/*
    * 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.commons.util;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.lang.reflect.Array;
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationTargetException;
  import java.security.AccessController;
  import java.security.PrivilegedActionException;
  import java.security.PrivilegedExceptionAction;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  
  import javax.el.ExpressionFactory;
  import javax.faces.FacesException;
  import javax.faces.context.FacesContext;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  
  /**
   * @author Manfred Geiler (latest modification by $Author: lu4242 $)
   * @author Anton Koinov
   * @version $Revision: 1004421 $ $Date: 2010-10-04 15:45:07 -0500 (Mon, 04 Oct 2010) $
   */
  public final class ClassUtils
  {
      //~ Static fields/initializers -----------------------------------------------------------------
  
      private static final Log log                  = LogFactory.getLog(ClassUtils.class);
  
      public static final Class BOOLEAN_ARRAY_CLASS = boolean[].class;
      public static final Class BYTE_ARRAY_CLASS    = byte[].class;
      public static final Class CHAR_ARRAY_CLASS    = char[].class;
      public static final Class SHORT_ARRAY_CLASS   = short[].class;
      public static final Class INT_ARRAY_CLASS     = int[].class;
      public static final Class LONG_ARRAY_CLASS    = long[].class;
      public static final Class FLOAT_ARRAY_CLASS   = float[].class;
      public static final Class DOUBLE_ARRAY_CLASS  = double[].class;
      public static final Class OBJECT_ARRAY_CLASS  = Object[].class;
      public static final Class BOOLEAN_OBJECT_ARRAY_CLASS = Boolean[].class;
      public static final Class BYTE_OBJECT_ARRAY_CLASS = Byte[].class;
      public static final Class CHARACTER_OBJECT_ARRAY_CLASS = Character[].class;
      public static final Class SHORT_OBJECT_ARRAY_CLASS = Short[].class;
      public static final Class INTEGER_OBJECT_ARRAY_CLASS = Integer[].class;
      public static final Class LONG_OBJECT_ARRAY_CLASS = Long[].class;
      public static final Class FLOAT_OBJECT_ARRAY_CLASS = Float[].class;
      public static final Class DOUBLE_OBJECT_ARRAY_CLASS = Double[].class;
      public static final Class STRING_OBJECT_ARRAY_CLASS = String[].class;
  
      public static final Map COMMON_TYPES = new HashMap(64);
      static
      {
          COMMON_TYPES.put("byte", Byte.TYPE);
          COMMON_TYPES.put("char", Character.TYPE);
          COMMON_TYPES.put("double", Double.TYPE);
          COMMON_TYPES.put("float", Float.TYPE);
          COMMON_TYPES.put("int", Integer.TYPE);
          COMMON_TYPES.put("long", Long.TYPE);
          COMMON_TYPES.put("short", Short.TYPE);
          COMMON_TYPES.put("boolean", Boolean.TYPE);
          COMMON_TYPES.put("void", Void.TYPE);
          COMMON_TYPES.put("java.lang.Object", Object.class);
          COMMON_TYPES.put("java.lang.Boolean", Boolean.class);
          COMMON_TYPES.put("java.lang.Byte", Byte.class);
          COMMON_TYPES.put("java.lang.Character", Character.class);
          COMMON_TYPES.put("java.lang.Short", Short.class);
          COMMON_TYPES.put("java.lang.Integer", Integer.class);
          COMMON_TYPES.put("java.lang.Long", Long.class);
          COMMON_TYPES.put("java.lang.Float", Float.class);
          COMMON_TYPES.put("java.lang.Double", Double.class);
          COMMON_TYPES.put("java.lang.String", String.class);
  
          COMMON_TYPES.put("byte[]", BYTE_ARRAY_CLASS);
          COMMON_TYPES.put("char[]", CHAR_ARRAY_CLASS);
         COMMON_TYPES.put("double[]", DOUBLE_ARRAY_CLASS);
         COMMON_TYPES.put("float[]", FLOAT_ARRAY_CLASS);
         COMMON_TYPES.put("int[]", INT_ARRAY_CLASS);
         COMMON_TYPES.put("long[]", LONG_ARRAY_CLASS);
         COMMON_TYPES.put("short[]", SHORT_ARRAY_CLASS);
         COMMON_TYPES.put("boolean[]", BOOLEAN_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Object[]", OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Boolean[]", BOOLEAN_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Byte[]", BYTE_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Character[]", CHARACTER_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Short[]", SHORT_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Integer[]", INTEGER_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Long[]", LONG_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Float[]", FLOAT_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.Double[]", DOUBLE_OBJECT_ARRAY_CLASS);
         COMMON_TYPES.put("java.lang.String[]", STRING_OBJECT_ARRAY_CLASS);
         // array of void is not a valid type
     }
 
