Federate participations

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon/actors/actors.ex

@@ -58,6 +58,10 @@ defmodule Mobilizon.Actors do
     Repo.get!(Actor, id)
   end
 
+  def get_actor(id) do
+    Repo.get(Actor, id)
+  end
+
   # Get actor by ID and preload organized events, followers and followings
   @spec get_actor_with_everything(integer()) :: Ecto.Query.t()
   defp do_get_actor_with_everything(id) do

lib/mobilizon/events/events.ex

@@ -214,6 +214,27 @@ defmodule Mobilizon.Events do
     ])
   end
 
+  @doc """
+  Gets a single event, with all associations loaded.
+  """
+  def get_event_full(id) do
+    case Repo.get(Event, id) do
+      %Event{} = event ->
+        {:ok,
+         Repo.preload(event, [
+           :organizer_actor,
+           :sessions,
+           :tracks,
+           :tags,
+           :participants,
+           :physical_address
+         ])}
+
+      err ->
+        {:error, err}
+    end
+  end
+
   @doc """
   Gets an event by it's URL
   """
@@ -700,17 +721,28 @@ defmodule Mobilizon.Events do
       [%Participant{}, ...]
 
   """
-  def list_participants_for_event(uuid, page \\ nil, limit \\ nil) do
-    Repo.all(
-      from(
-        p in Participant,
-        join: e in Event,
-        on: p.event_id == e.id,
-        where: e.uuid == ^uuid and p.role != ^:not_approved,
-        preload: [:actor]
-      )
-      |> paginate(page, limit)
+  def list_participants_for_event(uuid, page \\ nil, limit \\ nil, include_not_improved \\ false)
+
+  def list_participants_for_event(uuid, page, limit, false) do
+    query = do_list_participants_for_event(uuid, page, limit)
+    query = from(p in query, where: p.role != ^:not_approved)
+    Repo.all(query)
+  end
+
+  def list_participants_for_event(uuid, page, limit, true) do
+    query = do_list_participants_for_event(uuid, page, limit)
+    Repo.all(query)
+  end
+
+  defp do_list_participants_for_event(uuid, page, limit) do
+    from(
+      p in Participant,
+      join: e in Event,
+      on: p.event_id == e.id,
+      where: e.uuid == ^uuid,
+      preload: [:actor]
     )
+    |> paginate(page, limit)
   end
 
   @doc """
@@ -787,6 +819,15 @@ defmodule Mobilizon.Events do
     end
   end
 
+  def get_participant_by_url(url) do
+    Repo.one(
+      from(p in Participant,
+        where: p.url == ^url,
+        preload: [:actor, :event]
+      )
+    )
+  end
+
   @doc """
   Creates a participant.
 
@@ -800,9 +841,10 @@ defmodule Mobilizon.Events do
 
   """
   def create_participant(attrs \\ %{}) do
-    %Participant{}
-    |> Participant.changeset(attrs)
-    |> Repo.insert()
+    with {:ok, %Participant{} = participant} <-
+           %Participant{} |> Participant.changeset(attrs) |> Repo.insert() do
+      {:ok, Repo.preload(participant, [:event, :actor])}
+    end
   end
 
   @doc """

lib/mobilizon/events/participant.ex

@@ -17,9 +17,10 @@ defmodule Mobilizon.Events.Participant do
   alias Mobilizon.Events.{Participant, Event}
   alias Mobilizon.Actors.Actor
 
-  @primary_key false
+  @primary_key {:id, :binary_id, autogenerate: true}
   schema "participants" do
     field(:role, Mobilizon.Events.ParticipantRoleEnum, default: :participant)
+    field(:url, :string)
     belongs_to(:event, Event, primary_key: true)
     belongs_to(:actor, Actor, primary_key: true)
 
@@ -29,7 +30,49 @@ defmodule Mobilizon.Events.Participant do
   @doc false
   def changeset(%Participant{} = participant, attrs) do
     participant
-    |> Ecto.Changeset.cast(attrs, [:role, :event_id, :actor_id])
-    |> validate_required([:role, :event_id, :actor_id])
+    |> Ecto.Changeset.cast(attrs, [:url, :role, :event_id, :actor_id])
+    |> generate_url()
+    |> validate_required([:url, :role, :event_id, :actor_id])
+  end
+
+  # If there's a blank URL that's because we're doing the first insert
+  defp generate_url(%Ecto.Changeset{data: %Participant{url: nil}} = changeset) do
+    case fetch_change(changeset, :url) do
+      {:ok, _url} -> changeset
+      :error -> do_generate_url(changeset)
+    end
+  end
+
+  # Most time just go with the given URL
+  defp generate_url(%Ecto.Changeset{} = changeset), do: changeset
+
+  defp do_generate_url(%Ecto.Changeset{} = changeset) do
+    uuid = Ecto.UUID.generate()
+
+    changeset
+    |> put_change(
+      :url,
+      "#{MobilizonWeb.Endpoint.url()}/join/event/#{uuid}"
+    )
+    |> put_change(
+      :id,
+      uuid
+    )
+  end
+
+  @doc """
+  We check that the actor asking to leave the event is not it's only organizer
+  We start by fetching the list of organizers and if there's only one of them
+  and that it's the actor requesting leaving the event we return true
+  """
+  @spec check_that_participant_is_not_only_organizer(integer(), integer()) :: boolean()
+  def check_that_participant_is_not_only_organizer(event_id, actor_id) do
+    case Mobilizon.Events.list_organizers_participants_for_event(event_id) do
+      [%Participant{actor: %Actor{id: participant_actor_id}}] ->
+        participant_actor_id == actor_id
+
+      _ ->
+        false
+    end
   end
 end

lib/mobilizon_web/api/events.ex

@@ -2,15 +2,12 @@ defmodule MobilizonWeb.API.Events do
   @moduledoc """
   API for Events
   """
-  alias Mobilizon.Addresses
   alias Mobilizon.Actors
   alias Mobilizon.Actors.Actor
   alias Mobilizon.Service.ActivityPub
   alias Mobilizon.Service.ActivityPub.Utils, as: ActivityPubUtils
   alias MobilizonWeb.API.Utils
 
