1 files changed, 39 insertions, 0 deletions
diff --git a/lib/gitlab/github_import/importer/events/changed_milestone.rb b/lib/gitlab/github_import/importer/events/changed_milestone.rb
new file mode 100644
index 00000000000..3164c041dc3
--- /dev/null
+++ b/lib/gitlab/github_import/importer/events/changed_milestone.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GithubImport
+    module Importer
+      module Events
+        class ChangedMilestone < BaseImporter
+          # GitHub API doesn't provide the historical state of an issue for
+          # de/milestoned issue events. So we'll assign the default state to
+          # those events that are imported from GitHub.
+          DEFAULT_STATE = Issue.available_states[:opened]
+
+          def execute(issue_event)
+            create_event(issue_event)
+          end
+
+          private
+
+          def create_event(issue_event)
+            ResourceMilestoneEvent.create!(
+              issue_id: issuable_db_id(issue_event),
+              user_id: author_id(issue_event),
+              created_at: issue_event.created_at,
+              milestone_id: project.milestones.find_by_title(issue_event.milestone_title)&.id,
+              action: action(issue_event.event),
+              state: DEFAULT_STATE
+            )
+          end
+
+          def action(event_type)
+            return ResourceMilestoneEvent.actions[:remove] if event_type == 'demilestoned'
+
+            ResourceMilestoneEvent.actions[:add]
+          end
+        end
+      end
+    end
+  end
+end