package geniusweb.profile.utilityspace;

import java.math.BigDecimal;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonAutoDetect.Visibility;

import geniusweb.issuevalue.DiscreteValue;
import geniusweb.issuevalue.DiscreteValueSet;
import geniusweb.issuevalue.Value;
import geniusweb.issuevalue.ValueSet;

/**
 * Links a set of values to utilities for that value. Does not link to some
 * issue so may need further checking when used for an actual issue. Constructor
 * guarantees that
 * <ul>
 * <li>All values in the provided map (the utilities) are in [0,1]
 * <li>All keys are proper {@link DiscreteValue}s
 * </ul>
 */
@JsonAutoDetect(fieldVisibility = Visibility.ANY, getterVisibility = Visibility.NONE, setterVisibility = Visibility.NONE)
public class DiscreteValueSetUtilities implements ValueSetUtilities {

	private HashMap<DiscreteValue, BigDecimal> valueUtilities = new HashMap<>();

	@SuppressWarnings("unused") // for deserializer
	private DiscreteValueSetUtilities() {

	}

	/**
	 * create new object based on the given mapping from values to utilities.
	 * 
	 * @param valueUtils map with key {@link DiscreteValue}s and value a Double
	 *                   in the range [0,1].
	 * @throws NullPointerException     if one of the args is null
	 * @throws IllegalArgumentException if values are not in range [0,1].
	 */
	public DiscreteValueSetUtilities(
			Map<DiscreteValue, BigDecimal> valueUtils) {
		if (valueUtils == null) {
			throw new NullPointerException("valueUtils==null");
		}
		if (valueUtils.keySet().contains(null)) {
			throw new NullPointerException(
					"one of the keys in valueUtils is null");
		}
		if (valueUtils.values().stream()
				.anyMatch(v -> v == null || v.compareTo(BigDecimal.ZERO) < 0
						|| v.compareTo(BigDecimal.ONE) > 0)) {
			throw new IllegalArgumentException(
					"Weights in valueUtils must all be in [0,1]");
		}
		this.valueUtilities.putAll(valueUtils);

	}

	@Override
	public BigDecimal getUtility(Value value) {
		if (!valueUtilities.containsKey(value)) {
			return BigDecimal.ZERO;
		}
		return valueUtilities.get(value);
	}

	/**
	 * @return copy of the value-utility pair map.
	 */
	public Map<DiscreteValue, BigDecimal> getUtilities() {
		return Collections.unmodifiableMap(valueUtilities);
	}

	@Override
	public String isFitting(ValueSet valueset) {
		if (!(valueset instanceof DiscreteValueSet)) {
			return "The utilities are for a discrete valueset but the given values are "
					+ valueset;
		}
		DiscreteValueSet discvalueset = (DiscreteValueSet) valueset;
		if (!valueUtilities.keySet()
				.equals(new HashSet<>(discvalueset.getValues())))
			return "The values in the set " + valueset
					+ " do not match the values mapped to utilities "
					+ valueUtilities.keySet();
		return null;
	}

	@Override
	public String toString() {
		return "DiscreteValueSetUtilities" + valueUtilities;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result
				+ ((valueUtilities == null) ? 0 : valueUtilities.hashCode());
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		DiscreteValueSetUtilities other = (DiscreteValueSetUtilities) obj;
		if (valueUtilities == null) {
			if (other.valueUtilities != null)
				return false;
		} else if (!valueUtilities.equals(other.valueUtilities))
			return false;
		return true;
	}

}