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/*
 * SonarQube Java
 * Copyright (C) 2012-2018 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 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.naming;

import com.google.common.collect.ImmutableList;

import org.sonar.check.Rule;
import org.sonar.java.matcher.MethodMatcher;
import org.sonar.plugins.java.api.IssuableSubscriptionVisitor;
import org.sonar.plugins.java.api.semantic.Symbol;
import org.sonar.plugins.java.api.tree.MethodTree;
import org.sonar.plugins.java.api.tree.Tree;

import java.util.List;

@Rule(key = "S1201")
public class MethodNamedEqualsCheck extends IssuableSubscriptionVisitor {

  private static final String EQUALS = "equals";
  private static final MethodMatcher EQUALS_MATCHER = MethodMatcher.create().name(EQUALS).parameters("java.lang.Object");

  @Override
  public List nodesToVisit() {
    return ImmutableList.of(Tree.Kind.METHOD);
  }

  @Override
  public void visitNode(Tree tree) {
    if (!hasSemantic()) {
      return;
    }
    MethodTree methodTree = (MethodTree) tree;
    if (equalsWithSingleParam(methodTree) && !hasProperEquals(methodTree)) {
      reportIssue(methodTree.simpleName(), "Either override Object.equals(Object), or rename the method to prevent any confusion.");
    }
  }

  private static boolean equalsWithSingleParam(MethodTree methodTree) {
    return EQUALS.equalsIgnoreCase(methodTree.simpleName().name()) && methodTree.parameters().size() == 1;
  }

  private static boolean hasProperEquals(MethodTree methodTree) {
    Symbol.TypeSymbol enclosingClass = methodTree.symbol().enclosingClass();
    return enclosingClass != null && enclosingClass.lookupSymbols(EQUALS).stream().anyMatch(EQUALS_MATCHER::matches);
  }

}