eagle-core/eagle-query/eagle-query-base/src/main/java/org/apache/eagle/query/aggregate/timeseries/SortOptionsParser.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.timeseries;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

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

public class SortOptionsParser {
    private static final Logger LOG = LoggerFactory.getLogger(SortOptionsParser.class);
    private static Pattern pattern = Pattern.compile("^(.+)\\s+(asc|desc)$");

    public static List<SortOption> parse(List<String> groupbyFields, List<String> aggregatedFields, List<String> sortOptions, List<String> sortFields) {
        List<SortOption> list = new ArrayList<SortOption>();
        for (String sortOption : sortOptions) {
            Matcher m = pattern.matcher(sortOption);
            if (!m.find()) {
                throw new IllegalArgumentException("sort option must have the format of <groupbyfield|function> asc|desc");
            }
            String field = m.group(1);
            if (sortFields != null) {
                sortFields.add(field);
            }
            SortOption so = new SortOption();
            list.add(so);
            so.setAscendant(m.group(2).equals("asc") ? true : false);
            int index = aggregatedFields.indexOf(field);
            if (index > -1) {
                so.setInGroupby(false);
                so.setIndex(index);
                continue;
            }
            if (groupbyFields != null) {  // if groupbyFields is not provided, ignore this sort field
                index = groupbyFields.indexOf(field);
                if (index > -1) {
                    so.setInGroupby(true);
                    so.setIndex(index);
                    continue;
                }
            }
            logNonExistingSortByField(field);
            so.setInGroupby(false);
            so.setIndex(-1);
        }
        return list;
    }

    private static void logNonExistingSortByField(String sortByField) {
        LOG.warn("Sortby field is neither in aggregated fields or groupby fields, ignore " + sortByField);
    }
}