/*
    * Copyright 2012-2013 smartics, Kronseder & Reiner GmbH
    *
    * Licensed 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 de.smartics.properties.spi.core.util;
  
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.lang.reflect.Method;
  
  import javax.annotation.CheckForNull;
  
  import org.apache.commons.lang.ObjectUtils;
  
  /**
   * Wrapper to serialize {@link Method}s.
   */
  public final class SerializableMethod implements Serializable
  {
    // ********************************* Fields *********************************
  
    // --- constants ------------------------------------------------------------
  
    /**
     * The class version identifier.
     */
    private static final long serialVersionUID = 1L;
  
    // --- members --------------------------------------------------------------
  
    /**
     * The wrapped method. The method may be <code>null</code>.
     */
    private transient volatile Method method;
  
    /**
     * Default constructor.
     *
     * @param method the wrapped method. The method may be <code>null</code>.
     */
    public SerializableMethod(final Method method)
    {
      this.method = method;
    }
  
    // ****************************** Initializer *******************************
  
    // ****************************** Constructors ******************************
  
    // ****************************** Inner Classes *****************************
  
    // ********************************* Methods ********************************
  
    // --- init -----------------------------------------------------------------
  
    // --- get&set --------------------------------------------------------------
  
    /**
     * Returns the wrapped method.
     *
     * @return the wrapped method. The method may be <code>null</code>.
     */
    @CheckForNull
    public Method getMethod()
    {
      return method;
    }
  
    // --- business -------------------------------------------------------------
  
    // --- object basics --------------------------------------------------------
  
    /**
     * Method to write the object to the stream.
     *
     * @param out the stream to write to.
     * @throws IOException on any write problem.
     */
    private void writeObject(final ObjectOutputStream out) throws IOException
    {
      out.defaultWriteObject();
  
      if (method != null)
      {
        final Class<?> declaringType = method.getDeclaringClass();
        final String methodName = method.getName();
       final Class<?>[] parameterTypes = method.getParameterTypes();
 
       out.writeObject(declaringType);
       out.writeObject(methodName);
       out.writeObject(parameterTypes);
     }
     else
     {
       out.writeObject(null);
     }
   }
 
   /**
    * Reads the object from the given stream.
    *
    * @param in the stream to read from.
    * @throws IOException on read problems.
    * @throws ClassNotFoundException if a class cannot be found.
    */
   private void readObject(final ObjectInputStream in) throws IOException,
     ClassNotFoundException
   {
     in.defaultReadObject();
 
     final Class<?> declaringType = (Class<?>) in.readObject();
     if (declaringType != null)
     {
       final String methodName = (String) in.readObject();
       final Class<?>[] parameterTypes = (Class<?>[]) in.readObject();
 
       try
       {
         this.method =
             declaringType.getDeclaredMethod(methodName, parameterTypes);
       }
       catch (final Exception e)
       {
         final String message =
             message(declaringType, methodName, parameterTypes);
         throw new IOException(message, e);
       }
     }
     else
     {
       method = null;
     }
   }
 
   private static String message(final Class<?> declaringType,
       final String methodName, final Class<?>[] parameterTypes)
   {
     final StringBuilder buffer = new StringBuilder(256);
 
     buffer.append("Cannot recreate method ").append(declaringType.getName())
         .append('.').append(methodName).append('(');
     int counter = parameterTypes.length;
     for (final Class<?> parameterType : parameterTypes)
     {
       buffer.append(parameterType.getName());
 
       if (--counter > 0)
       {
         buffer.append(", ");
       }
     }
     buffer.append(").");
 
     return buffer.toString();
   }
 
   @Override
   public String toString()
   {
     return ObjectUtils.toString(method, null);
   }
 }