/*

 * Copyright (c) 2003, 2015, 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.sql.rowset.serial;

import java.sql.*;

import java.io.*;

import java.lang.reflect.*;

import java.util.Arrays;

/**

 * A serialized mapping in the Java programming language of an SQL

 * <code>BLOB</code> value.

 * <P>

 * The <code>SerialBlob</code> class provides a constructor for creating

 * an instance from a <code>Blob</code> object.  Note that the

 * <code>Blob</code>

 * object should have brought the SQL <code>BLOB</code> value's data over

 * to the client before a <code>SerialBlob</code> object

 * is constructed from it.  The data of an SQL <code>BLOB</code> value can

 * be materialized on the client as an array of bytes (using the method

 * <code>Blob.getBytes</code>) or as a stream of uninterpreted bytes

 * (using the method <code>Blob.getBinaryStream</code>).

 * <P>

 * <code>SerialBlob</code> methods make it possible to make a copy of a

 * <code>SerialBlob</code> object as an array of bytes or as a stream.

 * They also make it possible to locate a given pattern of bytes or a

 * <code>Blob</code> object within a <code>SerialBlob</code> object

 * and to update or truncate a <code>Blob</code> object.

 *

 * <h3> Thread safety </h3>

 *

 * <p> A SerialBlob is not safe for use by multiple concurrent threads.  If a

 * SerialBlob is to be used by more than one thread then access to the SerialBlob

 * should be controlled by appropriate synchronization.

 *

 * @author Jonathan Bruce

 * @since 1.5

 */

public class SerialBlob implements Blob, Serializable, Cloneable {

    /**

     * A serialized array of uninterpreted bytes representing the

     * value of this <code>SerialBlob</code> object.

     * @serial

     */

    private byte[] buf;

    /**

     * The internal representation of the <code>Blob</code> object on which this

     * <code>SerialBlob</code> object is based.

     */

    private Blob blob;

    /**

     * The number of bytes in this <code>SerialBlob</code> object's

     * array of bytes.

     * @serial

     */

    private long len;

    /**

     * The original number of bytes in this <code>SerialBlob</code> object's

     * array of bytes when it was first established.

     * @serial

     */

    private long origLen;

    /**

     * Constructs a <code>SerialBlob</code> object that is a serialized version of

     * the given <code>byte</code> array.

     * <p>

     * The new <code>SerialBlob</code> object is initialized with the data from the

     * <code>byte</code> array, thus allowing disconnected <code>RowSet</code>

     * objects to establish serialized <code>Blob</code> objects without

     * touching the data source.

     *

     * @param b the <code>byte</code> array containing the data for the

     *        <code>Blob</code> object to be serialized

     * @throws SerialException if an error occurs during serialization

     * @throws SQLException if a SQL errors occurs

     */

    public SerialBlob(byte[] b)

            throws SerialException, SQLException {

        len = b.length;

        buf = new byte[(int)len];

        for(int i = 0; i < len; i++) {

            buf[i] = b[i];

        }

        origLen = len;

    }

    /**

     * Constructs a <code>SerialBlob</code> object that is a serialized

     * version of the given <code>Blob</code> object.

     * <P>

     * The new <code>SerialBlob</code> object is initialized with the

     * data from the <code>Blob</code> object; therefore, the

     * <code>Blob</code> object should have previously brought the

     * SQL <code>BLOB</code> value's data over to the client from

     * the database. Otherwise, the new <code>SerialBlob</code> object

     * will contain no data.

     *

     * @param blob the <code>Blob</code> object from which this

     *     <code>SerialBlob</code> object is to be constructed;

     *     cannot be null.

     * @throws SerialException if an error occurs during serialization

     * @throws SQLException if the <code>Blob</code> passed to this

     *     to this constructor is a <code>null</code>.

     * @see java.sql.Blob

     */

    public SerialBlob (Blob blob)

            throws SerialException, SQLException {

        if (blob == null) {

            throw new SQLException(

                    "Cannot instantiate a SerialBlob object with a null Blob object");

        }

        len = blob.length();

        buf = blob.getBytes(1, (int)len );

        this.blob = blob;

        origLen = len;

    }

    /**

     * Copies the specified number of bytes, starting at the given

     * position, from this <code>SerialBlob</code> object to

     * another array of bytes.

