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/*
 * SonarQube JavaScript Plugin
 * Copyright (C) 2011 SonarSource and Eriks Nukis
 * [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.javascript.checks;

import org.sonar.api.server.rule.RulesDefinition;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.javascript.ast.resolve.Scope;
import org.sonar.javascript.ast.resolve.Symbol;
import org.sonar.javascript.ast.resolve.SymbolModel;
import org.sonar.javascript.ast.visitors.BaseTreeVisitor;
import org.sonar.javascript.model.implementations.JavaScriptTree;
import org.sonar.javascript.model.interfaces.Tree;
import org.sonar.javascript.model.interfaces.declaration.ScriptTree;
import org.sonar.squidbridge.annotations.ActivatedByDefault;
import org.sonar.squidbridge.annotations.SqaleConstantRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;

import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;

@Rule(
  key = "UnusedFunctionArgument",
  name = "Unused function parameters should be removed",
  priority = Priority.MAJOR,
  tags = {Tags.MISRA, Tags.UNUSED})
@ActivatedByDefault
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.UNDERSTANDABILITY)
@SqaleConstantRemediation("5min")
public class UnusedFunctionArgumentCheck extends BaseTreeVisitor {
  private static final String MESSAGE = "Remove the unused function parameter%s \"%s\".";

  private class PositionComparator implements Comparator {

    private int getLine(Symbol symbol){
      return ((JavaScriptTree)symbol.getFirstDeclaration().tree()).getLine();
    }

    private int getColumn(Symbol symbol){
      return ((JavaScriptTree)symbol.getFirstDeclaration().tree()).getToken().getColumn();
    }

    @Override
    public int compare(Symbol symbol1, Symbol symbol2) {
      int lineCompare = Integer.compare(getLine(symbol1), getLine(symbol2));
      if (lineCompare == 0) {
        return Integer.compare(getColumn(symbol1), getColumn(symbol2));
      } else {
        return lineCompare;
      }
    }
  }

  @Override
  public void visitScript(ScriptTree tree) {
    SymbolModel symbolModel = getContext().getSymbolModel();
    Collection scopes = symbolModel.getScopes();

    for (Scope scope : scopes){
      visitScope(symbolModel, scope);
    }
  }

  private void visitScope(SymbolModel symbolModel, Scope scope) {
    if (buildInArgumentsUsed(symbolModel, scope) || scope.getTree().is(Tree.Kind.SET_METHOD)){
      return;
    }

    List arguments = scope.getSymbols(Symbol.Kind.PARAMETER);
    List unusedArguments = getUnusedArguments(arguments, symbolModel);

    if (!unusedArguments.isEmpty()) {
      String ending = unusedArguments.size() == 1 ? "" : "s";
      getContext().addIssue(this, scope.getTree(), String.format(MESSAGE, ending, getListOfArguments(unusedArguments)));
    }
  }

  private List getUnusedArguments(List arguments, SymbolModel symbolModel){
    List unusedArguments = new LinkedList<>();
    Collections.sort(arguments, new PositionComparator());
    List usageInfo = getUsageInfo(symbolModel, arguments);
    boolean usedAfter = false;
    for (int i = arguments.size() - 1; i >= 0; i--){
      if (usageInfo.get(i)){
        usedAfter = true;
      } else if (!usedAfter){
        unusedArguments.add(0, arguments.get(i));
      }
    }
    return unusedArguments;
  }

  private boolean buildInArgumentsUsed(SymbolModel symbolModel, Scope scope) {
    Symbol argumentsBuildInVariable = scope.lookupSymbol("arguments");
    if (argumentsBuildInVariable == null){
      return false;
    }
    boolean isUsed = !symbolModel.getUsageFor(argumentsBuildInVariable).isEmpty();
    return argumentsBuildInVariable.buildIn() && isUsed;
  }

  private List getUsageInfo(SymbolModel symbolModel, List symbols) {
    List result = new LinkedList<>();
    for (Symbol symbol : symbols){
      if (symbolModel.getUsageFor(symbol).isEmpty()){
        result.add(false);
      } else {
        result.add(true);
      }
    }
    return result;
  }

  private String getListOfArguments(List unusedArguments) {
    StringBuilder result = new StringBuilder();
    for (Symbol symbol : unusedArguments){
      result.append(symbol.name());
      result.append(", ");
    }
    return result.toString().replaceFirst(", $", "");
  }

}