/*

  * 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.commons.configuration;

 import java.util.ArrayList;

 import java.util.HashSet;

 import java.util.Iterator;

 import java.util.List;

 import java.util.Set;

 import javax.naming.Context;

 import javax.naming.InitialContext;

 import javax.naming.NameClassPair;

 import javax.naming.NameNotFoundException;

 import javax.naming.NamingEnumeration;

 import javax.naming.NamingException;

 import org.apache.commons.lang.StringUtils;

 import org.apache.commons.logging.Log;

 import org.apache.commons.logging.LogFactory;

 /**

  * This Configuration class allows you to interface with a JNDI datasource.

  * A JNDIConfiguration is read-only, write operations will throw an

  * UnsupportedOperationException. The clear operations are supported but the

  * underlying JNDI data source is not changed.

  *

  * @author <a href="mailto:epugh@upstate.com">Eric Pugh</a>

  * @version $Id: JNDIConfiguration.java 439648 2006-09-02 20:42:10Z oheger $

  */

 public class JNDIConfiguration extends AbstractConfiguration

 {

     /** Logger. */

     private static Log log = LogFactory.getLog(JNDIConfiguration.class);

     /** The prefix of the context. */

     private String prefix;

     /** The initial JNDI context. */

     private Context context;

     /** The base JNDI context. */

     private Context baseContext;

     /** The Set of keys that have been virtually cleared. */

     private Set clearedProperties = new HashSet();

     /**

      * Creates a JNDIConfiguration using the default initial context as the

      * root of the properties.

      *

      * @throws NamingException thrown if an error occurs when initializing the default context

      */

     public JNDIConfiguration() throws NamingException

     {

         this((String) null);

     }

     /**

      * Creates a JNDIConfiguration using the default initial context, shifted

      * with the specified prefix, as the root of the properties.

      *

      * @param prefix the prefix

      *

      * @throws NamingException thrown if an error occurs when initializing the default context

      */

     public JNDIConfiguration(String prefix) throws NamingException

     {

         this(new InitialContext(), prefix);

     }

     /**

      * Creates a JNDIConfiguration using the specified initial context as the

      * root of the properties.

      *

      * @param context the initial context

      */

     public JNDIConfiguration(Context context)

     {

         this(context, null);

     }

     /**

      * Creates a JNDIConfiguration using the specified initial context shifted

      * by the specified prefix as the root of the properties.

      *

      * @param context the initial context

      * @param prefix the prefix

      */

     public JNDIConfiguration(Context context, String prefix)

     {

         this.context = context;

         this.prefix = prefix;

     }

     /**

      * This method recursive traverse the JNDI tree, looking for Context objects.

      * When it finds them, it traverses them as well.  Otherwise it just adds the

      * values to the list of keys found.

      *

      * @param keys All the keys that have been found.

      * @param context The parent context

      * @param prefix What prefix we are building on.

      * @throws NamingException If JNDI has an issue.

      */

     private void recursiveGetKeys(Set keys, Context context, String prefix) throws NamingException

     {

         NamingEnumeration elements = null;

         try

         {

             elements = context.list("");

             // iterates through the context's elements

             while (elements.hasMore())

             {

                 NameClassPair nameClassPair = (NameClassPair) elements.next();

                 String name = nameClassPair.getName();

                 Object object = context.lookup(name);

                 // build the key

                 StringBuffer key = new StringBuffer();

                 key.append(prefix);

                 if (key.length() > 0)

                 {

                     key.append(".");

                 }

                 key.append(name);

                 if (object instanceof Context)

                 {

                     // add the keys of the sub context

                     Context subcontext = (Context) object;

                     recursiveGetKeys(keys, subcontext, key.toString());

                 }

                 else

                 {

                     // add the key

                     keys.add(key.toString());

                 }

             }

         }

         finally

         {

             // close the enumeration

             if (elements != null)

             {

                 elements.close();

             }

         }

     }

     /**

      * Returns an iterator with all property keys stored in this configuration.

      *

      * @return an iterator with all keys

      */

     public Iterator getKeys()

     {

         return getKeys("");

     }

     /**

      * Returns an iterator with all property keys starting with the given

      * prefix.

      *

      * @param prefix the prefix

      * @return an iterator with the selected keys

      */

     public Iterator getKeys(String prefix)

     {

         // build the path

         String[] splitPath = StringUtils.split(prefix, ".");

         List path = new ArrayList();

         for (int i = 0; i < splitPath.length; i++)

         {

             path.add(splitPath[i]);

         }

         try

         {

             // find the context matching the specified path

             Context context = getContext(path, getBaseContext());

             // return all the keys under the context found

             Set keys = new HashSet();

             if (context != null)

             {

                 recursiveGetKeys(keys, context, prefix);

             }

             else if (containsKey(prefix))

             {

                 // add the prefix if it matches exactly a property key

                 keys.add(prefix);

             }

             return keys.iterator();

         }

         catch (NamingException e)

         {

             log.error(e.getMessage(), e);

             return new ArrayList().iterator();

         }

     }

     /**

      * Because JNDI is based on a tree configuration, we need to filter down the

      * tree, till we find the Context specified by the key to start from.

