Encoder.java

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

import cloudeventbus.pki.CertificateStoreLoader;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;
import io.netty.util.CharsetUtil;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.Base64OutputStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.ByteArrayOutputStream;
import java.io.OutputStream;

/**
 * @author Mike Heath <elcapo@gmail.com>
 */
public class Encoder extends MessageToByteEncoder<Frame> {

	private static final Logger LOGGER = LoggerFactory.getLogger(Encoder.class);

	@Override
	public void encode(ChannelHandlerContext ctx, Frame frame, ByteBuf out) throws Exception {
		LOGGER.debug("Encoding frame {}", frame);
		switch (frame.getFrameType()) {
			case AUTHENTICATE:
				final AuthenticationRequestFrame authenticationRequestFrame = (AuthenticationRequestFrame) frame;
				out.writeByte(FrameType.AUTHENTICATE.getOpcode());
				out.writeByte(' ');
				final String challenge = Base64.encodeBase64String(authenticationRequestFrame.getChallenge());
				writeString(out, challenge);
				break;
			case AUTH_RESPONSE:
				final AuthenticationResponseFrame authenticationResponseFrame = (AuthenticationResponseFrame) frame;
				out.writeByte(FrameType.AUTH_RESPONSE.getOpcode());
				out.writeByte(' ');

				// Write certificate chain
				final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
				final OutputStream base64Out = new Base64OutputStream(outputStream, true, Integer.MAX_VALUE, new byte[0]);
				CertificateStoreLoader.store(base64Out, authenticationResponseFrame.getCertificates());
				out.writeBytes(outputStream.toByteArray());
				out.writeByte(' ');

				// Write salt
				final byte[] encodedSalt = Base64.encodeBase64(authenticationResponseFrame.getSalt());
				out.writeBytes(encodedSalt);
				out.writeByte(' ');

				// Write signature
				final byte[] encodedDigitalSignature = Base64.encodeBase64(authenticationResponseFrame.getDigitalSignature());
				out.writeBytes(encodedDigitalSignature);
				break;
			case ERROR:
				final ErrorFrame errorFrame = (ErrorFrame) frame;
				out.writeByte(FrameType.ERROR.getOpcode());
				out.writeByte(' ');
				writeString(out, Integer.toString(errorFrame.getCode().getErrorNumber()));
				if (errorFrame.getMessage() != null) {
					out.writeByte(' ');
					writeString(out, errorFrame.getMessage());
				}
				break;
			case GREETING:
				final GreetingFrame greetingFrame = (GreetingFrame) frame;
				out.writeByte(FrameType.GREETING.getOpcode());
				out.writeByte(' ');
				writeString(out, Integer.toString(greetingFrame.getVersion()));
				out.writeByte(' ');
				writeString(out, greetingFrame.getAgent());
				out.writeByte(' ');
				writeString(out, Long.toString(greetingFrame.getId()));
				break;
			case PING:
				out.writeByte(FrameType.PING.getOpcode());
				break;
			case PONG:
				out.writeByte(FrameType.PONG.getOpcode());
				break;
			case PUBLISH:
				final PublishFrame publishFrame = (PublishFrame) frame;
				out.writeByte(FrameType.PUBLISH.getOpcode());
				out.writeByte(' ');
				writeString(out, publishFrame.getSubject().toString());
				if (publishFrame.getReplySubject() != null) {
					out.writeByte(' ');
					writeString(out, publishFrame.getReplySubject().toString());
				}
				out.writeByte(' ');
				final ByteBuf body = Unpooled.wrappedBuffer(publishFrame.getBody().getBytes(CharsetUtil.UTF_8));
				writeString(out, Integer.toString(body.readableBytes()));
				out.writeBytes(Codec.DELIMITER);
				out.writeBytes(body);
				break;
			case SERVER_READY:
				out.writeByte(FrameType.SERVER_READY.getOpcode());
				break;
			case SUBSCRIBE:
				final SubscribeFrame subscribeFrame = (SubscribeFrame) frame;
				out.writeByte(FrameType.SUBSCRIBE.getOpcode());
				out.writeByte(' ');
				writeString(out, subscribeFrame.getSubject().toString());
				break;
			case UNSUBSCRIBE:
				final UnsubscribeFrame unsubscribeFrame = (UnsubscribeFrame) frame;
				out.writeByte(FrameType.UNSUBSCRIBE.getOpcode());
				out.writeByte(' ');
				writeString(out, unsubscribeFrame.getSubject().toString());
				break;
			default:
				throw new EncodingException("Don't know how to encode message of type " + frame.getClass().getName());
		}
		out.writeBytes(Codec.DELIMITER);
	}

	private void writeString(ByteBuf out, String string) {
		out.writeBytes(string.getBytes(CharsetUtil.UTF_8));
	}

}