/*
 * Copyright (c) 2003, 2023, 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
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 */

package java.security;

import java.io.*;
import java.security.cert.CertPath;
import java.util.Objects;

/**
 * This class encapsulates information about a code signer.
 * It is immutable.
 *
 * @since 1.5
 * @author Vincent Ryan
 */

public final class CodeSigner implements Serializable {

    @java.io.Serial
    private static final long serialVersionUID = 6819288105193937581L;

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

    /**
     * The signature timestamp.
     *
     * @serial
     */
    private final Timestamp timestamp;

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

    /**
     * Constructs a {@code CodeSigner} object.
     *
     * @param signerCertPath The signer's certificate path.
     *                       It must not be {@code null}.
     * @param timestamp A signature timestamp.
     *                  If {@code null} then no timestamp was generated
     *                  for the signature.
     * @throws NullPointerException if {@code signerCertPath} is
     *                              {@code null}.
     */
    public CodeSigner(CertPath signerCertPath, Timestamp timestamp) {
        if (signerCertPath == null) {
            throw new NullPointerException();
        }
        this.signerCertPath = signerCertPath;
        this.timestamp = timestamp;
    }

    /**
     * Returns the signer's certificate path.
     *
     * @return A certificate path.
     */
    public CertPath getSignerCertPath() {
        return signerCertPath;
    }

    /**
     * Returns the signature timestamp.
     *
     * @return The timestamp or {@code null} if none is present.
     */
    public Timestamp getTimestamp() {
        return timestamp;
    }

    /**
     * {@return the hash code value for this code signer}
     * The hash code is generated using the signer's certificate path and the
     * timestamp, if present.
     */
    @Override
    public int hashCode() {
        if (myhash == -1) {
            myhash = signerCertPath.hashCode() + Objects.hashCode(timestamp);
        }
        return myhash;
    }

    /**
     * Tests for equality between the specified object and this
     * code signer. Two code signers are considered equal if their
     * signer certificate paths are equal and if their timestamps are equal,
     * if present in both.
     *
     * @param obj the object to test for equality with this object.
     *
     * @return {@code true} if the objects are considered equal,
     * {@code false} otherwise.
     */
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        return obj instanceof CodeSigner other
                && Objects.equals(timestamp, other.getTimestamp())
                && signerCertPath.equals(other.getSignerCertPath());
    }

    /**
     * Returns a string describing this code signer.
     *
     * @return A string comprising the signer's certificate and a timestamp,
     *         if present.
     */
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("(");
        sb.append("Signer: ").append(signerCertPath.getCertificates().get(0));
        if (timestamp != null) {
            sb.append("timestamp: ").append(timestamp);
        }
        sb.append(")");
        return sb.toString();
    }

    /**
     * Restores the state of this object from the stream, and explicitly
     * resets hash code value to -1.
     *
     * @param  ois the {@code ObjectInputStream} from which data is read
     * @throws IOException if an I/O error occurs
     * @throws ClassNotFoundException if a serialized class cannot be loaded
     */
    @java.io.Serial
    private void readObject(ObjectInputStream ois)
            throws IOException, ClassNotFoundException {
        ois.defaultReadObject();
        if (signerCertPath == null) {
            throw new InvalidObjectException("signerCertPath is null");
        }
        myhash = -1;
    }
}