/*
 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.security;

import java.io.*;
import java.security.cert.Certificate;
import java.security.cert.CertPath;
import java.security.cert.X509Extension;
import java.util.Date;
import java.util.List;

/**
 * This class encapsulates information about a signed timestamp.
 * It is immutable.
 * It includes the timestamp's date and time as well as information about the
 * Timestamping Authority (TSA) which generated and signed the timestamp.
 *
 * @since 1.5
 * @author Vincent Ryan
 */

public final class Timestamp implements Serializable {

 private static final long serialVersionUID = -5502683707821851294L;

 /**
 * The timestamp's date and time
 *
 * @serial
 */
 private Date timestamp;

 /**
 * The TSA's certificate path.
 *
 * @serial
 */
 private CertPath signerCertPath;

 /*
 * Hash code for this timestamp.
 */
 private transient int myhash = -1;

 /**
 * Constructs a Timestamp.
 *
 * @param timestamp is the timestamp's date and time. It must not be null.
 * @param signerCertPath is the TSA's certificate path. It must not be null.
 * @throws NullPointerException if timestamp or signerCertPath is null.
 */
 public Timestamp(Date timestamp, CertPath signerCertPath) {
 if (timestamp == null || signerCertPath == null) {
 throw new NullPointerException();
 }
 this.timestamp = new Date(timestamp.getTime()); // clone
 this.signerCertPath = signerCertPath;
 }

 /**
 * Returns the date and time when the timestamp was generated.
 *
 * @return The timestamp's date and time.
 */
 public Date getTimestamp() {
 return new Date(timestamp.getTime()); // clone
 }

 /**
 * Returns the certificate path for the Timestamping Authority.
 *
 * @return The TSA's certificate path.
 */
 public CertPath getSignerCertPath() {
 return signerCertPath;
 }

 /**
 * Returns the hash code value for this timestamp.
 * The hash code is generated using the date and time of the timestamp
 * and the TSA's certificate path.
 *
 * @return a hash code value for this timestamp.
 */
 public int hashCode() {
 if (myhash == -1) {
 myhash = timestamp.hashCode() + signerCertPath.hashCode();
 }
 return myhash;
 }

 /**
 * Tests for equality between the specified object and this
 * timestamp. Two timestamps are considered equal if the date and time of
 * their timestamp's and their signer's certificate paths are equal.
 *
 * @param obj the object to test for equality with this timestamp.
 *
 * @return true if the timestamp are considered equal, false otherwise.
 */
 public boolean equals(Object obj) {
 if (obj == null || (!(obj instanceof Timestamp))) {
 return false;
 }
 Timestamp that = (Timestamp)obj;

 if (this == that) {
 return true;
 }
 return (timestamp.equals(that.getTimestamp()) &&
 signerCertPath.equals(that.getSignerCertPath()));
 }

 /**
 * Returns a string describing this timestamp.
 *
 * @return A string comprising the date and time of the timestamp and
 * its signer's certificate.
 */
 public String toString() {
 StringBuilder sb = new StringBuilder();
 sb.append("(");
 sb.append("timestamp: " + timestamp);
 List<? extends Certificate> certs = signerCertPath.getCertificates();
 if (!certs.isEmpty()) {
 sb.append("TSA: " + certs.get(0));
 } else {
 sb.append("TSA: <empty>");
 }
 sb.append(")");
 return sb.toString();
 }

 // Explicitly reset hash code value to -1
 private void readObject(ObjectInputStream ois)
 throws IOException, ClassNotFoundException {
 ois.defaultReadObject();
 myhash = -1;
 timestamp = new Date(timestamp.getTime());
 }
}