content: /*
   * Copyright 1999-2017 Alibaba Group.
   *
   * Licensed 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 com.alibaba.p3c.pmd.lang.java.rule.exception;
  
  import java.util.List;
  import java.util.Map;
  
  import com.alibaba.p3c.pmd.I18nResources;
  import com.alibaba.p3c.pmd.lang.java.rule.AbstractAliRule;
  import com.alibaba.p3c.pmd.lang.java.util.ViolationUtils;
  import com.alibaba.p3c.pmd.lang.java.util.namelist.NameListConfig;
  
  import net.sourceforge.pmd.lang.ast.Node;
  import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceType;
  import net.sourceforge.pmd.lang.java.ast.ASTLocalVariableDeclaration;
  import net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration;
  import net.sourceforge.pmd.lang.java.ast.ASTName;
  import net.sourceforge.pmd.lang.java.ast.ASTPrimitiveType;
  import net.sourceforge.pmd.lang.java.ast.ASTVariableDeclaratorId;
  import org.jaxen.JaxenException;
  
  /**
   * [Recommended] If the return type is primitive, return a value of wrapper class may cause NullPointerException.
   *
   * @author changle.lq
   * @date 2017/04/16
   */
  public class MethodReturnWrapperTypeRule extends AbstractAliRule {
      private static final Map<String, String> PRIMITIVE_TYPE_TO_WAPPER_TYPE = NameListConfig.NAME_LIST_SERVICE
          .getNameMap("MethodReturnWrapperTypeRule", "PRIMITIVE_TYPE_TO_WAPPER_TYPE", String.class, String.class);
      private static final String METHOD_RETURN_TYPE_XPATH = "ResultType/Type/PrimitiveType";
      private static final String METHOD_RETURN_OBJECT_XPATH
          = "Block/BlockStatement/Statement/ReturnStatement/Expression/PrimaryExpression/PrimaryPrefix/Name";
      private static final String METHOD_VARIABLE_TYPE_XPATH = "Type/ReferenceType/ClassOrInterfaceType";
      private static final String METHOD_VARIABLE_NAME_XPATH
          = "Block/BlockStatement/LocalVariableDeclaration/VariableDeclarator/VariableDeclaratorId";
  
      @Override
      public Object visit(ASTMethodDeclaration node, Object data) {
          try {
              List<Node> astPrimitiveTypeList = node.findChildNodesWithXPath(METHOD_RETURN_TYPE_XPATH);
              //check the method return type
              if (!(astPrimitiveTypeList != null && astPrimitiveTypeList.size() == 1)) {
                  return super.visit(node, data);
              }
              ASTPrimitiveType astPrimitiveType = (ASTPrimitiveType)astPrimitiveTypeList.get(0);
              //If the return type is not a basic types,skip
              if (!(astPrimitiveType.getType() != null && astPrimitiveType.getType().isPrimitive())) {
                  return super.visit(node, data);
              }
              //the return type
              String primitiveTypeName = astPrimitiveType.getType().getName();
              //the return node
              List<Node> nameList = node.findChildNodesWithXPath(METHOD_RETURN_OBJECT_XPATH);
              if (nameList == null || nameList.size() != 1) {
                  return super.visit(node, data);
              }
              //if the local variable is empty,skip
              List<Node> methodVariableNameList = node.findChildNodesWithXPath(METHOD_VARIABLE_NAME_XPATH);
              if (methodVariableNameList == null || methodVariableNameList.size() == 0) {
                  return super.visit(node, data);
              }
              ASTName astName = (ASTName)nameList.get(0);
              String variableName = astName.getImage();
              //iterate all the method of variable nodes
              for (Node methodVariableNameNode : methodVariableNameList) {
                  ASTVariableDeclaratorId astVariableDeclaratorId
                      = (ASTVariableDeclaratorId)methodVariableNameNode;
                  //find out the variable named the same with return node
                  if (!variableName.equals(astVariableDeclaratorId.getImage())) {
                      continue;
                  }
                  ASTLocalVariableDeclaration astLocalVariableDeclaration = astVariableDeclaratorId
                      .getFirstParentOfType(ASTLocalVariableDeclaration.class);
                  //check local variables type
                  List<Node> nodeList = astLocalVariableDeclaration.findChildNodesWithXPath(
                      METHOD_VARIABLE_TYPE_XPATH);
  
                  if (nodeList != null && nodeList.size() == 1) {
                      ASTClassOrInterfaceType astClassOrInterfaceType = (ASTClassOrInterfaceType)nodeList.get(
                          0);
                      //if variable type is a value of wrapper
                      if (PRIMITIVE_TYPE_TO_WAPPER_TYPE.get(primitiveTypeName) != null
                          && PRIMITIVE_TYPE_TO_WAPPER_TYPE.get(primitiveTypeName).equals(
                          astClassOrInterfaceType.getType().getSimpleName())) {
                          ViolationUtils.addViolationWithPrecisePosition(this, node, data,
                              I18nResources.getMessage("java.exception.MethodReturnWrapperTypeRule.violation.msg",
                                  primitiveTypeName, astClassOrInterfaceType.getType().getSimpleName()));
                      }
                  }
              }
          } catch (JaxenException e) {
              return super.visit(node, data);
          }
          return super.visit(node, data);
      }
  }
  