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.om.typecomputer.impl;
  
  import java.util.ArrayDeque;
  import java.util.ArrayList;
  import java.util.Deque;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Set;
  
  import org.apache.asterix.om.base.AOrderedList;
  import org.apache.asterix.om.base.AString;
  import org.apache.asterix.om.base.IAObject;
  import org.apache.asterix.om.constants.AsterixConstantValue;
  import org.apache.asterix.om.exceptions.InvalidExpressionException;
  import org.apache.asterix.om.exceptions.TypeMismatchException;
  import org.apache.asterix.om.exceptions.UnsupportedTypeException;
  import org.apache.asterix.om.pointables.base.DefaultOpenFieldType;
  import org.apache.asterix.om.typecomputer.base.IResultTypeComputer;
  import org.apache.asterix.om.types.AOrderedListType;
  import org.apache.asterix.om.types.ARecordType;
  import org.apache.asterix.om.types.ATypeTag;
  import org.apache.asterix.om.types.AUnionType;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.IAType;
  import org.apache.asterix.om.types.TypeHelper;
  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.LogicalExpressionTag;
  import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractLogicalExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
  import org.apache.hyracks.api.exceptions.SourceLocation;
  
  /**
   * Cases to support:
   * remove-fields($record, ["foo", ["bar", "access"]]),
   * where ["bar", "access"] is equivalent to the path bar->access
   */
  public class RecordRemoveFieldsTypeComputer implements IResultTypeComputer {
  
      public static final RecordRemoveFieldsTypeComputer INSTANCE = new RecordRemoveFieldsTypeComputer();
  
      private RecordRemoveFieldsTypeComputer() {
      }
  
      private static void getPathFromConstantExpression(FunctionIdentifier funcId, ILogicalExpression fieldNameExpression,
              Set<String> fieldNameSet, List<List<String>> pathList, SourceLocation sourceLoc)
              throws AlgebricksException {
          ConstantExpression ce = (ConstantExpression) fieldNameExpression;
          if (!(ce.getValue() instanceof AsterixConstantValue)) {
              throw new InvalidExpressionException(sourceLoc, funcId, 1, ce, LogicalExpressionTag.CONSTANT);
          }
          IAObject fieldName = ((AsterixConstantValue) ce.getValue()).getObject();
          getPathOfFieldName(funcId, fieldName, fieldNameSet, pathList, sourceLoc);
      }
  
      private static void getPathOfFieldName(FunctionIdentifier funcId, IAObject fieldName, Set<String> fieldNameSet,
              List<List<String>> pathList, SourceLocation sourceLoc) throws UnsupportedTypeException {
          ATypeTag type = fieldName.getType().getTypeTag();
          switch (type) {
              case STRING:
                  String fn = ((AString) fieldName).getStringValue();
                  fieldNameSet.add(fn);
                  pathList.add(List.of(fn));
                  break;
              case ARRAY:
                  AOrderedList pathOrdereList = (AOrderedList) fieldName;
                  fieldNameSet.add(((AString) pathOrdereList.getItem(0)).getStringValue());
                  List<String> path = new ArrayList<>();
                  for (int i = 0; i < pathOrdereList.size(); i++) {
                      path.add(((AString) pathOrdereList.getItem(i)).getStringValue());
                  }
                  pathList.add(path);
                  break;
              default:
                  throw new UnsupportedTypeException(sourceLoc, funcId, type);
          }
      }
  
      private static List<String> getListFromExpression(FunctionIdentifier funcId, ILogicalExpression expression,
              SourceLocation sourceLoc) throws AlgebricksException {
          AbstractFunctionCallExpression funcExp = (AbstractFunctionCallExpression) expression;
          List<Mutable<ILogicalExpression>> args = funcExp.getArguments();
  
