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/*
 * SonarQube Java
 * Copyright (C) 2012-2024 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.ast.api.JavaKeyword;
import org.sonar.java.checks.helpers.MethodTreeUtils;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.semantic.Symbol;
import org.sonar.plugins.java.api.tree.BaseTreeVisitor;
import org.sonar.plugins.java.api.tree.BinaryExpressionTree;
import org.sonar.plugins.java.api.tree.ClassTree;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.InstanceOfTree;
import org.sonar.plugins.java.api.tree.MemberSelectExpressionTree;
import org.sonar.plugins.java.api.tree.MethodTree;
import org.sonar.plugins.java.api.tree.Tree;

@Rule(key = "S2162")
public class SymmetricEqualsCheck extends IssuableSubscriptionVisitor {

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

  @Override
  public void visitNode(Tree tree) {
    MethodTree methodTree = (MethodTree) tree;
    if (MethodTreeUtils.isEqualsMethod(methodTree) && methodTree.block() != null) {
      methodTree.block().accept(new SymmetryBrokePatterns(methodTree.symbol()));
    }
  }

  private class SymmetryBrokePatterns extends BaseTreeVisitor {

    private final Symbol.MethodSymbol methodSymbol;
    private final Symbol owner;

    public SymmetryBrokePatterns(Symbol.MethodSymbol methodSymbol) {
      this.methodSymbol = methodSymbol;
      this.owner = methodSymbol.owner();
    }

    private boolean isOwnerFinal() {
      return owner.isFinal();
    }

    @Override
    public void visitInstanceOf(InstanceOfTree tree) {
      if (tree.type().symbolType().erasure().equals(owner.type().erasure())) {
        if (!isOwnerFinal() && !methodSymbol.isFinal()) {
          reportIssue(tree, "Compare to \"this.getClass()\" instead.");
        }
      } else {
        reportIssue(tree, "Remove this comparison to an unrelated class.");
      }
      super.visitInstanceOf(tree);
    }

    @Override
    public void visitClass(ClassTree tree) {
      // inner classes will be visited by main visitor.
    }

    @Override
    public void visitBinaryExpression(BinaryExpressionTree tree) {
      if (tree.is(Tree.Kind.EQUAL_TO, Tree.Kind.NOT_EQUAL_TO)) {
        checkOperand(tree.leftOperand());
        checkOperand(tree.rightOperand());
      }
      super.visitBinaryExpression(tree);
    }

    private void checkOperand(ExpressionTree expressionTree) {
      if (expressionTree.is(Tree.Kind.MEMBER_SELECT)) {
        MemberSelectExpressionTree mset = (MemberSelectExpressionTree) expressionTree;
        if (isClassExpression(mset)) {
          if (isClassOfOwner(mset)) {
            if (!isOwnerFinal()) {
              reportIssue(expressionTree, "Compare to \"this.getClass()\" instead.");
            }
          } else {
            reportIssue(expressionTree, "Remove this comparison to an unrelated class.");
          }
        }
      }
    }

    private boolean isClassExpression(MemberSelectExpressionTree mset) {
      return JavaKeyword.CLASS.getValue().equals(mset.identifier().name());
    }

    private boolean isClassOfOwner(MemberSelectExpressionTree mset) {
      return mset.expression().symbolType().equals(owner.type());
    }

  }

}