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 io.activej.dataflow.calcite.optimizer;
  
  import io.activej.dataflow.calcite.rel.DataflowTableScan;
  import org.apache.calcite.plan.RelOptRule;
  import org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.calcite.plan.RelRule;
  import org.apache.calcite.rel.RelFieldCollation;
  import org.apache.calcite.rel.logical.LogicalProject;
  import org.apache.calcite.rel.logical.LogicalSort;
  import org.apache.calcite.rex.RexNode;
  
  import java.util.List;
  
  public class SortScanTableRule extends RelRule<SortScanTableRule.Config> {
  
  	private SortScanTableRule(SortScanTableRule.Config config) {
  		super(config);
  	}
  
  	public static SortScanTableRule create() {
  		return new SortScanTableRule(Config.INSTANCE);
  	}
  
  	@Override
  	public void onMatch(RelOptRuleCall call) {
  		LogicalSort sort = call.rel(0);
  		DataflowTableScan scan = call.rel(2);
  
  		RexNode offset = sort.offset;
  		RexNode limit = sort.fetch;
  
  		List<RelFieldCollation> fieldCollations = sort.getCollation().getFieldCollations();
  		if (!fieldCollations.isEmpty()) return;
  
  		if (offset != null) {
  			scan.setOffset(offset);
  		}
  		if (limit != null) {
  			scan.setLimit(limit);
  		}
  	}
  
  	public static final class Config extends LimitedConfig {
  		private static final SortScanTableRule.Config INSTANCE = new SortScanTableRule.Config();
  
  		@Override
  		public RelOptRule toRule() {
  			return new SortScanTableRule(this);
  		}
  
  		@Override
  		public RelRule.OperandTransform operandSupplier() {
  			return b -> b.operand(LogicalSort.class)
  				.oneInput(b0 -> b0.operand(LogicalProject.class)
  					.oneInput(b1 -> b1.operand(DataflowTableScan.class).noInputs()));
  		}
  	}
  }
  