3 files changed, 187 insertions, 0 deletions
diff --git a/app/services/issuable/clone/attributes_rewriter.rb b/app/services/issuable/clone/attributes_rewriter.rb
new file mode 100644
index 00000000000..0300cc0d8d3
--- /dev/null
+++ b/app/services/issuable/clone/attributes_rewriter.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+module Issuable
+  module Clone
+    class AttributesRewriter < ::Issuable::Clone::BaseService
+      def initialize(current_user, original_entity, new_entity)
+        @current_user = current_user
+        @original_entity = original_entity
+        @new_entity = new_entity
+      end
+
+      def execute
+        new_entity.update(milestone: cloneable_milestone, labels: cloneable_labels)
+        copy_resource_label_events
+      end
+
+      private
+
+      def cloneable_milestone
+        title = original_entity.milestone&.title
+        return unless title
+
+        params = { title: title, project_ids: new_entity.project&.id, group_ids: group&.id }
+
+        milestones = MilestonesFinder.new(params).execute
+        milestones.first
+      end
+
+      def cloneable_labels
+        params = {
+          project_id: new_entity.project&.id,
+          group_id: group&.id,
+          title: original_entity.labels.select(:title),
+          include_ancestor_groups: true
+        }
+
+        params[:only_group_labels] = true if new_parent.is_a?(Group)
+
+        LabelsFinder.new(current_user, params).execute
+      end
+
+      def copy_resource_label_events
+        original_entity.resource_label_events.find_in_batches do |batch|
+          events = batch.map do |event|
+            entity_key = new_entity.is_a?(Issue) ? 'issue_id' : 'epic_id'
+            # rubocop: disable CodeReuse/ActiveRecord
+            event.attributes
+              .except('id', 'reference', 'reference_html')
+              .merge(entity_key => new_entity.id, 'action' => ResourceLabelEvent.actions[event.action])
+            # rubocop: enable CodeReuse/ActiveRecord
+          end
+
+          Gitlab::Database.bulk_insert(ResourceLabelEvent.table_name, events)
+        end
+      end
+
+      def entity_key
+        new_entity.class.name.parameterize('_').foreign_key
+      end
+    end
+  end
+end
diff --git a/app/services/issuable/clone/base_service.rb b/app/services/issuable/clone/base_service.rb
new file mode 100644
index 00000000000..42dd9c666f5
--- /dev/null
+++ b/app/services/issuable/clone/base_service.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+module Issuable
+  module Clone
+    class BaseService < IssuableBaseService
+      attr_reader :original_entity, :new_entity
+
+      alias_method :old_project, :project
+
+      def execute(original_entity, new_project = nil)
+        @original_entity = original_entity
+
+        # Using transaction because of a high resources footprint
+        # on rewriting notes (unfolding references)
+        #
+        ActiveRecord::Base.transaction do
+          @new_entity = create_new_entity
+
+          update_new_entity
+          update_old_entity
+          create_notes
+        end
+      end
+
+      private
+
+      def update_new_entity
+        rewriters = [ContentRewriter, AttributesRewriter]
+
+        rewriters.each do |rewriter|
+          rewriter.new(current_user, original_entity, new_entity).execute
+        end
+      end
+
+      def update_old_entity
+        close_issue
+      end
+
+      def create_notes
+        add_note_from
+        add_note_to
+      end
+
+      def close_issue
+        close_service = Issues::CloseService.new(old_project, current_user)
+        close_service.execute(original_entity, notifications: false, system_note: false)
+      end
+
+      def new_parent
+        new_entity.project ? new_entity.project : new_entity.group
+      end
+
+      def group
+        if new_entity.project&.group && current_user.can?(:read_group, new_entity.project.group)
+          new_entity.project.group
+        end
+      end
+    end
+  end
+end
diff --git a/app/services/issuable/clone/content_rewriter.rb b/app/services/issuable/clone/content_rewriter.rb
new file mode 100644
index 00000000000..e1e0b75085d
--- /dev/null
+++ b/app/services/issuable/clone/content_rewriter.rb
@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+module Issuable
+  module Clone
+    class ContentRewriter < ::Issuable::Clone::BaseService
+      def initialize(current_user, original_entity, new_entity)
+        @current_user = current_user
+        @original_entity = original_entity
+        @new_entity = new_entity
+        @project = original_entity.project
+      end
+
+      def execute
+        rewrite_description
+        rewrite_award_emoji(original_entity, new_entity)
+        rewrite_notes
+      end
+
+      private
+
+      def rewrite_description
+        new_entity.update(description: rewrite_content(original_entity.description))
+      end
+
+      def rewrite_notes
+        original_entity.notes_with_associations.find_each do |note|
+          new_note = note.dup
+          new_params = {
+            project: new_entity.project, noteable: new_entity,
+            note: rewrite_content(new_note.note),
+            created_at: note.created_at,
+            updated_at: note.updated_at
+          }
+
+          if note.system_note_metadata
+            new_params[:system_note_metadata] = note.system_note_metadata.dup
+          end
+
+          new_note.update(new_params)
+
+          rewrite_award_emoji(note, new_note)
+        end
+      end
+
+      def rewrite_content(content)
+        return unless content
+
+        rewriters = [Gitlab::Gfm::ReferenceRewriter, Gitlab::Gfm::UploadsRewriter]
+
+        rewriters.inject(content) do |text, klass|
+          rewriter = klass.new(text, old_project, current_user)
+          rewriter.rewrite(new_parent)
+        end
+      end
+
+      def rewrite_award_emoji(old_awardable, new_awardable)
+        old_awardable.award_emoji.each do |award|
+          new_award = award.dup
+          new_award.awardable = new_awardable
+          new_award.save
+        end
+      end
+    end
+  end
+end