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.MethodDefinition;
  import com.strobel.assembler.metadata.TypeDefinition;
  import com.strobel.decompiler.ast.AstCode;
  import com.strobel.decompiler.ast.Expression;
  
  import one.util.huntbugs.flow.Inf;
  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.MethodVisitor;
  import one.util.huntbugs.registry.anno.WarningDefinition;
  import one.util.huntbugs.util.Nodes;
  import one.util.huntbugs.util.Types;
  
  /**
   * @author shustkost
   *
   */
  @WarningDefinition(category="BadPractice", name="CompareReturnsMinValue", maxScore=40)
  public class CompareContract {
      private static final Integer MIN_VALUE = Integer.valueOf(Integer.MIN_VALUE);
  
      @MethodVisitor
      public boolean check(MethodDefinition md, TypeDefinition td) {
          if(md.isSynthetic())
              return false;
          if(md.getName().equals("compare") && md.getParameters().size() == 2 && md.getReturnType().getSimpleType() == JvmType.Integer
                  && Types.isInstance(td, "java/util/Comparator"))
              return true;
          if(md.getName().equals("compareTo") && md.getParameters().size() == 1 && md.getReturnType().getSimpleType() == JvmType.Integer
                  && Types.isInstance(td, "java/lang/Comparable"))
              return true;
          return false;
      }
      
      @AstVisitor(nodes=AstNodes.EXPRESSIONS)
      public void visit(Expression expr, MethodContext mc) {
          if(MIN_VALUE.equals(Nodes.getConstant(expr))) {
              if(Inf.BACKLINK.findTransitiveUsages(expr, true).anyMatch(e -> e.getCode() == AstCode.Return)) {
                  mc.report("CompareReturnsMinValue", 0, expr);
              }
          }
      }
  }
  