/*
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */ 


package org.apache.naming.modules.java;

import java.util.Hashtable;

import javax.naming.Context;
import javax.naming.Name;
import javax.naming.NameParser;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;

import org.apache.naming.core.BaseContext;
import org.apache.naming.modules.memory.MemoryNamingContext;
import org.apache.tomcat.util.res.StringManager;

/* This delegates to another context, removing a prefix.
   XXX make it generic, move to core. The context thread can be
   selected only once - in the java: factory, to avoid overhead.
*/

/**
 * Per thread context, implementing java: like contexts.
 *
 * @author Remy Maucherat
 */
public class SelectorContext extends BaseContext {

    // -------------------------------------------------------------- Constants


    /**
     * Namespace URL.
     */
    public static final String prefix = "java:";


    /**
     * Namespace URL length.
     */
    public static final int prefixLength = prefix.length();


    /**
     * Initial context prefix.
     */
    public static final String IC_PREFIX = "IC_";


    // ----------------------------------------------------------- Constructors


    /**
     * Builds a Catalina selector context using the given environment.
     */
    public SelectorContext(Hashtable env) {
        super( env );
    }


    /**
     * Builds a Catalina selector context using the given environment.
     */
    public SelectorContext(Hashtable env, boolean initialContext) {
        this(env);
        this.initialContext = initialContext;
    }


    // ----------------------------------------------------- Instance Variables


    /**
     * Environment.
     */
    protected Hashtable env;


    /**
     * The string manager for this package.
     */
    protected StringManager sm = StringManager.getManager("org.apache.naming.res");


    /**
     * Request for an initial context.
     */
    protected boolean initialContext = false;


    // --------------------------------------------------------- Public Methods


    // -------------------------------------------------------- Context Methods


    public Object lookup(Name name)
        throws NamingException {
        // Strip the URL header
        // Find the appropriate NamingContext according to the current bindings
        // Execute the lookup on that context
        return getBoundContext().lookup(parseName(name));
    }


    /**
     * Retrieves the named object.
     * 
     * @param name the name of the object to look up
     * @return the object bound to name
     * @exception NamingException if a naming exception is encountered
     */
    public Object lookup(String name)
        throws NamingException {
        // Strip the URL header
        // Find the appropriate NamingContext according to the current bindings
        // Execute the lookup on that context
        return getBoundContext().lookup(parseName(name));
    }


    /**
     * Binds a name to an object. All intermediate contexts and the target 
     * context (that named by all but terminal atomic component of the name) 
     * must already exist.
     * 
     * @param name the name to bind; may not be empty
     * @param obj the object to bind; possibly null
     * @exception NameAlreadyBoundException if name is already bound
     * @exception InvalidAttributesException if object did not supply all 
     * mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public void bind(Name name, Object obj)
        throws NamingException {
        getBoundContext().bind(parseName(name), obj);
    }


    /**
     * Binds a name to an object.
     * 
     * @param name the name to bind; may not be empty
     * @param obj the object to bind; possibly null
     * @exception NameAlreadyBoundException if name is already bound
     * @exception InvalidAttributesException if object did not supply all 
     * mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public void bind(String name, Object obj)
        throws NamingException {
        getBoundContext().bind(parseName(name), obj);
    }


    /**
     * Binds a name to an object, overwriting any existing binding. All 
     * intermediate contexts and the target context (that named by all but 
     * terminal atomic component of the name) must already exist.
     * <p>
     * If the object is a DirContext, any existing attributes associated with 
     * the name are replaced with those of the object. Otherwise, any 
     * existing attributes associated with the name remain unchanged.
     * 
     * @param name the name to bind; may not be empty
     * @param obj the object to bind; possibly null
     * @exception InvalidAttributesException if object did not supply all 
     * mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public void rebind(Name name, Object obj)
        throws NamingException {
        getBoundContext().rebind(parseName(name), obj);
    }


    /**
     * Binds a name to an object, overwriting any existing binding.
     * 
     * @param name the name to bind; may not be empty
     * @param obj the object to bind; possibly null
     * @exception InvalidAttributesException if object did not supply all 
     * mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public void rebind(String name, Object obj)
        throws NamingException {
        getBoundContext().rebind(parseName(name), obj);
    }


    /**
     * Unbinds the named object. Removes the terminal atomic name in name 
     * from the target context--that named by all but the terminal atomic 
     * part of name.
     * <p>
     * This method is idempotent. It succeeds even if the terminal atomic 
     * name is not bound in the target context, but throws 
     * NameNotFoundException if any of the intermediate contexts do not exist. 
     * 
     * @param name the name to bind; may not be empty
     * @exception NameNotFoundException if an intermediate context does not 
     * exist
     * @exception NamingException if a naming exception is encountered
     */
    public void unbind(Name name)
        throws NamingException {
        getBoundContext().unbind(parseName(name));
    }


