {:ok, activity}
 302     else
 303       _e -> {:ok, nil}
 304     end
 305   end
 306
 307   def unblock(blocker, blocked, activity_id \\ nil, local \\ true) do
 308     with %Activity{} = block_activity <- fetch_latest_block(blocker, blocked),
 309          unblock_data <- make_unblock_data(blocker, blocked, block_activity, activity_id),
 310          {:ok, activity} <- insert(unblock_data, local),
 311          :ok <- maybe_federate(activity) do
 312       {:ok, activity}
 313     end
 314   end
 315
 316   def fetch_activities_for_context(context, opts \\ %{}) do
 317     public = ["https://www.w3.org/ns/activitystreams#Public"]
 318
 319     recipients =
 320       if opts["user"], do: [opts["user"].ap_id | opts["user"].following] ++ public, else: public
 321
 322     query = from(activity in Activity)
 323
 324     query =
 325       query
 326       |> restrict_blocked(opts)
 327       |> restrict_recipients(recipients, opts["user"])
 328
 329     query =
 330       from(
 331         activity in query,
 332         where:
 333           fragment(
 334             "?->>'type' = ? and ?->>'context' = ?",
 335             activity.data,
 336             "Create",
 337             activity.data,
 338             ^context
 339           ),
 340         order_by: [desc: :id]
 341       )
 342
 343     Repo.all(query)
 344   end
 345
 346   def fetch_public_activities(opts \\ %{}) do
 347     q = fetch_activities_query(["https://www.w3.org/ns/activitystreams#Public"], opts)
 348
 349     q
 350     |> restrict_unlisted()
 351     |> Repo.all()
 352     |> Enum.reverse()
 353   end
 354
 355   @valid_visibilities ~w[direct unlisted public private]
 356
 357   defp restrict_visibility(query, %{visibility: "direct"}) do
 358     public = "https://www.w3.org/ns/activitystreams#Public"
 359
 360     from(
 361       activity in query,
 362       join: sender in User,
 363       on: sender.ap_id == activity.actor,
 364       # Are non-direct statuses with no to/cc possible?
 365       where:
 366         fragment(
 367           "not (? && ?)",
 368           [^public, sender.follower_address],
 369           activity.recipients
 370         )
 371     )
 372   end
 373
 374   defp restrict_visibility(_query, %{visibility: visibility})
 375        when visibility not in @valid_visibilities do
 376     Logger.error("Could not restrict visibility to #{visibility}")
 377   end
 378
 379   defp restrict_visibility(query, _visibility), do: query
 380
 381   def fetch_user_activities(user, reading_user, params \\ %{}) do
 382     params =
 383       params
 384       |> Map.put("type", ["Create", "Announce"])
 385       |> Map.put("actor_id", user.ap_id)
 386       |> Map.put("whole_db", true)
 387
 388     recipients =
 389       if reading_user do
 390         ["https://www.w3.org/ns/activitystreams#Public"] ++
 391           [reading_user.ap_id | reading_user.following]
 392       else
 393         ["https://www.w3.org/ns/activitystreams#Public"]
 394       end
 395
 396     fetch_activities(recipients, params)
 397     |> Enum.reverse()
 398   end
 399
 400   defp restrict_since(query, %{"since_id" => since_id}) do
 401     from(activity in query, where: activity.id > ^since_id)
 402   end
 403
 404   defp restrict_since(query, _), do: query
 405
 406   defp restrict_tag(query, %{"tag" => tag}) do
 407     from(
 408       activity in query,
 409       where: fragment("? <@ (? #> '{\"object\",\"tag\"}')", ^tag, activity.data)
 410     )
 411   end
 412
 413   defp restrict_tag(query, _), do: query
 414
 415   defp restrict_to_cc(query, recipients_to, recipients_cc) do
 416     from(
 417       activity in query,
 418       where:
 419         fragment(
 420           "(?->'to' \\?| ?) or (?->'cc' \\?| ?)",
 421           activity.data,
 422           ^recipients_to,
 423           activity.data,
 424           ^recipients_cc
 425         )
 426     )
 427   end
 428
 429   defp restrict_recipients(query, [], _user), do: query
 430
 431   defp restrict_recipients(query, recipients, nil) do
 432     from(activity in query, where: fragment("? && ?", ^recipients, activity.recipients))
 433   end
 434
 435   defp restrict_recipients(query, recipients, user) do
 436     from(
 437       activity in query,
 438       where: fragment("? && ?", ^recipients, activity.recipients),
 439       or_where: activity.actor == ^user.ap_id
 440     )
 441   end
 442
 443   defp restrict_limit(query, %{"limit" => limit}) do
 444     from(activity in query, limit: ^limit)
 445   end
 446
 447   defp restrict_limit(query, _), do: query
 448
