1 files changed, 63 insertions, 0 deletions
diff --git a/lib/gitlab/github_import/importer/diff_note_importer.rb b/lib/gitlab/github_import/importer/diff_note_importer.rb
new file mode 100644
index 00000000000..8274f37d358
--- /dev/null
+++ b/lib/gitlab/github_import/importer/diff_note_importer.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module GithubImport
+    module Importer
+      class DiffNoteImporter
+        attr_reader :note, :project, :client, :user_finder
+
+        # note - An instance of `Gitlab::GithubImport::Representation::DiffNote`.
+        # project - An instance of `Project`.
+        # client - An instance of `Gitlab::GithubImport::Client`.
+        def initialize(note, project, client)
+          @note = note
+          @project = project
+          @client = client
+          @user_finder = UserFinder.new(project, client)
+        end
+
+        def execute
+          return unless (mr_id = find_merge_request_id)
+
+          author_id, author_found = user_finder.author_id_for(note)
+
+          note_body =
+            MarkdownText.format(note.note, note.author, author_found)
+
+          attributes = {
+            noteable_type: 'MergeRequest',
+            noteable_id: mr_id,
+            project_id: project.id,
+            author_id: author_id,
+            note: note_body,
+            system: false,
+            commit_id: note.commit_id,
+            line_code: note.line_code,
+            type: 'LegacyDiffNote',
+            created_at: note.created_at,
+            updated_at: note.updated_at,
+            st_diff: note.diff_hash.to_yaml
+          }
+
+          # It's possible that during an import we'll insert tens of thousands
+          # of diff notes. If we were to use the Note/LegacyDiffNote model here
+          # we'd also have to run additional queries for both validations and
+          # callbacks, putting a lot of pressure on the database.
+          #
+          # To work around this we're using bulk_insert with a single row. This
+          # allows us to efficiently insert data (even if it's just 1 row)
+          # without having to use all sorts of hacks to disable callbacks.
+          Gitlab::Database.bulk_insert(LegacyDiffNote.table_name, [attributes])
+        rescue ActiveRecord::InvalidForeignKey
+          # It's possible the project and the issue have been deleted since
+          # scheduling this job. In this case we'll just skip creating the note.
+        end
+
+        # Returns the ID of the merge request this note belongs to.
+        def find_merge_request_id
+          GithubImport::IssuableFinder.new(project, note).database_id
+        end
+      end
+    end
+  end
+end