/*

 * Copyright (c) 2003, 2018, 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 javax.sql.rowset.serial;

import java.sql.*;

import java.io.*;

import java.util.Arrays;

/**

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

 * <code>CLOB</code> value.

 * <P>

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

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

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

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

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

 * be materialized on the client as a stream of Unicode characters.

 * <P>

 * <code>SerialClob</code> methods make it possible to get a substring

 * from a <code>SerialClob</code> object or to locate the start of

 * a pattern of characters.

 *

 * <h3> Thread safety </h3>

 *

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

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

 * should be controlled by appropriate synchronization.

 *

 * @author Jonathan Bruce

 * @since 1.5

 */

public class SerialClob implements Clob, Serializable, Cloneable {

    /**

     * A serialized array of characters containing the data of the SQL

     * <code>CLOB</code> value that this <code>SerialClob</code> object

     * represents.

     *

     * @serial

     */

    private char buf[];

    /**

     * Internal Clob representation if SerialClob is initialized with a

     * Clob. Null if SerialClob is initialized with a char[].

     */

    private Clob clob;

    /**

     * The length in characters of this <code>SerialClob</code> object's

     * internal array of characters.

     *

     * @serial

     */

    private long len;

    /**

     * The original length in characters of this <code>SerialClob</code>

     * object's internal array of characters.

     *

     * @serial

     */

    private long origLen;

    /**

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

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

     * <p>

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

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

     * objects to establish a serialized <code>Clob</code> object without touching

     * the data source.

     *

     * @param ch the char array representing the <code>Clob</code> object to be

     *         serialized

     * @throws SerialException if an error occurs during serialization

     * @throws SQLException if a SQL error occurs

     */

    public SerialClob(char ch[]) throws SerialException, SQLException {

        // %%% JMB. Agreed. Add code here to throw a SQLException if no

        // support is available for locatorsUpdateCopy=false

        // Serializing locators is not supported.

        len = ch.length;

        buf = new char[(int)len];

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

           buf[i] = ch[i];

        }

        origLen = len;

        clob = null;

    }

    /**

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

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

     * <P>

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

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

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

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

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

     * object will contain no data.

     * <p>

     * Note: The <code>Clob</code> object supplied to this constructor must

     * return non-null for both the <code>Clob.getCharacterStream()</code>

     * and <code>Clob.getAsciiStream</code> methods. This <code>SerialClob</code>

     * constructor cannot serialize a <code>Clob</code> object in this instance

     * and will throw an <code>SQLException</code> object.

     *

     * @param  clob the <code>Clob</code> object from which this

     *     <code>SerialClob</code> object is to be constructed; cannot be null

     * @throws SerialException if an error occurs during serialization

     * @throws SQLException if a SQL error occurs in capturing the CLOB;

     *     if the <code>Clob</code> object is a null; or if either of the

     *     <code>Clob.getCharacterStream()</code> and <code>Clob.getAsciiStream()</code>

     *     methods on the <code>Clob</code> returns a null

     * @see java.sql.Clob

     */

    public SerialClob(Clob clob) throws SerialException, SQLException {

        if (clob == null) {

            throw new SQLException("Cannot instantiate a SerialClob " +

                "object with a null Clob object");

        }

        len = clob.length();

        this.clob = clob;

        buf = new char[(int)len];

        int read = 0;

        int offset = 0;

        try (Reader charStream = clob.getCharacterStream()) {

            if (charStream == null) {

                throw new SQLException("Invalid Clob object. The call to getCharacterStream " +

                    "returned null which cannot be serialized.");

            }

            // Note: get an ASCII stream in order to null-check it,

            // even though we don't do anything with it.

            try (InputStream asciiStream = clob.getAsciiStream()) {

                if (asciiStream == null) {

                    throw new SQLException("Invalid Clob object. The call to getAsciiStream " +

                        "returned null which cannot be serialized.");

                }

            }

            try (Reader reader = new BufferedReader(charStream)) {

                do {

                    read = reader.read(buf, offset, (int)(len - offset));

                    offset += read;

                } while (read > 0);

            }

        } catch (java.io.IOException ex) {

            throw new SerialException("SerialClob: " + ex.getMessage());

        }

        origLen = len;

    }

    /**

     * Retrieves the number of characters in this <code>SerialClob</code>

     * object's array of characters.

