content: /*
   * Copyright 2016 HuntBugs contributors
   * 
   * 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 one.util.huntbugs.detect;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import com.strobel.assembler.metadata.MethodDefinition;
  import com.strobel.assembler.metadata.TypeDefinition;
  import com.strobel.decompiler.ast.AstCode;
  import com.strobel.decompiler.ast.Expression;
  
  import one.util.huntbugs.registry.MethodContext;
  import one.util.huntbugs.registry.anno.AstNodes;
  import one.util.huntbugs.registry.anno.AstVisitor;
  import one.util.huntbugs.registry.anno.WarningDefinition;
  import one.util.huntbugs.util.Exprs;
  import one.util.huntbugs.util.NodeChain;
  import one.util.huntbugs.util.Types;
  import one.util.huntbugs.warning.Role.TypeRole;
  
  /**
   * @author Tagir Valeev
   *
   */
  @WarningDefinition(category = "BadPractice", name = "OptionalReturnNull", maxScore = 50)
  @WarningDefinition(category = "BadPractice", name = "BooleanReturnNull", maxScore = 50)
  @WarningDefinition(category = "BadPractice", name = "ArrayReturnNull", maxScore = 38)
  public class ReturnNull {
      private static final TypeRole RETURN_TYPE = TypeRole.forName("RETURN_TYPE");
  
      private static final Map<String, String> TYPE_TO_WARNING = new HashMap<>();
  
      static {
          TYPE_TO_WARNING.put("java/util/Optional", "OptionalReturnNull");
          TYPE_TO_WARNING.put("com/google/common/base/Optional", "OptionalReturnNull");
          TYPE_TO_WARNING.put("java/lang/Boolean", "BooleanReturnNull");
      }
  
      public boolean checkMethod(MethodDefinition md) {
          if(!md.getReturnType().isArray() && !TYPE_TO_WARNING.containsKey(md.getReturnType().getInternalName()))
              return false;
          if(md.getName().equals("getName") && md.getReturnType().getSignature().equals("[B") && md.getParameters().size() == 1
                  && Types.isInstance(md.getDeclaringType(), "java/sql/ResultSet"))
              return false;
          return true;
      }
  
      @AstVisitor(nodes = AstNodes.EXPRESSIONS)
      public void visit(Expression expr, NodeChain nc, MethodContext mc, MethodDefinition md, TypeDefinition td) {
          if (expr.getCode() == AstCode.Return && !expr.getArguments().isEmpty()) {
              Expression child = Exprs.getChild(expr, 0);
              if (child.getCode() == AstCode.AConstNull) {
                  MethodDefinition curMethod = nc.getLambdaMethod();
                  if (curMethod == null)
                      curMethod = md;
                  String warningType = curMethod.getReturnType().isArray() ? "ArrayReturnNull" : TYPE_TO_WARNING
                          .get(curMethod.getReturnType().getInternalName());
                  if (warningType != null) {
                      int priority = 0;
                      if (!td.isPublic() || md.isPrivate() || md.isPackagePrivate())
                          priority = 20;
                      else if (md.isProtected() || md != curMethod)
                          priority = 10;
                      // Method which simply contains "return null": probably stub or something
                      if(nc.getParent() == null && nc.isOnlyChild(expr))
                          priority += 10;
                      mc.report(warningType, priority, expr.getArguments().get(0), RETURN_TYPE.create(md
                              .getReturnType()));
                  }
              }
          }
      }
  }
  