/*
    * $Header$
    * $Revision$
    * $Date$
    *
    * ====================================================================
    *
    * Copyright 2000-2002 bob mcwhirter & James Strachan.
    * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are
   * met:
   * 
   *   * Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   * 
   *   * Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   * 
   *   * Neither the name of the Jaxen Project nor the names of its
   *     contributors may be used to endorse or promote products derived 
   *     from this software without specific prior written permission.
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
   * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
   * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * ====================================================================
   * This software consists of voluntary contributions made by many 
   * individuals on behalf of the Jaxen Project and was originally 
   * created by bob mcwhirter <bob@werken.com> and 
   * James Strachan <jstrachan@apache.org>.  For more information on the 
   * Jaxen Project, please see <http://www.jaxen.org/>.
   * 
   * $Id$
   */
  
  
  
  package org.jaxen.expr;
  
  import java.util.Iterator;
  import java.util.List;
  import org.jaxen.Context;
  import org.jaxen.JaxenException;
  import org.jaxen.Navigator;
  import org.jaxen.function.NumberFunction;
  
  abstract class DefaultRelationalExpr extends DefaultTruthExpr implements RelationalExpr 
    {
    DefaultRelationalExpr( Expr lhs, Expr rhs )
      {
      super( lhs, rhs );
      }
    
    @Override
    public String toString()
      {
      return "[(DefaultRelationalExpr): " + getLHS() + ", " + getRHS() + "]";
      }
  
    public Object evaluate( Context context ) throws JaxenException
      {
      Object lhsValue = getLHS().evaluate( context );
      Object rhsValue = getRHS().evaluate( context );
      Navigator nav = context.getNavigator();
  
      if( bothAreSets( lhsValue, rhsValue ) )
        {
        return evaluateSetSet( (List) lhsValue, (List) rhsValue, nav );
        }
      
      if (isBoolean(rhsValue) && isSet(lhsValue)) {
          List left = convertToList( lhsValue );
          if (left.isEmpty()) {
              return evaluateObjectObject(rhsValue, Boolean.FALSE, nav) ? Boolean.TRUE : Boolean.FALSE;
          }
          else {
              return evaluateObjectObject(rhsValue, Boolean.TRUE, nav) ? Boolean.TRUE : Boolean.FALSE;
          }
      }
      else if (isBoolean(lhsValue) && isSet(rhsValue)) {
          List right = convertToList( rhsValue );
          if (right.isEmpty()) {
              return evaluateObjectObject(lhsValue, Boolean.FALSE, nav) ? Boolean.TRUE : Boolean.FALSE;
          }
          else {
              return evaluateObjectObject(lhsValue, Boolean.TRUE, nav) ? Boolean.TRUE : Boolean.FALSE;
          }
     }
     
 
     if( eitherIsSet( lhsValue, rhsValue ) )
       {
       if( isSet( lhsValue ) )
         {        
         return evaluateSetSet( (List) lhsValue, convertToList( rhsValue ), nav );              
         }
       else
         {
         return evaluateSetSet( convertToList( lhsValue ), (List) rhsValue, nav );              
         }
       }
     
     return evaluateObjectObject( lhsValue, rhsValue, nav ) ? Boolean.TRUE : Boolean.FALSE;
     }
 
   private Object evaluateSetSet( List lhsSet, List rhsSet, Navigator nav )
     {
     if( setIsEmpty( lhsSet ) || setIsEmpty( rhsSet ) ) // return false if either is null or empty
       {
       return Boolean.FALSE;
       }    
     
     for( Iterator lhsIterator = lhsSet.iterator(); lhsIterator.hasNext(); )
       {
       Object lhs = lhsIterator.next();        
       
       for( Iterator rhsIterator = rhsSet.iterator(); rhsIterator.hasNext(); )
         {
         Object rhs = rhsIterator.next();
         
         if( evaluateObjectObject( lhs, rhs, nav ) )
           {
           return Boolean.TRUE;
           }
         }
       }      
     
     return Boolean.FALSE;
     }
   
   private boolean evaluateObjectObject( Object lhs, Object rhs, Navigator nav )
     {
     if( lhs == null || rhs == null )
       {
       return false;
       }
     
     Double lhsNum = NumberFunction.evaluate( lhs, nav );
     Double rhsNum = NumberFunction.evaluate( rhs, nav );      
     
     if( NumberFunction.isNaN( lhsNum ) || NumberFunction.isNaN( rhsNum ) )
       {
       return false;
       }
     
     return evaluateDoubleDouble( lhsNum, rhsNum );
     }
   
   protected abstract boolean evaluateDoubleDouble( Double lhs, Double rhs );    
   }