     *

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

     *         <code>SerialClob</code> object's array of character

     * @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>SerialClob</code> object's data as a stream

     * of Unicode characters. Unlike the related method, <code>getAsciiStream</code>,

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

     * was created with a <code>Clob</code> object or a <code>char</code> array.

     *

     * @return a <code>java.io.Reader</code> object containing this

     *         <code>SerialClob</code> object's data

     * @throws SerialException if an error occurs;

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

     */

    public java.io.Reader getCharacterStream() throws SerialException {

        isValid();

        return (java.io.Reader) new CharArrayReader(buf);

    }

    /**

     * Retrieves the <code>CLOB</code> value designated by this <code>SerialClob</code>

     * object as an ascii stream. This method forwards the <code>getAsciiStream</code>

     * call to the underlying <code>Clob</code> object in the event that this

     * <code>SerialClob</code> object is instantiated with a <code>Clob</code>

     * object. If this <code>SerialClob</code> object is instantiated with

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

     *

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

     *     this <code>SerialClob</code> object's data

     * @throws SerialException if this {@code SerialClob} object was not

     * instantiated with a <code>Clob</code> object;

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

     * @throws SQLException if there is an error accessing the

     *     <code>CLOB</code> value represented by the <code>Clob</code> object

     * that was used to create this <code>SerialClob</code> object

     */

    public java.io.InputStream getAsciiStream() throws SerialException, SQLException {

        isValid();

        if (this.clob != null) {

            return this.clob.getAsciiStream();

        } else {

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

                "return a the CLOB value as an ascii stream, unless instantiated " +

                "with a fully implemented Clob object.");

        }

    }

    /**

     * Returns a copy of the substring contained in this

     * <code>SerialClob</code> object, starting at the given position

     * and continuing for the specified number or characters.

     *

     * @param pos the position of the first character in the substring

     *            to be copied; the first character of the

     *            <code>SerialClob</code> object is at position

     *            <code>1</code>; must not be less than <code>1</code>,

     *            and the sum of the starting position and the length

     *            of the substring must be less than the length of this

     *            <code>SerialClob</code> object

     * @param length the number of characters in the substring to be

     *               returned; must not be greater than the length of

     *               this <code>SerialClob</code> object, and the

     *               sum of the starting position and the length

     *               of the substring must be less than the length of this

     *               <code>SerialClob</code> object

     * @return a <code>String</code> object containing a substring of

     *         this <code>SerialClob</code> object beginning at the

     *         given position and containing the specified number of

     *         consecutive characters

     * @throws SerialException if either of the arguments is out of bounds;

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

     */

    public String getSubString(long pos, int length) throws SerialException {

        isValid();

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

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

        }

        if ((pos-1) + length > this.length()) {

            throw new SerialException("Invalid position and substring length");

        }

        try {

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

        } catch (StringIndexOutOfBoundsException e) {

            throw new SerialException("StringIndexOutOfBoundsException: " +

                e.getMessage());

        }

    }

    /**

     * Returns the position in this <code>SerialClob</code> object

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

     * the search at the specified position. This method returns

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

     *

     * @param searchStr the <code>String</code> object for which to

     *                  search

     * @param start the position in this <code>SerialClob</code> object

     *         at which to start 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>SerialClob</code> object

     * @return the position at which the given <code>String</code> object

     *         begins, starting the search at the specified position;

     *         <code>-1</code> if the given <code>String</code> object is

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

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

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

     * previously called on this object

     * @throws SQLException if there is an error accessing the Clob value

     *         from the database.

     */

    public long position(String searchStr, long start)

        throws SerialException, SQLException {

        isValid();

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

            return -1;

        }

        char pattern[] = searchStr.toCharArray();

        int pos = (int)start-1;

        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>SerialClob</code> object

     * where the given <code>Clob</code> signature begins, starting

     * the search at the specified position. This method returns

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

     *

     * @param searchStr the <code>Clob</code> object for which to search

     * @param start the position in this <code>SerialClob</code> object

     *        at 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>SerialClob</code> object

     * @return the position at which the given <code>Clob</code>

     *         object begins in this <code>SerialClob</code> object,

     *         at or after the specified starting position

     * @throws SerialException if an error occurs locating the Clob signature;

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

     * @throws SQLException if there is an error accessing the Clob value

     *         from the database

     */

    public long position(Clob searchStr, long start)

        throws SerialException, SQLException {

        isValid();

        return position(searchStr.getSubString(1,(int)searchStr.length()), start);

    }

    /**

     * Writes the given Java <code>String</code> to the <code>CLOB</code>

     * value that this <code>SerialClob</code> object represents, at the position

     * <code>pos</code>.

