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.adapter.java.JavaTypeFactory;
  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.Project;
  import org.apache.calcite.rel.metadata.RelMetadataQuery;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.util.Pair;
  
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.ImmutableSet;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.stream.Collectors;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Implementation of {@link org.apache.calcite.rel.core.Project}
   * relational expression in Elasticsearch.
   */
  public class ElasticsearchProject extends Project implements ElasticsearchRel {
    ElasticsearchProject(RelOptCluster cluster, RelTraitSet traitSet, RelNode input,
        List<? extends RexNode> projects, RelDataType rowType) {
      super(cluster, traitSet, ImmutableList.of(), input, projects, rowType, ImmutableSet.of());
      assert getConvention() == ElasticsearchRel.CONVENTION;
      assert getConvention() == input.getConvention();
    }
  
    @Override public Project copy(RelTraitSet relTraitSet, RelNode input, List<RexNode> projects,
        RelDataType relDataType) {
      return new ElasticsearchProject(getCluster(), traitSet, input, projects, relDataType);
    }
  
    @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(Implementor implementor) {
      implementor.visitChild(0, getInput());
  
      final List<String> inFields =
              ElasticsearchRules.elasticsearchFieldNames(getInput().getRowType());
      final ElasticsearchRules.RexToElasticsearchTranslator translator =
              new ElasticsearchRules.RexToElasticsearchTranslator(
                      (JavaTypeFactory) getCluster().getTypeFactory(), inFields);
  
      final List<String> fields = new ArrayList<>();
      final List<String> scriptFields = new ArrayList<>();
      // registers wherever "select *" is present
      boolean hasSelectStar = false;
      for (Pair<RexNode, String> pair : getNamedProjects()) {
        final String name = pair.right;
        final String expr = pair.left.accept(translator);
  
        // "select *" present?
        hasSelectStar |= ElasticsearchConstants.isSelectAll(name);
  
        if (ElasticsearchRules.isItem(pair.left)) {
          implementor.addExpressionItemMapping(name, expr);
          fields.add(expr);
        } else if (expr.equals(name)) {
          fields.add(name);
        } else if (expr.matches("\"literal\":.+")) {
          scriptFields.add(ElasticsearchRules.quote(name)
                  + ":{\"script\": "
                  + expr.split(":")[1] + "}");
        } else {
          scriptFields.add(ElasticsearchRules.quote(name)
                  + ":{\"script\":"
                  // _source (ES2) vs params._source (ES5)
                  + "\"" + implementor.elasticsearchTable.scriptedFieldPrefix() + "."
                  + expr.replace("\"", "") + "\"}");
        }
      }
  
      if (hasSelectStar) {
        // means select * from elastic
        // this does not yet cover select *, _MAP['foo'], _MAP['bar'][0] from elastic
        return;
      }
  
      final StringBuilder query = new StringBuilder();
      if (scriptFields.isEmpty()) {
        List<String> newList = fields.stream()
            // _id field is available implicitly
            .filter(f -> !ElasticsearchConstants.ID.equals(f))
            .map(ElasticsearchRules::quote)
            .collect(Collectors.toList());
  
        final String findString = String.join(", ", newList);
        query.append("\"_source\" : [").append(findString).append("]");
      } else {
        // if scripted fields are present, ES ignores _source attribute
        for (String field : fields) {
          scriptFields.add(ElasticsearchRules.quote(field) + ":{\"script\": "
                  // _source (ES2) vs params._source (ES5)
                  + "\"" + implementor.elasticsearchTable.scriptedFieldPrefix() + "."
                  + field + "\"}");
        }
        query.append("\"script_fields\": {")
            .append(String.join(", ", scriptFields))
            .append("}");
      }
  
      implementor.list.removeIf(l -> l.startsWith("\"_source\""));
      implementor.add("{" + query + "}");
    }
  }
  