/*******************************************************************************
 * Copyright (c) MOBAC developers
 * 
 * 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, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
package mobac.utilities.tar;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

/**
 * A tar record contains the data of the file to be stored. The data size has to be dividable by 512 (internal tar block
 * length).
 * 
 */
public class TarRecord {

	private final byte[] fileData;

	public TarRecord(File theFile) throws IOException {
		fileData = new byte[calculateFileSizeInTar(theFile)];
		this.setRecordContent(theFile);
	}

	public TarRecord(byte[] data) throws IOException {
		this(data, 0, data.length);
	}

	public TarRecord(byte[] data, int off, int len) throws IOException {
		fileData = new byte[calculateFileSizeInTar(len)];
		System.arraycopy(data, off, fileData, 0, len);
	}

	public static int calculateFileSizeInTar(File theFile) {
		long fl = theFile.length();
		if (fl > Integer.MAX_VALUE)
			throw new RuntimeException("File size too large");
		return calculateFileSizeInTar((int) fl);
	}

	public static int calculateFileSizeInTar(int fileLength) {
		if (fileLength < 512) {
			return 512;
		} else {
			int mod = fileLength % 512;
			// align buffer size on 512 byte block length
			if (mod != 0)
				fileLength += 512 - mod;
			return fileLength;
		}
	}

	public void setRecordContent(File theFile) throws IOException {
		try (DataInputStream in = new DataInputStream(new FileInputStream(theFile))) {
			in.readFully(fileData, 0, (int) theFile.length());
		}
	}

	public byte[] getRecordContent() {
		return fileData;
	}
}