     *

     * @param pos the position at which to start writing to the <code>CLOB</code>

     *         value that this <code>SerialClob</code> object represents; the first

     *         position is <code>1</code>; must not be less than <code>1</code> nor

     *         greater than the length of this <code>SerialClob</code> object

     * @param str the string to be written to the <code>CLOB</code>

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

     * @return the number of characters written

     * @throws SerialException if there is an error accessing the

     *     <code>CLOB</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>SerialClob</code> length; or the combined

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

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

     */

    public int setString(long pos, String str) throws SerialException {

        return (setString(pos, str, 0, str.length()));

    }

    /**

     * Writes <code>len</code> characters of <code>str</code>, starting

     * at character <code>offset</code>, to the <code>CLOB</code> value

     * that this <code>Clob</code> represents.

     *

     * @param pos the position at which to start writing to the <code>CLOB</code>

     *         value that this <code>SerialClob</code> object represents; the first

     *         position is <code>1</code>; must not be less than <code>1</code> nor

     *         greater than the length of this <code>SerialClob</code> object

     * @param str the string to be written to the <code>CLOB</code>

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

     * @param offset the offset into <code>str</code> to start reading

     *        the characters to be written

     * @param length the number of characters to be written

     * @return the number of characters written

     * @throws SerialException if there is an error accessing the

     *     <code>CLOB</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>SerialClob</code> length; or the combined

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

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

     */

    public int setString(long pos, String str, int offset, int length)

        throws SerialException {

        isValid();

        String temp = str.substring(offset);

        char cPattern[] = temp.toCharArray();

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

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

        }

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

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

        }

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

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

        }

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

            // need check to ensure 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--;  //values in the array are at position one less

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

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

            i++;

        }

        return i;

    }

    /**

     * Retrieves a stream to be used to write Ascii characters to the

     * <code>CLOB</code> value that this <code>SerialClob</code> object represents,

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

     * <code>setAsciiStream()</code> call to the underlying <code>Clob</code> object in

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

     * <code>Clob</code> object. If this <code>SerialClob</code> object is instantiated

     *  with a <code>char</code> array, a <code>SerialException</code> object is thrown.

     *

     * @param pos the position at which to start writing to the

     *        <code>CLOB</code> object

     * @return the stream to which ASCII encoded characters can be written

     * @throws SerialException if SerialClob is not instantiated with a

     *     Clob object;

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

     * @throws SQLException if there is an error accessing the

     *     <code>CLOB</code> value

     * @see #getAsciiStream

     */

    public java.io.OutputStream setAsciiStream(long pos)

        throws SerialException, SQLException {

        isValid();

         if (this.clob != null) {

             return this.clob.setAsciiStream(pos);

         } else {

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

                "return a writable ascii stream\n unless instantiated with a Clob object " +

                "that has a setAsciiStream() implementation");

         }

    }

    /**

     * Retrieves a stream to be used to write a stream of Unicode characters

     * to the <code>CLOB</code> value that this <code>SerialClob</code> object

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

     * <code>setCharacterStream()</code> call to the underlying <code>Clob</code>

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

     * <code>Clob</code> object. If this <code>SerialClob</code> object is instantiated with

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

     *

     * @param  pos the position at which to start writing to the

     *        <code>CLOB</code> value

     *

     * @return a stream to which Unicode encoded characters can be written

     * @throws SerialException if the SerialClob is not instantiated with

     *     a Clob object;

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

     * @throws SQLException if there is an error accessing the

     *            <code>CLOB</code> value

     * @see #getCharacterStream

     */

    public java.io.Writer setCharacterStream(long pos)

        throws SerialException, SQLException {

        isValid();

        if (this.clob != null) {

            return this.clob.setCharacterStream(pos);

        } else {

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

                "return a writable character stream\n unless instantiated with a Clob object " +

                "that has a setCharacterStream implementation");

        }

    }

    /**

     * Truncates the <code>CLOB</code> value that this <code>SerialClob</code>

     * object represents so that it has a length of <code>len</code>

     * characters.

     * <p>

     * Truncating a <code>SerialClob</code> object to length 0 has the effect of

     * clearing its contents.

     *

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

     *        value should be truncated

     * @throws SerialException if there is an error accessing the

     *        <code>CLOB</code> value;

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

     */