-  @visibility %{"PUBLIC" => :public, "PRIVATE" => :private}
-
   @doc """
   Create an event
   """
@@ -51,15 +48,4 @@ defmodule MobilizonWeb.API.Events do
       })
     end
   end
-
-  defp get_physical_address(address_id) when is_number(address_id),
-    do: Addresses.get_address!(address_id)
-
-  defp get_physical_address(address_id) when is_binary(address_id) do
-    with {address_id, ""} <- Integer.parse(address_id) do
-      get_physical_address(address_id)
-    end
-  end
-
-  defp get_physical_address(nil), do: nil
 end

lib/mobilizon_web/api/participations.ex

@@ -0,0 +1,24 @@
+defmodule MobilizonWeb.API.Participations do
+  @moduledoc """
+  Common API to join events and groups
+  """
+
+  alias Mobilizon.Actors.Actor
+  alias Mobilizon.Events.{Event, Participant}
+  alias Mobilizon.Service.ActivityPub
+  require Logger
+
+  @spec join(Event.t(), Actor.t()) :: {:ok, Participant.t()}
+  def join(%Event{id: event_id} = event, %Actor{id: actor_id} = actor) do
+    with {:error, :participant_not_found} <- Mobilizon.Events.get_participant(event_id, actor_id),
+         {:ok, activity, participant} <- ActivityPub.join(event, actor, true) do
+      {:ok, activity, participant}
+    end
+  end
+
+  def leave(%Event{} = event, %Actor{} = actor) do
+    with {:ok, activity, participant} <- ActivityPub.leave(event, actor, true) do
+      {:ok, activity, participant}
+    end
+  end
+end

lib/mobilizon_web/resolvers/event.ex

@@ -8,7 +8,6 @@ defmodule MobilizonWeb.Resolvers.Event do
   alias Mobilizon.Events
   alias Mobilizon.Events.{Event, Participant}
   alias Mobilizon.Media.Picture
-  alias Mobilizon.Actors.Actor
   alias Mobilizon.Users.User
   alias MobilizonWeb.Resolvers.Person
 
@@ -108,20 +107,18 @@ defmodule MobilizonWeb.Resolvers.Event do
         }
       ) do
     with {:is_owned, true, actor} <- User.owns_actor(user, actor_id),
-         {:ok, %Event{} = event} <- Mobilizon.Events.get_event(event_id),
+         {:has_event, {:ok, %Event{} = event}} <-
+           {:has_event, Mobilizon.Events.get_event_full(event_id)},
          {:error, :participant_not_found} <- Mobilizon.Events.get_participant(event_id, actor_id),
-         role <- Mobilizon.Events.get_default_participant_role(event),
-         {:ok, participant} <-
-           Mobilizon.Events.create_participant(%{
-             role: role,
-             event_id: event.id,
-             actor_id: actor.id
-           }),
+         {:ok, _activity, participant} <- MobilizonWeb.API.Participations.join(event, actor),
          participant <-
            Map.put(participant, :event, event)
            |> Map.put(:actor, Person.proxify_pictures(actor)) do
       {:ok, participant}
     else
+      {:has_event, _} ->
+        {:error, "Event with this ID #{inspect(event_id)} doesn't exist"}
+
       {:is_owned, false} ->
         {:error, "Actor id is not owned by authenticated user"}
 
@@ -149,15 +146,15 @@ defmodule MobilizonWeb.Resolvers.Event do
           }
         }
       ) do
-    with {:is_owned, true, _} <- User.owns_actor(user, actor_id),
-         {:ok, %Participant{} = participant} <-
-           Mobilizon.Events.get_participant(event_id, actor_id),
-         {:only_organizer, false} <-
-           {:only_organizer, check_that_participant_is_not_only_organizer(event_id, actor_id)},
-         {:ok, _} <-
-           Mobilizon.Events.delete_participant(participant) do
+    with {:is_owned, true, actor} <- User.owns_actor(user, actor_id),
+         {:has_event, {:ok, %Event{} = event}} <-
+           {:has_event, Mobilizon.Events.get_event_full(event_id)},
+         {:ok, _activity, _participant} <- MobilizonWeb.API.Participations.leave(event, actor) do
       {:ok, %{event: %{id: event_id}, actor: %{id: actor_id}}}
     else
+      {:has_event, _} ->
+        {:error, "Event with this ID #{inspect(event_id)} doesn't exist"}
+
       {:is_owned, false} ->
         {:error, "Actor id is not owned by authenticated user"}
 
@@ -173,20 +170,6 @@ defmodule MobilizonWeb.Resolvers.Event do
     {:error, "You need to be logged-in to leave an event"}
   end
 
-  # We check that the actor asking to leave the event is not it's only organizer
-  # We start by fetching the list of organizers and if there's only one of them
-  # and that it's the actor requesting leaving the event we return true
-  @spec check_that_participant_is_not_only_organizer(integer(), integer()) :: boolean()
-  defp check_that_participant_is_not_only_organizer(event_id, actor_id) do
-    case Mobilizon.Events.list_organizers_participants_for_event(event_id) do
-      [%Participant{actor: %Actor{id: participant_actor_id}}] ->
-        participant_actor_id == actor_id
-
-      _ ->
-        false
-    end
-  end
-
   @doc """
   Create an event
   """

lib/service/activity_pub/activity_pub.ex

@@ -11,18 +11,19 @@ defmodule Mobilizon.Service.ActivityPub do
   """
 
   alias Mobilizon.Events
-  alias Mobilizon.Events.{Event, Comment}
+  alias Mobilizon.Events.{Event, Comment, Participant}
   alias Mobilizon.Service.ActivityPub.Transmogrifier
   alias Mobilizon.Service.WebFinger
   alias Mobilizon.Activity
 
   alias Mobilizon.Actors
-  alias Mobilizon.Actors.Actor
-  alias Mobilizon.Actors.Follower
+  alias Mobilizon.Actors.{Actor, Follower}
 
   alias Mobilizon.Service.Federator
   alias Mobilizon.Service.HTTPSignatures.Signature
 
