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/*
 * SonarQube Java
 * Copyright (C) 2012-2025 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the Sonar Source-Available License Version 1, as published by SonarSource SA.
 *
 * 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 Sonar Source-Available License for more details.
 *
 * You should have received a copy of the Sonar Source-Available License
 * along with this program; if not, see https://sonarsource.com/license/ssal/
 */
package org.sonar.java.checks;

import java.util.Collections;
import java.util.List;
import org.sonar.check.Rule;
import org.sonar.java.checks.helpers.ExpressionsHelper;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.semantic.Symbol;
import org.sonar.plugins.java.api.tree.ClassTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.Tree.Kind;

@Rule(key = "S2257")
public class CustomCryptographicAlgorithmCheck extends IssuableSubscriptionVisitor {

  private static final String MESSAGE_DIGEST_QUALIFIED_NAME = "java.security.MessageDigest";
  private static final String MESSAGE = "Make sure using a non-standard cryptographic algorithm is safe here.";

  @Override
  public List nodesToVisit() {
    return Collections.singletonList(Tree.Kind.CLASS);
  }

  @Override
  public void visitNode(Tree tree) {
    ClassTree classTree = (ClassTree) tree;
    if (isJavaSecurityMessageDigestSubClass(classTree)) {
      reportIssue(ExpressionsHelper.reportOnClassTree(classTree), MESSAGE);
    }
  }

  private static boolean isJavaSecurityMessageDigestSubClass(ClassTree tree) {
    Symbol.TypeSymbol classSymbol = tree.symbol();
    // Corner case: A type is a subtype of itself
    return classSymbol != null && !classSymbol.type().is(MESSAGE_DIGEST_QUALIFIED_NAME) &&
      classSymbol.type().isSubtypeOf(MESSAGE_DIGEST_QUALIFIED_NAME);
  }
}