      * Otherwise return null.

      *

      * @param path     the path of keys to traverse in order to find the context

      * @param context  the context to start from

      * @return The context at that key's location in the JNDI tree, or null if not found

      * @throws NamingException if JNDI has an issue

      */

     private Context getContext(List path, Context context) throws NamingException

     {

         // return the current context if the path is empty

         if (path == null || path.isEmpty())

         {

             return context;

         }

         String key = (String) path.get(0);

         // search a context matching the key in the context's elements

         NamingEnumeration elements = null;

         try

         {

             elements = context.list("");

             while (elements.hasMore())

             {

                 NameClassPair nameClassPair = (NameClassPair) elements.next();

                 String name = nameClassPair.getName();

                 Object object = context.lookup(name);

                 if (object instanceof Context && name.equals(key))

                 {

                     Context subcontext = (Context) object;

                     // recursive search in the sub context

                     return getContext(path.subList(1, path.size()), subcontext);

                 }

             }

         }

         finally

         {

             if (elements != null)

             {

                 elements.close();

             }

         }

         return null;

     }

     /**

      * Returns a flag whether this configuration is empty.

      *

      * @return the empty flag

      */

     public boolean isEmpty()

     {

         try

         {

             NamingEnumeration enumeration = null;

             try

             {

                 enumeration = getBaseContext().list("");

                 return !enumeration.hasMore();

             }

             finally

             {

                 // close the enumeration

                 if (enumeration != null)

                 {

                     enumeration.close();

                 }

             }

         }

         catch (NamingException e)

         {

             log.error(e.getMessage(), e);

             return true;

         }

     }

     /**

      * <p><strong>This operation is not supported and will throw an

      * UnsupportedOperationException.</strong></p>

      *

      * @param key the key

      * @param value the value

      * @throws UnsupportedOperationException

      */

     public void setProperty(String key, Object value)

     {

         throw new UnsupportedOperationException("This operation is not supported");

     }

     /**

      * Removes the specified property.

      *

      * @param key the key of the property to remove

      */

     public void clearProperty(String key)

     {

         clearedProperties.add(key);

     }

     /**

      * Checks whether the specified key is contained in this configuration.

      *

      * @param key the key to check

      * @return a flag whether this key is stored in this configuration

      */

     public boolean containsKey(String key)

     {

         if (clearedProperties.contains(key))

         {

             return false;

         }

         key = StringUtils.replace(key, ".", "/");

         try

         {

             // throws a NamingException if JNDI doesn't contain the key.

             getBaseContext().lookup(key);

             return true;

         }

         catch (NameNotFoundException e)

         {

             // expected exception, no need to log it

             return false;

         }

         catch (NamingException e)

         {

             log.error(e.getMessage(), e);

             return false;

         }

     }

     /**

      * Returns the prefix.

      * @return the prefix

      */

     public String getPrefix()

     {

         return prefix;

     }

     /**

      * Sets the prefix.

      *

      * @param prefix The prefix to set

      */

     public void setPrefix(String prefix)

     {

         this.prefix = prefix;

         // clear the previous baseContext

         baseContext = null;

     }

     /**

      * Returns the value of the specified property.

      *

      * @param key the key of the property

      * @return the value of this property

      */

     public Object getProperty(String key)

     {

         if (clearedProperties.contains(key))

         {

             return null;

         }

         try

         {

             key = StringUtils.replace(key, ".", "/");

             return getBaseContext().lookup(key);

         }

         catch (NameNotFoundException e)

         {

             // expected exception, no need to log it

             return null;

         }

         catch (NamingException e)

         {

             log.error(e.getMessage(), e);

             return null;

         }

     }

     /**

      * <p><strong>This operation is not supported and will throw an

      * UnsupportedOperationException.</strong></p>

      *

      * @param key the key

      * @param obj the value

      * @throws UnsupportedOperationException

      */

     protected void addPropertyDirect(String key, Object obj)

     {

         throw new UnsupportedOperationException("This operation is not supported");

     }

     /**

      * Return the base context with the prefix applied.

      *

      * @return the base context

      * @throws NamingException if an error occurs

      */

     public Context getBaseContext() throws NamingException

     {

         if (baseContext == null)

         {

             baseContext = (Context) getContext().lookup(prefix == null ? "" : prefix);

         }

         return baseContext;

     }

     /**

      * Return the initial context used by this configuration. This context is

      * independent of the prefix specified.

      *

      * @return the initial context

      */

     public Context getContext()

     {

         return context;

     }

     /**

      * Set the initial context of the configuration.

      *

      * @param context the context

      */

     public void setContext(Context context)

     {

         // forget the removed properties

         clearedProperties.clear();

         // change the context

         this.context = context;

     }

 }