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package javax.naming;

import java.util.Hashtable;
import javax.naming.spi.NamingManager;
import com.sun.naming.internal.ResourceManager;

/**
 * This class is the starting context for performing naming operations.
 *<p>
 * All naming operations are relative to a context.
 * The initial context implements the Context interface and
 * provides the starting point for resolution of names.
 *<p>
 * <a name=ENVIRONMENT></a>
 * When the initial context is constructed, its environment
 * is initialized with properties defined in the environment parameter
 * passed to the constructor, and in any
 * <a href=Context.html#RESOURCEFILES>application resource files</a>.
 * In addition, a small number of standard JNDI properties may
 * be specified as system properties or as applet parameters
 * (through the use of {@link Context#APPLET}).
 * These special properties are listed in the field detail sections of the
 * <a href=Context.html#field_detail><tt>Context</tt></a> and
 * <a href=ldap/LdapContext.html#field_detail><tt>LdapContext</tt></a>
 * interface documentation.
 *<p>
 * JNDI determines each property's value by merging
 * the values from the following two sources, in order:
 * <ol>
 * <li>
 * The first occurrence of the property from the constructor's
 * environment parameter and (for appropriate properties) the applet
 * parameters and system properties.
 * <li>
 * The application resource files (<tt>jndi.properties</tt>).
 * </ol>
 * For each property found in both of these two sources, or in
 * more than one application resource file, the property's value
 * is determined as follows. If the property is
 * one of the standard JNDI properties that specify a list of JNDI
 * factories (see <a href=Context.html#LISTPROPS><tt>Context</tt></a>),
 * all of the values are
 * concatenated into a single colon-separated list. For other
 * properties, only the first value found is used.
 *
 *<p>
 * The initial context implementation is determined at runtime.
 * The default policy uses the environment property
 * "{@link Context#INITIAL_CONTEXT_FACTORY java.naming.factory.initial}",
 * which contains the class name of the initial context factory.
 * An exception to this policy is made when resolving URL strings, as described
 * below.
 *<p>
 * When a URL string (a <tt>String</tt> of the form
 * <em>scheme_id:rest_of_name</em>) is passed as a name parameter to
 * any method, a URL context factory for handling that scheme is
 * located and used to resolve the URL. If no such factory is found,
 * the initial context specified by
 * <tt>"java.naming.factory.initial"</tt> is used. Similarly, when a
 * <tt>CompositeName</tt> object whose first component is a URL string is
 * passed as a name parameter to any method, a URL context factory is
 * located and used to resolve the first name component.
 * See {@link NamingManager#getURLContext
 * <tt>NamingManager.getURLContext()</tt>} for a description of how URL
 * context factories are located.
 *<p>
 * This default policy of locating the initial context and URL context
 * factories may be overridden
 * by calling
 * <tt>NamingManager.setInitialContextFactoryBuilder()</tt>.
 *<p>
 * NoInitialContextException is thrown when an initial context cannot
 * be instantiated. This exception can be thrown during any interaction
 * with the InitialContext, not only when the InitialContext is constructed.
 * For example, the implementation of the initial context might lazily
 * retrieve the context only when actual methods are invoked on it.
 * The application should not have any dependency on when the existence
 * of an initial context is determined.
 *<p>
 * When the environment property "java.naming.factory.initial" is
 * non-null, the InitialContext constructor will attempt to create the
 * initial context specified therein. At that time, the initial context factory
 * involved might throw an exception if a problem is encountered. However,
 * it is provider implementation-dependent when it verifies and indicates
 * to the users of the initial context any environment property- or
 * connection- related problems. It can do so lazily--delaying until
 * an operation is performed on the context, or eagerly, at the time
 * the context is constructed.
 *<p>
 * An InitialContext instance is not synchronized against concurrent
 * access by multiple threads. Multiple threads each manipulating a
 * different InitialContext instance need not synchronize.
 * Threads that need to access a single InitialContext instance
 * concurrently should synchronize amongst themselves and provide the
 * necessary locking.
 *
 * @author Rosanna Lee
 * @author Scott Seligman
 *
 * @see Context
 * @see NamingManager#setInitialContextFactoryBuilder
 * NamingManager.setInitialContextFactoryBuilder
 * @since JNDI 1.1 / Java 2 Platform, Standard Edition, v 1.3
 */

public class InitialContext implements Context {

 /**
 * The environment associated with this InitialContext.
 * It is initialized to null and is updated by the constructor
 * that accepts an environment or by the <tt>init()</tt> method.
 * @see #addToEnvironment
 * @see #removeFromEnvironment
 * @see #getEnvironment
 */
 protected Hashtable<Object,Object> myProps = null;

