Support pushing and receiving updates to poll tallies (#10209)

* Process incoming poll tallies update

* Send Update on poll vote

* Do not send Updates for a poll more often than once every 3 minutes

* Include voters in people to notify of results update

* Schedule closing poll worker on poll creation

* Add new notification type for ending polls

* Add front-end support for ended poll notifications

* Fix UpdatePollSerializer

* Fix Updates not being triggered by local votes

* Fix tests failure

* Fix web push notifications for closing polls

* Minor cleanup

* Notify voters of both remote and local polls when those close

* Fix delivery of poll updates to mentioned accounts and voters

app/services/activitypub/process_poll_service.rb

@@ -0,0 +1,64 @@
+# frozen_string_literal: true
+
+class ActivityPub::ProcessPollService < BaseService
+  include JsonLdHelper
+
+  def call(poll, json)
+    @json = json
+    return unless supported_context? && expected_type?
+
+    previous_expires_at = poll.expires_at
+
+    expires_at = begin
+      if @json['closed'].is_a?(String)
+        @json['closed']
+      elsif !@json['closed'].nil? && !@json['closed'].is_a?(FalseClass)
+        Time.now.utc
+      else
+        @json['endTime']
+      end
+    end
+
+    items = begin
+      if @json['anyOf'].is_a?(Array)
+        @json['anyOf']
+      else
+        @json['oneOf']
+      end
+    end
+
+    latest_options = items.map { |item| item['name'].presence || item['content'] }
+
+    # If for some reasons the options were changed, it invalidates all previous
+    # votes, so we need to remove them
+    poll.votes.delete_all if latest_options != poll.options
+
+    begin
+      poll.update!(
+        last_fetched_at: Time.now.utc,
+        expires_at: expires_at,
+        options: latest_options,
+        cached_tallies: items.map { |item| item.dig('replies', 'totalItems') || 0 }
+      )
+    rescue ActiveRecord::StaleObjectError
+      poll.reload
+      retry
+    end
+
+    # If the poll had no expiration date set but now has, and people have voted,
+    # schedule a notification.
+    if previous_expires_at.nil? && poll.expires_at.present? && poll.votes.exists?
+      PollExpirationNotifyWorker.perform_at(poll.expires_at + 5.minutes, poll.id)
+    end
+  end
+
+  private
+
+  def supported_context?
+    super(@json)
+  end
+
+  def expected_type?
+    equals_or_includes_any?(@json['type'], %w(Question))
+  end
+end