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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * 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
 *
 *    http://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 apoc.agg;

import apoc.util.Util;
import java.util.ArrayList;
import java.util.List;
import org.neo4j.procedure.*;

/**
 * Aggregation functions for collecting items with only the minimal or maximal values.
 * This is meant to replace queries like this:
 *
 *  * MATCH (p:Person)
 * WHERE p.born >= 1930
 * WITH p.born as born, collect(p.name) as persons
 * WITH min(born) as minBorn, collect({born:born, persons:persons}) as bornInfoList
 * UNWIND [info in bornInfoList WHERE info.born = minBorn] as bornInfo
 * RETURN bornInfo.born as born, [person in bornInfo.persons | person.name] as persons
 * 
 *
 * with an aggregation like this:
 *
 *  * MATCH (p:Person)
 * WHERE p.born >= 1930
 * WITH apoc.agg.minItems(p, p.born) as minResult
 * RETURN minResult.value as born, [person in minResult.items | person.name] as persons
 * 
 *
 * returns {born:1930, persons:["Gene Hackman", "Richard Harris", "Clint Eastwood"]}
 *
 */
public class MaxAndMinItems {

    @UserAggregationFunction("apoc.agg.maxItems")
    @Description(
            "Returns a `MAP` `{items: LIST, value: ANY}` where the `value` key is the maximum value present, and `items` represent all items with the same value. The size of the list of items can be limited to a given max size.")
    public MaxOrMinItemsFunction maxItems() {
        return new MaxOrMinItemsFunction(true);
    }

    @UserAggregationFunction("apoc.agg.minItems")
    @Description(
            "Returns a `MAP` `{items: LIST, value: ANY}` where the `value` key is the minimum value present, and `items` represent all items with the same value. The size of the list of items can be limited to a given max size.")
    public MaxOrMinItemsFunction minItems() {
        return new MaxOrMinItemsFunction(false);
    }

    public static class MaxOrMinItemsFunction {
        private final List