/*
 * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package javax.naming;

import java.util.Vector;
import java.util.Enumeration;

/**
 * This class represents a reference to an object that is found outside of
 * the naming/directory system.
 *<p>
 * Reference provides a way of recording address information about
 * objects which themselves are not directly bound to the naming/directory system.
 *<p>
 * A Reference consists of an ordered list of addresses and class information
 * about the object being referenced.
 * Each address in the list identifies a communications endpoint
 * for the same conceptual object. The "communications endpoint"
 * is information that indicates how to contact the object. It could
 * be, for example, a network address, a location in memory on the
 * local machine, another process on the same machine, etc.
 * The order of the addresses in the list may be of significance
 * to object factories that interpret the reference.
 *<p>
 * Multiple addresses may arise for
 * various reasons, such as replication or the object offering interfaces
 * over more than one communication mechanism. The addresses are indexed
 * starting with zero.
 *<p>
 * A Reference also contains information to assist in creating an instance
 * of the object to which this Reference refers. It contains the class name
 * of that object, and the class name and location of the factory to be used
 * to create the object.
 * The class factory location is a space-separated list of URLs representing
 * the class path used to load the factory. When the factory class (or
 * any class or resource upon which it depends) needs to be loaded,
 * each URL is used (in order) to attempt to load the class.
 *<p>
 * A Reference instance is not synchronized against concurrent access by multiple
 * threads. Threads that need to access a single Reference concurrently should
 * synchronize amongst themselves and provide the necessary locking.
 *
 * @author Rosanna Lee
 * @author Scott Seligman
 *
 * @see RefAddr
 * @see StringRefAddr
 * @see BinaryRefAddr
 * @since 1.3
 */

 /*<p>
 * The serialized form of a Reference object consists of the class
 * name of the object being referenced (a String), a Vector of the
 * addresses (each a RefAddr), the name of the class factory (a
 * String), and the location of the class factory (a String).
*/


public class Reference implements Cloneable, java.io.Serializable {
 /**
 * Contains the fully-qualified name of the class of the object to which
 * this Reference refers.
 * @serial
 * @see java.lang.Class#getName
 */
 protected String className;
 /**
 * Contains the addresses contained in this Reference.
 * Initialized by constructor.
 * @serial
 */
 protected Vector<RefAddr> addrs = null;

 /**
 * Contains the name of the factory class for creating
 * an instance of the object to which this Reference refers.
 * Initialized to null.
 * @serial
 */
 protected String classFactory = null;

 /**
 * Contains the location of the factory class.
 * Initialized to null.
 * @serial
 */
 protected String classFactoryLocation = null;

 /**
 * Constructs a new reference for an object with class name 'className'.
 * Class factory and class factory location are set to null.
 * The newly created reference contains zero addresses.
 *
 * @param className The non-null class name of the object to which
 * this reference refers.
 */
 public Reference(String className) {
 this.className = className;
 addrs = new Vector<>();
 }

 /**
 * Constructs a new reference for an object with class name 'className' and
 * an address.
 * Class factory and class factory location are set to null.
 *
 * @param className The non-null class name of the object to
 * which this reference refers.
 * @param addr The non-null address of the object.
 */
 public Reference(String className, RefAddr addr) {
 this.className = className;
 addrs = new Vector<>();
 addrs.addElement(addr);
 }

 /**
 * Constructs a new reference for an object with class name 'className',
 * and the class name and location of the object's factory.
 *
 * @param className The non-null class name of the object to which
 * this reference refers.
 * @param factory The possibly null class name of the object's factory.
 * @param factoryLocation
 * The possibly null location from which to load
 * the factory (e.g. URL)
 * @see javax.naming.spi.ObjectFactory
 * @see javax.naming.spi.NamingManager#getObjectInstance
 */
 public Reference(String className, String factory, String factoryLocation) {
 this(className);
 classFactory = factory;
 classFactoryLocation = factoryLocation;
 }

 /**
 * Constructs a new reference for an object with class name 'className',
 * the class name and location of the object's factory, and the address for
 * the object.
 *
 * @param className The non-null class name of the object to
 * which this reference refers.
 * @param factory The possibly null class name of the object's factory.
 * @param factoryLocation The possibly null location from which
 * to load the factory (e.g. URL)
 * @param addr The non-null address of the object.
 * @see javax.naming.spi.ObjectFactory
 * @see javax.naming.spi.NamingManager#getObjectInstance
 */
 public Reference(String className, RefAddr addr,
 String factory, String factoryLocation) {
 this(className, addr);
 classFactory = factory;
 classFactoryLocation = factoryLocation;
 }

 /**
 * Retrieves the class name of the object to which this reference refers.
 *
 * @return The non-null fully-qualified class name of the object.
 * (e.g. "java.lang.String")
 */
 public String getClassName() {
 return className;
 }

 /**
 * Retrieves the class name of the factory of the object
 * to which this reference refers.
 *
 * @return The possibly null fully-qualified class name of the factory.
 * (e.g. "java.lang.String")
 */
 public String getFactoryClassName() {
 return classFactory;
 }

 /**
 * Retrieves the location of the factory of the object
 * to which this reference refers.
 * If it is a codebase, then it is an ordered list of URLs,
 * separated by spaces, listing locations from where the factory
 * class definition should be loaded.
 *
 * @return The possibly null string containing the
 * location for loading in the factory's class.
 */
 public String getFactoryClassLocation() {
 return classFactoryLocation;
 }

