/*
    * 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.component;
  
  import javax.el.ELContext;
  import javax.el.ELException;
  import javax.el.MethodExpression;
  import javax.el.MethodInfo;
  import javax.el.MethodNotFoundException;
  import javax.el.PropertyNotFoundException;
  import javax.faces.component.StateHolder;
  import javax.faces.context.FacesContext;
  import javax.faces.el.EvaluationException;
  import javax.faces.el.MethodBinding;
  
  import org.apache.myfaces.shared_tomahawk.util.ClassUtils;
  
  /**
   * Converts a MethodBinding to a MethodExpression
   * 
   * TODO: find a way to share the implementation of class with impl.
   * 
   * This class could be moved or changed in the future
   * 
   * @since 1.1.7
   * @author Stan Silvert
   */
  @SuppressWarnings("deprecation")
  public class MethodBindingToMethodExpression extends MethodExpression implements StateHolder
  {
      private static final Class[] EXPECTED_TYPES = new Class[] { MethodBinding.class, StateHolder.class };
  
      private MethodBinding methodBinding;
  
      private boolean _transientFlag;
  
      private transient MethodInfo methodInfo;
  
      /**
       * No-arg constructor used during restoreState
       */
      public MethodBindingToMethodExpression()
      {
      }
  
      /** Creates a new instance of MethodBindingToMethodExpression */
      public MethodBindingToMethodExpression(MethodBinding methodBinding)
      {
          checkNullArgument(methodBinding, "methodBinding");
          this.methodBinding = methodBinding;
      }
  
      /**
       * Return the wrapped MethodBinding.
       */
      public MethodBinding getMethodBinding()
      {
          return methodBinding;
      }
      
      void setMethodBinding(MethodBinding methodBinding)
      {
          this.methodBinding = methodBinding;
      }
  
      /**
       * Note: MethodInfo.getParamTypes() may incorrectly return an empty class array if invoke() has not been called.
       * 
       * @throws IllegalStateException
       *             if expected params types have not been determined.
       */
      public MethodInfo getMethodInfo(ELContext context) throws PropertyNotFoundException, MethodNotFoundException,
              ELException
      {
          checkNullArgument(context, "elcontext");
          checkNullState(methodBinding, "methodBinding");
  
          if (methodInfo == null)
          {
              final FacesContext facesContext = (FacesContext) context.getContext(FacesContext.class);
              if (facesContext != null)
              {
                  methodInfo = invoke(new Invoker<MethodInfo>()
                 {
                     public MethodInfo invoke()
                     {
                         return new MethodInfo(null, methodBinding.getType(facesContext), null);
                     }
                 });
             }
         }
         return methodInfo;
     }
 
     public Object invoke(ELContext context, final Object[] params) throws PropertyNotFoundException,
             MethodNotFoundException, ELException
     {
         checkNullArgument(context, "elcontext");
         checkNullState(methodBinding, "methodBinding");
         final FacesContext facesContext = (FacesContext) context.getContext(FacesContext.class);
         if (facesContext != null)
         {
             return invoke(new Invoker<Object>()
             {
                 public Object invoke()
                 {
                     return methodBinding.invoke(facesContext, params);
                 }
             });
         }
         return null;
     }
 
     public boolean isLiteralText()
     {
         if (methodBinding == null)
             throw new IllegalStateException("methodBinding is null");
         String expr = methodBinding.getExpressionString();
         return !(expr.startsWith("#{") && expr.endsWith("}"));
     }
 
     public String getExpressionString()
     {
         return methodBinding.getExpressionString();
     }
 
     public Object saveState(FacesContext context)
     {
         if (!isTransient())
         {
             if (methodBinding instanceof StateHolder)
             {
                 Object[] state = new Object[2];
                 state[0] = methodBinding.getClass().getName();
                 state[1] = ((StateHolder) methodBinding).saveState(context);
                 return state;
             }
             else
             {
                 return methodBinding;
             }
         }
         return null;
     }
 
     public void restoreState(FacesContext context, Object state)
     {
         if (state instanceof MethodBinding)
         {
             methodBinding = (MethodBinding) state;
             methodInfo = null;
         }
         else if (state != null)
         {
             Object[] values = (Object[]) state;
             methodBinding = (MethodBinding) ClassUtils.newInstance(values[0].toString(), EXPECTED_TYPES);
             ((StateHolder) methodBinding).restoreState(context, values[1]);
             methodInfo = null;
         }
     }
 
     public void setTransient(boolean transientFlag)
     {
         _transientFlag = transientFlag;
     }
 
     public boolean isTransient()
     {
         return _transientFlag;
     }
 
     @Override
     public int hashCode()
     {
         final int PRIME = 31;
         int result = 1;
         result = PRIME * result + ((methodBinding == null) ? 0 : methodBinding.hashCode());
         return result;
     }
 
     @Override
     public boolean equals(Object obj)
     {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
             return false;
         final MethodBindingToMethodExpression other = (MethodBindingToMethodExpression) obj;
         if (methodBinding == null)
         {
             if (other.methodBinding != null)
                 return false;
         }
         else if (!methodBinding.equals(other.methodBinding))
             return false;
         return true;
     }
 
     private void checkNullState(Object notNullInstance, String instanceName)
     {
         if (notNullInstance == null)
             throw new IllegalStateException(instanceName + " is null");
     }
 
     private void checkNullArgument(Object notNullInstance, String instanceName)
     {
         if (notNullInstance == null)
             throw new IllegalArgumentException(instanceName + " is null");
     }
 
     private <T> T invoke(Invoker<T> invoker)
     {
         try
         {
             return invoker.invoke();
         }
         catch (javax.faces.el.MethodNotFoundException e)
         {
             throw new MethodNotFoundException(e.getMessage(), e);
         }
         catch (EvaluationException e)
         {
             throw new ELException(e.getMessage(), e);
         }
     }
 
     private interface Invoker<T>
     {
         T invoke();
     }
 }