source: src/main/java/negotiator/boaframework/omstrategy/NTFTstrategy.java@ 326

package negotiator.boaframework.omstrategy;

import java.util.List;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

import genius.core.Bid;
import genius.core.bidding.BidDetails;
import genius.core.bidding.BidDetailsSorterUtility;
import genius.core.boaframework.NegotiationSession;
import genius.core.boaframework.OMStrategy;
import genius.core.boaframework.OpponentModel;

/**
 * Implements the opponent model strategy used by the NiceTitForTat agent in the
 * ANAC2011. The strategy selects a random bid from the best N bids. What is
 * special in comparison to OfferBestN, is that N depends on the domain size.
 * Furthermore, the strategy stops updating the opponent model before the
 * deadline. The time at which the updating stops depends on the domain size.
 * 
 * This component is part of the NiceTitForTat strategy introduced by T.
 * Baarslag in the ANAC 2011.
 * 
 * @author Mark Hendrikx
 */
public class NTFTstrategy extends OMStrategy {

        private boolean domainIsBig;
        private long possibleBids;
        private Random random;
        private BidDetailsSorterUtility comp = new BidDetailsSorterUtility();

        @Override
        public void init(NegotiationSession negotiationSession, OpponentModel model, Map<String, Double> parameters) {
                initializeAgent(negotiationSession, model);
        }

        private void initializeAgent(NegotiationSession negoSession, OpponentModel model) {
                this.negotiationSession = negoSession;
                try {
                        super.init(negotiationSession, model, new HashMap<String, Double>());
                } catch (Exception e) {
                        e.printStackTrace();
                }
                this.possibleBids = negotiationSession.getUtilitySpace().getDomain().getNumberOfPossibleBids();
                domainIsBig = (possibleBids > 10000);
                random = new Random();
        }

        /**
         * Selects a random bid from the best N bids, where N depends on the domain
         * size.
         * 
         * @param set
         *            of similarly preferred bids.
         * @return nextBid to be offered
         */
        @Override
        public BidDetails getBid(List<BidDetails> bidsInRange) {
                ArrayList<BidDetails> bidsOM = new ArrayList<BidDetails>();
                for (BidDetails bid : bidsInRange) {
                        double utility;
                        try {
                                utility = model.getBidEvaluation(bid.getBid());
                                BidDetails bidDetails = new BidDetails(bid.getBid(), utility);
                                bidsOM.add(bidDetails);
                        } catch (Exception e) {
                                e.printStackTrace();
                        }
                }

                // Pick the top 3 to 20 bids, depending on the domain size
                int n = (int) Math.round(bidsOM.size() / 10.0);
                if (n < 3)
                        n = 3;
                if (n > 20)
                        n = 20;

                Collections.sort(bidsOM, comp);

                int entry = random.nextInt(Math.min(bidsOM.size(), n));
                Bid opponentBestBid = bidsOM.get(entry).getBid();
                BidDetails nextBid = null;
                try {
                        nextBid = new BidDetails(opponentBestBid, negotiationSession.getUtilitySpace().getUtility(opponentBestBid),
                                        negotiationSession.getTime());
                } catch (Exception e) {
                        e.printStackTrace();
                }
                return nextBid;
        }

        /**
         * Method which specifies when the opponent model may be updated. In small
         * domains the model may be updated up till 0.99 of the time. In large
         * domains the updating process stops half way.
         * 
         * @return true if the opponent model may be updated
         */
        @Override
        public boolean canUpdateOM() {
                // in the last seconds we don't want to lose any time
                if (negotiationSession.getTime() > 0.99)
                        return false;

                // in a big domain, we stop updating half-way
                if (domainIsBig) {
                        if (negotiationSession.getTime() > 0.5) {
                                return false;
                        }
                }
                return true;
        }

        @Override
        public String getName() {
                return "Offer Best Bids";
        }
}