auction_query.rb

class AuctionQuery
  def initialize(relation = Auction.all)
    @relation = relation.extending(Scopes)
  end

  module Scopes
    def delivery_deadline_expired
      where('delivery_deadline < ?', Time.zone.now)
    end

    def accepted
      where(result: accepted_enum)
    end

    def delivered
      where.not(delivery_url: [nil, ""])
    end

    def cap_submitted
      where.not(cap_proposal_url: [nil, ""])
    end

    def paid
      where(
        awardee_paid_status: paid_enum
      )
    end

    def not_paid
      where(
        awardee_paid_status: not_paid_enum
      )
    end

    private

    def paid_enum
      Auction.awardee_paid_statuses['paid']
    end

    def not_paid_enum
      Auction.awardee_paid_statuses['not_paid']
    end

    def accepted_enum
      Auction.results['accepted']
    end
  end

  [
    :delivery_deadline_expired,
    :accepted,
    :delivered,
    :cap_submitted,
    :paid,
    :not_paid
  ].each do |key|
    define_method key do
      @relation.send(key)
    end
  end

  def complete_and_successful
    @relation
      .delivery_deadline_expired
      .delivered
      .accepted
      .cap_submitted
      .paid
  end

  def payment_pending
    @relation
      .delivery_deadline_expired
      .delivered.accepted
      .cap_submitted
      .not_paid
  end
end

Cool!