/*
 * 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.naming;

import java.util.Hashtable;

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

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

/**
 * Catalina JNDI Context implementation.
 *
 * @author Remy Maucherat
 */
public class SelectorContext implements Context {


    // -------------------------------------------------------------- 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_";


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

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


    /**
     * Builds a Catalina selector context using the given environment.
     * @param env The environment
     */
    public SelectorContext(Hashtable<String,Object> env) {
        this.env = env;
        this.initialContext = false;
    }


    /**
     * Builds a Catalina selector context using the given environment.
     * @param env The environment
     * @param initialContext <code>true</code> if this is the main
     *  initial context
     */
    public SelectorContext(Hashtable<String,Object> env,
            boolean initialContext) {
        this.env = env;
        this.initialContext = initialContext;
    }


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


    /**
     * Environment.
     */
    protected final Hashtable<String,Object> env;


    /**
     * The string manager for this package.
     */
    protected static final StringManager sm = StringManager.getManager(SelectorContext.class);


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


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


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


    /**
     * Retrieves the named object. If name is empty, returns a new instance
     * of this context (which represents the same naming context as this
     * context, but its environment may be modified independently and it may
     * be accessed concurrently).
     *
     * @param name the name of the object to look up
     * @return the object bound to name
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public Object lookup(Name name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingName", "lookup",
                    name));
        }

        // 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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public Object lookup(String name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingString", "lookup",
                    name));
        }

        // 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
     * @throws javax.naming.NameAlreadyBoundException if name is already
     * bound
     * @throws javax.naming.directory.InvalidAttributesException if object did not
     * supply all mandatory attributes
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.NameAlreadyBoundException if name is already
     * bound
     * @throws javax.naming.directory.InvalidAttributesException if object did not
     * supply all mandatory attributes
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.directory.InvalidAttributesException if object did not
     * supply all mandatory attributes
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.directory.InvalidAttributesException if object did not
     * supply all mandatory attributes
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.NameNotFoundException if an intermediate context
     * does not exist
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.NameNotFoundException if an intermediate context
     * does not exist
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.NameAlreadyBoundException if name is already
     * bound
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.NameAlreadyBoundException if name is already
     * bound
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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.
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public NamingEnumeration<NameClassPair> list(Name name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingName", "list",
                    name));
        }

        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.
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public NamingEnumeration<NameClassPair> list(String name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingString", "list",
                    name));
        }

        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.
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public NamingEnumeration<Binding> listBindings(Name name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingName",
                    "listBindings", name));
        }

        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.
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public NamingEnumeration<Binding> listBindings(String name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingString",
                    "listBindings", name));
        }

        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
     * @throws javax.naming.NameNotFoundException if an intermediate context
     * does not exist
     * @throws javax.naming.NotContextException if the name is bound but does
     * not name a context, or does not name a context of the appropriate type
     */
    @Override
    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
     * @throws javax.naming.NameNotFoundException if an intermediate context
     * does not exist
     * @throws javax.naming.NotContextException if the name is bound but does
     * not name a context, or does not name a context of the appropriate type
     */
    @Override
    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
     * @throws javax.naming.NameAlreadyBoundException if name is already
     * bound
     * @throws javax.naming.directory.InvalidAttributesException if creation of the
     * sub-context requires specification of mandatory attributes
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.NameAlreadyBoundException if name is already
     * bound
     * @throws javax.naming.directory.InvalidAttributesException if creation of the
     * sub-context requires specification of mandatory attributes
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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).
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public Object lookupLink(Name name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingName",
                    "lookupLink", name));
        }

        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).
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public Object lookupLink(String name)
        throws NamingException {

        if (log.isDebugEnabled()) {
            log.debug(sm.getString("selectorContext.methodUsingString",
                    "lookupLink", name));
        }

        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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public Name composeName(Name name, Name prefix)
        throws NamingException {
        Name prefixClone = (Name) prefix.clone();
        return prefixClone.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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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.
     *
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    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
     * @throws javax.naming.OperationNotSupportedException if the naming
     * system does not have the notion of a full name
     * @throws NamingException if a naming exception is encountered
     */
    @Override
    public String getNameInNamespace()
        throws NamingException {
        return prefix;
    }


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


    /**
     * Get the bound context.
     * @return the Context bound with either the current thread or
     *  the current classloader
     * @throws NamingException Bindings exception
     */
    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
                initialContext = new NamingContext(env, ICName);
                ContextBindings.bindContext(ICName, initialContext);
            }
            return initialContext;
        } else {
            if (ContextBindings.isThreadBound()) {
                return ContextBindings.getThread();
            } else {
                return ContextBindings.getClassLoader();
            }
        }

    }


    /**
     * Strips the URL header.
     * @param name The name
     * @return the parsed name
     * @throws 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.
     * @param name The name
     * @return the parsed name
     * @throws 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).startsWith(prefix)) {
            if (name.get(0).equals(prefix)) {
                return name.getSuffix(1);
            } else {
                Name result = name.getSuffix(1);
                result.add(0, name.get(0).substring(prefixLength));
                return result;
            }
        } else {
            if (initialContext) {
                return name;
            } else {
                throw new NamingException(
                        sm.getString("selectorContext.noJavaUrl"));
            }
        }

    }


}