class PaperSearch

  def self.definition(q, options={})
    Elasticsearch::DSL::Search.search do

      sort do
        if options[:sort_by] == 'date'
          by :published_at, order: 'desc'
        end
        by '_score'
      end

      query do
        # search query
        unless q.blank?
          multi_match do
            query q
            fields ["name", "content"]
          end
        else
          match_all
        end
      end

      # apply filter after aggregations
      post_filter do
        bool do
          must { term paper_type: options[:paper_type] } if options[:paper_type].present?
          must { term originator: options[:originator] } if options[:originator].present?
          # catchall when no filters set
          must { match_all } if options.keys.none? {|k| [:paper_type, :originator].include?(k) }
        end
      end

      aggregation :paper_types do
        # filter by originator
        f = Elasticsearch::DSL::Search::Filters::Bool.new
        f.must { match_all }
        f.must { term originator: options[:originator] } if options[:originator].present?
        filter f.to_hash do
          aggregation :paper_types do
            terms do
              field 'paper_type'
            end
          end
        end
      end

      aggregation :originators do
        # filter by paper_type
        f = Elasticsearch::DSL::Search::Filters::Bool.new
        f.must { match_all }
        f.must { term paper_type: options[:paper_type] } if options[:paper_type].present?
        filter f.to_hash do
          aggregation :originators do
            terms do
              field 'originator'
            end
          end
        end
      end
    end
  end
end