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JDBC Driver for the Firebird RDBMS
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/*
 * Firebird Open Source JDBC Driver
 *
 * Distributable under LGPL license.
 * You may obtain a copy of the License at http://www.gnu.org/copyleft/lgpl.html
 *
 * This program 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
 * LGPL License for more details.
 *
 * This file was created by members of the firebird development team.
 * All individual contributions remain the Copyright (C) of those
 * individuals.  Contributors to this file are either listed here or
 * can be obtained from a source control history command.
 *
 * All rights reserved.
 */
package org.firebirdsql.jdbc;

import org.firebirdsql.gds.JaybirdErrorCodes;
import org.firebirdsql.gds.ng.FbExceptionBuilder;
import org.firebirdsql.util.InternalApi;

import java.sql.SQLException;
import java.sql.Blob;
import java.io.*;

/**
 * This class represents a cached blob field.
 * 
 * This class is internal API of Jaybird. Future versions may radically change, move, or make inaccessible this type.
 * For the public API, refer to the {@link java.sql.Blob} and {@link FirebirdBlob} interfaces.
 * 
 */
@InternalApi
public final class FBCachedBlob implements FirebirdBlob {

    // NOTE: Do not assign ByteArrayHelper.empty(), as this must be a unique instance
    private static final byte[] FREED_MARKER = new byte[0];
    static final String BLOB_READ_ONLY = "Cached blob is read-only";

    @SuppressWarnings("java:S3077")
    private volatile byte[] blobData;

    /**
     * Create an instance using the cached data.
     *
     * @param data
     *            array of bytes containing the cached data.
     */
    public FBCachedBlob(byte[] data) {
        blobData = data;
    }

    @Override
    public FirebirdBlob detach() throws SQLException {
        checkClosed();
        return new FBCachedBlob(blobData);
    }

    /**
     * {@inheritDoc}
     * 
     * An instance of FBCachedBlob returns false always.
     * 
     */
    @Override
    public boolean isSegmented() throws SQLException {
        checkClosed();
        return false;
    }

    /**
     * Get the length of the cached blob field.
     *
     * @return length of the cached blob field or -1 if the field is null.
     */
    @Override
    public long length() throws SQLException {
        checkClosed();
        return blobData != null ? blobData.length : -1;
    }

    @Override
    @SuppressWarnings("java:S1168")
    public byte[] getBytes(long pos, int length) throws SQLException {
        if (pos < 1) {
            throw new SQLException("Expected value of pos > 0, got " + pos,
                    SQLStateConstants.SQL_STATE_INVALID_STRING_LENGTH);
        }
        if (length < 0) {
            throw new SQLException("Expected value of length >= 0, got " + length,
                    SQLStateConstants.SQL_STATE_INVALID_STRING_LENGTH);
        }
        checkClosed();
        if (blobData == null) return null;

        // TODO What if pos or length are beyond blobData
        byte[] result = new byte[length];
        System.arraycopy(blobData, (int) pos - 1, result, 0, length);
        return result;
    }

    @Override
    public byte[] getBytes() throws SQLException {
        checkClosed();
        return blobData != null ? blobData.clone() : null;
    }

    /**
     * Find the first entry of the specified pattern.
     *
     * @throws SQLException
     *             always, not yet implemented.
     */
    @Override
    public long position(byte[] pattern, long start) throws SQLException {
        throw new FBDriverNotCapableException("Method Method position(byte[], long) is not supported");
    }

    /**
     * Find the first entry of the specified pattern.
     *
     * @throws SQLException
     *             always, not yet implemented.
     */
    @Override
    public long position(Blob pattern, long start) throws SQLException {
        throw new FBDriverNotCapableException("Method position(Blob, long) is not supported");
    }

    @Override
    public InputStream getBinaryStream() throws SQLException {
        checkClosed();
        if (blobData == null) return null;

        return new ByteArrayInputStream(blobData);
    }

    @Override
    public InputStream getBinaryStream(long pos, long length) throws SQLException {
        throw new FBDriverNotCapableException("Method getBinaryStream(long, long) is not supported");
    }

    /**
     * Set contents of the blob.
     *
     * @throws SQLException
     *             always, set methods are not relevant in cached state.
     */
    @Override
    public int setBytes(long pos, byte[] bytes) throws SQLException {
        throw new SQLException(BLOB_READ_ONLY, SQLStateConstants.SQL_STATE_GENERAL_ERROR);
    }

    /**
     * Set the contents of blob.
     *
     * @throws SQLException
     *             always, set methods are not relevant in cached state.
     */
    @Override
    public int setBytes(long pos, byte[] bytes, int offset, int len) throws SQLException {
        throw new SQLException(BLOB_READ_ONLY, SQLStateConstants.SQL_STATE_GENERAL_ERROR);
    }

    /**
     * Set the contents of blob as binary stream.
     *
     * @throws SQLException
     *             always, set methods are not relevant in cached state.
     */
    @Override
    public OutputStream setBinaryStream(long pos) throws SQLException {
        throw new SQLException(BLOB_READ_ONLY, SQLStateConstants.SQL_STATE_GENERAL_ERROR);
    }

    /**
     * Truncate the blob to specified length.
     *
     * @throws SQLException
     *             always, truncate is not relevant in cached state.
     */
    @Override
    public void truncate(long length) throws SQLException {
        throw new FBDriverNotCapableException("Method truncate(long) is not supported");
    }

    @Override
    public void free() throws SQLException {
        blobData = FREED_MARKER;
    }

    private void checkClosed() throws SQLException {
        if (blobData == FREED_MARKER) {
            throw FbExceptionBuilder.forException(JaybirdErrorCodes.jb_blobClosed).toSQLException();
        }
    }
}