/*

 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

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() {

        StringBuffer sb = new StringBuffer();

        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());

    }

}