package org.apache.lucene.store.je;

/**
 * Copyright 2002-2006 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;

import com.sleepycat.je.DatabaseEntry;
import com.sleepycat.je.DatabaseException;

/**
 * Port of Andi Vajda's DbDirectory to Java Edition of Berkeley Database
 * 
 * @author Aaron Donovan
 */

public class Block extends Object {
    protected DatabaseEntry key, data;

    protected Block(File file) throws IOException {
        byte[] fileKey = file.getKey();

        key = new DatabaseEntry(new byte[fileKey.length + 8]);
        data = new DatabaseEntry(new byte[JEIndexOutput.BLOCK_LEN]);

        System.arraycopy(fileKey, 0, key.getData(), 0, fileKey.length);
        seek(0L);
    }

    protected byte[] getKey() {
        return key.getData();
    }

    protected byte[] getData() {
        return data.getData();
    }

    protected void seek(long position) throws IOException {
        byte[] data = key.getData();
        int index = data.length - 8;

        position >>>= JEIndexOutput.BLOCK_SHIFT;

        data[index + 0] = (byte) (0xff & (position >>> 56));
        data[index + 1] = (byte) (0xff & (position >>> 48));
        data[index + 2] = (byte) (0xff & (position >>> 40));
        data[index + 3] = (byte) (0xff & (position >>> 32));
        data[index + 4] = (byte) (0xff & (position >>> 24));
        data[index + 5] = (byte) (0xff & (position >>> 16));
        data[index + 6] = (byte) (0xff & (position >>> 8));
        data[index + 7] = (byte) (0xff & (position >>> 0));
    }

    protected void get(JEDirectory directory) throws IOException {
        try {
            // TODO check LockMode
            directory.blocks.get(directory.txn, key, data, null);
        } catch (DatabaseException e) {
            throw new IOException(e.getMessage());
        }
    }

    protected void put(JEDirectory directory) throws IOException {
        try {
            directory.blocks.put(directory.txn, key, data);
        } catch (DatabaseException e) {
            throw new IOException(e.getMessage());
        }
    }
}