/*

 * Copyright (c) 2005, 2013, 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 javax.smartcardio;

import java.util.Arrays;

/**

 * A response APDU as defined in ISO/IEC 7816-4. It consists of a conditional

 * body and a two byte trailer.

 * This class does not attempt to verify that the APDU encodes a semantically

 * valid response.

 *

 * <p>Instances of this class are immutable. Where data is passed in or out

 * via byte arrays, defensive cloning is performed.

 *

 * @see CommandAPDU

 * @see CardChannel#transmit CardChannel.transmit

 *

 * @since   1.6

 * @author  Andreas Sterbenz

 * @author  JSR 268 Expert Group

 */

public final class ResponseAPDU implements java.io.Serializable {

    private static final long serialVersionUID = 6962744978375594225L;

    /** @serial */

    private byte[] apdu;

    /**

     * Constructs a ResponseAPDU from a byte array containing the complete

     * APDU contents (conditional body and trailed).

     *

     * <p>Note that the byte array is cloned to protect against subsequent

     * modification.

     *

     * @param apdu the complete response APDU

     *

     * @throws NullPointerException if apdu is null

     * @throws IllegalArgumentException if apdu.length is less than 2

     */

    public ResponseAPDU(byte[] apdu) {

        apdu = apdu.clone();

        check(apdu);

        this.apdu = apdu;

    }

    private static void check(byte[] apdu) {

        if (apdu.length < 2) {

            throw new IllegalArgumentException("apdu must be at least 2 bytes long");

        }

    }

    /**

     * Returns the number of data bytes in the response body (Nr) or 0 if this

     * APDU has no body. This call is equivalent to

     * <code>getData().length</code>.

     *

     * @return the number of data bytes in the response body or 0 if this APDU

     * has no body.

     */

    public int getNr() {

        return apdu.length - 2;

    }

    /**

     * Returns a copy of the data bytes in the response body. If this APDU as

     * no body, this method returns a byte array with a length of zero.

     *

     * @return a copy of the data bytes in the response body or the empty

     *    byte array if this APDU has no body.

     */

    public byte[] getData() {

        byte[] data = new byte[apdu.length - 2];

        System.arraycopy(apdu, 0, data, 0, data.length);

        return data;

    }

    /**

     * Returns the value of the status byte SW1 as a value between 0 and 255.

     *

     * @return the value of the status byte SW1 as a value between 0 and 255.

     */

    public int getSW1() {

        return apdu[apdu.length - 2] & 0xff;

    }

    /**

     * Returns the value of the status byte SW2 as a value between 0 and 255.

     *

     * @return the value of the status byte SW2 as a value between 0 and 255.

     */

    public int getSW2() {

        return apdu[apdu.length - 1] & 0xff;

    }

    /**

     * Returns the value of the status bytes SW1 and SW2 as a single

     * status word SW.

     * It is defined as

     * {@code (getSW1() << 8) | getSW2()}

     *

     * @return the value of the status word SW.

     */

    public int getSW() {

        return (getSW1() << 8) | getSW2();

    }

    /**

     * Returns a copy of the bytes in this APDU.

     *

     * @return a copy of the bytes in this APDU.

     */

    public byte[] getBytes() {

        return apdu.clone();

    }

    /**

     * Returns a string representation of this response APDU.

     *

     * @return a String representation of this response APDU.

     */

    public String toString() {

        return "ResponseAPDU: " + apdu.length + " bytes, SW="

            + Integer.toHexString(getSW());

    }

    /**

     * Compares the specified object with this response APDU for equality.

     * Returns true if the given object is also a ResponseAPDU and its bytes are

     * identical to the bytes in this ResponseAPDU.

     *

     * @param obj the object to be compared for equality with this response APDU

     * @return true if the specified object is equal to this response APDU

     */

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (obj instanceof ResponseAPDU == false) {

            return false;

        }

        ResponseAPDU other = (ResponseAPDU)obj;

        return Arrays.equals(this.apdu, other.apdu);

    }

    /**

     * Returns the hash code value for this response APDU.

     *

     * @return the hash code value for this response APDU.

     */

    public int hashCode() {

        return Arrays.hashCode(apdu);

    }

    private void readObject(java.io.ObjectInputStream in)

            throws java.io.IOException, ClassNotFoundException {

        apdu = (byte[])in.readUnshared();

        check(apdu);

    }

}