source: profile/src/main/java/geniusweb/profile/utilityspace/DiscreteValueSetUtilities.java

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;
        }

}