          List<String> list = new ArrayList<>();
          for (Mutable<ILogicalExpression> arg : args) {
              // At this point all elements has to be a constant
              // Input list has only one level of nesting (list of list or list of strings)
              ConstantExpression ce = (ConstantExpression) arg.getValue();
              if (!(ce.getValue() instanceof AsterixConstantValue)) {
                  throw new InvalidExpressionException(sourceLoc, funcId, 1, ce, LogicalExpressionTag.CONSTANT);
              }
              IAObject item = ((AsterixConstantValue) ce.getValue()).getObject();
              ATypeTag type = item.getType().getTypeTag();
              if (type == ATypeTag.STRING) {
                  list.add(((AString) item).getStringValue());
              } else {
                  throw new UnsupportedTypeException(sourceLoc, funcId, type);
              }
          }
  
          return list;
      }
  
      private static void getPathFromFunctionExpression(FunctionIdentifier funcId, ILogicalExpression expression,
              Set<String> fieldNameSet, List<List<String>> pathList, SourceLocation sourceLoc)
              throws AlgebricksException {
          List<String> path = getListFromExpression(funcId, expression, sourceLoc);
          // Add the path head to remove set
          fieldNameSet.add(path.get(0));
          pathList.add(path);
  
      }
  
      private static void computeTypeFromExpression(FunctionIdentifier funcId, ILogicalExpression e,
              Set<String> fieldNameSet, List<List<String>> pathList) throws AlgebricksException {
          // e is the field to remove, ["foo", "bar"] = foo.bar, either an ordered list function call or a constant array
          SourceLocation sourceLocation = e.getSourceLocation();
          if (e.getExpressionTag() == LogicalExpressionTag.CONSTANT) {
              AOrderedList list = (AOrderedList) ((AsterixConstantValue) ((ConstantExpression) e).getValue()).getObject();
              for (int i = 0, size = list.size(); i < size; i++) {
                  getPathOfFieldName(funcId, list.getItem(i), fieldNameSet, pathList, sourceLocation);
              }
          } else {
              AbstractFunctionCallExpression funcExp = (AbstractFunctionCallExpression) e;
              List<Mutable<ILogicalExpression>> args = funcExp.getArguments();
  
              for (Mutable<ILogicalExpression> arg : args) {
                  ILogicalExpression le = arg.getValue();
                  switch (le.getExpressionTag()) {
                      case CONSTANT:
                          getPathFromConstantExpression(funcId, le, fieldNameSet, pathList, sourceLocation);
                          break;
                      case FUNCTION_CALL:
                          getPathFromFunctionExpression(funcId, le, fieldNameSet, pathList, sourceLocation);
                          break;
                      default:
                          throw new InvalidExpressionException(sourceLocation, funcId, 1, le,
                                  LogicalExpressionTag.CONSTANT, LogicalExpressionTag.FUNCTION_CALL);
                  }
              }
          }
      }
  
      @Override
      public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
              IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
          AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) expression;
          FunctionIdentifier funcId = funcExpr.getFunctionIdentifier();
  
          IAType type0 = (IAType) env.getType(funcExpr.getArguments().get(0).getValue());
          List<List<String>> pathList = new ArrayList<>();
          Set<String> fieldNameSet = new HashSet<>();
          Deque<String> fieldPathStack = new ArrayDeque<>();
  
          ARecordType inputRecordType = getRecordTypeFromType(funcId, type0, funcExpr.getSourceLocation());
          if (inputRecordType == null) {
              return BuiltinType.ANY;
          }
  
          AbstractLogicalExpression arg1 = (AbstractLogicalExpression) funcExpr.getArguments().get(1).getValue();
          IAType inputListType = (IAType) env.getType(arg1);
          AOrderedListType inputOrderedListType = TypeComputeUtils.extractOrderedListType(inputListType);
          if (inputOrderedListType == null) {
              throw new TypeMismatchException(funcExpr.getSourceLocation(), funcId, 1, inputListType.getTypeTag(),
                      ATypeTag.ARRAY);
          }
  
