code: /*
   * 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.skywalking.oap.query.graphql.mqe.rt.operation;
  
  import java.util.Collections;
  import java.util.List;
  import org.apache.skywalking.mqe.rt.grammar.MQEParser;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.exception.IllegalExpressionException;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.operation.aggregatelabels.AggregateLabelsFunc;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.operation.aggregatelabels.AggregateLabelsFuncFactory;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.operation.aggregatelabels.AvgAggregateLabelsFunc;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.operation.aggregatelabels.MaxAggregateLabelsFunc;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.operation.aggregatelabels.MinAggregateLabelsFunc;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.operation.aggregatelabels.SumAggregateLabelsFunc;
  import org.apache.skywalking.oap.query.graphql.type.mql.ExpressionResult;
  import org.apache.skywalking.oap.query.graphql.type.mql.MQEValue;
  import org.apache.skywalking.oap.query.graphql.type.mql.MQEValues;
  import org.apache.skywalking.oap.query.graphql.type.mql.Metadata;
  
  public class AggregateLabelsOp {
  
      public static ExpressionResult doAggregateLabelsOp(ExpressionResult result,
                                                         int funcType) throws IllegalExpressionException {
          switch (funcType) {
              case MQEParser.AVG:
                  return aggregateLabeledValueResult(result, AvgAggregateLabelsFunc::new);
              case MQEParser.SUM:
                  return aggregateLabeledValueResult(result, SumAggregateLabelsFunc::new);
              case MQEParser.MAX:
                  return aggregateLabeledValueResult(result, MaxAggregateLabelsFunc::new);
              case MQEParser.MIN:
                  return aggregateLabeledValueResult(result, MinAggregateLabelsFunc::new);
              default:
                  throw new IllegalExpressionException("Unsupported aggregateLabels function.");
          }
      }
  
      private static ExpressionResult aggregateLabeledValueResult(ExpressionResult expResult,
                                                                  AggregateLabelsFuncFactory factory) {
          List<MQEValues> results = expResult.getResults();
  
          List<MQEValue> combineTo = results.get(0).getValues();
          for (int i = 0; i < combineTo.size(); i++) {
              AggregateLabelsFunc aggregateLabelsFunc = factory.getAggregateLabelsFunc();
              for (MQEValues result : results) {
                  MQEValue toCombine = result.getValues().get(i);
                  if (!toCombine.isEmptyValue()) {
                      aggregateLabelsFunc.combine(toCombine.getDoubleValue());
                  }
              }
  
              MQEValue mqeValue = combineTo.get(i);
              mqeValue.setTraceID(null);
              mqeValue.setEmptyValue(true);
              mqeValue.setDoubleValue(0);
  
              Double result = aggregateLabelsFunc.getResult();
              if (result != null) {
                  mqeValue.setEmptyValue(false);
                  mqeValue.setDoubleValue(result);
              }
          }
  
          MQEValues mqeValues = new MQEValues();
          mqeValues.setMetric(new Metadata());
          mqeValues.setValues(combineTo);
          expResult.setResults(Collections.singletonList(mqeValues));
          expResult.setLabeledResult(false);
          return expResult;
      }
  }
  