    /**
     * Unbinds the named object.
     * 
     * @param name the name to bind; may not be empty
     * @exception NameNotFoundException if an intermediate context does not 
     * exist
     * @exception NamingException if a naming exception is encountered
     */
    public void unbind(String name)
        throws NamingException {
        getBoundContext().unbind(parseName(name));
    }


    /**
     * Binds a new name to the object bound to an old name, and unbinds the 
     * old name. Both names are relative to this context. Any attributes 
     * associated with the old name become associated with the new name. 
     * Intermediate contexts of the old name are not changed.
     * 
     * @param oldName the name of the existing binding; may not be empty
     * @param newName the name of the new binding; may not be empty
     * @exception NameAlreadyBoundException if newName is already bound
     * @exception NamingException if a naming exception is encountered
     */
    public void rename(Name oldName, Name newName)
        throws NamingException {
        getBoundContext().rename(parseName(oldName), parseName(newName));
    }


    /**
     * Binds a new name to the object bound to an old name, and unbinds the 
     * old name.
     * 
     * @param oldName the name of the existing binding; may not be empty
     * @param newName the name of the new binding; may not be empty
     * @exception NameAlreadyBoundException if newName is already bound
     * @exception NamingException if a naming exception is encountered
     */
    public void rename(String oldName, String newName)
        throws NamingException {
        getBoundContext().rename(parseName(oldName), parseName(newName));
    }


    /**
     * Enumerates the names bound in the named context, along with the class 
     * names of objects bound to them. The contents of any subcontexts are 
     * not included.
     * <p>
     * If a binding is added to or removed from this context, its effect on 
     * an enumeration previously returned is undefined.
     * 
     * @param name the name of the context to list
     * @return an enumeration of the names and class names of the bindings in 
     * this context. Each element of the enumeration is of type NameClassPair.
     * @exception NamingException if a naming exception is encountered
     */
    public NamingEnumeration list(Name name)
        throws NamingException {
        return getBoundContext().list(parseName(name));
    }


    /**
     * Enumerates the names bound in the named context, along with the class 
     * names of objects bound to them.
     * 
     * @param name the name of the context to list
     * @return an enumeration of the names and class names of the bindings in 
     * this context. Each element of the enumeration is of type NameClassPair.
     * @exception NamingException if a naming exception is encountered
     */
    public NamingEnumeration list(String name)
        throws NamingException {
        return getBoundContext().list(parseName(name));
    }


    /**
     * Enumerates the names bound in the named context, along with the 
     * objects bound to them. The contents of any subcontexts are not 
     * included.
     * <p>
     * If a binding is added to or removed from this context, its effect on 
     * an enumeration previously returned is undefined.
     * 
     * @param name the name of the context to list
     * @return an enumeration of the bindings in this context. 
     * Each element of the enumeration is of type Binding.
     * @exception NamingException if a naming exception is encountered
     */
    public NamingEnumeration listBindings(Name name)
        throws NamingException {
        return getBoundContext().listBindings(parseName(name));
    }


    /**
     * Enumerates the names bound in the named context, along with the 
     * objects bound to them.
     * 
     * @param name the name of the context to list
     * @return an enumeration of the bindings in this context. 
     * Each element of the enumeration is of type Binding.
     * @exception NamingException if a naming exception is encountered
     */
    public NamingEnumeration listBindings(String name)
        throws NamingException {
        return getBoundContext().listBindings(parseName(name));
    }


    /**
     * Destroys the named context and removes it from the namespace. Any 
     * attributes associated with the name are also removed. Intermediate 
     * contexts are not destroyed.
     * <p>
     * This method is idempotent. It succeeds even if the terminal atomic 
     * name is not bound in the target context, but throws 
     * NameNotFoundException if any of the intermediate contexts do not exist. 
     * 
     * In a federated naming system, a context from one naming system may be 
     * bound to a name in another. One can subsequently look up and perform 
     * operations on the foreign context using a composite name. However, an 
     * attempt destroy the context using this composite name will fail with 
     * NotContextException, because the foreign context is not a "subcontext" 
     * of the context in which it is bound. Instead, use unbind() to remove 
     * the binding of the foreign context. Destroying the foreign context 
     * requires that the destroySubcontext() be performed on a context from 
     * the foreign context's "native" naming system.
     * 
     * @param name the name of the context to be destroyed; may not be empty
     * @exception NameNotFoundException if an intermediate context does not 
     * exist
     * @exception NotContextException if the name is bound but does not name 
     * a context, or does not name a context of the appropriate type
     */
    public void destroySubcontext(Name name)
        throws NamingException {
        getBoundContext().destroySubcontext(parseName(name));
    }