          ATypeTag tt = inputOrderedListType.getItemType().getTypeTag();
          if (tt == ATypeTag.STRING) {
              // all fields to be removed are top-level fields, e.g. remove_fields(obj, ["f1", "f2", "f3"])
              if (setFieldNameSet(arg1, fieldNameSet)) {
                  return buildOutputType(fieldPathStack, inputRecordType, fieldNameSet, pathList);
              } else {
                  return DefaultOpenFieldType.NESTED_OPEN_RECORD_TYPE;
              }
          } else {
              // some fields to be removed are nested, e.g. remove_fields(obj, ["f1", ["f2", "nested_field"], "f3"])
              computeTypeFromExpression(funcId, arg1, fieldNameSet, pathList);
              return buildOutputType(fieldPathStack, inputRecordType, fieldNameSet, pathList);
          }
      }
  
      private static boolean setFieldNameSet(ILogicalExpression expr, Set<String> fieldNameSet) {
          if (expr.getExpressionTag() == LogicalExpressionTag.CONSTANT) {
              AOrderedList orderedList =
                      (AOrderedList) (((AsterixConstantValue) ((ConstantExpression) expr).getValue()).getObject());
              for (int i = 0; i < orderedList.size(); i++) {
                  AString as = (AString) orderedList.getItem(i);
                  fieldNameSet.add(as.getStringValue());
              }
              return true; // Success
          }
          return false;
      }
  
      private static void addField(ARecordType inputRecordType, String fieldName, List<String> resultFieldNames,
              List<IAType> resultFieldTypes) {
          resultFieldNames.add(fieldName);
          if (inputRecordType.getFieldType(fieldName).getTypeTag() == ATypeTag.OBJECT) {
              ARecordType nestedType = (ARecordType) inputRecordType.getFieldType(fieldName);
              //Deep Copy prevents altering of input types
              resultFieldTypes.add(nestedType.deepCopy(nestedType));
          } else {
              resultFieldTypes.add(inputRecordType.getFieldType(fieldName));
          }
      }
  
      private static IAType buildOutputType(Deque<String> fieldPathStack, ARecordType inputRecordType,
              Set<String> fieldNameSet, List<List<String>> pathList) {
          List<String> resultFieldNames = new ArrayList<>();
          List<IAType> resultFieldTypes = new ArrayList<>();
  
          String[] fieldNames = inputRecordType.getFieldNames();
          IAType[] fieldTypes = inputRecordType.getFieldTypes();
  
          for (int i = 0; i < fieldNames.length; i++) {
              IAType originalType = fieldTypes[i];
              IAType actualType = TypeComputeUtils.getActualType(originalType);
              if (!fieldNameSet.contains(fieldNames[i])) { // The main field is to be kept
                  addField(inputRecordType, fieldNames[i], resultFieldNames, resultFieldTypes);
              } else if (!pathList.isEmpty() && actualType.getTypeTag() == ATypeTag.OBJECT) {
                  ARecordType subRecord = (ARecordType) actualType;
                  fieldPathStack.push(fieldNames[i]);
                  subRecord = deepCheckAndCopy(fieldPathStack, subRecord, pathList, subRecord.isOpen());
                  fieldPathStack.pop();
                  if (subRecord != null) {
                      resultFieldNames.add(fieldNames[i]);
                      resultFieldTypes.add(wrapWithOriginalType(subRecord, originalType));
                  }
              }
          }
  
          int n = resultFieldNames.size();
          String resultTypeName = "result-record(" + inputRecordType.getTypeName() + ")";
  
          return new ARecordType(resultTypeName, resultFieldNames.toArray(new String[n]),
                  resultFieldTypes.toArray(new IAType[n]), true); // Make the output type open always
  
      }
  
      private static IAType wrapWithOriginalType(IAType typeToModify, IAType originalType) {
          if (TypeHelper.canBeMissing(originalType) && !TypeHelper.canBeNull(originalType)) {
              return AUnionType.createMissableType(typeToModify);
          } else if (!TypeHelper.canBeMissing(originalType) && TypeHelper.canBeNull(originalType)) {
              return AUnionType.createNullableType(typeToModify);
          } else if (TypeHelper.canBeUnknown(originalType)) {
              return AUnionType.createUnknownableType(typeToModify);
          } else {
              return typeToModify;
          }
      }
  
