////////////////////////////////////////////////////////////////////////////////
   // checkstyle: Checks Java source code for adherence to a set of rules.
   // Copyright (C) 2001-2015 the original author or authors.
   //
   // This library 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 2.1 of the License, or (at your option) any later version.
   //
  // This library 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 library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ////////////////////////////////////////////////////////////////////////////////
  package com.puppycrawl.tools.checkstyle.checks.metrics;
  
  import java.math.BigInteger;
  
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  
  /**
   * Checks the npath complexity against a specified limit (default = 200).
   * The npath metric computes the number of possible execution paths
   * through a function. Similar to the cyclomatic complexity but also
   * takes into account the nesting of conditional statements and
   * multi-part boolean expressions.
   *
   * @author <a href="mailto:simon@redhillconsulting.com.au">Simon Harris</a>
   * @author o_sukhodolsky
   * TODO: For every or: _value += (_orCount * (nestedValue - 1));
   * TODO: For every and: ???
   */
  public final class NPathComplexityCheck extends AbstractComplexityCheck
  {
  
      /**
       * A key is pointing to the warning message text in "messages.properties"
       * file.
       */
      public static final String MSG_KEY = "npathComplexity";
  
      /** Default allowed complexity. */
      private static final int DEFAULT_MAX = 200;
  
      /** Creates new instance of the check. */
      public NPathComplexityCheck()
      {
          super(DEFAULT_MAX);
      }
  
      @Override
      public int[] getDefaultTokens()
      {
          return new int[] {
              TokenTypes.CTOR_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.STATIC_INIT,
              TokenTypes.INSTANCE_INIT,
              TokenTypes.LITERAL_WHILE,
              TokenTypes.LITERAL_DO,
              TokenTypes.LITERAL_FOR,
              TokenTypes.LITERAL_IF,
              TokenTypes.LITERAL_ELSE,
              TokenTypes.LITERAL_SWITCH,
              TokenTypes.LITERAL_CASE,
              TokenTypes.LITERAL_TRY,
              TokenTypes.LITERAL_CATCH,
              TokenTypes.QUESTION,
          };
      }
  
      @Override
      public int[] getAcceptableTokens()
      {
          return new int[] {
              TokenTypes.CTOR_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.STATIC_INIT,
              TokenTypes.INSTANCE_INIT,
              TokenTypes.LITERAL_WHILE,
              TokenTypes.LITERAL_DO,
              TokenTypes.LITERAL_FOR,
              TokenTypes.LITERAL_IF,
              TokenTypes.LITERAL_ELSE,
              TokenTypes.LITERAL_SWITCH,
              TokenTypes.LITERAL_CASE,
              TokenTypes.LITERAL_TRY,
              TokenTypes.LITERAL_CATCH,
              TokenTypes.QUESTION,
          };
      }
  
      @Override
      public void visitToken(DetailAST ast)
     {
         switch (ast.getType()) {
             case TokenTypes.LITERAL_WHILE:
             case TokenTypes.LITERAL_DO:
             case TokenTypes.LITERAL_FOR:
             case TokenTypes.LITERAL_IF:
             case TokenTypes.QUESTION:
             case TokenTypes.LITERAL_TRY:
             case TokenTypes.LITERAL_SWITCH:
                 visitMultiplyingConditional();
                 break;
             case TokenTypes.LITERAL_ELSE:
             case TokenTypes.LITERAL_CATCH:
             case TokenTypes.LITERAL_CASE:
                 visitAddingConditional();
                 break;
             default:
                 super.visitToken(ast);
         }
     }
 
     @Override
     public void leaveToken(DetailAST ast)
     {
         switch (ast.getType()) {
             case TokenTypes.LITERAL_WHILE:
             case TokenTypes.LITERAL_DO:
             case TokenTypes.LITERAL_FOR:
             case TokenTypes.LITERAL_IF:
             case TokenTypes.QUESTION:
             case TokenTypes.LITERAL_TRY:
             case TokenTypes.LITERAL_SWITCH:
                 leaveMultiplyingConditional();
                 break;
             case TokenTypes.LITERAL_ELSE:
             case TokenTypes.LITERAL_CATCH:
             case TokenTypes.LITERAL_CASE:
                 leaveAddingConditional();
                 break;
             default:
                 super.leaveToken(ast);
         }
     }
 
     @Override
     protected String getMessageID()
     {
         return MSG_KEY;
     }
 
     /** Visits else, catch or case. */
     private void visitAddingConditional()
     {
         pushValue();
     }
 
     /** Leaves else, catch or case. */
     private void leaveAddingConditional()
     {
         setCurrentValue(
                 getCurrentValue().subtract(BigInteger.ONE).add(popValue()));
     }
 
     /** Visits while, do, for, if, try, ? (in ?::) or switch. */
     private void visitMultiplyingConditional()
     {
         pushValue();
     }
 
     /** Leaves while, do, for, if, try, ? (in ?::) or switch. */
     private void leaveMultiplyingConditional()
     {
         setCurrentValue(
                 getCurrentValue().add(BigInteger.ONE).multiply(popValue()));
     }
 }