    /**
     * Destroys the named context and removes it from the namespace.
     * 
     * @param name the name of the context to be destroyed; may not be empty
     * @exception NameNotFoundException if an intermediate context does not 
     * exist
     * @exception NotContextException if the name is bound but does not name 
     * a context, or does not name a context of the appropriate type
     */
    public void destroySubcontext(String name)
        throws NamingException {
        getBoundContext().destroySubcontext(parseName(name));
    }


    /**
     * Creates and binds a new context. Creates a new context with the given 
     * name and binds it in the target context (that named by all but 
     * terminal atomic component of the name). All intermediate contexts and 
     * the target context must already exist.
     * 
     * @param name the name of the context to create; may not be empty
     * @return the newly created context
     * @exception NameAlreadyBoundException if name is already bound
     * @exception InvalidAttributesException if creation of the subcontext 
     * requires specification of mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public Context createSubcontext(Name name)
        throws NamingException {
        return getBoundContext().createSubcontext(parseName(name));
    }


    /**
     * Creates and binds a new context.
     * 
     * @param name the name of the context to create; may not be empty
     * @return the newly created context
     * @exception NameAlreadyBoundException if name is already bound
     * @exception InvalidAttributesException if creation of the subcontext 
     * requires specification of mandatory attributes
     * @exception NamingException if a naming exception is encountered
     */
    public Context createSubcontext(String name)
        throws NamingException {
        return getBoundContext().createSubcontext(parseName(name));
    }


    /**
     * Retrieves the named object, following links except for the terminal 
     * atomic component of the name. If the object bound to name is not a 
     * link, returns the object itself.
     * 
     * @param name the name of the object to look up
     * @return the object bound to name, not following the terminal link 
     * (if any).
     * @exception NamingException if a naming exception is encountered
     */
    public Object lookupLink(Name name)
        throws NamingException {
        return getBoundContext().lookupLink(parseName(name));
    }


    /**
     * Retrieves the named object, following links except for the terminal 
     * atomic component of the name.
     * 
     * @param name the name of the object to look up
     * @return the object bound to name, not following the terminal link 
     * (if any).
     * @exception NamingException if a naming exception is encountered
     */
    public Object lookupLink(String name)
        throws NamingException {
        return getBoundContext().lookupLink(parseName(name));
    }


    /**
     * Retrieves the parser associated with the named context. In a 
     * federation of namespaces, different naming systems will parse names 
     * differently. This method allows an application to get a parser for 
     * parsing names into their atomic components using the naming convention 
     * of a particular naming system. Within any single naming system, 
     * NameParser objects returned by this method must be equal (using the 
     * equals() test).
     * 
     * @param name the name of the context from which to get the parser
     * @return a name parser that can parse compound names into their atomic 
     * components
     * @exception NamingException if a naming exception is encountered
     */
    public NameParser getNameParser(Name name)
        throws NamingException {
        return getBoundContext().getNameParser(parseName(name));
    }


    /**
     * Retrieves the parser associated with the named context.
     * 
     * @param name the name of the context from which to get the parser
     * @return a name parser that can parse compound names into their atomic 
     * components
     * @exception NamingException if a naming exception is encountered
     */
    public NameParser getNameParser(String name)
        throws NamingException {
        return getBoundContext().getNameParser(parseName(name));
    }


    /**
     * Composes the name of this context with a name relative to this context.
     * <p>
     * Given a name (name) relative to this context, and the name (prefix) 
     * of this context relative to one of its ancestors, this method returns 
     * the composition of the two names using the syntax appropriate for the 
     * naming system(s) involved. That is, if name names an object relative 
     * to this context, the result is the name of the same object, but 
     * relative to the ancestor context. None of the names may be null.
     * 
     * @param name a name relative to this context
     * @param prefix the name of this context relative to one of its ancestors
     * @return the composition of prefix and name
     * @exception NamingException if a naming exception is encountered
     */
    public Name composeName(Name name, Name prefix)
        throws NamingException {
	prefix = (Name) name.clone();
	return prefix.addAll(name);
    }


    /**
     * Composes the name of this context with a name relative to this context.
     * 
     * @param name a name relative to this context
     * @param prefix the name of this context relative to one of its ancestors
     * @return the composition of prefix and name
     * @exception NamingException if a naming exception is encountered
     */
    public String composeName(String name, String prefix)
        throws NamingException {
        return prefix + "/" + name;
    }


