/**
 * 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.drill.exec.planner.physical;

import org.apache.drill.exec.planner.logical.DrillFilterRel;
import org.apache.drill.exec.planner.logical.RelOptHelper;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.plan.RelOptRule;
import org.apache.calcite.plan.RelOptRuleCall;
import org.apache.calcite.plan.RelTraitSet;

public class FilterPrule extends Prule {
  public static final RelOptRule INSTANCE = new FilterPrule();

  private FilterPrule() {
    super(RelOptHelper.some(DrillFilterRel.class, RelOptHelper.any(RelNode.class)), "FilterPrule");
  }

  @Override
  public void onMatch(RelOptRuleCall call) {
    final DrillFilterRel  filter = (DrillFilterRel) call.rel(0);
    final RelNode input = filter.getInput();

    RelTraitSet traits = input.getTraitSet().plus(Prel.DRILL_PHYSICAL);
    RelNode convertedInput = convert(input, traits);

    boolean transform = new Subset(call).go(filter, convertedInput);

    if (!transform) {
      call.transformTo(new FilterPrel(filter.getCluster(), convertedInput.getTraitSet(), convertedInput, filter.getCondition()));
    }
  }


  private class Subset extends SubsetTransformer<DrillFilterRel, RuntimeException> {

    public Subset(RelOptRuleCall call) {
      super(call);
    }

    @Override
    public RelNode convertChild(DrillFilterRel filter, RelNode rel) {
      return new FilterPrel(filter.getCluster(), rel.getTraitSet(), rel, filter.getCondition());
    }

  }
}