 /**
 * Field holding the result of calling NamingManager.getInitialContext().
 * It is set by getDefaultInitCtx() the first time getDefaultInitCtx()
 * is called. Subsequent invocations of getDefaultInitCtx() return
 * the value of defaultInitCtx.
 * @see #getDefaultInitCtx
 */
 protected Context defaultInitCtx = null;

 /**
 * Field indicating whether the initial context has been obtained
 * by calling NamingManager.getInitialContext().
 * If true, its result is in <code>defaultInitCtx</code>.
 */
 protected boolean gotDefault = false;

 /**
 * Constructs an initial context with the option of not
 * initializing it. This may be used by a constructor in
 * a subclass when the value of the environment parameter
 * is not yet known at the time the <tt>InitialContext</tt>
 * constructor is called. The subclass's constructor will
 * call this constructor, compute the value of the environment,
 * and then call <tt>init()</tt> before returning.
 *
 * @param lazy
 * true means do not initialize the initial context; false
 * is equivalent to calling <tt>new InitialContext()</tt>
 * @throws NamingException if a naming exception is encountered
 *
 * @see #init(Hashtable)
 * @since 1.3
 */
 protected InitialContext(boolean lazy) throws NamingException {
 if (!lazy) {
 init(null);
 }
 }

 /**
 * Constructs an initial context.
 * No environment properties are supplied.
 * Equivalent to <tt>new InitialContext(null)</tt>.
 *
 * @throws NamingException if a naming exception is encountered
 *
 * @see #InitialContext(Hashtable)
 */
 public InitialContext() throws NamingException {
 init(null);
 }

 /**
 * Constructs an initial context using the supplied environment.
 * Environment properties are discussed in the class description.
 *
 * <p> This constructor will not modify <tt>environment</tt>
 * or save a reference to it, but may save a clone.
 * Caller should not modify mutable keys and values in
 * <tt>environment</tt> after it has been passed to the constructor.
 *
 * @param environment
 * environment used to create the initial context.
 * Null indicates an empty environment.
 *
 * @throws NamingException if a naming exception is encountered
 */
 public InitialContext(Hashtable<?,?> environment)
 throws NamingException
 {
 if (environment != null) {
 environment = (Hashtable)environment.clone();
 }
 init(environment);
 }

 /**
 * Initializes the initial context using the supplied environment.
 * Environment properties are discussed in the class description.
 *
 * <p> This method will modify <tt>environment</tt> and save
 * a reference to it. The caller may no longer modify it.
 *
 * @param environment
 * environment used to create the initial context.
 * Null indicates an empty environment.
 *
 * @throws NamingException if a naming exception is encountered
 *
 * @see #InitialContext(boolean)
 * @since 1.3
 */
 @SuppressWarnings("unchecked")
 protected void init(Hashtable<?,?> environment)
 throws NamingException
 {
 myProps = (Hashtable<Object,Object>)
 ResourceManager.getInitialEnvironment(environment);

 if (myProps.get(Context.INITIAL_CONTEXT_FACTORY) != null) {
 // user has specified initial context factory; try to get it
 getDefaultInitCtx();
 }
 }

 /**
 * A static method to retrieve the named object.
 * This is a shortcut method equivalent to invoking:
 * <p>
 * <code>
 * InitialContext ic = new InitialContext();
 * Object obj = ic.lookup();
 * </code>
 * <p> If <tt>name</tt> 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 <T> the type of the returned object
 * @param name
 * the name of the object to look up
 * @return the object bound to <tt>name</tt>
 * @throws NamingException if a naming exception is encountered
 *
 * @see #doLookup(String)
 * @see #lookup(Name)
 * @since 1.6
 */
 @SuppressWarnings("unchecked")
 public static <T> T doLookup(Name name)
 throws NamingException {
 return (T) (new InitialContext()).lookup(name);
 }

 /**
 * A static method to retrieve the named object.
 * See {@link #doLookup(Name)} for details.
 * @param <T> the type of the returned object
 * @param name
 * the name of the object to look up
 * @return the object bound to <tt>name</tt>
 * @throws NamingException if a naming exception is encountered
 * @since 1.6
 */
 @SuppressWarnings("unchecked")
 public static <T> T doLookup(String name)
 throws NamingException {
 return (T) (new InitialContext()).lookup(name);
 }

 private static String getURLScheme(String str) {
 int colon_posn = str.indexOf(':');
 int slash_posn = str.indexOf('/');

 if (colon_posn > 0 && (slash_posn == -1 || colon_posn < slash_posn))
 return str.substring(0, colon_posn);
 return null;
 }

