1 files changed, 68 insertions, 0 deletions
diff --git a/lib/gitlab/import_export/members_mapper.rb b/lib/gitlab/import_export/members_mapper.rb
new file mode 100644
index 00000000000..c569a35a48b
--- /dev/null
+++ b/lib/gitlab/import_export/members_mapper.rb
@@ -0,0 +1,68 @@
+module Gitlab
+  module ImportExport
+    class MembersMapper
+
+      attr_reader :missing_author_ids
+
+      def initialize(exported_members:, user:, project:)
+        @exported_members = exported_members
+        @user = user
+        @project = project
+        @missing_author_ids = []
+
+        # This needs to run first, as second call would be from #map
+        # which means project members already exist.
+        ensure_default_member!
+      end
+
+      def map
+        @map ||=
+          begin
+            @exported_members.inject(missing_keys_tracking_hash) do |hash, member|
+              existing_user = User.where(find_project_user_query(member)).first
+              old_user_id = member['user']['id']
+              if existing_user && add_user_as_team_member(existing_user, member)
+                hash[old_user_id] = existing_user.id
+              end
+              hash
+            end
+          end
+      end
+
+      def default_user_id
+        @user.id
+      end
+
+      private
+
+      def missing_keys_tracking_hash
+        Hash.new do |_, key|
+          @missing_author_ids << key
+          default_user_id
+        end
+      end
+
+      def ensure_default_member!
+        ProjectMember.create!(user: @user, access_level: ProjectMember::MASTER, source_id: @project.id, importing: true)
+      end
+
+      def add_user_as_team_member(existing_user, member)
+        member['user'] = existing_user
+
+        ProjectMember.create(member_hash(member)).persisted?
+      end
+
+      def member_hash(member)
+        member.except('id').merge(source_id: @project.id, importing: true)
+      end
+
+      def find_project_user_query(member)
+        user_arel[:username].eq(member['user']['username']).or(user_arel[:email].eq(member['user']['email']))
+      end
+
+      def user_arel
+        @user_arel ||= User.arel_table
+      end
+    end
+  end
+end