source: boa/src/main/java/geniusweb/boa/biddingstrategy/TimeDependentBiddingStrategy.java@ 21

package geniusweb.boa.biddingstrategy;

import java.math.BigDecimal;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;
import java.util.logging.Level;

import geniusweb.actions.Accept;
import geniusweb.actions.Action;
import geniusweb.actions.EndNegotiation;
import geniusweb.actions.Offer;
import geniusweb.actions.PartyId;
import geniusweb.boa.BoaState;
import geniusweb.inform.Settings;
import geniusweb.issuevalue.Bid;
import geniusweb.profile.Profile;
import geniusweb.profile.utilityspace.LinearAdditive;
import tudelft.utilities.immutablelist.ImmutableList;

/**
 * This is an abstract class used to implement a TimeDependentAgent Strategy
 * adapted from S. Shaheen Fatima Michael Wooldridge Nicholas R. Jennings
 * Optimal Negotiation Strategies for Agents with Incomplete Information
 * http://eprints.ecs.soton.ac.uk/6151/1/atal01.pdf
 * <p>
 * Required: the profile is {@link LinearAdditive}. Does not currently handle
 * profile changes.
 * <p>
 * As basis, the original Genius'
 * negotiator.boaframework.offeringstrategy.other.GeniusTimeDependent_Offering
 * was used. However that seems to ignore the reservation value. This was fixed
 * here.
 * <p>
 * The default strategy was extended to enable the usage of opponent models.
 * <p>
 * The time-dependent utility target function is f(t) = k + (1.0 - k) *
 * Math.pow((t - startTime) / (1.0 - startTime), 1.0 / e). The utility target is
 * then set at min+(max-min)*f(t) where the default values for min = either the
 * utility of the reservation bid or the absolute minimum utility of the
 * profile, and default for max the maximum attainable utility.
 * <p>
 * 
 * Parameters:
 * <ul>
 * <li>e: see {@link #getE(BoaState)}
 * <li>k: see {@link #getK(BoaState)}
 * <li>min: see {@link #getMin(BoaState)}.
 * <li>max: see {@link #getMax(BoaState)}
 * </ul>
 */
public class TimeDependentBiddingStrategy implements BiddingStrategy {
        // bidSpace=null means we're not yet initialized.
        private ExtendedUtilSpace bidSpace = null;
        private Double e, k, min, max; // min, max attainable utility
        private PartyId me;

        @Override
        public Action getAction(BoaState state) {
                if (bidSpace == null) {
                        init(state);
                }

                double utilityGoal = p(
                                state.getProgress().get(System.currentTimeMillis()));

                // if there is no opponent model available
                ImmutableList<Bid> bidOptions = bidSpace
                                .getBids((BigDecimal.valueOf(utilityGoal)));

                if (bidOptions.size().intValue() == 0) {
                        // should not happen, emergency exit
                        state.getReporter().log(Level.WARNING,
                                        "No viable bids found around current utility target");
                        Bid lastBid = getLastBid(state.getActionHistory());
                        if (lastBid == null)
                                return new EndNegotiation(me);
                        return new Accept(me, lastBid);
                }
                Bid pickedBid = bidOptions.get(ThreadLocalRandom.current()
                                .nextInt(bidOptions.size().intValue()));
                return new Offer(me, pickedBid);

        }

        /**
         * Overrideable for hard configuring this component.
         * 
         * @param state the {@link BoaState}
         * @return the parameter e for the time depemdency function
         *         {@link #f(double)}. The parameter is 1 by default, or the value
         *         for the "e" parameter in the {@link Settings} if available.
         */
        protected Double getE(BoaState state) {
                HashMap<String, Object> params = state.getSettings().getParameters();
                Double e = 1d;
                if (params.containsKey("e")) {
                        e = (Double) params.get("e");
                        if (e < 0 || e > 1)
                                throw new IllegalArgumentException(
                                                "e must be in [0,1] but got " + this.e);
                }
                return e;
        }

