eagle-core/eagle-query/eagle-query-base/src/main/java/org/apache/eagle/query/aggregate/PostAggregateSorting.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.eagle.query.aggregate;

import java.lang.reflect.Method;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class PostAggregateSorting {
    private static final Logger LOG = LoggerFactory.getLogger(PostAggregateSorting.class);

    private static SortedSet<Map.Entry<String, AggregateAPIEntity>> sortByValue(Map<String, AggregateAPIEntity> map, List<AggregateParams.SortFieldOrder> sortedFields) {
        SortedSet<Map.Entry<String, AggregateAPIEntity>> sortedEntries = new TreeSet<Map.Entry<String, AggregateAPIEntity>>(new MapKeyValueComparator(sortedFields));
        sortedEntries.addAll(map.entrySet());
        return sortedEntries;
    }

    /**
     * recursively populate sorted list from entity list
     * @param entity
     */
    public static void sort(AggregateAPIEntity entity, List<AggregateParams.SortFieldOrder> sortFieldOrders) {
        // sort should internally add key field to AggregateAPIEntity before the sorting starts as "key" could be sorted against
        Map<String, AggregateAPIEntity> children = entity.getEntityList();
        for (Map.Entry<String, AggregateAPIEntity> e : children.entrySet()) {
            e.getValue().setKey(e.getKey());
        }
        SortedSet<Map.Entry<String, AggregateAPIEntity>> set = sortByValue(children, sortFieldOrders);
        for (Map.Entry<String, AggregateAPIEntity> entry : set) {
            entity.getSortedList().add(entry.getValue());
        }
        for (Map.Entry<String, AggregateAPIEntity> entry : entity.getEntityList().entrySet()) {
            sort(entry.getValue(), sortFieldOrders);
        }
        entity.setEntityList(null);
    }

    private static class MapKeyValueComparator implements Comparator<Map.Entry<String, AggregateAPIEntity>> {
        private List<AggregateParams.SortFieldOrder> sortedFieldOrders;

        public MapKeyValueComparator(List<AggregateParams.SortFieldOrder> sortedFields) {
            this.sortedFieldOrders = sortedFields;
        }

        @Override
        public int compare(Map.Entry<String, AggregateAPIEntity> e1, Map.Entry<String, AggregateAPIEntity> e2) {
            int r = 0;
            AggregateAPIEntity entity1 = e1.getValue();
            AggregateAPIEntity entity2 = e2.getValue();
            for (AggregateParams.SortFieldOrder sortFieldOrder : sortedFieldOrders) {
                // TODO count should not be literal, compare numTotalDescendants
                if (sortFieldOrder.getField().equals(AggregateParams.SortFieldOrder.SORT_BY_COUNT)) {
                    long tmp = entity1.getNumTotalDescendants() - entity2.getNumTotalDescendants();
                    r = (tmp == 0) ? 0 : ((tmp > 0) ? 1 : -1);
                } else if (sortFieldOrder.getField().equals(AggregateParams.SortFieldOrder.SORT_BY_AGGREGATE_KEY)) {
                    r = entity1.getKey().compareTo(entity2.getKey());
                } else {
                    try {
                        String sortedField = sortFieldOrder.getField();
                        String tmp1 = sortedField.substring(0, 1).toUpperCase() + sortedField.substring(1);
                        Method getMethod1 = entity1.getClass().getMethod("get" + tmp1);
                        Object r1 = getMethod1.invoke(entity1);
                        Long comp1 = (Long)r1;
                        String tmp2 = sortedField.substring(0, 1).toUpperCase() + sortedField.substring(1);
                        Method getMethod2 = entity2.getClass().getMethod("get" + tmp2);
                        Object r2 = getMethod2.invoke(entity2);
                        Long comp2 = (Long)r2;
                        r = comp1.compareTo(comp2);
                    } catch (Exception ex) {
                        LOG.error("Can not get corresponding field for sorting", ex);
                        r = 0;
                    }
                }
                if (r == 0) {
                    continue;
                }
                if (!sortFieldOrder.isAscendant()) {
                    r = -r;
                }
                return r;
            }
            return r;
        }
    }
}