     * <P>

     * Note that if the given number of bytes to be copied is larger than

     * the length of this <code>SerialBlob</code> object's array of

     * bytes, the given number will be shortened to the array's length.

     *

     * @param pos the ordinal position of the first byte in this

     *            <code>SerialBlob</code> object to be copied;

     *            numbering starts at <code>1</code>; must not be less

     *            than <code>1</code> and must be less than or equal

     *            to the length of this <code>SerialBlob</code> object

     * @param length the number of bytes to be copied

     * @return an array of bytes that is a copy of a region of this

     *         <code>SerialBlob</code> object, starting at the given

     *         position and containing the given number of consecutive bytes

     * @throws SerialException if the given starting position is out of bounds;

     * if {@code free} had previously been called on this object

     */

    public byte[] getBytes(long pos, int length) throws SerialException {

        isValid();

        if (length > len) {

            length = (int)len;

        }

        if (pos < 1 || len - pos < 0 ) {

            throw new SerialException("Invalid arguments: position cannot be "

                    + "less than 1 or greater than the length of the SerialBlob");

        }

        pos--; // correct pos to array index

        byte[] b = new byte[length];

        for (int i = 0; i < length; i++) {

            b[i] = this.buf[(int)pos];

            pos++;

        }

        return b;

    }

    /**

     * Retrieves the number of bytes in this <code>SerialBlob</code>

     * object's array of bytes.

     *

     * @return a <code>long</code> indicating the length in bytes of this

     *         <code>SerialBlob</code> object's array of bytes

     * @throws SerialException if an error occurs;

     * if {@code free} had previously been called on this object

     */

    public long length() throws SerialException {

        isValid();

        return len;

    }

    /**

     * Returns this <code>SerialBlob</code> object as an input stream.

     * Unlike the related method, <code>setBinaryStream</code>,

     * a stream is produced regardless of whether the <code>SerialBlob</code>

     * was created with a <code>Blob</code> object or a <code>byte</code> array.

     *

     * @return a <code>java.io.InputStream</code> object that contains

     *         this <code>SerialBlob</code> object's array of bytes

     * @throws SerialException if an error occurs;

     * if {@code free} had previously been called on this object

     * @see #setBinaryStream

     */

    public java.io.InputStream getBinaryStream() throws SerialException {

        isValid();

        InputStream stream = new ByteArrayInputStream(buf);

        return stream;

    }

    /**

     * Returns the position in this <code>SerialBlob</code> object where

     * the given pattern of bytes begins, starting the search at the

     * specified position.

     *

     * @param pattern the pattern of bytes for which to search

     * @param start the position of the byte in this

     *              <code>SerialBlob</code> object from which to begin

     *              the search; the first position is <code>1</code>;

     *              must not be less than <code>1</code> nor greater than

     *              the length of this <code>SerialBlob</code> object

     * @return the position in this <code>SerialBlob</code> object

     *         where the given pattern begins, starting at the specified

     *         position; <code>-1</code> if the pattern is not found

     *         or the given starting position is out of bounds; position

     *         numbering for the return value starts at <code>1</code>

     * @throws SerialException if an error occurs when serializing the blob;

     * if {@code free} had previously been called on this object

     * @throws SQLException if there is an error accessing the <code>BLOB</code>

     *         value from the database

     */

    public long position(byte[] pattern, long start)

            throws SerialException, SQLException {

        isValid();

        if (start < 1 || start > len) {

            return -1;

        }

        int pos = (int)start-1; // internally Blobs are stored as arrays.

        int i = 0;

        long patlen = pattern.length;

        while (pos < len) {

            if (pattern[i] == buf[pos]) {

                if (i + 1 == patlen) {

                    return (pos + 1) - (patlen - 1);

                }

                i++; pos++; // increment pos, and i

            } else if (pattern[i] != buf[pos]) {

                pos++; // increment pos only

            }

        }

        return -1; // not found

    }

    /**

     * Returns the position in this <code>SerialBlob</code> object where

     * the given <code>Blob</code> object begins, starting the search at the

     * specified position.

