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.elasticsearch;
  
  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.RelCollation;
  import org.apache.calcite.rel.RelFieldCollation;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.Sort;
  import org.apache.calcite.rel.metadata.RelMetadataQuery;
  import org.apache.calcite.rel.type.RelDataTypeField;
  import org.apache.calcite.rex.RexLiteral;
  import org.apache.calcite.rex.RexNode;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Implementation of {@link org.apache.calcite.rel.core.Sort}
   * relational expression in Elasticsearch.
   */
  public class ElasticsearchSort extends Sort implements ElasticsearchRel {
    ElasticsearchSort(RelOptCluster cluster, RelTraitSet traitSet, RelNode input,
        RelCollation collation, @Nullable RexNode offset,
        @Nullable RexNode fetch) {
      super(cluster, traitSet, input, collation, offset, fetch);
      assert getConvention() == ElasticsearchRel.CONVENTION;
      assert getConvention() == input.getConvention();
    }
  
    @Override public @Nullable RelOptCost computeSelfCost(RelOptPlanner planner,
        RelMetadataQuery mq) {
      final RelOptCost cost = requireNonNull(super.computeSelfCost(planner, mq));
      return cost.multiplyBy(0.05);
    }
  
    @Override public Sort copy(RelTraitSet traitSet, RelNode input,
        RelCollation relCollation, @Nullable RexNode offset,
        @Nullable RexNode fetch) {
      return new ElasticsearchSort(getCluster(), traitSet, input, collation,
          offset, fetch);
    }
  
    @Override public void implement(Implementor implementor) {
      implementor.visitChild(0, getInput());
      final List<RelDataTypeField> fields = getRowType().getFieldList();
  
      for (RelFieldCollation fieldCollation : collation.getFieldCollations()) {
        final String name = fields.get(fieldCollation.getFieldIndex()).getName();
        final String rawName = implementor.expressionItemMap.getOrDefault(name, name);
        // if nulls order is not specified, default NULLS LAST/FIRST for ASC/DESC
        implementor.addNullsSort(rawName, fieldCollation.nullDirection);
        implementor.addSort(rawName, fieldCollation.getDirection());
      }
  
      if (offset != null) {
        implementor.offset(RexLiteral.numberValue(offset).longValue());
      }
  
      if (fetch != null) {
        implementor.fetch(RexLiteral.numberValue(fetch).longValue());
      }
    }
  
  }
  