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