envoy/src/main/java/envoy/server/ObjectMessageProcessor.java

package envoy.server;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import com.jenkov.nioserver.IMessageProcessor;
import com.jenkov.nioserver.Message;
import com.jenkov.nioserver.WriteProxy;

import envoy.data.LoginCredentials;
import envoy.data.User;
import envoy.event.Event;

/**
 * Project: <strong>envoy-server-standalone</strong><br>
 * File: <strong>ObjectMessageProcessor.java</strong><br>
 * Created: <strong>28.12.2019</strong><br>
 * 
 * @author Kai S. K. Engelbart
 * @since Envoy Server Standalone v0.1-alpha
 */
public class ObjectMessageProcessor implements IMessageProcessor {

	@Override
	public void process(Message message, WriteProxy writeProxy) {
		try (ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(message.sharedArray, message.offset + 4, message.length - 4))) {
			Object obj = in.readObject();

			System.out.println("Read object: " + obj.toString());
			handleObject(message, writeProxy, obj);
		} catch (IOException | ClassNotFoundException e) {
			e.printStackTrace();
		}
	}

	/**
	 * This method splits incoming objects into the different objects that are
	 * relevant to the server and guides them to their predestined spot.
	 * 
	 * @param request    the {@link Message} in which the objects are saved
	 * @param writeProxy the writeProxy to define the resulting socket for
	 * @param obj        the object that has been read out of the {@link Message}
	 * @throws IllegalArgumentException if the object given is neither an
	 *                                  {@link envoy.data.Message}, an {@link Event}
	 *                                  nor a {@link LoginCredentials}
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	private void handleObject(Message request, WriteProxy writeProxy, Object obj) throws IllegalArgumentException {

		long	currentUserID			= 0;								// TODO temporary. Only for testing purposes
		boolean	responseToSameSocket	= false, immediateResponse = true;
		Object	usage;

		// determining the type of the incoming object
		if (obj instanceof envoy.data.Message) {// if object is Message
			envoy.data.Message cast = (envoy.data.Message) obj;
			usage				= cast.getClass();
			immediateResponse	= isRecipientAvailable(-1);	// TODO replace with wanted clientID
		} else if (obj instanceof Event) {// if object is Event
			usage				= (Event<?>) obj;
			immediateResponse	= isRecipientAvailable(-1);	// TODO replace with wanted clientID
		} else if (obj instanceof LoginCredentials) {// if object is LoginCredential
			responseToSameSocket = true;
			LoginCredentials cast = (LoginCredentials) obj;
			usage = new User(currentUserID++, cast.getName());
		} else throw new IllegalArgumentException();

		// handling of incoming object
		if (immediateResponse) {
			Message response = writeProxy.getMessage();
			if (responseToSameSocket) {
				response.socketId = request.socketId;
			} else {
				response.socketId = -0;// TODO temporary.Needs to be replaced
				return;
			}
			// Serialize object to byte array
			ByteArrayOutputStream baos = new ByteArrayOutputStream();
			try (ObjectOutputStream oout = new ObjectOutputStream(baos)) {
				oout.writeObject(usage);
			} catch (IOException e) {
				e.printStackTrace();
			}
			byte[] objBytes = baos.toByteArray();
			response.writeToMessage(objBytes);
			writeProxy.enqueue(response);
		}
	}

	/**
	 * This method determines if the recipient is online
	 * 
	 * @param otherClientID the ID of the recipient
	 * @return true, if the recipient is online
	 * @since Envoy Server Standalone v0.1-alpha
	 */
	private boolean isRecipientAvailable(long otherClientID) {
		return false;// TODO needs to be adapted to return true if the wanted client is online
	}
}