+  alias Mobilizon.Service.ActivityPub.Convertible
+
   require Logger
   import Mobilizon.Service.ActivityPub.Utils
   import Mobilizon.Service.ActivityPub.Visibility
@@ -148,7 +149,7 @@ defmodule Mobilizon.Service.ActivityPub do
     end
   end
 
-  def accept(%{to: to, actor: actor, object: object} = params, activity_follow_id \\ nil) do
+  def accept(%{to: to, actor: actor, object: object} = params, activity_wrapper_id \\ nil) do
     # only accept false as false value
     local = !(params[:local] == false)
 
@@ -157,7 +158,7 @@ defmodule Mobilizon.Service.ActivityPub do
            "type" => "Accept",
            "actor" => actor,
            "object" => object,
-           "id" => activity_follow_id || get_url(object) <> "/activity"
+           "id" => activity_wrapper_id || get_url(object) <> "/activity"
          },
          {:ok, activity, object} <- insert(data, local),
          :ok <- maybe_federate(activity) do
@@ -165,11 +166,17 @@ defmodule Mobilizon.Service.ActivityPub do
     end
   end
 
-  def reject(%{to: to, actor: actor, object: object} = params) do
+  def reject(%{to: to, actor: actor, object: object} = params, activity_wrapper_id \\ nil) do
     # only accept false as false value
     local = !(params[:local] == false)
 
-    with data <- %{"to" => to, "type" => "Reject", "actor" => actor.url, "object" => object},
+    with data <- %{
+           "to" => to,
+           "type" => "Reject",
+           "actor" => actor,
+           "object" => object,
+           "id" => activity_wrapper_id || get_url(object) <> "/activity"
+         },
          {:ok, activity, object} <- insert(data, local),
          :ok <- maybe_federate(activity) do
       {:ok, activity, object}
@@ -383,6 +390,65 @@ defmodule Mobilizon.Service.ActivityPub do
     end
   end
 
+  def join(object, actor, local \\ true)
+
+  def join(%Event{} = event, %Actor{} = actor, local) do
+    with role <- Mobilizon.Events.get_default_participant_role(event),
+         {:ok, %Participant{} = participant} <-
+           Mobilizon.Events.create_participant(%{
+             role: role,
+             event_id: event.id,
+             actor_id: actor.id
+           }),
+         join_data <- Convertible.model_to_as(participant),
+         join_data <- Map.put(join_data, "to", [event.organizer_actor.url]),
+         join_data <- Map.put(join_data, "cc", []),
+         {:ok, activity, _} <- insert(join_data, local),
+         :ok <- maybe_federate(activity) do
+      if role === :participant do
+        accept(
+          %{to: [actor.url], actor: event.organizer_actor.url, object: join_data["id"]},
+          "#{MobilizonWeb.Endpoint.url()}/accept/join/#{participant.id}"
+        )
+      end
+
+      {:ok, activity, participant}
+    end
+  end
+
+  # TODO: Implement me
+  def join(%Actor{type: :Group} = _group, %Actor{} = _actor, _local) do
+    :error
+  end
+
+  def leave(object, actor, local \\ true)
+
+  # TODO: If we want to use this for exclusion we need to have an extra field for the actor that excluded the participant
+  def leave(
+        %Event{id: event_id, url: event_url} = event,
+        %Actor{id: actor_id, url: actor_url} = _actor,
+        local
+      ) do
+    with {:only_organizer, false} <-
+           {:only_organizer,
+            Participant.check_that_participant_is_not_only_organizer(event_id, actor_id)},
+         {:ok, %Participant{} = participant} <-
+           Mobilizon.Events.get_participant(event_id, actor_id),
+         {:ok, %Participant{} = participant} <- Mobilizon.Events.delete_participant(participant),
+         leave_data <- %{
+           "type" => "Leave",
+           # If it's an exclusion it should be something else
+           "actor" => actor_url,
+           "object" => event_url,
+           "to" => [event.organizer_actor.url],
+           "cc" => []
+         },
+         {:ok, activity, _} <- insert(leave_data, local),
+         :ok <- maybe_federate(activity) do
+      {:ok, activity, participant}
+    end
+  end
+
   @doc """
   Create an actor locally by it's URL (AP ID)
   """
@@ -482,7 +548,7 @@ defmodule Mobilizon.Service.ActivityPub do
   """
   def publish_one(%{inbox: inbox, json: json, actor: actor, id: id}) do
     Logger.info("Federating #{id} to #{inbox}")
-    %URI{host: host, path: path} = URI.parse(inbox)
+    %URI{host: host, path: _path} = URI.parse(inbox)
 
     digest = Signature.build_digest(json)
     date = Signature.generate_date_header()

lib/service/activity_pub/converters/comment.ex

@@ -10,8 +10,6 @@ defmodule Mobilizon.Service.ActivityPub.Converters.Comment do
   alias Mobilizon.Events.Event
   alias Mobilizon.Service.ActivityPub.Converter
   alias Mobilizon.Service.ActivityPub
-  alias MobilizonWeb.Router.Helpers, as: Routes
-  alias MobilizonWeb.Endpoint
   require Logger
 
