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/*
 * 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.arrow;

import org.apache.calcite.adapter.enumerable.EnumerableRel;
import org.apache.calcite.adapter.enumerable.EnumerableRelImplementor;
import org.apache.calcite.adapter.enumerable.PhysType;
import org.apache.calcite.adapter.enumerable.PhysTypeImpl;
import org.apache.calcite.linq4j.tree.Blocks;
import org.apache.calcite.linq4j.tree.Expressions;
import org.apache.calcite.plan.ConventionTraitDef;
import org.apache.calcite.plan.RelOptCluster;
import org.apache.calcite.plan.RelOptCost;
import org.apache.calcite.plan.RelOptPlanner;
import org.apache.calcite.plan.RelOptTable;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.convert.ConverterImpl;
import org.apache.calcite.rel.metadata.RelMetadataQuery;
import org.apache.calcite.util.BuiltInMethod;

import com.google.common.primitives.Ints;

import java.util.List;

import static java.util.Objects.requireNonNull;

/**
 * Relational expression representing a scan of a table in an Arrow data source.
 */
class ArrowToEnumerableConverter
    extends ConverterImpl implements EnumerableRel {

  protected ArrowToEnumerableConverter(RelOptCluster cluster,
      RelTraitSet traitSet, RelNode input) {
    super(cluster, ConventionTraitDef.INSTANCE, traitSet, input);
  }

  @Override public RelNode copy(RelTraitSet traitSet, List inputs) {
    return new ArrowToEnumerableConverter(getCluster(), traitSet, sole(inputs));
  }

  @Override public RelOptCost computeSelfCost(RelOptPlanner planner,
      RelMetadataQuery mq) {
    RelOptCost cost = super.computeSelfCost(planner, mq);
    return requireNonNull(cost, "cost").multiplyBy(0.1);
  }

  @Override public Result implement(EnumerableRelImplementor implementor,
      Prefer pref) {
    final ArrowRel.Implementor arrowImplementor = new ArrowRel.Implementor();
    arrowImplementor.visitInput(0, getInput());
    PhysType physType =
        PhysTypeImpl.of(
            implementor.getTypeFactory(),
            getRowType(),
            pref.preferArray());

    final RelOptTable table = requireNonNull(arrowImplementor.table, "table");
    final int fieldCount = table.getRowType().getFieldCount();
    return implementor.result(physType,
        Blocks.toBlock(
            Expressions.call(table.getExpression(ArrowTable.class),
                ArrowMethod.ARROW_QUERY.method, implementor.getRootExpression(),
                arrowImplementor.selectFields != null
                    ? Expressions.call(
                        BuiltInMethod.IMMUTABLE_INT_LIST_COPY_OF.method,
                        Expressions.constant(
                            Ints.toArray(arrowImplementor.selectFields)))
                    : Expressions.call(
                        BuiltInMethod.IMMUTABLE_INT_LIST_IDENTITY.method,
                        Expressions.constant(fieldCount)),
                Expressions.constant(arrowImplementor.whereClause))));
  }
}