 /**
 * Retrieves the first address that has the address type 'addrType'.
 * String.compareTo() is used to test the equality of the address types.
 *
 * @param addrType The non-null address type for which to find the address.
 * @return The address in this reference with address type 'addrType;
 * null if no such address exist.
 */
 public RefAddr get(String addrType) {
 int len = addrs.size();
 RefAddr addr;
 for (int i = 0; i < len; i++) {
 addr = addrs.elementAt(i);
 if (addr.getType().compareTo(addrType) == 0)
 return addr;
 }
 return null;
 }

 /**
 * Retrieves the address at index posn.
 * @param posn The index of the address to retrieve.
 * @return The address at the 0-based index posn. It must be in the
 * range [0,getAddressCount()).
 * @exception ArrayIndexOutOfBoundsException If posn not in the specified
 * range.
 */
 public RefAddr get(int posn) {
 return addrs.elementAt(posn);
 }

 /**
 * Retrieves an enumeration of the addresses in this reference.
 * When addresses are added, changed or removed from this reference,
 * its effects on this enumeration are undefined.
 *
 * @return An non-null enumeration of the addresses
 * (<tt>RefAddr</tt>) in this reference.
 * If this reference has zero addresses, an enumeration with
 * zero elements is returned.
 */
 public Enumeration<RefAddr> getAll() {
 return addrs.elements();
 }

 /**
 * Retrieves the number of addresses in this reference.
 *
 * @return The nonnegative number of addresses in this reference.
 */
 public int size() {
 return addrs.size();
 }

 /**
 * Adds an address to the end of the list of addresses.
 *
 * @param addr The non-null address to add.
 */
 public void add(RefAddr addr) {
 addrs.addElement(addr);
 }

 /**
 * Adds an address to the list of addresses at index posn.
 * All addresses at index posn or greater are shifted up
 * the list by one (away from index 0).
 *
 * @param posn The 0-based index of the list to insert addr.
 * @param addr The non-null address to add.
 * @exception ArrayIndexOutOfBoundsException If posn not in the specified
 * range.
 */
 public void add(int posn, RefAddr addr) {
 addrs.insertElementAt(addr, posn);
 }

 /**
 * Deletes the address at index posn from the list of addresses.
 * All addresses at index greater than posn are shifted down
 * the list by one (towards index 0).
 *
 * @param posn The 0-based index of in address to delete.
 * @return The address removed.
 * @exception ArrayIndexOutOfBoundsException If posn not in the specified
 * range.
 */
 public Object remove(int posn) {
 Object r = addrs.elementAt(posn);
 addrs.removeElementAt(posn);
 return r;
 }

 /**
 * Deletes all addresses from this reference.
 */
 public void clear() {
 addrs.setSize(0);
 }

 /**
 * Determines whether obj is a reference with the same addresses
 * (in same order) as this reference.
 * The addresses are checked using RefAddr.equals().
 * In addition to having the same addresses, the Reference also needs to
 * have the same class name as this reference.
 * The class factory and class factory location are not checked.
 * If obj is null or not an instance of Reference, null is returned.
 *
 * @param obj The possibly null object to check.
 * @return true if obj is equal to this reference; false otherwise.
 */
 public boolean equals(Object obj) {
 if ((obj != null) && (obj instanceof Reference)) {
 Reference target = (Reference)obj;
 // ignore factory information
 if (target.className.equals(this.className) &&
 target.size() == this.size()) {
 Enumeration<RefAddr> mycomps = getAll();
 Enumeration<RefAddr> comps = target.getAll();
 while (mycomps.hasMoreElements())
 if (!(mycomps.nextElement().equals(comps.nextElement())))
 return false;
 return true;
 }
 }
 return false;
 }

 /**
 * Computes the hash code of this reference.
 * The hash code is the sum of the hash code of its addresses.
 *
 * @return A hash code of this reference as an int.
 */
 public int hashCode() {
 int hash = className.hashCode();
 for (Enumeration<RefAddr> e = getAll(); e.hasMoreElements();)
 hash += e.nextElement().hashCode();
 return hash;
 }

 /**
 * Generates the string representation of this reference.
 * The string consists of the class name to which this reference refers,
 * and the string representation of each of its addresses.
 * This representation is intended for display only and not to be parsed.
 *
 * @return The non-null string representation of this reference.
 */
 public String toString() {
 StringBuffer buf = new StringBuffer("Reference Class Name: " +
 className + "\n");
 int len = addrs.size();
 for (int i = 0; i < len; i++)
 buf.append(get(i).toString());

 return buf.toString();
 }

 /**
 * Makes a copy of this reference using its class name
 * list of addresses, class factory name and class factory location.
 * Changes to the newly created copy does not affect this Reference
 * and vice versa.
 */
 public Object clone() {
 Reference r = new Reference(className, classFactory, classFactoryLocation);
 Enumeration<RefAddr> a = getAll();
 r.addrs = new Vector<>();

 while (a.hasMoreElements())
 r.addrs.addElement(a.nextElement());
 return r;
 }
 /**
 * Use serialVersionUID from JNDI 1.1.1 for interoperability
 */
 private static final long serialVersionUID = -1673475790065791735L;
};