   @behaviour Converter

lib/service/activity_pub/converters/participant.ex

@@ -0,0 +1,29 @@
+defmodule Mobilizon.Service.ActivityPub.Converters.Participant do
+  @moduledoc """
+  Flag converter
+
+  This module allows to convert reports from ActivityStream format to our own internal one, and back.
+
+  Note: Reports are named Flag in AS.
+  """
+  alias Mobilizon.Events.Participant, as: ParticipantModel
+
+  @doc """
+  Convert an event struct to an ActivityStream representation
+  """
+  @spec model_to_as(ParticipantModel.t()) :: map()
+  def model_to_as(%ParticipantModel{} = participant) do
+    %{
+      "type" => "Join",
+      "id" => participant.url,
+      "actor" => participant.actor.url,
+      "object" => participant.event.url
+    }
+  end
+
+  defimpl Mobilizon.Service.ActivityPub.Convertible, for: Mobilizon.Events.Participant do
+    alias Mobilizon.Service.ActivityPub.Converters.Participant, as: ParticipantConverter
+
+    defdelegate model_to_as(event), to: ParticipantConverter
+  end
+end

lib/service/activity_pub/transmogrifier.ex

@@ -10,7 +10,7 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
   alias Mobilizon.Actors
   alias Mobilizon.Actors.{Actor, Follower}
   alias Mobilizon.Events
-  alias Mobilizon.Events.{Event, Comment}
+  alias Mobilizon.Events.{Event, Comment, Participant}
   alias Mobilizon.Service.ActivityPub
   alias Mobilizon.Service.ActivityPub.Utils
   alias Mobilizon.Service.ActivityPub.Visibility
@@ -185,7 +185,7 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
   end
 
   def handle_incoming(
-        %{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = data
+        %{"type" => "Follow", "object" => followed, "actor" => follower, "id" => id} = _data
       ) do
     with {:ok, %Actor{} = followed} <- Actors.get_or_fetch_by_url(followed, true),
          {:ok, %Actor{} = follower} <- Actors.get_or_fetch_by_url(follower),
@@ -198,61 +198,65 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
     end
   end
 
-  # TODO : Handle object being a Link
   def handle_incoming(
         %{
           "type" => "Accept",
-          "object" => follow_object,
+          "object" => accepted_object,
           "actor" => _actor,
-          "id" => _id
+          "id" => id
         } = data
       ) do
-    with followed_actor_url <- get_actor(data),
-         {:ok, %Actor{} = followed} <- Actors.get_or_fetch_by_url(followed_actor_url),
-         {:ok, %Follower{approved: false, actor: follower, id: follow_id} = follow} <-
-           get_follow(follow_object),
-         {:ok, activity, _} <-
-           ActivityPub.accept(
-             %{
-               to: [follower.url],
-               actor: followed.url,
-               object: follow_object,
-               local: false
-             },
-             "#{MobilizonWeb.Endpoint.url()}/accept/follow/#{follow_id}"
-           ),
-         {:ok, %Follower{approved: true}} <- Actors.update_follower(follow, %{"approved" => true}) do
-      {:ok, activity, follow}
+    with actor_url <- get_actor(data),
+         {:ok, %Actor{} = actor} <- Actors.get_or_fetch_by_url(actor_url),
+         {:object_not_found, {:ok, activity, object}} <-
+           {:object_not_found,
+            do_handle_incoming_accept_following(accepted_object, actor) ||
+              do_handle_incoming_accept_join(accepted_object, actor)} do
+      {:ok, activity, object}
     else
-      {:ok, %Follower{approved: true} = _follow} ->
-        {:error, "Follow already accepted"}
+      {:object_not_found, nil} ->
+        Logger.warn(
+          "Unable to process Accept activity #{inspect(id)}. Object #{inspect(accepted_object)} wasn't found."
+        )
+
+        :error
 
       e ->
-        Logger.warn("Unable to process Accept Follow activity #{inspect(e)}")
+        Logger.warn(
+          "Unable to process Accept activity #{inspect(id)} for object #{inspect(accepted_object)} only returned #{
+            inspect(e)
+          }"
+        )
+
         :error
     end
   end
 
   def handle_incoming(
-        %{"type" => "Reject", "object" => follow_object, "actor" => _actor, "id" => _id} = data
+        %{"type" => "Reject", "object" => rejected_object, "actor" => _actor, "id" => id} = data
       ) do
-    with followed_actor_url <- get_actor(data),
-         {:ok, %Actor{} = followed} <- Actors.get_or_fetch_by_url(followed_actor_url),
-         {:ok, %Follower{approved: false, actor: follower, id: follow_id} = follow} <-
-           get_follow(follow_object),
-         {:ok, activity, object} <-
-           ActivityPub.reject(%{
-             to: [follower.url],
-             type: "Reject",
-             actor: followed,
-             object: follow_object,
-             local: false
-           }),
-         {:ok, _follower} <- Actor.unfollow(followed, follower) do
+    with actor_url <- get_actor(data),
+         {:ok, %Actor{} = actor} <- Actors.get_or_fetch_by_url(actor_url),
+         {:object_not_found, {:ok, activity, object}} <-
+           {:object_not_found,
+            do_handle_incoming_reject_following(rejected_object, actor) ||
+              do_handle_incoming_reject_join(rejected_object, actor)} do
       {:ok, activity, object}
     else
+      {:object_not_found, nil} ->
+        Logger.warn(
+          "Unable to process Reject activity #{inspect(id)}. Object #{inspect(rejected_object)} wasn't found."
+        )
+
+        :error
+
       e ->
-        Logger.debug(inspect(e))
+        Logger.warn(
+          "Unable to process Reject activity #{inspect(id)} for object #{inspect(rejected_object)} only returned #{
+            inspect(e)
+          }"
+        )
+
         :error
     end
   end
@@ -272,7 +276,7 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
   #  end
   # #
   def handle_incoming(
-        %{"type" => "Announce", "object" => object_id, "actor" => actor, "id" => id} = data
+        %{"type" => "Announce", "object" => object_id, "actor" => _actor, "id" => id} = data
       ) do
     with actor <- get_actor(data),
          {:ok, %Actor{} = actor} <- Actors.get_or_fetch_by_url(actor),
@@ -320,7 +324,7 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
             "object" => object_id,
             "id" => cancelled_activity_id
           },
-          "actor" => actor,
+          "actor" => _actor,
           "id" => id
         } = data
       ) do
@@ -378,6 +382,43 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
     end
   end
 