 449   defp restrict_local(query, %{"local_only" => true}) do
 450     from(activity in query, where: activity.local == true)
 451   end
 452
 453   defp restrict_local(query, _), do: query
 454
 455   defp restrict_max(query, %{"max_id" => max_id}) do
 456     from(activity in query, where: activity.id < ^max_id)
 457   end
 458
 459   defp restrict_max(query, _), do: query
 460
 461   defp restrict_actor(query, %{"actor_id" => actor_id}) do
 462     from(activity in query, where: activity.actor == ^actor_id)
 463   end
 464
 465   defp restrict_actor(query, _), do: query
 466
 467   defp restrict_type(query, %{"type" => type}) when is_binary(type) do
 468     restrict_type(query, %{"type" => [type]})
 469   end
 470
 471   defp restrict_type(query, %{"type" => type}) do
 472     from(activity in query, where: fragment("?->>'type' = ANY(?)", activity.data, ^type))
 473   end
 474
 475   defp restrict_type(query, _), do: query
 476
 477   defp restrict_favorited_by(query, %{"favorited_by" => ap_id}) do
 478     from(
 479       activity in query,
 480       where: fragment("? <@ (? #> '{\"object\",\"likes\"}')", ^ap_id, activity.data)
 481     )
 482   end
 483
 484   defp restrict_favorited_by(query, _), do: query
 485
 486   defp restrict_media(query, %{"only_media" => val}) when val == "true" or val == "1" do
 487     from(
 488       activity in query,
 489       where: fragment("not (? #> '{\"object\",\"attachment\"}' = ?)", activity.data, ^[])
 490     )
 491   end
 492
 493   defp restrict_media(query, _), do: query
 494
 495   defp restrict_replies(query, %{"exclude_replies" => val}) when val == "true" or val == "1" do
 496     from(
 497       activity in query,
 498       where: fragment("?->'object'->>'inReplyTo' is null", activity.data)
 499     )
 500   end
 501
 502   defp restrict_replies(query, _), do: query
 503
 504   # Only search through last 100_000 activities by default
 505   defp restrict_recent(query, %{"whole_db" => true}), do: query
 506
 507   defp restrict_recent(query, _) do
 508     since = (Repo.aggregate(Activity, :max, :id) || 0) - 100_000
 509
 510     from(activity in query, where: activity.id > ^since)
 511   end
 512
 513   defp restrict_blocked(query, %{"blocking_user" => %User{info: info}}) do
 514     blocks = info["blocks"] || []
 515     domain_blocks = info["domain_blocks"] || []
 516
 517     from(
 518       activity in query,
 519       where: fragment("not (? = ANY(?))", activity.actor, ^blocks),
 520       where: fragment("not (?->'to' \\?| ?)", activity.data, ^blocks),
 521       where: fragment("not (split_part(?, '/', 3) = ANY(?))", activity.actor, ^domain_blocks)
 522     )
 523   end
 524
 525   defp restrict_blocked(query, _), do: query
 526
 527   defp restrict_unlisted(query) do
 528     from(
 529       activity in query,
 530       where:
 531         fragment(
 532           "not (coalesce(?->'cc', '{}'::jsonb) \\?| ?)",
 533           activity.data,
 534           ^["https://www.w3.org/ns/activitystreams#Public"]
 535         )
 536     )
 537   end
 538
 539   def fetch_activities_query(recipients, opts \\ %{}) do
 540     base_query =
 541       from(
 542         activity in Activity,
 543         limit: 20,
 544         order_by: [fragment("? desc nulls last", activity.id)]
 545       )
 546
 547     base_query
 548     |> restrict_recipients(recipients, opts["user"])
 549     |> restrict_tag(opts)
 550     |> restrict_since(opts)
 551     |> restrict_local(opts)
 552     |> restrict_limit(opts)
 553     |> restrict_max(opts)
 554     |> restrict_actor(opts)
 555     |> restrict_type(opts)
 556     |> restrict_favorited_by(opts)
 557     |> restrict_recent(opts)
 558     |> restrict_blocked(opts)
 559     |> restrict_media(opts)
 560     |> restrict_visibility(opts)
 561     |> restrict_replies(opts)
 562   end
 563
 564   def fetch_activities(recipients, opts \\ %{}) do
 565     fetch_activities_query(recipients, opts)
 566     |> Repo.all()
 567     |> Enum.reverse()
 568   end
 569
 570   def fetch_activities_bounded(recipients_to, recipients_cc, opts \\ %{}) do
 571     fetch_activities_query([], opts)
 572     |> restrict_to_cc(recipients_to, recipients_cc)
 573     |> Repo.all()
 574     |> Enum.reverse()
 575   end
 576
 577   def upload(file, size_limit \\ nil) do
 578     with data <-
 579            Upload.store(file, Application.get_env(:pleroma, :instance)[:dedupe_media], size_limit),
 580          false <- is_nil(data) do
 581       Repo.insert(%Object{data: data})
 582     end
 583   end
 584
 585   def user_data_from_user_object(data) do
 586     avatar =
 587       data["icon"]["url"] &&
