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.beam.sdk.extensions.sql.impl.rule;
  
  import java.util.List;
  import org.apache.beam.sdk.extensions.sql.impl.rel.BeamCalcRel;
  import org.apache.beam.sdk.extensions.sql.impl.rel.BeamLogicalConvention;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.plan.Convention;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.plan.RelOptRule;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.RelNode;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.convert.ConverterRule;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.core.Calc;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.logical.LogicalCalc;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexNode;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexOver;
  
  /** A {@code ConverterRule} to replace {@link Calc} with {@link BeamCalcRel}. */
  public class BeamCalcRule extends ConverterRule {
    public static final BeamCalcRule INSTANCE = new BeamCalcRule();
  
    private BeamCalcRule() {
      super(LogicalCalc.class, Convention.NONE, BeamLogicalConvention.INSTANCE, "BeamCalcRule");
    }
  
    @Override
    public boolean matches(RelOptRuleCall x) {
      /**
       * The Analytic Functions (a.k.a. window functions) match with both Calc and Window rules. So,
       * it is necessary to skip the Calc rule in order to execute the more suitable conversion
       * (BeamWindowRule).
       */
      boolean hasRexOver = false;
      List<RelNode> resList = x.getRelList();
      for (RelNode relNode : resList) {
        if (relNode instanceof LogicalCalc) {
          LogicalCalc logicalCalc = (LogicalCalc) relNode;
          for (RexNode rexNode : logicalCalc.getProgram().getExprList()) {
            if (rexNode instanceof RexOver) {
              hasRexOver = true;
              break;
            }
          }
        }
      }
      return !hasRexOver;
    }
  
    @Override
    public RelNode convert(RelNode rel) {
      final Calc calc = (Calc) rel;
      final RelNode input = calc.getInput();
  
      return new BeamCalcRel(
          calc.getCluster(),
          calc.getTraitSet().replace(BeamLogicalConvention.INSTANCE),
          RelOptRule.convert(input, input.getTraitSet().replace(BeamLogicalConvention.INSTANCE)),
          calc.getProgram());
    }
  }
  