/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 *
 *   https://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.
 *
 *   SPDX-License-Identifier: Apache-2.0
 */

package org.apache.jena.dboe.base.file;

import java.io.RandomAccessFile;

import org.apache.jena.atlas.lib.Closeable;
import org.apache.jena.atlas.lib.Sync;

/**
 * An append-only, read-anywhere, binary file.
 * A {@code BinaryDataFile} does not record the length of items in the file
 * and assumes the entries are self-defining.
 *
 *  @see RandomAccessFile
 */
public interface BinaryDataFile extends Closeable, Sync {
    // What about java.nio.channels.FileChannel?
    // On OpenJDK,  RandomAccessFile and FileChannelImpl both dive into native code.
    //
    // The choice seems to come down to ByteBuffers vs byte[]
    // which in turn is a small/large data (scattered data)
    // issue.  We are currently expecting small(er) I/O so byte[]
    // and being like Thrift is better.

    // byte[] vs ByteBuffer

    /** Open the file */
    public void open();

    /** Is it open? */
    public boolean isOpen();

    /** Read into a byte array, returning the number of bytes read.
     * Reads are at an absolute position and a read is atomic/thread-safe.
     *
     * @param posn Location of the read operation.
     * @param b byte array
     *
     * @return The number of bytes read
     */
    public default int read(long posn, byte b[]) {
        return read(posn, b, 0, b.length);
    }

    /** Read into a byte array, returning the number of bytes read.
     * Reads are at an absolute position and a read is atomic/thread-safe.
     *
     * @param posn Location of the read operation.
     * @param b
     * @param start of bytesarray to read into
     * @param length Maximum number of bytes to read.
     * @return The number of bytes read
     */

    public int read(long posn, byte b[], int start, int length);

    /** Write bytes - bytes are always written to the end of the file.
     * Return the location where the write started.
     */
    public default long write(byte b[]) {
        return write(b, 0, b.length);
    }

    /** Write bytes - bytes are always written to the end of the file.
     * Return the location where the write started.
     */
    public long write(byte b[], int start, int length);

    /** Return the length of the file (including any buffered writes) */
    public long length();

    /** Truncate the file */
    public void truncate(long length);

    /** Return whether this is an empty file or not */
    public default boolean isEmpty() { return length() == 0; }

    @Override
    public void sync();

    @Override
    public void close();
}

