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.asterix.optimizer.rules;
  
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.asterix.builders.RecordBuilder;
  import org.apache.asterix.common.exceptions.CompilationException;
  import org.apache.asterix.common.exceptions.ErrorCode;
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.asterix.om.typecomputer.impl.ClosedRecordConstructorResultType;
  import org.apache.asterix.om.typecomputer.impl.OpenRecordConstructorResultType;
  import org.apache.asterix.om.utils.ConstantExpressionUtil;
  import org.apache.commons.lang3.mutable.Mutable;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator;
  import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
  import org.apache.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
  import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
  import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
  import org.apache.hyracks.api.exceptions.IWarningCollector;
  import org.apache.hyracks.api.exceptions.Warning;
  import org.apache.hyracks.util.LogRedactionUtil;
  
  /**
   * <pre>
   * This rule removes duplicate fields from record constructors. For example:
   * {"f1": 87, "f2": "val2", "f1": "str"}.
   * For records where the field name is not a constant string, {@link ConstantFoldingRule} will evaluate the
   * expression and remove the field if it is a duplicate. If the field name expression cannot be constant folded, then
   * {@link RecordBuilder} will take care of not adding the field at runtime if it is a duplicate. Such field names
   * will be added in the open part of the record. Examples:
   * <ol>
   *     <li>{"f1": 11, lowercase("F1"): 12}</li>
   *     <li>{"f1": 11, lowercase($$var): 12}</li>
   * </ol>
   *
   * Note: {@link OpenRecordConstructorResultType} and {@link ClosedRecordConstructorResultType} still have a sanity
   * check that tests that there are no duplicate fields during compilation.
   * </pre>
   */
  public class RemoveDuplicateFieldsRule implements IAlgebraicRewriteRule {
  
      private final Set<String> fieldNames = new HashSet<>();
      private IOptimizationContext context;
  
      @Override
      public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext ctx) throws AlgebricksException {
          return false;
      }
  
      @Override
      public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext ctx) throws AlgebricksException {
          if (ctx.checkIfInDontApplySet(this, opRef.getValue())) {
              // children should've already been visited and marked through the root operator
              return false;
          }
          context = ctx;
          return rewriteOpAndInputs(opRef, true);
      }
  
      private boolean rewriteOpAndInputs(Mutable<ILogicalOperator> opRef, boolean first) throws AlgebricksException {
          AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
          if (!first) {
              context.addToDontApplySet(this, op);
          }
          List<Mutable<ILogicalOperator>> inputs = op.getInputs();
          boolean changed = false;
          for (int i = 0, size = inputs.size(); i < size; i++) {
              changed |= rewriteOpAndInputs(inputs.get(i), false);
          }
          changed |= op.acceptExpressionTransform(this::transform);
          return changed;
      }
  
      private boolean transform(Mutable<ILogicalExpression> expressionRef) throws AlgebricksException {
          ILogicalExpression expr = expressionRef.getValue();
          if (expr.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) {
              return false;
          }
          AbstractFunctionCallExpression function = (AbstractFunctionCallExpression) expr;
          boolean changed = false;
          if (function.getFunctionIdentifier().equals(BuiltinFunctions.OPEN_RECORD_CONSTRUCTOR)
                  || function.getFunctionIdentifier().equals(BuiltinFunctions.CLOSED_RECORD_CONSTRUCTOR)) {
              if (function.getArguments().size() % 2 != 0) {
                  String functionName = function.getFunctionIdentifier().getName();
                  throw CompilationException.create(ErrorCode.COMPILATION_INVALID_NUM_OF_ARGS, expr.getSourceLocation(),
                          functionName);
              }
              fieldNames.clear();
              Iterator<Mutable<ILogicalExpression>> iterator = function.getArguments().iterator();
              while (iterator.hasNext()) {
                  ILogicalExpression fieldNameExpr = iterator.next().getValue();
                  String fieldName = ConstantExpressionUtil.getStringConstant(fieldNameExpr);
                  if (fieldName != null && !fieldNames.add(fieldName)) {
                      IWarningCollector warningCollector = context.getWarningCollector();
                      if (warningCollector.shouldWarn()) {
                          warningCollector.warn(Warning.of(fieldNameExpr.getSourceLocation(),
                                  ErrorCode.COMPILATION_DUPLICATE_FIELD_NAME, LogRedactionUtil.userData(fieldName)));
                      }
                      iterator.remove();
                      iterator.next();
                      iterator.remove();
                      changed = true;
                  } else {
                      iterator.next();
                  }
              }
          }
          List<Mutable<ILogicalExpression>> arguments = function.getArguments();
          for (int i = 0, size = arguments.size(); i < size; i++) {
              changed |= transform(arguments.get(i));
          }
          return changed;
      }
  }
  