content: /**
   * 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.activemq.jndi;
  
  import java.io.Serializable;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Hashtable;
  import java.util.Iterator;
  import java.util.Map;
  import javax.naming.Binding;
  import javax.naming.CompositeName;
  import javax.naming.Context;
  import javax.naming.LinkRef;
  import javax.naming.Name;
  import javax.naming.NameClassPair;
  import javax.naming.NameNotFoundException;
  import javax.naming.NameParser;
  import javax.naming.NamingEnumeration;
  import javax.naming.NamingException;
  import javax.naming.NotContextException;
  import javax.naming.OperationNotSupportedException;
  import javax.naming.Reference;
  import javax.naming.spi.NamingManager;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A read-only Context <p/> This version assumes it and all its subcontext are
   * read-only and any attempt to modify (e.g. through bind) will result in an
   * OperationNotSupportedException. Each Context in the tree builds a cache of
   * the entries in all sub-contexts to optimise the performance of lookup.
   * </p>
   * <p>
   * This implementation is intended to optimise the performance of lookup(String)
   * to about the level of a HashMap get. It has been observed that the scheme
   * resolution phase performed by the JVM takes considerably longer, so for
   * optimum performance lookups should be coded like:
   * </p>
   * <code>
   * Context componentContext = (Context)new InitialContext().lookup("java:comp");
   * String envEntry = (String) componentContext.lookup("env/myEntry");
   * String envEntry2 = (String) componentContext.lookup("env/myEntry2");
   * </code>
   * 
   *  $Date: 2005/08/27 03:52:39 $
   */
  @SuppressWarnings("unchecked")
  public class ReadOnlyContext implements Context, Serializable {
      private static final Logger LOG = LoggerFactory.getLogger(ReadOnlyContext.class);
      public static final String SEPARATOR = "/";
      protected static final NameParser NAME_PARSER = new NameParserImpl();
      private static final long serialVersionUID = -5754338187296859149L;
  
      protected final Hashtable<String, Object> environment; // environment for this context
      protected final Map<String, Object> bindings; // bindings at my level
      protected final Map<String, Object> treeBindings; // all bindings under me
  
      private boolean frozen;
      private String nameInNamespace = "";
  
      public ReadOnlyContext() {
          environment = new Hashtable<String, Object>();
          bindings = new HashMap<String, Object>();
          treeBindings = new HashMap<String, Object>();
      }
  
      public ReadOnlyContext(Hashtable env) {
          if (env == null) {
              this.environment = new Hashtable<String, Object>();
          } else {
              this.environment = new Hashtable<String, Object>(env);
          }
          this.bindings = Collections.EMPTY_MAP;
          this.treeBindings = Collections.EMPTY_MAP;
      }
  
      public ReadOnlyContext(Hashtable environment, Map<String, Object> bindings) {
          if (environment == null) {
              this.environment = new Hashtable<String, Object>();
          } else {
              this.environment = new Hashtable<String, Object>(environment);
          }
          this.bindings = new HashMap<String, Object>();
          treeBindings = new HashMap<String, Object>();
          if (bindings != null) {
              for (Map.Entry<String, Object> binding : bindings.entrySet()) {
                  try {
                      internalBind(binding.getKey(), binding.getValue());
                  } catch (Throwable e) {
                      LOG.error("Failed to bind " + binding.getKey() + "=" + binding.getValue(), e);
                  }
              }
          }
          frozen = true;
      }
  
      public ReadOnlyContext(Hashtable environment, Map bindings, String nameInNamespace) {
          this(environment, bindings);
          this.nameInNamespace = nameInNamespace;
      }
  
      protected ReadOnlyContext(ReadOnlyContext clone, Hashtable env) {
          this.bindings = clone.bindings;
          this.treeBindings = clone.treeBindings;
          this.environment = new Hashtable<String, Object>(env);
      }
  
      protected ReadOnlyContext(ReadOnlyContext clone, Hashtable<String, Object> env, String nameInNamespace) {
          this(clone, env);
          this.nameInNamespace = nameInNamespace;
      }
  