    /**
     * Adds a new environment property to the environment of this context. If 
     * the property already exists, its value is overwritten.
     * 
     * @param propName the name of the environment property to add; may not 
     * be null
     * @param propVal the value of the property to add; may not be null
     * @exception NamingException if a naming exception is encountered
     */
    public Object addToEnvironment(String propName, Object propVal)
        throws NamingException {
        return getBoundContext().addToEnvironment(propName, propVal);
    }


    /**
     * Removes an environment property from the environment of this context. 
     * 
     * @param propName the name of the environment property to remove; 
     * may not be null
     * @exception NamingException if a naming exception is encountered
     */
    public Object removeFromEnvironment(String propName)
        throws NamingException {
        return getBoundContext().removeFromEnvironment(propName);
    }


    /**
     * Retrieves the environment in effect for this context. See class 
     * description for more details on environment properties. 
     * The caller should not make any changes to the object returned: their 
     * effect on the context is undefined. The environment of this context 
     * may be changed using addToEnvironment() and removeFromEnvironment().
     * 
     * @return the environment of this context; never null
     * @exception NamingException if a naming exception is encountered
     */
    public Hashtable getEnvironment()
        throws NamingException {
        return getBoundContext().getEnvironment();
    }


    /**
     * Closes this context. This method releases this context's resources 
     * immediately, instead of waiting for them to be released automatically 
     * by the garbage collector.
     * This method is idempotent: invoking it on a context that has already 
     * been closed has no effect. Invoking any other method on a closed 
     * context is not allowed, and results in undefined behaviour.
     * 
     * @exception NamingException if a naming exception is encountered
     */
    public void close()
        throws NamingException {
        getBoundContext().close();
    }


    /**
     * Retrieves the full name of this context within its own namespace.
     * <p>
     * Many naming services have a notion of a "full name" for objects in 
     * their respective namespaces. For example, an LDAP entry has a 
     * distinguished name, and a DNS record has a fully qualified name. This 
     * method allows the client application to retrieve this name. The string 
     * returned by this method is not a JNDI composite name and should not be 
     * passed directly to context methods. In naming systems for which the 
     * notion of full name does not make sense, 
     * OperationNotSupportedException is thrown.
     * 
     * @return this context's name in its own namespace; never null
     * @exception OperationNotSupportedException if the naming system does 
     * not have the notion of a full name
     * @exception NamingException if a naming exception is encountered
     */
    public String getNameInNamespace()
        throws NamingException {
        return prefix;
    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Get the bound context.
     */
    protected Context getBoundContext()
        throws NamingException {

        if (initialContext) {
            String ICName = IC_PREFIX;
            if (ContextBindings.isThreadBound()) {
                ICName += ContextBindings.getThreadName();
            } else if (ContextBindings.isClassLoaderBound()) {
                ICName += ContextBindings.getClassLoaderName();
            }
            Context initialContext = ContextBindings.getContext(ICName);
            if (initialContext == null) {
                // Allocating a new context and binding it to the appropriate 
                // name
                // XXX Should return null, let the caller create something
                // Or use a different constructor.
                initialContext = new MemoryNamingContext(env);
                ContextBindings.bindContext(ICName, initialContext);
            }
            return initialContext;
        } else {
            if (ContextBindings.isThreadBound()) {
                return ContextBindings.getThread();
            } else {
                return ContextBindings.getClassLoader();
            }
        }

    }


    /**
     * Strips the URL header.
     * 
     * @return the parsed name
     * @exception NamingException if there is no "java:" header or if no 
     * naming context has been bound to this thread
     */
    protected String parseName(String name) 
        throws NamingException {
        
	if ((!initialContext) && (name.startsWith(prefix))) {
            return (name.substring(prefixLength));
        } else {
            if (initialContext) {
                return (name);
            } else {
                throw new NamingException
                    (sm.getString("selectorContext.noJavaUrl"));
            }
        }
        
    }


    /**
     * Strips the URL header.
     * 
     * @return the parsed name
     * @exception NamingException if there is no "java:" header or if no 
     * naming context has been bound to this thread
     */
    protected Name parseName(Name name) 
        throws NamingException {

	if ((!initialContext) && (!name.isEmpty()) 
            && (name.get(0).equals(prefix))) {
            return (name.getSuffix(1));
        } else {
            if (initialContext) {
                return (name);
            } else {
                throw new NamingException
                    (sm.getString("selectorContext.noJavaUrl"));
            }
        }

    }
}

