Federate participations

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

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