     *

     * @param pattern the <code>Blob</code> object for which to search;

     * @param start the position of the byte in this

     *              <code>SerialBlob</code> object from which to begin

     *              the search; the first position is <code>1</code>;

     *              must not be less than <code>1</code> nor greater than

     *              the length of this <code>SerialBlob</code> object

     * @return the position in this <code>SerialBlob</code> object

     *         where the given <code>Blob</code> object begins, starting

     *         at the specified position; <code>-1</code> if the pattern is

     *         not found or the given starting position is out of bounds;

     *         position numbering for the return value starts at <code>1</code>

     * @throws SerialException if an error occurs when serializing the blob;

     * if {@code free} had previously been called on this object

     * @throws SQLException if there is an error accessing the <code>BLOB</code>

     *         value from the database

     */

    public long position(Blob pattern, long start)

            throws SerialException, SQLException {

        isValid();

        return position(pattern.getBytes(1, (int)(pattern.length())), start);

    }

    /**

     * Writes the given array of bytes to the <code>BLOB</code> value that

     * this <code>Blob</code> object represents, starting at position

     * <code>pos</code>, and returns the number of bytes written.

     *

     * @param pos the position in the SQL <code>BLOB</code> value at which

     *     to start writing. The first position is <code>1</code>;

     *     must not be less than <code>1</code> nor greater than

     *     the length of this <code>SerialBlob</code> object.

     * @param bytes the array of bytes to be written to the <code>BLOB</code>

     *        value that this <code>Blob</code> object represents

     * @return the number of bytes written

     * @throws SerialException if there is an error accessing the

     *     <code>BLOB</code> value; or if an invalid position is set; if an

     *     invalid offset value is set;

     * if {@code free} had previously been called on this object

     * @throws SQLException if there is an error accessing the <code>BLOB</code>

     *         value from the database

     * @see #getBytes

     */

    public int setBytes(long pos, byte[] bytes)

            throws SerialException, SQLException {

        return setBytes(pos, bytes, 0, bytes.length);

    }

    /**

     * Writes all or part of the given <code>byte</code> array to the

     * <code>BLOB</code> value that this <code>Blob</code> object represents

     * and returns the number of bytes written.

     * Writing starts at position <code>pos</code> in the <code>BLOB</code>

     * value; <i>len</i> bytes from the given byte array are written.

     *

     * @param pos the position in the <code>BLOB</code> object at which

     *     to start writing. The first position is <code>1</code>;

     *     must not be less than <code>1</code> nor greater than

     *     the length of this <code>SerialBlob</code> object.

     * @param bytes the array of bytes to be written to the <code>BLOB</code>

     *     value

     * @param offset the offset in the <code>byte</code> array at which

     *     to start reading the bytes. The first offset position is

     *     <code>0</code>; must not be less than <code>0</code> nor greater

     *     than the length of the <code>byte</code> array

     * @param length the number of bytes to be written to the

     *     <code>BLOB</code> value from the array of bytes <i>bytes</i>.

     *

     * @return the number of bytes written

     * @throws SerialException if there is an error accessing the

     *     <code>BLOB</code> value; if an invalid position is set; if an

     *     invalid offset value is set; if number of bytes to be written

     *     is greater than the <code>SerialBlob</code> length; or the combined

     *     values of the length and offset is greater than the Blob buffer;

     * if {@code free} had previously been called on this object

     * @throws SQLException if there is an error accessing the <code>BLOB</code>

     *         value from the database.

     * @see #getBytes

     */

    public int setBytes(long pos, byte[] bytes, int offset, int length)

            throws SerialException, SQLException {

        isValid();

        if (offset < 0 || offset > bytes.length) {

            throw new SerialException("Invalid offset in byte array set");

        }

        if (pos < 1 || pos > this.length()) {

            throw new SerialException("Invalid position in BLOB object set");

        }

        if ((long)(length) > origLen) {

            throw new SerialException("Buffer is not sufficient to hold the value");

        }

        if ((length + offset) > bytes.length) {

            throw new SerialException("Invalid OffSet. Cannot have combined offset " +

                    "and length that is greater that the Blob buffer");

        }

        int i = 0;

        pos--; // correct to array indexing

        while ( i < length || (offset + i +1) < (bytes.length-offset) ) {

            this.buf[(int)pos + i] = bytes[offset + i ];

            i++;

        }

        return i;

    }

    /**

     * Retrieves a stream that can be used to write to the <code>BLOB</code>

     * value that this <code>Blob</code> object represents.  The stream begins

     * at position <code>pos</code>. This method forwards the

     * <code>setBinaryStream()</code> call to the underlying <code>Blob</code> in

     * the event that this <code>SerialBlob</code> object is instantiated with a

     * <code>Blob</code>. If this <code>SerialBlob</code> is instantiated with

     * a <code>byte</code> array, a <code>SerialException</code> is thrown.

