module Gitlab
  module Database
    module RenameReservedPathsMigration
      module V1
        class RenameBase
          attr_reader :paths, :migration

          delegate :update_column_in_batches,
                   :replace_sql,
                   to: :migration

          def initialize(paths, migration)
            @paths = paths
            @migration = migration
          end

          def path_patterns
            @path_patterns ||= paths.flat_map { |path| ["%/#{path}", path] }
          end

          def rename_path_for_routable(routable)
            old_path = routable.path
            old_full_path = routable.full_path
            # Only remove the last occurrence of the path name to get the parent namespace path
            namespace_path = remove_last_occurrence(old_full_path, old_path)
            new_path = rename_path(namespace_path, old_path)
            new_full_path = join_routable_path(namespace_path, new_path)

            # skips callbacks & validations
            routable.class.where(id: routable).
              update_all(path: new_path)

            rename_routes(old_full_path, new_full_path)

            [old_full_path, new_full_path]
          end

          def rename_routes(old_full_path, new_full_path)
            replace_statement = replace_sql(Route.arel_table[:path],
                                            old_full_path,
                                            new_full_path)

            update_column_in_batches(:routes, :path, replace_statement)  do |table, query|
              path_or_children = table[:path].matches_any([old_full_path, "#{old_full_path}/%"])
              query.where(path_or_children)
            end
          end

          def rename_path(namespace_path, path_was)
            counter = 0
            path = "#{path_was}#{counter}"

            while route_exists?(join_routable_path(namespace_path, path))
              counter += 1
              path = "#{path_was}#{counter}"
            end

            path
          end

          def remove_last_occurrence(string, pattern)
            string.reverse.sub(pattern.reverse, "").reverse
          end

          def join_routable_path(namespace_path, top_level)
            if namespace_path.present?
              File.join(namespace_path, top_level)
            else
              top_level
            end
          end

          def route_exists?(full_path)
            MigrationClasses::Route.where(Route.arel_table[:path].matches(full_path)).any?
          end

          def move_pages(old_path, new_path)
            move_folders(pages_dir, old_path, new_path)
          end

          def move_uploads(old_path, new_path)
            return unless file_storage?

            move_folders(uploads_dir, old_path, new_path)
          end

          def move_folders(directory, old_relative_path, new_relative_path)
            old_path = File.join(directory, old_relative_path)
            return unless File.directory?(old_path)

            new_path = File.join(directory, new_relative_path)
            FileUtils.mv(old_path, new_path)
          end

          def remove_cached_html_for_projects(project_ids)
            update_column_in_batches(:projects, :description_html, nil) do |table, query|
              query.where(table[:id].in(project_ids))
            end

            update_column_in_batches(:issues, :description_html, nil) do |table, query|
              query.where(table[:project_id].in(project_ids))
            end

            update_column_in_batches(:merge_requests, :description_html, nil) do |table, query|
              query.where(table[:target_project_id].in(project_ids))
            end

            update_column_in_batches(:notes, :note_html, nil) do |table, query|
              query.where(table[:project_id].in(project_ids))
            end

            update_column_in_batches(:milestones, :description_html, nil) do |table, query|
              query.where(table[:project_id].in(project_ids))
            end
          end

          def file_storage?
            CarrierWave::Uploader::Base.storage == CarrierWave::Storage::File
          end

          def uploads_dir
            File.join(CarrierWave.root, "uploads")
          end

          def pages_dir
            Settings.pages.path
          end
        end
      end
    end
  end
end