content: /*
   * 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.calcite.adapter.geode.rel;
  
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelOptCost;
  import org.apache.calcite.plan.RelOptPlanner;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.Aggregate;
  import org.apache.calcite.rel.core.AggregateCall;
  import org.apache.calcite.rel.metadata.RelMetadataQuery;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeField;
  import org.apache.calcite.util.ImmutableBitSet;
  import org.apache.calcite.util.Util;
  
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableMap;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Implementation of
   * {@link org.apache.calcite.rel.core.Aggregate} relational expression
   * in Geode.
   */
  public class GeodeAggregate extends Aggregate implements GeodeRel {
  
    /** Creates a GeodeAggregate. */
    public GeodeAggregate(RelOptCluster cluster,
        RelTraitSet traitSet,
        RelNode input,
        ImmutableBitSet groupSet,
        List<ImmutableBitSet> groupSets,
        List<AggregateCall> aggCalls) {
      super(cluster, traitSet, ImmutableList.of(), input, groupSet, groupSets, aggCalls);
  
      assert getConvention() == GeodeRel.CONVENTION;
      assert getConvention() == this.input.getConvention();
      assert getConvention() == input.getConvention();
      assert this.groupSets.size() == 1 : "Grouping sets not supported";
  
      for (AggregateCall aggCall : aggCalls) {
        if (aggCall.isDistinct()) {
          System.out.println("DISTINCT based aggregation!");
        }
      }
    }
  
    @Deprecated // to be removed before 2.0
    public GeodeAggregate(RelOptCluster cluster,
        RelTraitSet traitSet,
        RelNode input,
        boolean indicator,
        ImmutableBitSet groupSet,
        List<ImmutableBitSet> groupSets,
        List<AggregateCall> aggCalls) {
      this(cluster, traitSet, input, groupSet, groupSets, aggCalls);
      checkIndicator(indicator);
    }
  
    @Override public Aggregate copy(RelTraitSet traitSet, RelNode input,
        ImmutableBitSet groupSet, List<ImmutableBitSet> groupSets,
        List<AggregateCall> aggCalls) {
      return new GeodeAggregate(getCluster(), traitSet, input, groupSet,
          groupSets, aggCalls);
    }
  
    @Override public @Nullable RelOptCost computeSelfCost(RelOptPlanner planner,
        RelMetadataQuery mq) {
      final RelOptCost cost = requireNonNull(super.computeSelfCost(planner, mq));
      return cost.multiplyBy(0.1);
    }
  
    @Override public void implement(GeodeImplementContext geodeImplementContext) {
      geodeImplementContext.visitChild(getInput());
  
      List<String> inputFields = fieldNames(getInput().getRowType());
  
      List<String> groupByFields = new ArrayList<>();
  
      for (int group : groupSet) {
        groupByFields.add(inputFields.get(group));
      }
  
      geodeImplementContext.addGroupBy(groupByFields);
  
      // Find the aggregate functions (e.g. MAX, SUM ...)
      ImmutableMap.Builder<String, String> aggregateFunctionMap = ImmutableMap.builder();
      for (AggregateCall aggCall : aggCalls) {
  
        List<String> aggCallFieldNames = new ArrayList<>();
        for (int i : aggCall.getArgList()) {
          aggCallFieldNames.add(inputFields.get(i));
        }
        String functionName = aggCall.getAggregation().getName();
  
        // Workaround to handle count(*) case. Geode doesn't allow "AS" aliases on
        // 'count(*)' but allows it for count('any column name'). So we are
        // converting the count(*) into count (first input ColumnName).
        if ("COUNT".equalsIgnoreCase(functionName) && aggCallFieldNames.isEmpty()) {
          aggCallFieldNames.add(inputFields.get(0));
        }
  
        String oqlAggregateCall =
            Util.toString(aggCallFieldNames, functionName + "(", ", ", ")");
  
        aggregateFunctionMap.put(aggCall.getName(), oqlAggregateCall);
      }
  
      geodeImplementContext.addAggregateFunctions(aggregateFunctionMap.build());
  
    }
  
    private static List<String> fieldNames(RelDataType relDataType) {
      ArrayList<String> names = new ArrayList<>();
  
      for (RelDataTypeField rdtf : relDataType.getFieldList()) {
        names.add(rdtf.getName());
      }
      return names;
    }
  }
  