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/*
 * SonarQube Java
 * Copyright (C) 2012-2016 SonarSource SA
 * mailto:contact AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.java.checks;

import org.sonar.api.server.rule.RulesDefinition;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.java.checks.helpers.ExpressionsHelper;
import org.sonar.java.tag.Tag;
import org.sonar.plugins.java.api.JavaFileScanner;
import org.sonar.plugins.java.api.JavaFileScannerContext;
import org.sonar.plugins.java.api.semantic.Type;
import org.sonar.plugins.java.api.semantic.Type.Primitives;
import org.sonar.plugins.java.api.tree.BaseTreeVisitor;
import org.sonar.plugins.java.api.tree.BinaryExpressionTree;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.LiteralTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.squidbridge.annotations.ActivatedByDefault;
import org.sonar.squidbridge.annotations.SqaleConstantRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;

import java.util.LinkedList;
import java.util.List;

@Rule(
  key = "S3034",
  name = "Raw byte values should not be used in bitwise operations in combination with shifts",
  priority = Priority.CRITICAL,
  tags = {Tag.BUG})
@ActivatedByDefault
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.INSTRUCTION_RELIABILITY)
@SqaleConstantRemediation("5min")
public class RawByteBitwiseOperationsCheck extends BaseTreeVisitor implements JavaFileScanner {

  JavaFileScannerContext context;
  List shifts = new LinkedList<>();
  List byteContainments = new LinkedList<>();


  @Override
  public void scanFile(JavaFileScannerContext context) {
    this.context = context;
    scan(context.getTree());
    shifts.clear();
    byteContainments.clear();
  }

  @Override
  public void visitBinaryExpression(BinaryExpressionTree tree) {
    super.visitBinaryExpression(tree);
    if (isShifting(tree)) {
      shifts.add(tree);
      return;
    }
    if (isSecuringByte(tree)) {
      byteContainments.add(tree);
      return;
    }
    if (isIntegerOrLongExpected(tree.symbolType())) {
      ExpressionTree leftOperand = ExpressionsHelper.skipParentheses(tree.leftOperand());
      ExpressionTree rightOperand = ExpressionsHelper.skipParentheses(tree.rightOperand());
      checkShiftWithoutByteSecuring(leftOperand, rightOperand);
      checkShiftWithoutByteSecuring(rightOperand, leftOperand);
    }
  }

  private static boolean isShifting(BinaryExpressionTree tree) {
    return tree.is(Tree.Kind.LEFT_SHIFT, Tree.Kind.RIGHT_SHIFT, Tree.Kind.UNSIGNED_RIGHT_SHIFT);
  }

  private static boolean isSecuringByte(BinaryExpressionTree tree) {
    return tree.is(Tree.Kind.AND) && (is0xff(tree.rightOperand()) || is0xff(tree.leftOperand()));
  }

  private static boolean is0xff(ExpressionTree expression) {
    return expression.is(Tree.Kind.INT_LITERAL) && "0xff".equals(((LiteralTree) expression).value());
  }

  private static boolean isIntegerOrLongExpected(Type type) {
    return type.isPrimitive(Primitives.INT) || type.isPrimitive(Primitives.LONG);
  }

  private void checkShiftWithoutByteSecuring(ExpressionTree shiftExpr, ExpressionTree byteExpr) {
    if (shifts.contains(shiftExpr) && !byteContainments.contains(byteExpr) && byteExpr.symbolType().isPrimitive(Primitives.BYTE)) {
      context.reportIssue(this, byteExpr, "Prevent \"int\" promotion by adding \"& 0xff\" to this expression.");
    }
  }

}