+  def handle_incoming(
+        %{"type" => "Join", "object" => object, "actor" => _actor, "id" => _id} = data
+      ) do
+    with actor <- get_actor(data),
+         {:ok, %Actor{url: _actor_url} = actor} <- Actors.get_actor_by_url(actor),
+         {:ok, object} <- fetch_obj_helper(object),
+         {:ok, activity, object} <- ActivityPub.join(object, actor, false) do
+      {:ok, activity, object}
+    else
+      e ->
+        Logger.debug(inspect(e))
+        :error
+    end
+  end
+
+  def handle_incoming(
+        %{"type" => "Leave", "object" => object, "actor" => actor, "id" => _id} = data
+      ) do
+    with actor <- get_actor(data),
+         {:ok, %Actor{} = actor} <- Actors.get_actor_by_url(actor),
+         {:ok, object} <- fetch_obj_helper(object),
+         {:ok, activity, object} <- ActivityPub.leave(object, actor, false) do
+      {:ok, activity, object}
+    else
+      {:only_organizer, true} ->
+        Logger.warn(
+          "Actor #{inspect(actor)} tried to leave event #{inspect(object)} but it was the only organizer so we didn't detach it"
+        )
+
+        :error
+
+      e ->
+        Logger.error(inspect(e))
+        :error
+    end
+  end
+
   #
   #  # TODO
   #  # Accept
@@ -406,13 +447,187 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
     {:error, :not_supported}
   end
 
+  @doc """
+  Handle incoming `Accept` activities wrapping a `Follow` activity
+  """
+  def do_handle_incoming_accept_following(follow_object, %Actor{} = actor) do
+    with {:follow,
+          {:ok,
+           %Follower{approved: false, actor: follower, id: follow_id, target_actor: followed} =
+             follow}} <-
+           {:follow, get_follow(follow_object)},
+         {:same_actor, true} <- {:same_actor, actor.id == followed.id},
+         {:ok, activity, _} <-
+           ActivityPub.accept(
+             %{
+               to: [follower.url],
+               actor: actor.url,
+               object: follow_object,
+               local: false
+             },
+             "#{MobilizonWeb.Endpoint.url()}/accept/follow/#{follow_id}"
+           ),
+         {:ok, %Follower{approved: true}} <- Actors.update_follower(follow, %{"approved" => true}) do
+      {:ok, activity, follow}
+    else
+      {:follow, _} ->
+        Logger.debug(
+          "Tried to handle an Accept activity but it's not containing a Follow activity"
+        )
+
+        nil
+
+      {:same_actor} ->
+        {:error, "Actor who accepted the follow wasn't the target. Quite odd."}
+
+      {:ok, %Follower{approved: true} = _follow} ->
+        {:error, "Follow already accepted"}
+    end
+  end
+
+  @doc """
+  Handle incoming `Reject` activities wrapping a `Follow` activity
+  """
+  def do_handle_incoming_reject_following(follow_object, %Actor{} = actor) do
+    with {:follow,
+          {:ok,
+           %Follower{approved: false, actor: follower, id: follow_id, target_actor: followed} =
+             follow}} <-
+           {:follow, get_follow(follow_object)},
+         {:same_actor, true} <- {:same_actor, actor.id == followed.id},
+         {:ok, activity, _} <-
+           ActivityPub.reject(
+             %{
+               to: [follower.url],
+               actor: actor.url,
+               object: follow_object,
+               local: false
+             },
+             "#{MobilizonWeb.Endpoint.url()}/reject/follow/#{follow_id}"
+           ),
+         {:ok, %Follower{}} <- Actors.delete_follower(follow) do
+      {:ok, activity, follow}
+    else
+      {:follow, _} ->
+        Logger.debug(
+          "Tried to handle a Reject activity but it's not containing a Follow activity"
+        )
+
+        nil
+
+      {:same_actor} ->
+        {:error, "Actor who rejected the follow wasn't the target. Quite odd."}
+
+      {:ok, %Follower{approved: true} = _follow} ->
+        {:error, "Follow already accepted"}
+    end
+  end
+
+  @doc """
+  Handle incoming `Accept` activities wrapping a `Join` activity on an event
+  """
+  def do_handle_incoming_accept_join(join_object, %Actor{} = actor_accepting) do
+    with {:join_event,
+          {:ok,
+           %Participant{role: :not_approved, actor: actor, id: join_id, event: event} =
+             participant}} <-
+           {:join_event, get_participant(join_object)},
+         # TODO: The actor that accepts the Join activity may another one that the event organizer ?
+         # Or maybe for groups it's the group that sends the Accept activity
+         {:same_actor, true} <- {:same_actor, actor_accepting.id == event.organizer_actor_id},
+         {:ok, activity, _} <-
+           ActivityPub.accept(
+             %{
+               to: [actor.url],
+               actor: actor_accepting.url,
+               object: join_object,
+               local: false
+             },
+             "#{MobilizonWeb.Endpoint.url()}/accept/join/#{join_id}"
+           ),
+         {:ok, %Participant{role: :participant}} <-
+           Events.update_participant(participant, %{"role" => :participant}) do
+      {:ok, activity, participant}
+    else
+      {:join_event, {:ok, %Participant{role: :participant}}} ->
+        Logger.debug(
+          "Tried to handle an Accept activity on a Join activity with a event object but the participant is already validated"
+        )
+
+        nil
+
+      {:join_event, _err} ->
+        Logger.debug(
+          "Tried to handle an Accept activity but it's not containing a Join activity on a event"
+        )
+
+        nil
+
+      {:same_actor} ->
+        {:error, "Actor who accepted the join wasn't the event organizer. Quite odd."}
+
+      {:ok, %Participant{role: :participant} = _follow} ->
+        {:error, "Participant"}
+    end
+  end
+
+  @doc """
+  Handle incoming `Reject` activities wrapping a `Join` activity on an event
+  """
+  def do_handle_incoming_reject_join(join_object, %Actor{} = actor_accepting) do
+    with {:join_event,
+          {:ok,
+           %Participant{role: :not_approved, actor: actor, id: join_id, event: event} =
+             participant}} <-
+           {:join_event, get_participant(join_object)},
+         # TODO: The actor that accepts the Join activity may another one that the event organizer ?
+         # Or maybe for groups it's the group that sends the Accept activity
+         {:same_actor, true} <- {:same_actor, actor_accepting.id == event.organizer_actor_id},
+         {:ok, activity, _} <-
+           ActivityPub.reject(
+             %{
+               to: [actor.url],
+               actor: actor_accepting.url,
+               object: join_object,
+               local: false
+             },
+             "#{MobilizonWeb.Endpoint.url()}/reject/join/#{join_id}"
+           ),
+         {:ok, %Participant{}} <-
+           Events.delete_participant(participant) do
+      {:ok, activity, participant}
+    else
+      {:join_event, {:ok, %Participant{role: :participant}}} ->
+        Logger.debug(
+          "Tried to handle an Reject activity on a Join activity with a event object but the participant is already validated"
+        )
+
+        nil
+
+      {:join_event, _err} ->
+        Logger.debug(
+          "Tried to handle an Reject activity but it's not containing a Join activity on a event"
+        )
+
+        nil
+
+      {:same_actor} ->
+        {:error, "Actor who rejected the join wasn't the event organizer. Quite odd."}
+
+      {:ok, %Participant{role: :participant} = _follow} ->
+        {:error, "Participant"}
+    end
+  end
+
+  # TODO: Add do_handle_incoming_accept_join/1 on Groups
+
   defp get_follow(follow_object) do
     with follow_object_id when not is_nil(follow_object_id) <- Utils.get_url(follow_object),
          {:not_found, %Follower{} = follow} <-
            {:not_found, Actors.get_follow_by_url(follow_object_id)} do
       {:ok, follow}
     else
-      {:not_found, err} ->
+      {:not_found, _err} ->
         {:error, "Follow URL not found"}
 
