/*
 * AppleCommander - An Apple ][ image utility.
 * Copyright (C) 2003 by Robert Greene
 * robgreene at users.sourceforge.net
 *
 * This program is free software; you can redistribute it and/or modify it 
 * under the terms of the GNU General Public License as published by the 
 * Free Software Foundation; either version 2 of the License, or (at your 
 * option) any later version.
 *
 * 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 GNU General Public License 
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along 
 * with this program; if not, write to the Free Software Foundation, Inc., 
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package com.webcodepro.applecommander.storage.physical;

/**
 * Manages the layout of the physical disk.  This hides implementation details, 
 * such as if the disk is in 2IMG order.
 * <p>
 * @author Rob Greene (RobGreene@users.sourceforge.net)
 */
public class ByteArrayImageLayout {
	/**
	 * This is the physical copy of the disk image which a particular
	 * implementation of ImageOrder will interpret.
	 */
	private byte[] diskImage;
	/**
	 * Indicates if the disk image has changed.
	 */
	private boolean changed;
	
	/**
	 * Construct a ByteArrayImageLayout.
	 */
	public ByteArrayImageLayout(byte[] diskImage) {
		setDiskImage(diskImage);
	}

	/**
	 * Construct a ByteArrayImageLayout.
	 */
	public ByteArrayImageLayout(byte[] diskImage, boolean changed) {
		setDiskImage(diskImage);
		this.changed = changed;
	}
	
	/**
	 * Construct a ByteArrayImageLayout.
	 */
	public ByteArrayImageLayout(int size) {
		diskImage = new byte[size];
		changed = true;
	}

	/**
	 * Get the physical disk image.
	 */
	public byte[] getDiskImage() {
		return diskImage;
	}
	
	/**
	 * Set the physical disk image.
	 */
	public void setDiskImage(byte[] diskImage) {
		this.diskImage = diskImage;
		changed = true;
	}

	/**
	 * Answer with the physical size of this disk volume.
	 */
	public int getPhysicalSize() {
		return (diskImage != null) ? diskImage.length : 0;
	}
	
	/**
	 * Extract a portion of the disk image.
	 */
	public byte[] readBytes(int start, int length) {
		byte[] buffer = new byte[length];
		System.arraycopy(diskImage, start, buffer, 0, length);
		return buffer;
	}
	
	/**
	 * Write data to the disk image.
	 */
	public void writeBytes(int start, byte[] bytes) {
		changed = true;
		System.arraycopy(bytes, 0, diskImage, start, bytes.length);
	}

	/**
	 * Indicates if the disk has changed. Triggered when data is
	 * written and cleared when data is saved.
	 */
	public boolean hasChanged() {
		return changed;
	}
	
	/**
	 * Set the changed indicator.
	 */
	public void setChanged(boolean changed) {
		this.changed = changed;
	}
}