/*
 * Copyright (c) 2010-2012 Sonatype, Inc. All rights reserved.
 *
 * This program is licensed to you under the Apache License Version 2.0,
 * and you may not use this file except in compliance with the Apache License Version 2.0.
 * You may obtain a copy of the Apache License Version 2.0 at http://www.apache.org/licenses/LICENSE-2.0.
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the Apache License Version 2.0 is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Apache License Version 2.0 for the specific language governing permissions and limitations there under.
 */
package com.ning.http.client.providers.netty;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import com.ning.http.util.Base64;

public final class WebSocketUtil {
	public static final String MAGIC_GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

	public static String getKey() {
		final byte[] nonce = createRandomBytes(16);
		return base64Encode(nonce);
	}

	public static String getAcceptKey(final String key)
			throws UnsupportedEncodingException {
		final String acceptSeed = key + MAGIC_GUID;
		final byte[] sha1 = sha1(acceptSeed.getBytes("US-ASCII"));
		return base64Encode(sha1);
	}

	public static byte[] md5(final byte[] bytes) {
		try {
			final MessageDigest md = MessageDigest.getInstance("MD5");
			return md.digest(bytes);
		} catch (final NoSuchAlgorithmException e) {
			throw new InternalError("MD5 not supported on this platform");
		}
	}

	public static byte[] sha1(final byte[] bytes) {
		try {
			final MessageDigest md = MessageDigest.getInstance("SHA1");
			return md.digest(bytes);
		} catch (final NoSuchAlgorithmException e) {
			throw new InternalError("SHA-1 not supported on this platform");
		}
	}

	public static String base64Encode(final byte[] bytes) {
		return Base64.encode(bytes);
	}

	public static byte[] createRandomBytes(final int size) {
		final byte[] bytes = new byte[size];

		for (int i = 0; i < size; i++) {
			bytes[i] = (byte) createRandomNumber(0, 255);
		}

		return bytes;
	}

	public static int createRandomNumber(final int min, final int max) {
		return (int) (Math.random() * max + min);
	}

}