     *

     * @param pos the position in the <code>BLOB</code> value at which

     *        to start writing

     * @return a <code>java.io.OutputStream</code> object to which data can

     *         be written

     * @throws SQLException if there is an error accessing the

     *            <code>BLOB</code> value

     * @throws SerialException if the SerialBlob in not instantiated with a

     *     <code>Blob</code> object that supports <code>setBinaryStream()</code>;

     * if {@code free} had previously been called on this object

     * @see #getBinaryStream

     */

    public java.io.OutputStream setBinaryStream(long pos)

            throws SerialException, SQLException {

        isValid();

        if (this.blob != null) {

            return this.blob.setBinaryStream(pos);

        } else {

            throw new SerialException("Unsupported operation. SerialBlob cannot " +

                "return a writable binary stream, unless instantiated with a Blob object " +

                "that provides a setBinaryStream() implementation");

        }

    }

    /**

     * Truncates the <code>BLOB</code> value that this <code>Blob</code>

     * object represents to be <code>len</code> bytes in length.

     *

     * @param length the length, in bytes, to which the <code>BLOB</code>

     *        value that this <code>Blob</code> object represents should be

     *        truncated

     * @throws SerialException if there is an error accessing the Blob value;

     *     or the length to truncate is greater that the SerialBlob length;

     * if {@code free} had previously been called on this object

     */

    public void truncate(long length) throws SerialException {

        isValid();

        if (length > len) {

            throw new SerialException(

                    "Length more than what can be truncated");

        } else if((int)length == 0) {

            buf = new byte[0];

            len = length;

        } else {

            len = length;

            buf = this.getBytes(1, (int)len);

        }

    }

    /**

     * Returns an

     * <code>InputStream</code> object that contains a partial

     * {@code Blob} value, starting with the byte specified by pos, which is

     * length bytes in length.

     *

     * @param pos the offset to the first byte of the partial value to be

     * retrieved. The first byte in the {@code Blob} is at position 1

     * @param length the length in bytes of the partial value to be retrieved

     * @return

     * <code>InputStream</code> through which the partial {@code Blob} value can

     * be read.

     * @throws SQLException if pos is less than 1 or if pos is greater than the

     * number of bytes in the {@code Blob} or if pos + length is greater than

     * the number of bytes in the {@code Blob}

     * @throws SerialException if the {@code free} method had been previously

     * called on this object

     *

     * @since 1.6

     */

    public InputStream getBinaryStream(long pos, long length) throws SQLException {

        isValid();

        if (pos < 1 || pos > this.length()) {

            throw new SerialException("Invalid position in BLOB object set");

        }

        if (length < 1 || length > len - pos + 1) {

            throw new SerialException(

                    "length is < 1 or pos + length > total number of bytes");

        }

        return new ByteArrayInputStream(buf, (int) pos - 1, (int) length);

    }

    /**

     * This method frees the {@code SerialBlob} object and releases the

     * resources that it holds. The object is invalid once the {@code free}

     * method is called. <p> If {@code free} is called multiple times, the

     * subsequent calls to {@code free} are treated as a no-op. </P>

     *

     * @throws SQLException if an error occurs releasing the Blob's resources

     * @since 1.6

     */

    public void free() throws SQLException {

        if (buf != null) {

            buf = null;

            if (blob != null) {

                blob.free();

            }

            blob = null;

        }

    }

    /**

     * Compares this SerialBlob to the specified object.  The result is {@code

     * true} if and only if the argument is not {@code null} and is a {@code

     * SerialBlob} object that represents the same sequence of bytes as this

     * object.

     *

     * @param  obj The object to compare this {@code SerialBlob} against

     *

     * @return {@code true} if the given object represents a {@code SerialBlob}

     *          equivalent to this SerialBlob, {@code false} otherwise

     *

     */

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (obj instanceof SerialBlob) {

            SerialBlob sb = (SerialBlob)obj;