 588         %{
 589           "type" => "Image",
 590           "url" => [%{"href" => data["icon"]["url"]}]
 591         }
 592
 593     banner =
 594       data["image"]["url"] &&
 595         %{
 596           "type" => "Image",
 597           "url" => [%{"href" => data["image"]["url"]}]
 598         }
 599
 600     locked = data["manuallyApprovesFollowers"] || false
 601     data = Transmogrifier.maybe_fix_user_object(data)
 602
 603     user_data = %{
 604       ap_id: data["id"],
 605       info: %{
 606         "ap_enabled" => true,
 607         "source_data" => data,
 608         "banner" => banner,
 609         "locked" => locked
 610       },
 611       avatar: avatar,
 612       name: data["name"],
 613       follower_address: data["followers"],
 614       bio: data["summary"]
 615     }
 616
 617     # nickname can be nil because of virtual actors
 618     user_data =
 619       if data["preferredUsername"] do
 620         Map.put(
 621           user_data,
 622           :nickname,
 623           "#{data["preferredUsername"]}@#{URI.parse(data["id"]).host}"
 624         )
 625       else
 626         Map.put(user_data, :nickname, nil)
 627       end
 628
 629     {:ok, user_data}
 630   end
 631
 632   def fetch_and_prepare_user_from_ap_id(ap_id) do
 633     with {:ok, %{status_code: 200, body: body}} <-
 634            @httpoison.get(ap_id, [Accept: "application/activity+json"], follow_redirect: true),
 635          {:ok, data} <- Jason.decode(body) do
 636       user_data_from_user_object(data)
 637     else
 638       e -> Logger.error("Could not decode user at fetch #{ap_id}, #{inspect(e)}")
 639     end
 640   end
 641
 642   def make_user_from_ap_id(ap_id) do
 643     if _user = User.get_by_ap_id(ap_id) do
 644       Transmogrifier.upgrade_user_from_ap_id(ap_id)
 645     else
 646       with {:ok, data} <- fetch_and_prepare_user_from_ap_id(ap_id) do
 647         User.insert_or_update_user(data)
 648       else
 649         e -> {:error, e}
 650       end
 651     end
 652   end
 653
 654   def make_user_from_nickname(nickname) do
 655     with {:ok, %{"ap_id" => ap_id}} when not is_nil(ap_id) <- WebFinger.finger(nickname) do
 656       make_user_from_ap_id(ap_id)
 657     else
 658       _e -> {:error, "No AP id in WebFinger"}
 659     end
 660   end
 661
 662   @quarantined_instances Keyword.get(@instance, :quarantined_instances, [])
 663
 664   def should_federate?(inbox, public) do
 665     if public do
 666       true
 667     else
 668       inbox_info = URI.parse(inbox)
 669       inbox_info.host not in @quarantined_instances
 670     end
 671   end
 672
 673   def publish(actor, activity) do
 674     followers =
 675       if actor.follower_address in activity.recipients do
 676         {:ok, followers} = User.get_followers(actor)
 677         followers |> Enum.filter(&(!&1.local))
 678       else
 679         []
 680       end
 681
 682     public = is_public?(activity)
 683
 684     remote_inboxes =
 685       (Pleroma.Web.Salmon.remote_users(activity) ++ followers)
 686       |> Enum.filter(fn user -> User.ap_enabled?(user) end)
 687       |> Enum.map(fn %{info: %{"source_data" => data}} ->
 688         (is_map(data["endpoints"]) && Map.get(data["endpoints"], "sharedInbox")) || data["inbox"]
 689       end)
 690       |> Enum.uniq()
 691       |> Enum.filter(fn inbox -> should_federate?(inbox, public) end)
 692
 693     {:ok, data} = Transmogrifier.prepare_outgoing(activity.data)
 694     json = Jason.encode!(data)
 695
 696     Enum.each(remote_inboxes, fn inbox ->
 697       Federator.enqueue(:publish_single_ap, %{
 698         inbox: inbox,
 699         json: json,
 700         actor: actor,
 701         id: activity.data["id"]
 702       })
 703     end)
 704   end
 705
 706   def publish_one(%{inbox: inbox, json: json, actor: actor, id: id}) do
 707     Logger.info("Federating #{id} to #{inbox}")
 708     host = URI.parse(inbox).host
 709
 710     digest = "SHA-256=" <> (:crypto.hash(:sha256, json) |> Base.encode64())
 711
 712     signature =
 713       Pleroma.Web.HTTPSignatures.sign(actor, %{
 714         host: host,
 715         "content-length": byte_size(json),
 716         digest: digest
 717       })
 718
 719     @httpoison.post(
 720       inbox,
 721       json,
 722       [
 723         {"Content-Type", "application/activity+json"},
 724         {"signature", signature},
 725         {"digest", digest}
 726       ],
 727       hackney: [pool: :default]
 728     )
 729   end
 730
 731   # TODO:
 732   # This will create a Create activity, which we need internally at the moment.
