Various refactoring and typespec improvements

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

lib/graphql/resolvers/participant.ex

@@ -117,7 +117,7 @@ defmodule Mobilizon.GraphQL.Resolvers.Participant do
            |> Map.put(:actor, actor) do
       {:ok, participant}
     else
-      {:maximum_attendee_capacity, _} ->
+      {:error, :maximum_attendee_capacity_reached} ->
         {:error, dgettext("errors", "The event has already reached its maximum capacity")}
 
       {:has_event, _} ->
@@ -127,11 +127,33 @@ defmodule Mobilizon.GraphQL.Resolvers.Participant do
       {:error, :event_not_found} ->
         {:error, dgettext("errors", "Event id not found")}
 
-      {:ok, %Participant{}} ->
+      {:error, :already_participant} ->
         {:error, dgettext("errors", "You are already a participant of this event")}
     end
   end
 
+  @spec check_anonymous_participation(String.t(), String.t()) ::
+          {:ok, Event.t()} | {:error, String.t()}
+  defp check_anonymous_participation(actor_id, event_id) do
+    cond do
+      Config.anonymous_participation?() == false ->
+        {:error, dgettext("errors", "Anonymous participation is not enabled")}
+
+      to_string(Config.anonymous_actor_id()) != actor_id ->
+        {:error, dgettext("errors", "The anonymous actor ID is invalid")}
+
+      true ->
+        case Mobilizon.Events.get_event_with_preload(event_id) do
+          {:ok, %Event{} = event} ->
+            {:ok, event}
+
+          {:error, :event_not_found} ->
+            {:error,
+             dgettext("errors", "Event with this ID %{id} doesn't exist", id: inspect(event_id))}
+        end
+    end
+  end
+
   @doc """
   Leave an event for an anonymous actor
   """
@@ -141,33 +163,27 @@ defmodule Mobilizon.GraphQL.Resolvers.Participant do
         _resolution
       )
       when not is_nil(token) do
-    with {:anonymous_participation_enabled, true} <-
-           {:anonymous_participation_enabled, Config.anonymous_participation?()},
-         {:anonymous_actor_id, true} <-
-           {:anonymous_actor_id, to_string(Config.anonymous_actor_id()) == actor_id},
-         {:has_event, {:ok, %Event{} = event}} <-
-           {:has_event, Mobilizon.Events.get_event_with_preload(event_id)},
-         %Actor{} = actor <- Actors.get_actor_with_preload(actor_id),
-         {:ok, _activity, %Participant{id: participant_id} = _participant} <-
-           Participations.leave(event, actor, %{local: false, cancellation_token: token}) do
-      {:ok, %{event: %{id: event_id}, actor: %{id: actor_id}, id: participant_id}}
-    else
-      {:has_event, _} ->
-        {:error,
-         dgettext("errors", "Event with this ID %{id} doesn't exist", id: inspect(event_id))}
+    case check_anonymous_participation(actor_id, event_id) do
+      {:ok, %Event{} = event} ->
+        %Actor{} = actor = Actors.get_actor_with_preload!(actor_id)
 
-      {:is_owned, nil} ->
-        {:error, dgettext("errors", "Profile is not owned by authenticated user")}
+        case Participations.leave(event, actor, %{local: false, cancellation_token: token}) do
+          {:ok, _activity, %Participant{id: participant_id} = _participant} ->
+            {:ok, %{event: %{id: event_id}, actor: %{id: actor_id}, id: participant_id}}
 
-      {:only_organizer, true} ->
-        {:error,
-         dgettext(
-           "errors",
-           "You can't leave event because you're the only event creator participant"
-         )}
+          {:error, :is_only_organizer} ->
+            {:error,
+             dgettext(
+               "errors",
+               "You can't leave event because you're the only event creator participant"
+             )}
 
-      {:error, :participant_not_found} ->
-        {:error, dgettext("errors", "Participant not found")}
+          {:error, :participant_not_found} ->
+            {:error, dgettext("errors", "Participant not found")}
+
+          {:error, _err} ->
+            {:error, dgettext("errors", "Failed to leave the event")}
+        end
     end
   end
 
@@ -188,7 +204,7 @@ defmodule Mobilizon.GraphQL.Resolvers.Participant do
       {:is_owned, nil} ->
         {:error, dgettext("errors", "Profile is not owned by authenticated user")}
 
-      {:only_organizer, true} ->
+      {:error, :is_only_organizer} ->
         {:error,
          dgettext(
            "errors",