source: src/main/java/negotiator/boaframework/omstrategy/BestBid.java@ 209

package negotiator.boaframework.omstrategy;

import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;

import genius.core.bidding.BidDetails;
import genius.core.boaframework.BOAparameter;
import genius.core.boaframework.NegotiationSession;
import genius.core.boaframework.OMStrategy;
import genius.core.boaframework.OpponentModel;

/**
 * This class uses an opponent model to determine the next bid for the opponent,
 * while taking the opponent's preferences into account. The opponent model is
 * used to select the best bid.
 * 
 * @author Mark Hendrikx
 */
public class BestBid extends OMStrategy {

        /**
         * when to stop updating the opponentmodel. Note that this value is not
         * exactly one as a match sometimes lasts slightly longer.
         */
        double updateThreshold = 1.1;

        /**
         * Initializes the opponent model strategy. If a value for the parameter t
         * is given, then it is set to this value. Otherwise, the default value is
         * used.
         * 
         * @param negotiationSession
         *            state of the negotiation.
         * @param model
         *            opponent model used in conjunction with this opponent modeling
         *            strategy.
         * @param parameters
         *            set of parameters for this opponent model strategy.
         */
        @Override
        public void init(NegotiationSession negotiationSession, OpponentModel model, Map<String, Double> parameters) {
                super.init(negotiationSession, model, new HashMap<String, Double>());
                if (parameters.get("t") != null) {
                        updateThreshold = parameters.get("t").doubleValue();
                } else {
                        System.out.println("OMStrategy assumed t = 1.1");
                }
        }

        /**
         * Returns the best bid for the opponent given a set of similarly preferred
         * bids.
         * 
         * @param allBids
         *            of the bids considered for offering.
         * @return bid to be offered to opponent.
         */
        @Override
        public BidDetails getBid(List<BidDetails> allBids) {

                // 1. If there is only a single bid, return this bid
                if (allBids.size() == 1) {
                        return allBids.get(0);
                }
                double bestUtil = -1;
                BidDetails bestBid = allBids.get(0);

                // 2. Check that not all bids are assigned at utility of 0
                // to ensure that the opponent model works. If the opponent model
                // does not work, offer a random bid.
                boolean allWereZero = true;
                // 3. Determine the best bid
                for (BidDetails bid : allBids) {
                        double evaluation = model.getBidEvaluation(bid.getBid());
                        if (evaluation > 0.0001) {
                                allWereZero = false;
                        }
                        if (evaluation > bestUtil) {
                                bestBid = bid;
                                bestUtil = evaluation;
                        }
                }
                // 4. The opponent model did not work, therefore, offer a random bid.
                if (allWereZero) {
                        Random r = new Random();
                        return allBids.get(r.nextInt(allBids.size()));
                }
                return bestBid;
        }

        /**
         * The opponent model may be updated, unless the time is higher than a given
         * constant.
         * 
         * @return true if model may be updated.
         */
        @Override
        public boolean canUpdateOM() {
                return negotiationSession.getTime() < updateThreshold;
        }

        @Override
        public Set<BOAparameter> getParameterSpec() {
                Set<BOAparameter> set = new HashSet<BOAparameter>();
                set.add(new BOAparameter("t", 1.1, "Time after which the OM should not be updated"));
                return set;
        }

        @Override
        public String getName() {
                return "BestBid";
        }
}