org.springframework.data.geo.GeoResults.java Source code

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/*
 * Copyright 2011-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.data.geo;

import lombok.EqualsAndHashCode;

import java.io.Serializable;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.springframework.data.annotation.PersistenceConstructor;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * Value object to capture {@link GeoResult}s as well as the average distance they have.
 *
 * @author Oliver Gierke
 * @author Thomas Darimont
 * @since 1.8
 */
@EqualsAndHashCode
public class GeoResults<T> implements Iterable<GeoResult<T>>, Serializable {

    private static final long serialVersionUID = 8347363491300219485L;

    private final List<? extends GeoResult<T>> results;
    private final Distance averageDistance;

    /**
     * Creates a new {@link GeoResults} instance manually calculating the average distance from the distance values of the
     * given {@link GeoResult}s.
     *
     * @param results must not be {@literal null}.
     */
    public GeoResults(List<? extends GeoResult<T>> results) {
        this(results, Metrics.NEUTRAL);
    }

    /**
     * Creates a new {@link GeoResults} instance manually calculating the average distance in the given {@link Metric}
     * from the distance values of the given {@link GeoResult}s.
     *
     * @param results must not be {@literal null}.
     * @param metric must not be {@literal null}.
     */
    public GeoResults(List<? extends GeoResult<T>> results, Metric metric) {
        this(results, calculateAverageDistance(results, metric));
    }

    /**
     * Creates a new {@link GeoResults} instance from the given {@link GeoResult}s and average distance.
     *
     * @param results must not be {@literal null}.
     * @param averageDistance must not be {@literal null}.
     */
    @PersistenceConstructor
    public GeoResults(List<? extends GeoResult<T>> results, Distance averageDistance) {

        Assert.notNull(results, "Results must not be null!");
        Assert.notNull(averageDistance, "Average Distance must not be null!");

        this.results = results;
        this.averageDistance = averageDistance;
    }

    /**
     * Returns the average distance of all {@link GeoResult}s in this list.
     *
     * @return the averageDistance
     */
    public Distance getAverageDistance() {
        return averageDistance;
    }

    /**
     * Returns the actual content of the {@link GeoResults}.
     *
     * @return
     */
    public List<GeoResult<T>> getContent() {
        return Collections.unmodifiableList(results);
    }

    /*
     * (non-Javadoc)
     * @see java.lang.Iterable#iterator()
     */
    @SuppressWarnings("unchecked")
    public Iterator<GeoResult<T>> iterator() {
        return (Iterator<GeoResult<T>>) results.iterator();
    }

    /*
     * (non-Javadoc)
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return String.format("GeoResults: [averageDistance: %s, results: %s]", averageDistance.toString(),
                StringUtils.collectionToCommaDelimitedString(results));
    }

    private static Distance calculateAverageDistance(List<? extends GeoResult<?>> results, Metric metric) {

        Assert.notNull(results, "Results must not be null!");
        Assert.notNull(metric, "Metric must not be null!");

        if (results.isEmpty()) {
            return new Distance(0, metric);
        }

        double averageDistance = results.stream()//
                .mapToDouble(it -> it.getDistance().getValue())//
                .average().orElse(0);

        return new Distance(averageDistance, metric);
    }
}