     /** utility class, do not instantiate */
     private ClassUtils()
     {
         // utility class, disable instantiation
     }
 
     //~ Methods ------------------------------------------------------------------------------------
 
     /**
      * Tries a Class.loadClass with the context class loader of the current thread first and
      * automatically falls back to the ClassUtils class loader (i.e. the loader of the
      * myfaces.jar lib) if necessary.
      *
      * @param type fully qualified name of a non-primitive non-array class
      * @return the corresponding Class
      * @throws NullPointerException if type is null
      * @throws ClassNotFoundException
      */
     public static Class classForName(String type)
         throws ClassNotFoundException
     {
         if (type == null) throw new NullPointerException("type");
         try
         {
             // Try WebApp ClassLoader first
             return Class.forName(type,
                                  false, // do not initialize for faster startup
                                  getContextClassLoader());
         }
         catch (ClassNotFoundException ignore)
         {
             // fallback: Try ClassLoader for ClassUtils (i.e. the myfaces.jar lib)
             return Class.forName(type,
                                  false, // do not initialize for faster startup
                                  ClassUtils.class.getClassLoader());
         }
     }
 
 
     /**
      * Same as {@link #classForName(String)}, but throws a RuntimeException
      * (FacesException) instead of a ClassNotFoundException.
      *
      * @return the corresponding Class
      * @throws NullPointerException if type is null
      * @throws FacesException if class not found
      */
     public static Class simpleClassForName(String type)
     {
         try
         {
             return classForName(type);
         }
         catch (ClassNotFoundException e)
         {
             log.error("Class " + type + " not found", e);
             throw new FacesException(e);
         }
     }
 
 
     /**
      * Similar as {@link #classForName(String)}, but also supports primitive types
      * and arrays as specified for the JavaType element in the JavaServer Faces Config DTD.
      *
      * @param type fully qualified class name or name of a primitive type, both optionally
      *             followed by "[]" to indicate an array type
      * @return the corresponding Class
      * @throws NullPointerException if type is null
      * @throws ClassNotFoundException
      */
     public static Class javaTypeToClass(String type)
         throws ClassNotFoundException
     {
         if (type == null) throw new NullPointerException("type");
 
         // try common types and arrays of common types first
         Class clazz = (Class) COMMON_TYPES.get(type);
         if (clazz != null)
         {
             return clazz;
         }
 
         int len = type.length();
         if (len > 2 && type.charAt(len - 1) == ']' && type.charAt(len - 2) == '[')
         {
             String componentType = type.substring(0, len - 2);
             Class componentTypeClass = classForName(componentType);
             return Array.newInstance(componentTypeClass, 0).getClass();
         }
 
         return classForName(type);
         
     }
 
 
     /**
      * Same as {@link #javaTypeToClass(String)}, but throws a RuntimeException
      * (FacesException) instead of a ClassNotFoundException.
      *
      * @return the corresponding Class
      * @throws NullPointerException if type is null
      * @throws FacesException if class not found
      */
     public static Class simpleJavaTypeToClass(String type)
     {
         try
         {
             return javaTypeToClass(type);
         }
         catch (ClassNotFoundException e)
         {
             log.error("Class " + type + " not found", e);
             throw new FacesException(e);
         }
     }
 
     public static InputStream getResourceAsStream(String resource)
     {
         InputStream stream = getContextClassLoader()
                                 .getResourceAsStream(resource);
         if (stream == null)
         {
             // fallback
             stream = ClassUtils.class.getClassLoader().getResourceAsStream(resource);
         }
         return stream;
     }
 
