module PostSets
  class Base
    def has_wiki?
      false
    end

    def raw
      false
    end

    def wiki_page
      nil
    end

    def has_artist?
      false
    end

    def artist
      nil
    end

    def is_single_tag?
      false
    end

    def tag_string
      nil
    end

    def presenter
      raise NotImplementedError
    end

    def arbitrary_sql_order_clause(ids, table_name)
      if ids.empty?
        return "#{table_name}.id desc"
      end

      conditions = []

      ids.each_with_index do |x, n|
        conditions << "when #{x} then #{n}"
      end

      "case #{table_name}.id " + conditions.join(" ") + " end"
    end
  end
end