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.math.BigInteger;
  import java.util.ArrayList;
  import java.util.List;
  
  import com.strobel.assembler.metadata.MethodDefinition;
  import com.strobel.assembler.metadata.MethodReference;
  import com.strobel.decompiler.ast.AstCode;
  import com.strobel.decompiler.ast.Expression;
  import com.strobel.decompiler.ast.Variable;
  
  import one.util.huntbugs.flow.Inf;
  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.Methods;
  import one.util.huntbugs.util.NodeChain;
  import one.util.huntbugs.util.Nodes;
  import one.util.huntbugs.warning.Role.LocationRole;
  import one.util.huntbugs.warning.Role.StringRole;
  import one.util.huntbugs.warning.Roles;
  import one.util.huntbugs.warning.WarningAnnotation;
  import one.util.huntbugs.warning.WarningAnnotation.Location;
  
  /**
   * @author Tagir Valeev
   *
   */
  @WarningDefinition(category = "Correctness", name = "IntegerMultiplicationPromotedToLong", maxScore = 65)
  @WarningDefinition(category = "Correctness", name = "IntegerDivisionPromotedToFloat", maxScore = 65)
  @WarningDefinition(category = "Correctness", name = "IntegerPromotionInCeilOrRound", maxScore = 65)
  public class NumericPromotion {
      private static final StringRole SOURCE_TYPE = StringRole.forName("SOURCE_TYPE");
      private static final StringRole TARGET_TYPE = StringRole.forName("TARGET_TYPE");
      private static final LocationRole DIVISION_AT = LocationRole.forName("DIVISION_AT");
      
      @AstVisitor(nodes = AstNodes.EXPRESSIONS)
      public void visit(Expression expr, NodeChain nc, MethodContext mc, MethodDefinition md) {
          if (expr.getCode() == AstCode.I2L) {
              Expression arg = expr.getArguments().get(0);
              if (arg.getCode() == AstCode.Mul) {
                  BigInteger res = getMultiplicationConstant(arg);
                  int priority = 0;
                  if (Methods.isHashCodeMethod(md))
                      priority += 30;
                  try {
                      int factor = Math.abs(res.intValueExact());
                      if (factor > 1) {
                          if (factor <= 4) {
                              priority += 50;
                          } else if (factor <= 100) {
                              priority += 40;
                          } else if (factor <= 10000) {
                              priority += 30;
                          } else if (factor <= 60 * 60 * 1000) {
                              priority += 20;
                          } else
                              priority += 10;
                          mc.report("IntegerMultiplicationPromotedToLong", priority, expr, Roles.NUMBER.create(res));
                      }
                  } catch (ArithmeticException e) {
                      mc.report("IntegerMultiplicationPromotedToLong", priority, expr, Roles.NUMBER.create(res));
                  }
              }
          }
          if (Nodes.isToFloatingPointConversion(expr)) {
              if (Nodes.isOp(nc.getNode(), AstCode.InvokeStatic)) {
                  MethodReference mr = (MethodReference) ((Expression) nc.getNode()).getOperand();
                  if (mr.getDeclaringType().getInternalName().equals("java/lang/Math")
                      && (mr.getName().equals("ceil") || mr.getName().equals("round"))) {
                      mc.report("IntegerPromotionInCeilOrRound", 0, nc.getNode(), SOURCE_TYPE.create(getSourceType(expr)), 
                          TARGET_TYPE.create(getTargetType(expr)));
                      return;
                  }
              }
              Expression arg = ValuesFlow.getSource(expr.getArguments().get(0));
              if (arg.getCode() == AstCode.Div) {
                  if(!Inf.BACKLINK.findTransitiveUsages(arg, true).allMatch(NumericPromotion::isToFloatingPointConversion))
                      return;
                  Object constant = Nodes.getConstant(arg.getArguments().get(1));
                  int priority = 0;
                  boolean isPowerOfTen = false;
                  if (constant instanceof Number) {
                      long val = Math.abs(((Number) constant).longValue());
                      if (val >= 2 && val <= 4)
                          priority += 10;
                      else if(isPowerOfTen(val)) {
                          isPowerOfTen = true;
                          priority += 15;
                      }
                  }
                  if (Nodes.isOp(nc.getNode(), AstCode.Div)) {
                      Expression parent = (Expression) nc.getNode();
                      if (parent.getArguments().get(0) == expr) {
                          Object divisor = Nodes.getConstant(parent.getArguments().get(1));
                          if (divisor instanceof Number) {
                              long divisorVal = ((Number) divisor).longValue();
                              if(isPowerOfTen(divisorVal)) {
                                  // some rounding like ((double)a/10)/10;
                                  priority += isPowerOfTen ? 50 : 10;
                              }
                              // Lower priority for scenarios like
                              // ((a*1000)/b)/10.0
                              Expression divident = arg.getArguments().get(0);
                              if (divident.getCode() == AstCode.Mul) {
                                  BigInteger multiplier = getMultiplicationConstant(divident);
                                  if ((multiplier.equals(BigInteger.valueOf(divisorVal * 100)) || multiplier
                                          .equals(BigInteger.valueOf(divisorVal))))
                                  priority += 100;
                              }
                          }
                      }
                  }
                  if (Inf.BACKLINK.findTransitiveUsages(expr, true).allMatch(Nodes::isComparison)) {
                      priority += 15;
                  }
                  if (Inf.BACKLINK.findTransitiveUsages(expr, true).allMatch(e ->
                          e.getCode() == AstCode.InvokeStatic && 
                          Methods.is((MethodReference) e.getOperand(), "java/lang/Math", "pow", "(DD)D") &&
                          Exprs.getChild(e, 1) == expr)) {
                      priority += 15;
                  }
                  List<WarningAnnotation<?>> anno = new ArrayList<>();
                  anno.add(SOURCE_TYPE.create(getSourceType(expr)));
                  anno.add(TARGET_TYPE.create(getTargetType(expr)));
                  Location divLoc = mc.getLocation(arg);
                  if(divLoc.getSourceLine() != mc.getLocation(expr).getSourceLine())
                      anno.add(DIVISION_AT.create(divLoc));
                  Object op = expr.getArguments().get(0).getOperand();
                  if(op instanceof Variable) {
                      anno.add(WarningAnnotation.forVariable((Variable)op));
                  }
                  mc.report("IntegerDivisionPromotedToFloat", priority, expr, anno);
              }
          }
      }
  
