1 files changed, 41 insertions, 0 deletions
diff --git a/lib/gitlab/import_export/merge_request_parser.rb b/lib/gitlab/import_export/merge_request_parser.rb
new file mode 100644
index 00000000000..c20adc20bfd
--- /dev/null
+++ b/lib/gitlab/import_export/merge_request_parser.rb
@@ -0,0 +1,41 @@
+module Gitlab
+  module ImportExport
+    class MergeRequestParser
+      FORKED_PROJECT_ID = -1
+
+      def initialize(project, diff_head_sha, merge_request, relation_hash)
+        @project = project
+        @diff_head_sha = diff_head_sha
+        @merge_request = merge_request
+        @relation_hash = relation_hash
+      end
+
+      def parse!
+        if fork_merge_request? && @diff_head_sha
+          @merge_request.source_project_id = @relation_hash['project_id']
+
+          fetch_ref unless branch_exists?(@merge_request.source_branch)
+          create_target_branch unless branch_exists?(@merge_request.target_branch)
+        end
+
+        @merge_request
+      end
+
+      def create_target_branch
+        @project.repository.create_branch(@merge_request.target_branch, @merge_request.target_branch_sha)
+      end
+
+      def fetch_ref
+        @project.repository.fetch_ref(@project.repository.path, @diff_head_sha, @merge_request.source_branch)
+      end
+
+      def branch_exists?(branch_name)
+        @project.repository.branch_exists?(branch_name)
+      end
+
+      def fork_merge_request?
+        @relation_hash['source_project_id'] == FORKED_PROJECT_ID
+      end
+    end
+  end
+end