/*
 *  Copyright (C) 2021-2022  The Exult Team
 *
 *  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 info.exult;

import java.io.IOException;
import java.io.InputStream;
import java.util.Set;
import org.apache.commons.compress.archivers.ArchiveException;
import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.archivers.ArchiveStreamFactory;
import org.apache.commons.io.IOUtils;

/**
 * Adds detection of Xar archives to ArchiveStreamFactory, which is missing in
 * Apache Commons Compress 1.20 API.
 *
 * @see https://commons.apache.org/proper/commons-compress/javadocs/api-1.20/
 */
class ArchiveStreamFactoryWithXar extends ArchiveStreamFactory {
	/** Constant (value {@value}) used to identify the XAR archive format. */
	public static final String XAR = "xar";

	/** Sufficient bytes from start of a XAR file to match magic number. */
	private static final int XAR_SIGNATURE_SIZE = 4;

	@Override
	public ArchiveInputStream createArchiveInputStream(final InputStream in)
			throws ArchiveException {
		return createArchiveInputStream(detect(in), in);
	}

	@Override
	public ArchiveInputStream createArchiveInputStream(
			String archiverName, InputStream in) throws ArchiveException {
		if (archiverName.equals(XAR)) {
			return new XarArchiveInputStream(in);
		} else {
			return super.createArchiveInputStream(archiverName, in);
		}
	}

	/**
	 * Adds XAR detection to
	 * org.apache.commons.compress.archivers.ArchiveStreamFactory.detect().
	 */
	public static String detect(InputStream in) throws ArchiveException {
		if (in != null && in.markSupported()) {
			final byte[] signature = new byte[XAR_SIGNATURE_SIZE];
			in.mark(signature.length);
			try {
				IOUtils.readFully(in, signature);
				in.reset();
			} catch (IOException e) {
				throw new ArchiveException(
						"IOException while reading signature.", e);
			}
			if (XarArchiveInputStream.matches(signature, signature.length)) {
				return XAR;
			}
		}
		return ArchiveStreamFactory.detect(in);
	}

	@Override
	public Set<String> getInputStreamArchiveNames() {
		Set<String> inputStreamArchiveNames
				= super.getInputStreamArchiveNames();
		inputStreamArchiveNames.add(XAR);
		return inputStreamArchiveNames;
	}
}
