package geniusweb.exampleparties.simpleshaop;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;

import geniusweb.issuevalue.Bid;
import geniusweb.issuevalue.Domain;
import geniusweb.profile.DefaultPartialOrdering;
import geniusweb.profile.Profile;
import geniusweb.profile.utilityspace.UtilitySpace;

/**
 * A simple list of bids, but all bids are fully ordered (better or worse than
 * other bids in the list).
 */
public class SimpleLinearOrdering implements UtilitySpace {

	private final Domain domain;
	private final List<Bid> bids; // worst bid first, best bid last.

	SimpleLinearOrdering(Profile profile) {
		this(profile.getDomain(), getSortedBids(profile));
	}

	/**
	 * 
	 * @param domain
	 * @param bids   a list of bids, ordered from lowest to highest util. The
	 *               first bid will have utility 0, the last utility 1. If only
	 *               0 or 1 bid in the list, or if the bid is not known, it will
	 *               have utility 0.
	 */
	SimpleLinearOrdering(Domain domain, List<Bid> bids) {
		this.domain = domain;
		this.bids = bids;
	}

	@Override
	public String getName() {
		throw new UnsupportedOperationException();
	}

	@Override
	public Domain getDomain() {
		return domain;
	}

	@Override
	public Bid getReservationBid() {
		throw new UnsupportedOperationException();
	}

	@Override
	public BigDecimal getUtility(Bid bid) {
		if (bids.size() < 2 || !bids.contains(bid)) {
			return BigDecimal.ZERO;
		}
		// using 8 decimals, we have to pick something here
		return new BigDecimal(bids.indexOf(bid)).divide(
				new BigDecimal((bids.size() - 1)), 8, RoundingMode.HALF_UP);
	}

	/**
	 * 
	 * @param bid
	 * @return true iff bid is contained in this ordering
	 */
	public boolean contains(Bid bid) {
		return bids.contains(bid);
	}

	/**
	 * 
	 * @return list of all bids in the current ordering.
	 */
	public List<Bid> getBids() {
		return Collections.unmodifiableList(bids);
	}

	/**
	 * 
	 * @param profile
	 * @return a list of bids in the profile sorted from low to high utility.
	 */
	private static List<Bid> getSortedBids(Profile profile) {
		if (!(profile instanceof DefaultPartialOrdering)) {
			throw new UnsupportedOperationException(
					"Only DefaultPartialOrdering supported");
		}
		DefaultPartialOrdering prof = (DefaultPartialOrdering) profile;
		List<Bid> bidslist = prof.getBids();
		// NOTE sort defaults to ascending order, this is missing in docs.
		Collections.sort(bidslist, new Comparator<Bid>() {

			@Override
			public int compare(Bid b1, Bid b2) {
				return prof.isPreferredOrEqual(b1, b2) ? 1 : -1;
			}

		});

		return bidslist;
	}

	/**
	 * @param bid       a new bid to be inserted
	 * @param worseBids all bids that are worse than this bid.
	 * @return a SimpleLinearOrdering, updated with the given comparison. Thee
	 *         bid will be inserted after the first bid that is not worse than
	 *         bid.
	 */
	public SimpleLinearOrdering with(Bid bid, List<Bid> worseBids) {
		int n = 0;
		while (n < bids.size() && worseBids.contains(bids.get(n)))
			n++;
		LinkedList<Bid> newbids = new LinkedList<Bid>(bids);
		newbids.add(n, bid);
		return new SimpleLinearOrdering(domain, newbids);
	}

}