fix: add rake task to delete unwanted follows of ex private users

RELEASE_NOTES.md

@@ -51,6 +51,11 @@ You can read more about this change on PR [#12616](https://github.com/decidim/de
 
 These are one time actions that need to be done after the code is updated in the production database.
 
+To delete the follows of ex private users of non transparent assemblies or processes, run from decidim-admin
+```console
+bundle exec rake decidim:upgrade:fix_deleted_private_follows
+```
+
 ### 3.1. CarrierWave removal
 
 Back in Decidim 0.25 we have added ActiveStorage (via [\#7902](https://github.com/decidim/decidim/pull/7902)) as main uploader instead of CarrierWave.

decidim-admin/lib/tasks/delete_follows_of_ex_private_users_task.rake

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+namespace :decidim do
+  namespace :upgrade do
+    desc "Delete follows of ex private users"
+    task fix_deleted_private_follows: :environment do
+      def find_object(follow)
+        follow.decidim_followable_type.constantize.find(follow.decidim_followable_id)
+      end
+
+      def delete_unwanted_follows(model, elements, children_follows)
+        count = 0
+        p "begin deleting follows"
+        elements.each do |element|
+          # for each element, find their private users
+          private_users_ids = Decidim::ParticipatorySpacePrivateUser.where(privatable_to_id: element.id, privatable_to_type: model.to_s).pluck(:decidim_user_id)
+          # delete follows from non private users
+          direct_follows_to_delete = Decidim::Follow.where(followable: element.id, decidim_followable_type: model.to_s)
+                                                    .reject { |follow| private_users_ids.include?(follow.decidim_user_id) }
+          count += direct_follows_to_delete.size
+          direct_follows_to_delete.map { |follow| Decidim::Follow.delete(follow.id) }
+          # children of element
+          element_components_ids = element.components.ids
+          children_follows_to_delete = children_follows.select { |follow| element_components_ids.include?(find_object(follow).decidim_component_id) }
+                                                       .reject { |follow| private_users_ids.include?(follow.decidim_user_id) }
+          count += children_follows_to_delete.size
+          children_follows_to_delete.map { |follow| Decidim::Follow.delete(follow.id) }
+        end
+        p "#{count} follows have been deleted for #{model} and their children"
+      end
+      children_follows = Decidim::Follow.select { |follow| find_object(follow).respond_to?(:decidim_component_id) }
+      # find private non transparent assemblies
+      assemblies = Decidim::Assembly.where(private_space: true, is_transparent: false).published
+      # delete unwanted follows
+      delete_unwanted_follows(Decidim::Assembly, assemblies, children_follows)
+      # find private processes
+      processes = Decidim::ParticipatoryProcess.where(private_space: true).published
+      # delete unwanted follows
+      delete_unwanted_follows(Decidim::ParticipatoryProcess, processes, children_follows)
+    end
+  end
+end