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/*
 * SonarQube Java
 * Copyright (C) 2012 SonarSource
 * [email protected]
 *
 * 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  02
 */
package org.sonar.java.checks;

import com.google.common.collect.ImmutableList;
import org.sonar.api.server.rule.RulesDefinition;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.IdentifierTree;
import org.sonar.plugins.java.api.tree.MemberSelectExpressionTree;
import org.sonar.plugins.java.api.tree.MethodTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.VariableTree;
import org.sonar.squidbridge.annotations.ActivatedByDefault;
import org.sonar.squidbridge.annotations.SqaleConstantRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;

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

@Rule(
  key = "S1201",
  name = "Methods named \"equals\" should override Object.equals(Object)",
  tags = {"pitfall"},
  priority = Priority.CRITICAL)
@ActivatedByDefault
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.ARCHITECTURE_RELIABILITY)
@SqaleConstantRemediation("10min")
public class MethodNamedEqualsCheck extends SubscriptionBaseVisitor {

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

  @Override
  public void visitNode(Tree tree) {
    MethodTree methodTree = (MethodTree) tree;
    if ("equals".equalsIgnoreCase(methodTree.simpleName().name()) && !hasSingleObjectParameter(methodTree)) {
      addIssue(tree, "Either override Object.equals(Object), or totally rename the method to prevent any confusion.");
    }
  }

  private boolean hasSingleObjectParameter(MethodTree methodTree) {
    List parameters = methodTree.parameters();
    if (parameters.size() != 1) {
      return false;
    }
    return isObjectType(parameters.get(0));
  }

  private boolean isObjectType(VariableTree variableTree) {
    String type = concatenate((ExpressionTree) variableTree.type());
    return "Object".equals(type)|| "java.lang.Object".equals(type);
  }

  private String concatenate(ExpressionTree tree) {
    Deque pieces = new LinkedList();
    ExpressionTree expr = tree;
    while (expr.is(Tree.Kind.MEMBER_SELECT)) {
      MemberSelectExpressionTree mse = (MemberSelectExpressionTree) expr;
      pieces.push(mse.identifier().name());
      pieces.push(".");
      expr = mse.expression();
    }
    if (expr.is(Tree.Kind.IDENTIFIER)) {
      IdentifierTree idt = (IdentifierTree) expr;
      pieces.push(idt.name());
    }

    StringBuilder sb = new StringBuilder();
    for (String piece: pieces) {
      sb.append(piece);
    }
    return sb.toString();
  }


}