      private boolean isPowerOfTen(long divisorVal) {
          return divisorVal == 10 || divisorVal == 100 || divisorVal == 1000 || divisorVal == 10000
              || divisorVal == 100000 || divisorVal == 1000000 || divisorVal == 10000000 || divisorVal == 100000000
              || divisorVal == 1000000000;
      }
  
      private static String getSourceType(Expression expr) {
          switch(expr.getCode()) {
          case I2F:
          case I2D:
              return "int";
          case L2F:
          case L2D:
              return "long";
          default:
              throw new InternalError(expr.getCode().toString());
          }
      }
  
      private static String getTargetType(Expression expr) {
          switch(expr.getCode()) {
          case I2F:
          case L2F:
              return "float";
          case I2D:
          case L2D:
              return "double";
          default:
              throw new InternalError(expr.getCode().toString());
          }
      }
      
      private static BigInteger getMultiplicationConstant(Expression arg) {
          Expression left = arg.getArguments().get(0);
          Expression right = arg.getArguments().get(1);
          Object leftConst = Nodes.getConstant(left);
          Object rightConst = Nodes.getConstant(right);
          BigInteger leftOperand = BigInteger.ONE;
          BigInteger rightOperand = BigInteger.ONE;
          if (leftConst instanceof Number) {
              leftOperand = BigInteger.valueOf(((Number) leftConst).longValue());
          } else if (left.getCode() == AstCode.Mul) {
              leftOperand = getMultiplicationConstant(left);
          }
          if (rightConst instanceof Number) {
              rightOperand = BigInteger.valueOf(((Number) rightConst).longValue());
          } else if (right.getCode() == AstCode.Mul) {
              rightOperand = getMultiplicationConstant(right);
          }
          return leftOperand.multiply(rightOperand);
      }
      
      private static boolean isToFloatingPointConversion(Expression expr) {
          if(Nodes.isToFloatingPointConversion(expr))
              return true;
          if(expr.getCode() == AstCode.Neg)
              return Inf.BACKLINK.findTransitiveUsages(expr, true).allMatch(NumericPromotion::isToFloatingPointConversion);
          return false;
      }
  }
  