     /**
      * @param resource       Name of resource(s) to find in classpath
      * @param defaultObject  The default object to use to determine the class loader (if none associated with current thread.)
      * @return Iterator over URL Objects
      */
     public static Iterator getResources(String resource, Object defaultObject)
     {
         try
         {
             Enumeration resources = getCurrentLoader(defaultObject).getResources(resource);
             List lst = new ArrayList();
             while (resources.hasMoreElements())
             {
                 lst.add(resources.nextElement());
             }
             return lst.iterator();
         }
         catch (IOException e)
         {
             log.error(e.getMessage(), e);
             throw new FacesException(e);
         }
     }
 
 
     public static Object newInstance(String type)
         throws FacesException
     {
         if (type == null) return null;
         return newInstance(simpleClassForName(type));
     }
 
     public static Object newInstance(String type, Class expectedType) throws FacesException
     {
         return newInstance(type, expectedType == null ? null : new Class[] {expectedType});
     }
 
     public static Object newInstance(String type, Class[] expectedTypes)
     {
         if (type == null)
             return null;        
         
         Class clazzForName = simpleClassForName(type);
         
         if(expectedTypes != null)
         {
             for (int i = 0, size = expectedTypes.length; i < size; i++)
             {
                 if (!expectedTypes[i].isAssignableFrom(clazzForName))
                 {
                     throw new FacesException("'" + type + "' does not implement expected type '" + expectedTypes[i]
                             + "'");
                 }
             }
         }
         
         return newInstance(clazzForName);
     }
 
     public static Object newInstance(Class clazz)
         throws FacesException
     {
         try
         {
             return clazz.newInstance();
         }
         catch(NoClassDefFoundError e)
         {
             log.error("Class : "+clazz.getName()+" not found.",e);
             throw new FacesException(e);
         }
         catch (InstantiationException e)
         {
             log.error(e.getMessage(), e);
             throw new FacesException(e);
         }
         catch (IllegalAccessException e)
         {
             log.error(e.getMessage(), e);
             throw new FacesException(e);
         }
     }
 
     public static Object convertToType(Object value, Class desiredClass)
     {
         if (value == null) return null;
 
         try
         {
             ExpressionFactory expFactory = FacesContext.getCurrentInstance().getApplication().getExpressionFactory();
             return expFactory.coerceToType(value, desiredClass);
         }
         catch (Exception e)
         {
             String message = "Cannot coerce " + value.getClass().getName()
                              + " to " + desiredClass.getName();
             log.error(message, e);
             throw new FacesException(message, e);
         }
     }
 
     /**
      * Gets the ClassLoader associated with the current thread.  Returns the class loader associated with
      * the specified default object if no context loader is associated with the current thread.
      *
      * @param defaultObject The default object to use to determine the class loader (if none associated with current thread.)
      * @return ClassLoader
      */
     protected static ClassLoader getCurrentLoader(Object defaultObject)
     {
         ClassLoader loader = getContextClassLoader();
         if(loader == null)
         {
             loader = defaultObject.getClass().getClassLoader();
         }
         return loader;
     }
     
     /**
      * Gets the ClassLoader associated with the current thread.  Includes a check for priviledges 
      * against java2 security to ensure no security related exceptions are encountered. 
      *
      * @since 1.0.1
      * @return ClassLoader
      */
     public static ClassLoader getContextClassLoader()
     {
         if (System.getSecurityManager() != null) 
         {
             try {
                 ClassLoader cl = AccessController.doPrivileged(new PrivilegedExceptionAction<ClassLoader>()
                         {
                             public ClassLoader run() throws PrivilegedActionException
                             {
                                 return Thread.currentThread().getContextClassLoader();
                             }
                         });
                 return cl;
             }
             catch (PrivilegedActionException pae)
             {
                 throw new FacesException(pae);
             }
         }
         else
         {
             return Thread.currentThread().getContextClassLoader();
         }
     }
     
     /**
      * Creates ApplicationObjects like NavigationHandler or StateManager and creates 
      * the right wrapping chain of the ApplicationObjects known as the decorator pattern. 
      * @param <T>
      * @param interfaceClass The class from which the implementation has to inherit from.
      * @param classNamesIterator All the class names of the actual ApplicationObject implementations
      *                           from the faces-config.xml.
      * @param defaultObject The default implementation for the given ApplicationObject.
      * @return
      * @since 1.0.1
      */    
     public static <T> T buildApplicationObject(Class<T> interfaceClass, Collection<String> classNamesIterator, T defaultObject)
     {
         return buildApplicationObject(interfaceClass, null, null, classNamesIterator, defaultObject);
     }
 