       _ ->
@@ -420,6 +635,20 @@ defmodule Mobilizon.Service.ActivityPub.Transmogrifier do
     end
   end
 
+  defp get_participant(join_object) do
+    with join_object_id when not is_nil(join_object_id) <- Utils.get_url(join_object),
+         {:not_found, %Participant{} = participant} <-
+           {:not_found, Events.get_participant_by_url(join_object_id)} do
+      {:ok, participant}
+    else
+      {:not_found, _err} ->
+        {:error, "Participant URL not found"}
+
+      _ ->
+        {:error, "ActivityPub ID not found in Accept Join object"}
+    end
+  end
+
   def set_reply_to_uri(%{"inReplyTo" => in_reply_to} = object) do
     with false <- String.starts_with?(in_reply_to, "http"),
          {:ok, replied_to_object} <- fetch_obj_helper(in_reply_to) do

lib/service/activity_pub/utils.ex

@@ -512,7 +512,7 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
          object_actor_url,
          object_url,
          activity_id,
-         public \\ true
+         public
        ) do
     {to, cc} =
       if public do
@@ -611,6 +611,24 @@ defmodule Mobilizon.Service.ActivityPub.Utils do
     |> Map.merge(additional)
   end
 
+  def make_join_data(%Event{} = event, %Actor{} = actor) do
+    %{
+      "type" => "Join",
+      "id" => "#{actor.url}/join/event/id",
+      "actor" => actor.url,
+      "object" => event.url
+    }
+  end
+
+  def make_join_data(%Actor{type: :Group} = event, %Actor{} = actor) do
+    %{
+      "type" => "Join",
+      "id" => "#{actor.url}/join/group/id",
+      "actor" => actor.url,
+      "object" => event.url
+    }
+  end
+
   @doc """
   Converts PEM encoded keys to a public key representation
   """

lib/service/activity_pub/visibility.ex

@@ -8,7 +8,6 @@ defmodule Mobilizon.Service.ActivityPub.Visibility do
   Utility functions related to content visibility
   """
   alias Mobilizon.Activity
-  alias Mobilizon.Events.Event
 
   @public "https://www.w3.org/ns/activitystreams#Public"
 

priv/repo/migrations/20190813160207_add_url_and_uuid_to_participants.exs

@@ -0,0 +1,43 @@
+defmodule Mobilizon.Repo.Migrations.AddUrlAndUuidToParticipants do
+  use Ecto.Migration
+
+  def up do
+    drop(index(:participants, :event_id))
+    drop_if_exists(index(:participants, :account_id))
+    drop_if_exists(index(:participants, :actor_id))
+    drop(constraint(:participants, "participants_event_id_fkey"))
+
+    # This is because even though we renamed the table accounts to actors indexes kept this name
+    drop_if_exists(constraint(:participants, "participants_account_id_fkey"))
+    drop_if_exists(constraint(:participants, "participants_actor_id_fkey"))
+    drop(constraint(:participants, "participants_pkey"))
+
+    alter table(:participants, primary_key: false) do
+      modify(:event_id, references(:events, on_delete: :delete_all), primary_key: false)
+      modify(:actor_id, references(:actors, on_delete: :delete_all), primary_key: false)
+      add(:id, :uuid, primary_key: true)
+      add(:url, :string, null: false)
+    end
+
+    create(index(:participants, :event_id))
+    create(index(:participants, :actor_id))
+  end
+
+  def down do
+    drop(index(:participants, :event_id))
+    drop(index(:participants, :actor_id))
+    drop(constraint(:participants, "participants_event_id_fkey"))
+    drop(constraint(:participants, "participants_actor_id_fkey"))
+    drop(constraint(:participants, "participants_pkey"))
+
+    alter table(:participants, primary_key: false) do
+      modify(:event_id, references(:events, on_delete: :nothing), primary_key: true)
+      modify(:actor_id, references(:actors, on_delete: :nothing), primary_key: true)
+      remove(:id)
+      remove(:url)
+    end
+
+    create(index(:participants, :event_id))
+    create(index(:participants, :actor_id))
+  end
+end