 /**
 * Retrieves the initial context by calling
 * <code>NamingManager.getInitialContext()</code>
 * and cache it in defaultInitCtx.
 * Set <code>gotDefault</code> so that we know we've tried this before.
 * @return The non-null cached initial context.
 * @exception NoInitialContextException If cannot find an initial context.
 * @exception NamingException If a naming exception was encountered.
 */
 protected Context getDefaultInitCtx() throws NamingException{
 if (!gotDefault) {
 defaultInitCtx = NamingManager.getInitialContext(myProps);
 gotDefault = true;
 }
 if (defaultInitCtx == null)
 throw new NoInitialContextException();

 return defaultInitCtx;
 }

 /**
 * Retrieves a context for resolving the string name <code>name</code>.
 * If <code>name</code> name is a URL string, then attempt
 * to find a URL context for it. If none is found, or if
 * <code>name</code> is not a URL string, then return
 * <code>getDefaultInitCtx()</code>.
 *<p>
 * See getURLOrDefaultInitCtx(Name) for description
 * of how a subclass should use this method.
 * @param name The non-null name for which to get the context.
 * @return A URL context for <code>name</code> or the cached
 * initial context. The result cannot be null.
 * @exception NoInitialContextException If cannot find an initial context.
 * @exception NamingException In a naming exception is encountered.
 * @see javax.naming.spi.NamingManager#getURLContext
 */
 protected Context getURLOrDefaultInitCtx(String name)
 throws NamingException {
 if (NamingManager.hasInitialContextFactoryBuilder()) {
 return getDefaultInitCtx();
 }
 String scheme = getURLScheme(name);
 if (scheme != null) {
 Context ctx = NamingManager.getURLContext(scheme, myProps);
 if (ctx != null) {
 return ctx;
 }
 }
 return getDefaultInitCtx();
 }

 /**
 * Retrieves a context for resolving <code>name</code>.
 * If the first component of <code>name</code> name is a URL string,
 * then attempt to find a URL context for it. If none is found, or if
 * the first component of <code>name</code> is not a URL string,
 * then return <code>getDefaultInitCtx()</code>.
 *<p>
 * When creating a subclass of InitialContext, use this method as
 * follows.
 * Define a new method that uses this method to get an initial
 * context of the desired subclass.
 * <blockquote><pre>
 * protected XXXContext getURLOrDefaultInitXXXCtx(Name name)
 * throws NamingException {
 * Context answer = getURLOrDefaultInitCtx(name);
 * if (!(answer instanceof XXXContext)) {
 * if (answer == null) {
 * throw new NoInitialContextException();
 * } else {
 * throw new NotContextException("Not an XXXContext");
 * }
 * }
 * return (XXXContext)answer;
 * }
 * </pre></blockquote>
 * When providing implementations for the new methods in the subclass,
 * use this newly defined method to get the initial context.
 * <blockquote><pre>
 * public Object XXXMethod1(Name name, ...) {
 * throws NamingException {
 * return getURLOrDefaultInitXXXCtx(name).XXXMethod1(name, ...);
 * }
 * </pre></blockquote>
 *
 * @param name The non-null name for which to get the context.
 * @return A URL context for <code>name</code> or the cached
 * initial context. The result cannot be null.
 * @exception NoInitialContextException If cannot find an initial context.
 * @exception NamingException In a naming exception is encountered.
 *
 * @see javax.naming.spi.NamingManager#getURLContext
 */
 protected Context getURLOrDefaultInitCtx(Name name)
 throws NamingException {
 if (NamingManager.hasInitialContextFactoryBuilder()) {
 return getDefaultInitCtx();
 }
 if (name.size() > 0) {
 String first = name.get(0);
 String scheme = getURLScheme(first);
 if (scheme != null) {
 Context ctx = NamingManager.getURLContext(scheme, myProps);
 if (ctx != null) {
 return ctx;
 }
 }
 }
 return getDefaultInitCtx();
 }

// Context methods
// Most Javadoc is deferred to the Context interface.