      public void freeze() {
          frozen = true;
      }
  
      boolean isFrozen() {
          return frozen;
      }
  
      /**
       * internalBind is intended for use only during setup or possibly by
       * suitably synchronized superclasses. It binds every possible lookup into a
       * map in each context. To do this, each context strips off one name segment
       * and if necessary creates a new context for it. Then it asks that context
       * to bind the remaining name. It returns a map containing all the bindings
       * from the next context, plus the context it just created (if it in fact
       * created it). (the names are suitably extended by the segment originally
       * lopped off).
       * 
       * @param name
       * @param value
       * @return
       * @throws javax.naming.NamingException
       */
      protected Map<String, Object> internalBind(String name, Object value) throws NamingException {
          assert name != null && name.length() > 0;
          assert !frozen;
  
          Map<String, Object> newBindings = new HashMap<String, Object>();
          int pos = name.indexOf('/');
          if (pos == -1) {
              if (treeBindings.put(name, value) != null) {
                  throw new NamingException("Something already bound at " + name);
              }
              bindings.put(name, value);
              newBindings.put(name, value);
          } else {
              String segment = name.substring(0, pos);
              assert segment != null;
              assert !segment.equals("");
              Object o = treeBindings.get(segment);
              if (o == null) {
                  o = newContext();
                  treeBindings.put(segment, o);
                  bindings.put(segment, o);
                  newBindings.put(segment, o);
              } else if (!(o instanceof ReadOnlyContext)) {
                  throw new NamingException("Something already bound where a subcontext should go");
              }
              ReadOnlyContext readOnlyContext = (ReadOnlyContext)o;
              String remainder = name.substring(pos + 1);
              Map<String, Object> subBindings = readOnlyContext.internalBind(remainder, value);
              for (Iterator iterator = subBindings.entrySet().iterator(); iterator.hasNext();) {
                  Map.Entry entry = (Map.Entry)iterator.next();
                  String subName = segment + "/" + (String)entry.getKey();
                  Object bound = entry.getValue();
                  treeBindings.put(subName, bound);
                  newBindings.put(subName, bound);
              }
          }
          return newBindings;
      }
  
      protected ReadOnlyContext newContext() {
          return new ReadOnlyContext();
      }
  
      public Object addToEnvironment(String propName, Object propVal) throws NamingException {
          return environment.put(propName, propVal);
      }
  
      public Hashtable<String, Object> getEnvironment() throws NamingException {
          return (Hashtable<String, Object>)environment.clone();
      }
  
      public Object removeFromEnvironment(String propName) throws NamingException {
          return environment.remove(propName);
      }
  
      public Object lookup(String name) throws NamingException {
          if (name.length() == 0) {
              return this;
          }
          Object result = treeBindings.get(name);
          if (result == null) {
              result = bindings.get(name);
          }
          if (result == null) {
              int pos = name.indexOf(':');
              if (pos > 0) {
                  String scheme = name.substring(0, pos);
                  Context ctx = NamingManager.getURLContext(scheme, environment);
                  if (ctx == null) {
                      throw new NamingException("scheme " + scheme + " not recognized");
                  }
                  return ctx.lookup(name);
              } else {
                  // Split out the first name of the path
                  // and look for it in the bindings map.
                  CompositeName path = new CompositeName(name);
  