test/fixtures/mobilizon-join-activity.json

@@ -0,0 +1,22 @@
+{
+  "type": "Join",
+  "signature": {
+    "type": "RsaSignature2017",
+    "signatureValue": "Kn1/UkAQGJVaXBfWLAHcnwHg8YMAUqlEaBuYLazAG+pz5hqivsyrBmPV186Xzr+B4ZLExA9+SnOoNx/GOz4hBm0kAmukNSILAsUd84tcJ2yT9zc1RKtembK4WiwOw7li0+maeDN0HaB6t+6eTqsCWmtiZpprhXD8V1GGT8yG7X24fQ9oFGn+ng7lasbcCC0988Y1eGqNe7KryxcPuQz57YkDapvtONzk8gyLTkZMV4De93MyRHq6GVjQVIgtiYabQAxrX6Q8C+4P/jQoqdWJHEe+MY5JKyNaT/hMPt2Md1ok9fZQBGHlErk22/zy8bSN19GdG09HmIysBUHRYpBLig==",
+    "creator": "http://mobilizon.test/users/tcit#main-key",
+    "created": "2018-02-17T13:29:31Z"
+  },
+  "object": "http://mobilizon.test/events/some-uuid",
+  "id": "http://mobilizon2.test/@admin/join/event/1",
+  "actor": "http://mobilizon2.test/@admin",
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1",
+    {
+      "sensitive": "as:sensitive",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "Hashtag": "as:Hashtag"
+    }
+  ]
+}

test/fixtures/mobilizon-leave-activity.json

@@ -0,0 +1,22 @@
+{
+  "type": "Leave",
+  "signature": {
+    "type": "RsaSignature2017",
+    "signatureValue": "Kn1/UkAQGJVaXBfWLAHcnwHg8YMAUqlEaBuYLazAG+pz5hqivsyrBmPV186Xzr+B4ZLExA9+SnOoNx/GOz4hBm0kAmukNSILAsUd84tcJ2yT9zc1RKtembK4WiwOw7li0+maeDN0HaB6t+6eTqsCWmtiZpprhXD8V1GGT8yG7X24fQ9oFGn+ng7lasbcCC0988Y1eGqNe7KryxcPuQz57YkDapvtONzk8gyLTkZMV4De93MyRHq6GVjQVIgtiYabQAxrX6Q8C+4P/jQoqdWJHEe+MY5JKyNaT/hMPt2Md1ok9fZQBGHlErk22/zy8bSN19GdG09HmIysBUHRYpBLig==",
+    "creator": "http://mobilizon.test/users/tcit#main-key",
+    "created": "2018-02-17T13:29:31Z"
+  },
+  "object": "http://mobilizon.test/events/some-uuid",
+  "id": "http://mobilizon2.test/@admin/join/event/1",
+  "actor": "http://mobilizon2.test/@admin",
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+    "https://w3id.org/security/v1",
+    {
+      "sensitive": "as:sensitive",
+      "movedTo": "as:movedTo",
+      "manuallyApprovesFollowers": "as:manuallyApprovesFollowers",
+      "Hashtag": "as:Hashtag"
+    }
+  ]
+}