     /**
      * Creates ApplicationObjects like NavigationHandler or StateManager and creates 
      * the right wrapping chain of the ApplicationObjects known as the decorator pattern. 
      * @param <T>
      * @param interfaceClass The class from which the implementation has to inherit from.
      * @param extendedInterfaceClass A subclass of interfaceClass which specifies a more
      *                               detailed implementation.
      * @param extendedInterfaceWrapperClass A wrapper class for the case that you have an ApplicationObject
      *                                      which only implements the interfaceClass but not the 
      *                                      extendedInterfaceClass.
      * @param classNamesIterator All the class names of the actual ApplicationObject implementations
      *                           from the faces-config.xml.
      * @param defaultObject The default implementation for the given ApplicationObject.
      * @return
      * @since 1.0.1
      */
     @SuppressWarnings("unchecked")
     public static <T> T buildApplicationObject(Class<T> interfaceClass, Class<? extends T> extendedInterfaceClass,
             Class<? extends T> extendedInterfaceWrapperClass,
             Collection<String> classNamesIterator, T defaultObject)
     {
         T current = defaultObject;
         
 
         for (String implClassName : classNamesIterator)
         {
             Class<? extends T> implClass = ClassUtils.simpleClassForName(implClassName);
 
             // check, if class is of expected interface type
             if (!interfaceClass.isAssignableFrom(implClass))
             {
                 throw new IllegalArgumentException("Class " + implClassName + " is no " + interfaceClass.getName());
             }
 
             if (current == null)
             {
                 // nothing to decorate
                 current = (T) ClassUtils.newInstance(implClass);
             }
             else
             {
                 // let's check if class supports the decorator pattern
                 T newCurrent = null;
                 try
                 {
                     Constructor<? extends T> delegationConstructor = null;
                     
                     // first, if there is a extendedInterfaceClass,
                     // try to find a constructor that uses that
                     if (extendedInterfaceClass != null 
                             && extendedInterfaceClass.isAssignableFrom(current.getClass()))
                     {
                         try
                         {
                             delegationConstructor = 
                                     implClass.getConstructor(new Class[] {extendedInterfaceClass});
                         }
                         catch (NoSuchMethodException mnfe)
                         {
                             // just eat it
                         }
                     }
                     if (delegationConstructor == null)
                     {
                         // try to find the constructor with the "normal" interfaceClass
                         delegationConstructor = 
                                 implClass.getConstructor(new Class[] {interfaceClass});
                     }
                     // impl class supports decorator pattern at this point
                     try
                     {
                         // create new decorator wrapping current
                         newCurrent = delegationConstructor.newInstance(new Object[] { current });
                     }
                     catch (InstantiationException e)
                     {
                         log.error(e.getMessage(), e);
                         throw new FacesException(e);
                     }
                     catch (IllegalAccessException e)
                     {
                         log.error(e.getMessage(), e);
                         throw new FacesException(e);
                     }
                     catch (InvocationTargetException e)
                     {
                         log.error(e.getMessage(), e);
                         throw new FacesException(e);
                     }
                 }
                 catch (NoSuchMethodException e)
                 {
                     // no decorator pattern support
                     newCurrent = (T) ClassUtils.newInstance(implClass);
                 }
                 
                 // now we have a new current object (newCurrent)
                 // --> find out if it is assignable from extendedInterfaceClass
                 // and if not, wrap it in a backwards compatible wrapper (if available)
                 if (extendedInterfaceWrapperClass != null
                         && !extendedInterfaceClass.isAssignableFrom(newCurrent.getClass()))
                 {
                     try
                     {
                         Constructor<? extends T> wrapperConstructor
                                 = extendedInterfaceWrapperClass.getConstructor(
                                         new Class[] {interfaceClass, extendedInterfaceClass});
                         newCurrent = wrapperConstructor.newInstance(new Object[] {newCurrent, current});
                     }
                     catch (NoSuchMethodException e)
                     {
                         log.error(e.getMessage(), e);
                         throw new FacesException(e);
                     }
                     catch (InstantiationException e)
                     {
                         log.error(e.getMessage(), e);
                         throw new FacesException(e);
                     }
                     catch (IllegalAccessException e)
                     {
                         log.error(e.getMessage(), e);
                         throw new FacesException(e);
                     }
                     catch (InvocationTargetException e)
                     {
                         log.error(e.getMessage(), e);
                         throw new FacesException(e);
                     }
                 }
                 
                 current = newCurrent;
             }
         }
 
         return current;
     }
 }