 733   def fetch_object_from_id(id) do
 734     if object = Object.get_cached_by_ap_id(id) do
 735       {:ok, object}
 736     else
 737       Logger.info("Fetching #{id} via AP")
 738
 739       with true <- String.starts_with?(id, "http"),
 740            {:ok, %{body: body, status_code: code}} when code in 200..299 <-
 741              @httpoison.get(
 742                id,
 743                [Accept: "application/activity+json"],
 744                follow_redirect: true,
 745                timeout: 10000,
 746                recv_timeout: 20000
 747              ),
 748            {:ok, data} <- Jason.decode(body),
 749            nil <- Object.normalize(data),
 750            params <- %{
 751              "type" => "Create",
 752              "to" => data["to"],
 753              "cc" => data["cc"],
 754              "actor" => data["attributedTo"],
 755              "object" => data
 756            },
 757            :ok <- Transmogrifier.contain_origin(id, params),
 758            {:ok, activity} <- Transmogrifier.handle_incoming(params) do
 759         {:ok, Object.normalize(activity.data["object"])}
 760       else
 761         {:error, {:reject, nil}} ->
 762           {:reject, nil}
 763
 764         object = %Object{} ->
 765           {:ok, object}
 766
 767         _e ->
 768           Logger.info("Couldn't get object via AP, trying out OStatus fetching...")
 769
 770           case OStatus.fetch_activity_from_url(id) do
 771             {:ok, [activity | _]} -> {:ok, Object.normalize(activity.data["object"])}
 772             e -> e
 773           end
 774       end
 775     end
 776   end
 777
 778   def is_public?(activity) do
 779     "https://www.w3.org/ns/activitystreams#Public" in (activity.data["to"] ++
 780                                                          (activity.data["cc"] || []))
 781   end
 782
 783   def visible_for_user?(activity, nil) do
 784     is_public?(activity)
 785   end
 786
 787   def visible_for_user?(activity, user) do
 788     x = [user.ap_id | user.following]
 789     y = activity.data["to"] ++ (activity.data["cc"] || [])
 790     visible_for_user?(activity, nil) || Enum.any?(x, &(&1 in y))
 791   end
 792
 793   # guard
 794   def entire_thread_visible_for_user?(nil, user), do: false
 795
 796   # child
 797   def entire_thread_visible_for_user?(
 798         %Activity{data: %{"object" => %{"inReplyTo" => parent_id}}} = tail,
 799         user
 800       )
 801       when is_binary(parent_id) do
 802     parent = Activity.get_in_reply_to_activity(tail)
 803     visible_for_user?(tail, user) && entire_thread_visible_for_user?(parent, user)
 804   end
 805
 806   # root
 807   def entire_thread_visible_for_user?(tail, user), do: visible_for_user?(tail, user)
 808
 809   # filter out broken threads
 810   def contain_broken_threads(%Activity{} = activity, %User{} = user) do
 811     entire_thread_visible_for_user?(activity, user)
 812   end
 813
 814   # do post-processing on a specific activity
 815   def contain_activity(%Activity{} = activity, %User{} = user) do
 816     contain_broken_threads(activity, user)
 817   end
 818
 819   # do post-processing on a timeline
 820   def contain_timeline(timeline, user) do
 821     timeline
 822     |> Enum.filter(fn activity ->
 823       contain_activity(activity, user)
 824     end)
 825   end
 826 end