test/mobilizon/service/activity_pub/transmogrifier_test.exs

@@ -12,7 +12,7 @@ defmodule Mobilizon.Service.ActivityPub.TransmogrifierTest do
   alias Mobilizon.Actors
   alias Mobilizon.Actors.Actor
   alias Mobilizon.Events
-  alias Mobilizon.Events.{Comment, Event}
+  alias Mobilizon.Events.{Comment, Event, Participant}
   alias Mobilizon.Service.ActivityPub
   alias Mobilizon.Service.ActivityPub.Utils
   alias Mobilizon.Service.ActivityPub.Transmogrifier
@@ -695,6 +695,120 @@ defmodule Mobilizon.Service.ActivityPub.TransmogrifierTest do
       assert activity.data["actor"] == reporter_url
       assert activity.data["cc"] == [reported_url]
     end
+
+    test "it accepts Join activities" do
+      %Actor{url: _organizer_url} = organizer = insert(:actor)
+      %Actor{url: participant_url} = _participant = insert(:actor)
+
+      %Event{url: event_url} = _event = insert(:event, organizer_actor: organizer)
+
+      join_data =
+        File.read!("test/fixtures/mobilizon-join-activity.json")
+        |> Jason.decode!()
+        |> Map.put("actor", participant_url)
+        |> Map.put("object", event_url)
+
+      assert {:ok, activity, _} = Transmogrifier.handle_incoming(join_data)
+
+      assert activity.data["object"] == event_url
+      assert activity.data["actor"] == participant_url
+    end
+
+    test "it accepts Accept activities for Join activities" do
+      %Actor{url: organizer_url} = organizer = insert(:actor)
+      %Actor{} = participant_actor = insert(:actor)
+
+      %Event{} = event = insert(:event, organizer_actor: organizer, join_options: :restricted)
+
+      {:ok, join_activity, participation} = ActivityPub.join(event, participant_actor)
+
+      accept_data =
+        File.read!("test/fixtures/mastodon-accept-activity.json")
+        |> Jason.decode!()
+        |> Map.put("actor", organizer_url)
+        |> Map.put("object", participation.url)
+
+      {:ok, accept_activity, _} = Transmogrifier.handle_incoming(accept_data)
+      assert accept_activity.data["object"] == join_activity.data["id"]
+      assert accept_activity.data["object"] =~ "/join/"
+      assert accept_activity.data["id"] =~ "/accept/join/"
+
+      # We don't accept already accepted Accept activities
+      :error = Transmogrifier.handle_incoming(accept_data)
+    end
+
+    test "it accepts Reject activities for Join activities" do
+      %Actor{url: organizer_url} = organizer = insert(:actor)
+      %Actor{} = participant_actor = insert(:actor)
+
+      %Event{} = event = insert(:event, organizer_actor: organizer, join_options: :restricted)
+
+      {:ok, join_activity, participation} = ActivityPub.join(event, participant_actor)
+
+      reject_data =
+        File.read!("test/fixtures/mastodon-reject-activity.json")
+        |> Jason.decode!()
+        |> Map.put("actor", organizer_url)
+        |> Map.put("object", participation.url)
+
+      {:ok, reject_activity, _} = Transmogrifier.handle_incoming(reject_data)
+      assert reject_activity.data["object"] == join_activity.data["id"]
+      assert reject_activity.data["object"] =~ "/join/"
+      assert reject_activity.data["id"] =~ "/reject/join/"
+
+      # We don't accept already rejected Reject activities
+      assert :error == Transmogrifier.handle_incoming(reject_data)
+
+      # Organiser is not present since we use factories directly
+      assert Events.list_participants_for_event(event.uuid, 1, 10, true) |> Enum.map(& &1.id) ==
+               []
+    end
+
+    test "it accepts Leave activities" do
+      %Actor{url: _organizer_url} = organizer = insert(:actor)
+      %Actor{url: participant_url} = participant_actor = insert(:actor)
+
+      %Event{url: event_url} =
+        event = insert(:event, organizer_actor: organizer, join_options: :restricted)
+
+      organizer_participation =
+        %Participant{} = insert(:participant, event: event, actor: organizer, role: :creator)
+
+      {:ok, _join_activity, _participation} = ActivityPub.join(event, participant_actor)
+
+      join_data =
+        File.read!("test/fixtures/mobilizon-leave-activity.json")
+        |> Jason.decode!()
+        |> Map.put("actor", participant_url)
+        |> Map.put("object", event_url)
+
+      assert {:ok, activity, _} = Transmogrifier.handle_incoming(join_data)
+
+      assert activity.data["object"] == event_url
+      assert activity.data["actor"] == participant_url
+
+      # The only participant left is the organizer
+      assert Events.list_participants_for_event(event.uuid, 1, 10, true) |> Enum.map(& &1.id) == [
+               organizer_participation.id
+             ]
+    end
+
+    test "it refuses Leave activities when actor is the only organizer" do
+      %Actor{url: organizer_url} = organizer = insert(:actor)
+
+      %Event{url: event_url} =
+        event = insert(:event, organizer_actor: organizer, join_options: :restricted)
+
+      %Participant{} = insert(:participant, event: event, actor: organizer, role: :creator)
+
+      join_data =
+        File.read!("test/fixtures/mobilizon-leave-activity.json")
+        |> Jason.decode!()
+        |> Map.put("actor", organizer_url)
+        |> Map.put("object", event_url)
+
+      assert :error = Transmogrifier.handle_incoming(join_data)
+    end
   end
 
   describe "prepare outgoing" do

test/mobilizon_web/resolvers/participant_resolver_test.exs

@@ -116,7 +116,8 @@ defmodule MobilizonWeb.Resolvers.ParticipantResolverTest do
         |> auth_conn(user)
         |> post("/api", AbsintheHelpers.mutation_skeleton(mutation))
 
-      assert hd(json_response(res, 200)["errors"])["message"] =~ "Event id not found"
+      assert hd(json_response(res, 200)["errors"])["message"] ==
+               "Event with this ID 1042 doesn't exist"
     end
 
     test "actor_leave_event/3 should delete a participant from an event", %{
@@ -290,13 +291,14 @@ defmodule MobilizonWeb.Resolvers.ParticipantResolverTest do
       user: user,
       actor: actor
     } do
+      event = insert(:event)
       participant = insert(:participant, %{actor: actor})
 
       mutation = """
           mutation {
             leaveEvent(
               actor_id: #{participant.actor.id},
-              event_id: 1042
+              event_id: #{event.id}
             ) {
                 actor {
                   id
@@ -355,13 +357,13 @@ defmodule MobilizonWeb.Resolvers.ParticipantResolverTest do
         |> get("/api", AbsintheHelpers.query_skeleton(query, "participants"))
 
       assert json_response(res, 200)["data"]["participants"] == [
-               %{
-                 "actor" => %{"preferredUsername" => context.actor.preferred_username},
-                 "role" => "creator"
-               },
                %{
                  "actor" => %{"preferredUsername" => participant2.actor.preferred_username},
                  "role" => "participant"
+               },
+               %{
+                 "actor" => %{"preferredUsername" => context.actor.preferred_username},
+                 "role" => "creator"
                }
              ]
     end

test/support/factory.ex

@@ -124,15 +124,20 @@ defmodule Mobilizon.Factory do
       tags: build_list(3, :tag),
       url: Routes.page_url(Endpoint, :event, uuid),
       picture: insert(:picture),
-      uuid: uuid
+      uuid: uuid,
+      join_options: :free
     }
   end
 
   def participant_factory do
+    uuid = Ecto.UUID.generate()
+
     %Mobilizon.Events.Participant{
       event: build(:event),
       actor: build(:actor),
-      role: :creator
+      role: :creator,
+      url: "#{Endpoint.url()}/join/event/#{uuid}",
+      id: uuid
     }
   end