/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.apache.myfaces.view.facelets.el;
  
  import java.io.Externalizable;
  import java.io.IOException;
  import java.io.ObjectInput;
  import java.io.ObjectOutput;
  
  import javax.el.ELContext;
  import javax.el.MethodExpression;
  import javax.el.MethodInfo;
  import javax.el.ValueExpression;
  import javax.faces.FacesWrapper;
  import javax.faces.context.FacesContext;
  
  /**
   * This MethodExpression contains a ValueExpression which resolves to 
   * the "real" MethodExpression that should be invoked. This is needed 
   * when the MethodExpression is on the parent composite component attribute map.
   * See FaceletViewDeclarationLanguage.retargetMethodExpressions() for details.
   * 
   * @author Jakob Korherr (latest modification by $Author$)
   * @version $Revision$ $Date$
   */
  public class ValueExpressionMethodExpression extends MethodExpression 
      implements FacesWrapper<ValueExpression>, Externalizable
  {
      
      private static final long serialVersionUID = -2847633717581167765L;
      
      private ValueExpression valueExpression;
      
      public ValueExpressionMethodExpression()
      {
      }
      
      public ValueExpressionMethodExpression(ValueExpression valueExpression)
      {
          this.valueExpression = valueExpression;   
      }
  
      @Override
      public MethodInfo getMethodInfo(ELContext context)
      {
          MethodExpression me = getMethodExpression(context);
          if (me != null)
          {
              return me.getMethodInfo(context);
          }
          return null;
      }
  
      @Override
      public Object invoke(ELContext context, Object[] params)
      {
          MethodExpression me = getMethodExpression(context);
          if (me != null)
          {        
              return me.invoke(context, params);
          }
          return null;
      }
  
      @Override
      public boolean equals(Object obj)
      {
          MethodExpression me = getMethodExpression();
          if (me != null)
          {        
              return me.equals(obj);
          }
          if (!(obj instanceof ValueExpressionMethodExpression))
          {
              return false;
          }
          ValueExpressionMethodExpression other = (ValueExpressionMethodExpression) obj;
          if ((this.valueExpression == null && other.valueExpression != null) || 
               (this.valueExpression != null && !this.valueExpression.equals(other.valueExpression)))
          {
              return false;
          }
          return true;
     }
 
     @Override
     public String getExpressionString()
     {
         //getMethodExpression().getExpressionString()
         return valueExpression.getExpressionString();
     }
 
     @Override
     public int hashCode()
     {
         MethodExpression me = getMethodExpression();
         if (me != null)
         {        
             return me.hashCode();
         }
         return valueExpression.hashCode();
     }
 
     @Override
     public boolean isLiteralText()
     {
         MethodExpression me = getMethodExpression();
         if (me != null)
         {
             return me.isLiteralText();
         }
         return valueExpression.isLiteralText();
     }
     
     private MethodExpression getMethodExpression()
     {
         return getMethodExpression(FacesContext.getCurrentInstance().getELContext());
     }
     
     private MethodExpression getMethodExpression(ELContext context)
     {
         Object meOrVe = valueExpression.getValue(context);
         if (meOrVe instanceof MethodExpression)
         {
             return (MethodExpression) meOrVe;
         }
         else if (meOrVe instanceof ValueExpression)
         {
             while (meOrVe != null && meOrVe instanceof ValueExpression)
             {
                 meOrVe = ((ValueExpression)meOrVe).getValue(context);
             }
             return (MethodExpression) meOrVe;
         }
         else
         {
             return null;
         }
     }
 
     public ValueExpression getWrapped()
     {
         return valueExpression;
     }
     public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
     {
         this.valueExpression = (ValueExpression) in.readObject();
     }
 
     public void writeExternal(ObjectOutput out) throws IOException
     {
         out.writeObject(this.valueExpression);
     }
 }