package geniusweb.partiesserver.websocket;

import java.util.concurrent.LinkedBlockingQueue;
import java.util.logging.Level;

import javax.websocket.RemoteEndpoint.Basic;

import tudelft.utilities.logging.Reporter;

/**
 * A send buffer for @ServerEndpoint objects that makes websockets asynchronous.
 * The "asynchronous" mode for websockets can not be used because it throws
 * exceptions the moment you try to send a second datapacket into the socket
 * while the first is not yet finished.
 * 
 * <p>
 * After use, {@link #stop()} must be called to stop the thread managing this
 * queue. Failure to do this may cause memory leaks.
 */
public class SendBuffer {

	private final Basic remote;
	/**
	 * Buffer contains jackson-serialized objects, so can be "null" or "" but
	 * not null. "" (empty string) indicates buffer should be closed and
	 * terminated.
	 */
	private final LinkedBlockingQueue<String> fifo = new LinkedBlockingQueue<String>();
	private final Reporter log;

	public SendBuffer(final Basic basicRemote, final Reporter logger) {
		this.remote = basicRemote;
		this.log = logger;
		Thread thread = new Thread(new Runnable() {

			@Override
			public void run() {
				String txt = "-";
				try {
					while (true) {
						txt = fifo.take();
						if (txt.isEmpty())
							break;
						remote.sendText(txt);
					}
				} catch (InterruptedException e) {
					// normal termination
					log.log(Level.FINE,
							"sendbuffer is interrupted, assuming the party died.");
				} catch (Exception e) {
					logger.log(Level.SEVERE,
							"Failed to write '" + txt + "' to stream", e);
				}
				log.log(Level.INFO, "SendBuffer is closed.");
			}
		}, "SendBuffer");
		thread.start();
	}

	/**
	 * 
	 * @param text (non-emptyy) text to be sent. Typically a jackson-serialized
	 *             string.
	 */
	public void send(String text) {
		if (fifo.contains(""))
			return;
		if (text == null || text.isEmpty())
			throw new IllegalArgumentException(
					"Text must not be null or empty");
		try {
			fifo.put(text);
		} catch (InterruptedException e) {
			log.log(Level.WARNING,
					"sender queue has been interrupted, message may have not been sent",
					e);
		}
	}

	/**
	 * Stop the que, disable, terminate threads
	 */
	public synchronized void stop() {
		if (!fifo.contains(""))
			try {
				fifo.put("");
			} catch (InterruptedException e) {
				log.log(Level.WARNING,
						"Queue termination was interrupted, unsure about thread state");
			}
	}

}