                  if (path.size() == 0) {
                      return this;
                  } else {
                      String first = path.get(0);
                      Object obj = bindings.get(first);
                      if (obj == null) {
                          throw new NameNotFoundException(name);
                      } else if (obj instanceof Context && path.size() > 1) {
                          Context subContext = (Context)obj;
                          obj = subContext.lookup(path.getSuffix(1));
                      }
                      return obj;
                  }
              }
          }
          if (result instanceof LinkRef) {
              LinkRef ref = (LinkRef)result;
              result = lookup(ref.getLinkName());
          }
          if (result instanceof Reference) {
              try {
                  result = NamingManager.getObjectInstance(result, null, null, this.environment);
              } catch (NamingException e) {
                  throw e;
              } catch (Exception e) {
                  throw (NamingException)new NamingException("could not look up : " + name).initCause(e);
              }
          }
          if (result instanceof ReadOnlyContext) {
              String prefix = getNameInNamespace();
              if (prefix.length() > 0) {
                  prefix = prefix + SEPARATOR;
              }
              result = new ReadOnlyContext((ReadOnlyContext)result, environment, prefix + name);
          }
          return result;
      }
  
      public Object lookup(Name name) throws NamingException {
          return lookup(name.toString());
      }
  
      public Object lookupLink(String name) throws NamingException {
          return lookup(name);
      }
  
      public Name composeName(Name name, Name prefix) throws NamingException {
          Name result = (Name)prefix.clone();
          result.addAll(name);
          return result;
      }
  
      public String composeName(String name, String prefix) throws NamingException {
          CompositeName result = new CompositeName(prefix);
          result.addAll(new CompositeName(name));
          return result.toString();
      }
  
      public NamingEnumeration list(String name) throws NamingException {
          Object o = lookup(name);
          if (o == this) {
              return new ListEnumeration();
          } else if (o instanceof Context) {
              return ((Context)o).list("");
          } else {
              throw new NotContextException();
          }
      }
  
      public NamingEnumeration listBindings(String name) throws NamingException {
          Object o = lookup(name);
          if (o == this) {
              return new ListBindingEnumeration();
          } else if (o instanceof Context) {
              return ((Context)o).listBindings("");
          } else {
              throw new NotContextException();
          }
      }
  
      public Object lookupLink(Name name) throws NamingException {
          return lookupLink(name.toString());
      }
  
      public NamingEnumeration list(Name name) throws NamingException {
          return list(name.toString());
      }
  
      public NamingEnumeration listBindings(Name name) throws NamingException {
          return listBindings(name.toString());
      }
  
      public void bind(Name name, Object obj) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void bind(String name, Object obj) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void close() throws NamingException {
          // ignore
      }
  
      public Context createSubcontext(Name name) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public Context createSubcontext(String name) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void destroySubcontext(Name name) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void destroySubcontext(String name) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public String getNameInNamespace() throws NamingException {
          return nameInNamespace;
      }
  
      public NameParser getNameParser(Name name) throws NamingException {
          return NAME_PARSER;
      }
  
      public NameParser getNameParser(String name) throws NamingException {
          return NAME_PARSER;
      }
  
      public void rebind(Name name, Object obj) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void rebind(String name, Object obj) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void rename(Name oldName, Name newName) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void rename(String oldName, String newName) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void unbind(Name name) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      public void unbind(String name) throws NamingException {
          throw new OperationNotSupportedException();
      }
  
      private abstract class LocalNamingEnumeration implements NamingEnumeration {
          private final Iterator i = bindings.entrySet().iterator();
  
          public boolean hasMore() throws NamingException {
              return i.hasNext();
          }
  
          public boolean hasMoreElements() {
              return i.hasNext();
          }
  
          protected Map.Entry getNext() {
              return (Map.Entry)i.next();
          }
  
          public void close() throws NamingException {
          }
      }
  
      private class ListEnumeration extends LocalNamingEnumeration {
          ListEnumeration() {
          }
  
          public Object next() throws NamingException {
              return nextElement();
          }
  
          public Object nextElement() {
              Map.Entry entry = getNext();
              return new NameClassPair((String)entry.getKey(), entry.getValue().getClass().getName());
          }
      }
  
      private class ListBindingEnumeration extends LocalNamingEnumeration {
          ListBindingEnumeration() {
          }
  
          public Object next() throws NamingException {
              return nextElement();
          }
  
          public Object nextElement() {
              Map.Entry entry = getNext();
              return new Binding((String)entry.getKey(), entry.getValue());
          }
      }
  }
  