        /**
         * Overrideable for hard configuring this component.
         * 
         * @param state the {@link BoaState}
         * @return the parameter k for the time depemdency function
         *         {@link #f(double)}. The parameter is 0 by default, or the value
         *         for the "k" parameter in the {@link Settings} if available.
         */
        protected Double getK(BoaState state) {
                HashMap<String, Object> params = state.getSettings().getParameters();
                Double k = 0d; // default
                if (params.containsKey("k")) {
                        k = (Double) params.get("k");
                        if (k < 0 || k > 1)
                                throw new IllegalArgumentException(
                                                "k must be in [0,1] but got " + this.e);
                }
                return k;
        }

        /**
         * Assumes {@link #bidSpace} has been initialized.
         * <p>
         * Overrideable for hard configuring this component.
         * 
         * @param state the {@link BoaState}
         * @return the min value for {@link #p(double)}. We use the "min" parameter
         *         in the {@link Settings} if available. If not available, the
         *         parameter is computed as the utility of the reservation bid. If
         *         there is no reservation bid, we use the minimum utility of the
         *         available profile.
         */
        protected Double getMin(BoaState state) {
                HashMap<String, Object> params = state.getSettings().getParameters();
                if (params.containsKey("min")) {
                        return Math.max(0f, Math.min(1f, (Double) params.get("min")));
                }
                LinearAdditive profile = (LinearAdditive) state.getProfile();
                if (profile.getReservationBid() != null) {
                        return profile.getUtility(profile.getReservationBid())
                                        .doubleValue();
                }

                return bidSpace.getMin().doubleValue();
        }

        /**
         * Assumes {@link #bidSpace} has been initialized.
         * <p>
         * Overrideable for hard configuring this component.
         * 
         * @param state the {@link BoaState}
         * @return the max value for {@link #p(double)}. We use the "max" parameter
         *         in the {@link Settings} if available. If not available, we use
         *         the maximum utility of the available profile.
         */
        protected Double getMax(BoaState state) {
                HashMap<String, Object> params = state.getSettings().getParameters();
                if (params.containsKey("max")) {
                        return Math.max(0f, Math.min(1f, (Double) params.get("max")));
                }
                return bidSpace.getMax().doubleValue();

        }

        /**
         * @return the most recent bid that was offered, or null if no offer has
         *         been done yet.
         */
        private Bid getLastBid(List<Action> history) {
                for (int n = history.size() - 1; n >= 0; n--) {
                        Action action = history.get(n);
                        if (action instanceof Offer) {
                                return ((Offer) action).getBid();
                        }
                }
                return null;
        }

        /**
         * initializes bidSpace
         * 
         * @param state
         */
        private void init(BoaState state) {
                this.me = state.getSettings().getID();
                Profile prof = state.getProfile();
                if (!(prof instanceof LinearAdditive))
                        throw new IllegalArgumentException(
                                        "Requires a LinearAdditive space but got " + prof);
                LinearAdditive profile = (LinearAdditive) prof;

                this.bidSpace = getBidSpace(profile);
                this.e = getE(state);
                this.k = getK(state);
                this.min = getMin(state);
                this.max = getMax(state);

                state.getReporter().log(Level.INFO,
                                "BOA biddingstrategy min util = " + this.min);
        }

        /**
         * Makes sure the target utility with in the acceptable range according to
         * the domain
         * 
         * @param t the normalized current time in the negotiation, where t=9 at
         *          start of negotiation and t=1 at end of negotiation.
         * @return double
         */
        private double p(double t) {
                return this.min + (this.max - this.min) * (1.0 - f(t));
        }

        /**
         * From the paper:
         * 
         * A wide range of time dependent functions can be defined by varying the
         * way in which f(t) is computed. However, functions must ensure that 0 <=
         * f(t) <= 1, f(0) = k, and f(1) = 1.
         * 
         * That is, the offer will always be between the value range, at the
         * beginning it will give the initial constant and when the deadline is
         * reached, it will offer the reservation value.
         * 
         * @param t the normalized current time in the negotiation, where t=9 at
         *          start of negotiation and t=1 at end of negotiation.
         * @return
         */
        private double f(double t) {
                double ft = k + (1.0 - k) * Math.pow(t, 1.0 / e);
                return ft;
        }

        /**
         * Factory method to get the {@link ExtendedUtilSpace} helper class.
         * Overridable eg for tests
         * 
         * @param profile
         * 
         * @return {@link ExtendedUtilSpace}
         */
        protected ExtendedUtilSpace getBidSpace(LinearAdditive profile) {
                return new ExtendedUtilSpace(profile);
        }
}