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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.check.Priority;
import org.sonar.check.Rule;
import org.sonar.check.RuleProperty;
import org.sonar.javascript.checks.utils.SubscriptionBaseVisitor;
import org.sonar.javascript.model.interfaces.Tree;
import org.sonar.javascript.model.interfaces.Tree.Kind;
import org.sonar.squidbridge.annotations.ActivatedByDefault;
import org.sonar.squidbridge.annotations.NoSqale;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;

import java.util.List;

@Rule(
  key = "S1067",
  name = "Expressions should not be too complex",
  priority = Priority.MAJOR,
  tags = {Tags.BRAIN_OVERLOAD})
@ActivatedByDefault
@NoSqale
public class ExpressionComplexityCheck extends SubscriptionBaseVisitor {

  private static final int DEFAULT = 3;

  @RuleProperty(defaultValue = "" + DEFAULT, description = "Maximum number of allowed conditional operators in an expression")
  public int max = DEFAULT;

  private List statementLevel = Lists.newArrayList();
  private static final Kind[] SCOPES = {
    Kind.FUNCTION_EXPRESSION,
    Kind.GENERATOR_FUNCTION_EXPRESSION
  };

  private static final Kind[] CONDITIONAL_EXPRS = {
    Kind.CONDITIONAL_EXPRESSION,
    Kind.CONDITIONAL_AND,
    Kind.CONDITIONAL_OR
  };

  @Override
  public List nodesToVisit() {
    return ImmutableList.builder()
      .add(CONDITIONAL_EXPRS)
      .add(SCOPES).build();
  }

  public static class ExpressionComplexity {
    private int nestedLevel = 0;
    private int counterOperator = 0;

    public void increaseOperatorCounter(int nbOperator) {
      counterOperator += nbOperator;
    }

    public void incrementNestedExprLevel() {
      nestedLevel++;
    }

    public void decrementNestedExprLevel() {
      nestedLevel--;
    }

    public boolean isOnFirstExprLevel() {
      return nestedLevel == 0;
    }

    public int getExprNumberOfOperator() {
      return counterOperator;
    }

    public void resetExprOperatorCounter() {
      counterOperator = 0;
    }
  }

  @Override
  public void visitFile(Tree scriptTree) {
    statementLevel.clear();
    statementLevel.add(new ExpressionComplexity());
  }

  @Override
  public void visitNode(Tree tree) {
    if (tree.is(CONDITIONAL_EXPRS)) {
      Iterables.getLast(statementLevel).incrementNestedExprLevel();
      Iterables.getLast(statementLevel).increaseOperatorCounter(1);

    } else if (tree.is(SCOPES)) {
      statementLevel.add(new ExpressionComplexity());
    }
  }

  @Override
  public void leaveNode(Tree tree) {
    if (tree.is(CONDITIONAL_EXPRS)) {
      ExpressionComplexity currentExpression = Iterables.getLast(statementLevel);
      currentExpression.decrementNestedExprLevel();

      if (currentExpression.isOnFirstExprLevel()) {
        if (currentExpression.getExprNumberOfOperator() > max) {
          addIssue(
            tree,
            "Reduce the number of conditional operators (" + currentExpression.getExprNumberOfOperator() + ") used in the expression (maximum allowed " + max + ").");
        }
        currentExpression.resetExprOperatorCounter();
      }

    } else if (tree.is(SCOPES)) {
      statementLevel.remove(statementLevel.size() - 1);
    }
  }

}