# frozen_string_literal: true

module Gitlab
  module ImportExport
    class MergeRequestParser
      FORKED_PROJECT_ID = nil

      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']

          create_source_branch unless branch_exists?(@merge_request.source_branch)
          create_target_branch unless branch_exists?(@merge_request.target_branch)
        end

        # The merge_request_diff associated with the current @merge_request might
        # be invalid. Than means, when the @merge_request object is saved, the
        # @merge_request.merge_request_diff won't. This can leave the merge request
        # in an invalid state, because a merge request must have an associated
        # merge request diff.
        # In this change, if the associated merge request diff is invalid, we set
        # it to nil. This change, in association with the after callback
        # :ensure_merge_request_diff in the MergeRequest class, makes that
        # when the merge request is going to be created and it doesn't have
        # one, a default one will be generated.
        @merge_request.merge_request_diff = nil unless @merge_request.merge_request_diff&.valid?
        @merge_request
      end

      # When the exported MR was in a fork, the source branch does not exist in
      # the imported bundle - although the commits usually do - so it must be
      # created manually. Ignore failures so we get the merge request itself if
      # the commits are missing.
      def create_source_branch
        if @merge_request.open?
          @project.repository.create_branch(@merge_request.source_branch, @diff_head_sha)
        end
      rescue StandardError => err
        Gitlab::Import::Logger.warn(
          message: 'Import warning: Failed to create source branch',
          source_branch: @merge_request.source_branch,
          diff_head_sha: @diff_head_sha,
          merge_request_iid: @merge_request.iid,
          error: err.message
        )
      end

      def create_target_branch
        @project.repository.create_branch(@merge_request.target_branch, @merge_request.target_branch_sha)
      end

      def branch_exists?(branch_name)
        @project.repository.raw.branch_exists?(branch_name)
      end

      def fork_merge_request?
        @relation_hash['source_project_id'] == FORKED_PROJECT_ID
      end
    end
  end
end