      /**
       * Comparison elements of two paths
       * Note: l2 uses a LIFO insert and removal.
       */
      private static <E> boolean isEqualPaths(List<E> l1, Deque<E> l2) {
          if ((l1 == null) || (l2 == null)) {
              return false;
          }
  
          if (l1.size() != l2.size()) {
              return false;
          }
  
          Iterator<E> it2 = l2.iterator();
  
          int len = l1.size();
          for (int i = len - 1; i >= 0; i--) {
              E o1 = l1.get(i);
              E o2 = it2.next();
              if (!o1.equals(o2)) {
                  return false;
              }
          }
          return true;
      }
  
      private static boolean isRemovePath(Deque<String> fieldPath, List<List<String>> pathList) {
          for (List<String> removePath : pathList) {
              if (isEqualPaths(removePath, fieldPath)) {
                  return true;
              }
          }
          return false;
      }
  
      /*
          A method to deep copy a record the path validation
               i.e., keep only fields that are valid
       */
      private static ARecordType deepCheckAndCopy(Deque<String> fieldPath, ARecordType srcRecType,
              List<List<String>> pathList, boolean isOpen) {
          // Make sure the current path is valid before going further
          if (isRemovePath(fieldPath, pathList)) {
              return null;
          }
  
          String srcFieldNames[] = srcRecType.getFieldNames();
          IAType srcFieldTypes[] = srcRecType.getFieldTypes();
  
          List<IAType> destFieldTypes = new ArrayList<>();
          List<String> destFieldNames = new ArrayList<>();
  
          for (int i = 0; i < srcFieldNames.length; i++) {
              fieldPath.push(srcFieldNames[i]);
              if (!isRemovePath(fieldPath, pathList)) {
                  IAType originalType = srcFieldTypes[i];
                  IAType actualType = TypeComputeUtils.getActualType(originalType);
                  if (actualType.getTypeTag() == ATypeTag.OBJECT) {
                      ARecordType subRecord = (ARecordType) actualType;
                      subRecord = deepCheckAndCopy(fieldPath, subRecord, pathList, subRecord.isOpen());
                      if (subRecord != null) {
                          destFieldNames.add(srcFieldNames[i]);
                          destFieldTypes.add(wrapWithOriginalType(subRecord, originalType));
                      }
                  } else {
                      destFieldNames.add(srcFieldNames[i]);
                      destFieldTypes.add(srcFieldTypes[i]);
                  }
              }
              fieldPath.pop();
          }
  
          int n = destFieldNames.size();
          return new ARecordType(srcRecType.getTypeName(), destFieldNames.toArray(new String[n]),
                  destFieldTypes.toArray(new IAType[n]), isOpen);
      }
  
      private static ARecordType getRecordTypeFromType(FunctionIdentifier funcId, IAType type0, SourceLocation sourceLoc)
              throws AlgebricksException {
          switch (type0.getTypeTag()) {
              case OBJECT:
                  return (ARecordType) type0;
              case ANY:
                  return DefaultOpenFieldType.NESTED_OPEN_RECORD_TYPE;
              case UNION:
                  IAType t1 = ((AUnionType) type0).getActualType();
                  if (t1.getTypeTag() == ATypeTag.OBJECT) {
                      return (ARecordType) t1;
                  } else if (t1.getTypeTag() == ATypeTag.ANY) {
                      return DefaultOpenFieldType.NESTED_OPEN_RECORD_TYPE;
                  }
                  // Falls through for other cases.
              default:
                  throw new TypeMismatchException(sourceLoc, funcId, 0, type0.getTypeTag(), ATypeTag.OBJECT);
          }
      }
  }
  