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 com.strobel.assembler.metadata.JvmType;
  import com.strobel.assembler.metadata.MemberReference;
  import com.strobel.assembler.metadata.MethodReference;
  import com.strobel.decompiler.ast.AstCode;
  import com.strobel.decompiler.ast.Expression;
  
  import one.util.huntbugs.flow.ValuesFlow;
  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.Nodes;
  import one.util.huntbugs.util.Types;
  import one.util.huntbugs.warning.Roles;
  
  /**
   * @author Tagir Valeev
   *
   */
  @WarningDefinition(category = "BadPractice", name = "NegatingComparatorResult", maxScore = 50)
  @WarningDefinition(category = "Correctness", name = "ComparingComparatorResultWithNumber", maxScore = 70)
  public class CompareUsage {
      @AstVisitor(nodes = AstNodes.EXPRESSIONS)
      public void visit(Expression expr, MethodContext mc) {
          if (expr.getCode() == AstCode.Neg) {
              Expression child = ValuesFlow.findFirst(Exprs.getChild(expr, 0), this::isCompare);
              if (child != null) {
                  mc.report("NegatingComparatorResult", 0, expr, Roles.CALLED_METHOD.create((MethodReference) child
                          .getOperand()));
              }
          }
          if (expr.getCode() == AstCode.CmpEq || expr.getCode() == AstCode.CmpNe) {
              Nodes.ifBinaryWithConst(expr, (arg, constant) -> {
                  if (constant instanceof Integer && (int) constant != 0) {
                      Expression child = ValuesFlow.findFirst(ValuesFlow.getSource(arg), this::isCompare);
                      if (child != null) {
                          mc.report("ComparingComparatorResultWithNumber", 0, expr, Roles.CALLED_METHOD.create(
                              (MemberReference) child.getOperand()), Roles.NUMBER.create((Number) constant));
                      }
                  }
              });
          }
      }
  
      private boolean isCompare(Expression child) {
          if (child.getCode() == AstCode.InvokeVirtual || child.getCode() == AstCode.InvokeSpecial
              || child.getCode() == AstCode.InvokeInterface) {
              MethodReference mr = (MethodReference) child.getOperand();
              if (mr.getReturnType().getSimpleType() == JvmType.Integer
                  && ((mr.getName().equals("compare") && Types.isInstance(mr.getDeclaringType(), "java/util/Comparator")) || mr
                          .getName().equals("compareTo"))) {
                  return true;
              }
          }
          return false;
      }
  }
  