package org.firebirdsql.jdbc;

import java.sql.SQLException;
import java.sql.Blob;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.ByteArrayInputStream;

/**
 * This class represents a cached blob field.
 */
public class FBCachedBlob implements FirebirdBlob {

    static final byte[] BYTES_NULL_VALUE = null;

    static final InputStream STREAM_NULL_VALUE = null;

    private byte[] blobData;

    /* (non-Javadoc)
     * @see org.firebirdsql.jdbc.FirebirdBlob#detach()
     */
    public FirebirdBlob detach() throws SQLException {
        return this;
    }
    
    /* (non-Javadoc)
     * @see org.firebirdsql.jdbc.FirebirdBlob#isSegmented()
     */
    public boolean isSegmented() throws SQLException {
        return false;
    }
    
    /**
     * Create an instance using the cached data.
     * 
     * @param data
     *            array of bytes containing the cached data.
     */
    public FBCachedBlob(byte[] data) {
        blobData = data;
    }

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

        return blobData.length;
    }

    /**
     * Get part of the blob field.
     * 
     * @param pos
     *            starting position to copy.
     * @param length
     *            amount of bytes to copy.
     */
    public byte[] getBytes(long pos, int length) throws SQLException {
        if (blobData == null) return BYTES_NULL_VALUE;

        byte[] result = new byte[length];
        System.arraycopy(blobData, (int) pos - 1, result, 0, length);
        return result;
    }

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

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

    /**
     * Get contents of blob as binary stream.
     */
    public InputStream getBinaryStream() throws SQLException {
        if (blobData == null) return STREAM_NULL_VALUE;

        return new ByteArrayInputStream(blobData);
    }

    /**
     * Set contents of the blob.
     * 
     * @throws SQLException
     *             always, set methods are not relevant in cached state.
     */
    public int setBytes(long l, byte abyte0[]) throws SQLException {
        throw new FBSQLException("Blob in auto-commit mode is read-only.");
    }

    /**
     * Set the contents of blob.
     * 
     * @throws SQLException
     *             always, set methods are not relevant in cached state.
     */
    public int setBytes(long l, byte abyte0[], int i, int j)
            throws SQLException {
        throw new FBSQLException("Blob in auto-commit mode is read-only.");
    }

    /**
     * Set the contents of blob as binary stream.
     * 
     * @throws SQLException
     *             always, set methods are not relevant in cached state.
     */
    public OutputStream setBinaryStream(long pos) throws SQLException {
        throw new FBSQLException("Blob in auto-commit mode is read-only.");
    }

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