package geniusweb.bidspace;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import geniusweb.issuevalue.Value;
import geniusweb.issuevalue.ValueSet;
import geniusweb.profile.utilityspace.ValueSetUtilities;

/**
 * Tool class to collect all relevant info about one issue (from LinearAdditive)
 * in one class. Used for internally grouping data for more efficient
 * processing. This class may change in the future, not recommended for direct
 * use.
 * <p>
 * immutable
 */
public class IssueInfo {
	private final String name;
	private final ValueSet values;
	private final Interval interval;
	private final Map<Value, BigDecimal> weightedUtils;

	public IssueInfo(String name, ValueSet values, ValueSetUtilities utils,
			BigDecimal weight, int precision) {
		this.name = name;
		this.values = values;
		this.weightedUtils = computeWeightedUtils(utils, weight, precision);
		this.interval = getRange();
	}

	public ValueSet getValues() {
		return values;
	}

	public String getName() {
		return name;
	}

	/**
	 * 
	 * @return weighted minimum and maximum utility achievable with this issue,
	 *         rounded to the {@link #precision}.
	 */
	public Interval getInterval() {
		return interval;
	}

	/**
	 * @param val the issue value to be evaluated
	 * @return weighted utility of given value, rounded to nearest value with
	 *         {@link #precision} digits.
	 */
	public BigDecimal getWeightedUtil(Value val) {
		return weightedUtils.get(val);
	}

	/**
	 * 
	 * @param interval an {@link Interval} of utility values.
	 * @return all values that are inside the interval.
	 */
	protected List<Value> subset(Interval interval) {

		List<Value> selection = new ArrayList<>();
		for (Value value : values) {
			if (interval.contains(getWeightedUtil(value)))
				selection.add(value);
		}
		return selection;
	}

	/**
	 * Faster way to determine subset size, it does not create a list
	 * 
	 * @param interval an {@link Interval} of utility values.
	 * @return size of the subset that you will get from calling subset
	 */
	protected int subsetSize(Interval interval) {
		int n = 0;
		for (Value value : values)
			if (interval.contains(getWeightedUtil(value)))
				n++;
		return n;
	}

	/**
	 * @return the {@link Interval} (minimum and maximum) of the utility of the
	 *         weighted utility of this issue, properly rounded to the
	 *         {@link #precision}/
	 * 
	 */
	private Interval getRange() {
		BigDecimal min = BigDecimal.ONE;
		BigDecimal max = BigDecimal.ZERO;
		for (Value value : values) {
			BigDecimal util = getWeightedUtil(value);
			if (util.compareTo(min) < 0)
				min = util;
			if (util.compareTo(max) > 0)
				max = util;
		}
		return new Interval(min, max);

	}

	private Map<Value, BigDecimal> computeWeightedUtils(
			ValueSetUtilities utilities, BigDecimal w, int prec) {
		Map<Value, BigDecimal> map = new HashMap<>();

		for (Value val : values) {
			map.put(val, utilities.getUtility(val).multiply(w).setScale(prec,
					RoundingMode.HALF_UP));
		}
		return map;
	}

}