 public Object lookup(String name) throws NamingException {
 return getURLOrDefaultInitCtx(name).lookup(name);
 }

 public Object lookup(Name name) throws NamingException {
 return getURLOrDefaultInitCtx(name).lookup(name);
 }

 public void bind(String name, Object obj) throws NamingException {
 getURLOrDefaultInitCtx(name).bind(name, obj);
 }

 public void bind(Name name, Object obj) throws NamingException {
 getURLOrDefaultInitCtx(name).bind(name, obj);
 }

 public void rebind(String name, Object obj) throws NamingException {
 getURLOrDefaultInitCtx(name).rebind(name, obj);
 }

 public void rebind(Name name, Object obj) throws NamingException {
 getURLOrDefaultInitCtx(name).rebind(name, obj);
 }

 public void unbind(String name) throws NamingException {
 getURLOrDefaultInitCtx(name).unbind(name);
 }

 public void unbind(Name name) throws NamingException {
 getURLOrDefaultInitCtx(name).unbind(name);
 }

 public void rename(String oldName, String newName) throws NamingException {
 getURLOrDefaultInitCtx(oldName).rename(oldName, newName);
 }

 public void rename(Name oldName, Name newName)
 throws NamingException
 {
 getURLOrDefaultInitCtx(oldName).rename(oldName, newName);
 }

 public NamingEnumeration<NameClassPair> list(String name)
 throws NamingException
 {
 return (getURLOrDefaultInitCtx(name).list(name));
 }

 public NamingEnumeration<NameClassPair> list(Name name)
 throws NamingException
 {
 return (getURLOrDefaultInitCtx(name).list(name));
 }

 public NamingEnumeration<Binding> listBindings(String name)
 throws NamingException {
 return getURLOrDefaultInitCtx(name).listBindings(name);
 }

 public NamingEnumeration<Binding> listBindings(Name name)
 throws NamingException {
 return getURLOrDefaultInitCtx(name).listBindings(name);
 }

 public void destroySubcontext(String name) throws NamingException {
 getURLOrDefaultInitCtx(name).destroySubcontext(name);
 }

 public void destroySubcontext(Name name) throws NamingException {
 getURLOrDefaultInitCtx(name).destroySubcontext(name);
 }

 public Context createSubcontext(String name) throws NamingException {
 return getURLOrDefaultInitCtx(name).createSubcontext(name);
 }

 public Context createSubcontext(Name name) throws NamingException {
 return getURLOrDefaultInitCtx(name).createSubcontext(name);
 }

 public Object lookupLink(String name) throws NamingException {
 return getURLOrDefaultInitCtx(name).lookupLink(name);
 }

 public Object lookupLink(Name name) throws NamingException {
 return getURLOrDefaultInitCtx(name).lookupLink(name);
 }

 public NameParser getNameParser(String name) throws NamingException {
 return getURLOrDefaultInitCtx(name).getNameParser(name);
 }

 public NameParser getNameParser(Name name) throws NamingException {
 return getURLOrDefaultInitCtx(name).getNameParser(name);
 }

 /**
 * Composes the name of this context with a name relative to
 * this context.
 * Since an initial context may never be named relative
 * to any context other than itself, the value of the
 * <tt>prefix</tt> parameter must be an empty name (<tt>""</tt>).
 */
 public String composeName(String name, String prefix)
 throws NamingException {
 return name;
 }

 /**
 * Composes the name of this context with a name relative to
 * this context.
 * Since an initial context may never be named relative
 * to any context other than itself, the value of the
 * <tt>prefix</tt> parameter must be an empty name.
 */
 public Name composeName(Name name, Name prefix)
 throws NamingException
 {
 return (Name)name.clone();
 }

 public Object addToEnvironment(String propName, Object propVal)
 throws NamingException {
 myProps.put(propName, propVal);
 return getDefaultInitCtx().addToEnvironment(propName, propVal);
 }

 public Object removeFromEnvironment(String propName)
 throws NamingException {
 myProps.remove(propName);
 return getDefaultInitCtx().removeFromEnvironment(propName);
 }

 public Hashtable<?,?> getEnvironment() throws NamingException {
 return getDefaultInitCtx().getEnvironment();
 }

 public void close() throws NamingException {
 myProps = null;
 if (defaultInitCtx != null) {
 defaultInitCtx.close();
 defaultInitCtx = null;
 }
 gotDefault = false;
 }

 public String getNameInNamespace() throws NamingException {
 return getDefaultInitCtx().getNameInNamespace();
 }
};