/*
 * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.protocol.bgp.parser.spi;

import java.util.Arrays;

import org.opendaylight.protocol.util.ByteArray;

import com.google.common.primitives.UnsignedBytes;


public final class MessageUtil {

	public static final int LENGTH_FIELD_LENGTH = 2; // bytes
	public static final int MARKER_LENGTH = 16; // bytes
	public static final int TYPE_FIELD_LENGTH = 1; // bytes
	public static final int COMMON_HEADER_LENGTH = LENGTH_FIELD_LENGTH + TYPE_FIELD_LENGTH + MARKER_LENGTH;

	private MessageUtil() {

	}

	/**
	 * Serializes this BGP Message header to byte array.
	 * 
	 * @param type message type to be formatted
	 * @param body message body
	 * 
	 * @return byte array representation of this header
	 */
	public static byte[] formatMessage(final int type, final byte[] body) {
		final byte[] retBytes = new byte[COMMON_HEADER_LENGTH + body.length];

		Arrays.fill(retBytes, 0, MARKER_LENGTH, (byte) 0xff);
		System.arraycopy(ByteArray.intToBytes(body.length + COMMON_HEADER_LENGTH),
				Integer.SIZE / Byte.SIZE - LENGTH_FIELD_LENGTH,
				retBytes, MARKER_LENGTH, LENGTH_FIELD_LENGTH);

		retBytes[MARKER_LENGTH + LENGTH_FIELD_LENGTH] = UnsignedBytes.checkedCast(type);
		ByteArray.copyWhole(body, retBytes, COMMON_HEADER_LENGTH);

		return retBytes;
	}
}