package geniusweb.runserver;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.logging.Level;

import javax.websocket.ClientEndpoint;
import javax.websocket.CloseReason;
import javax.websocket.ContainerProvider;
import javax.websocket.DeploymentException;
import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.WebSocketContainer;

import geniusweb.actions.Action;
import geniusweb.actions.PartyId;
import geniusweb.inform.Inform;
import geniusweb.protocol.partyconnection.ProtocolToPartyConn;
import geniusweb.references.Reference;
import tudelft.utilities.listener.DefaultListenable;
import tudelft.utilities.logging.ReportToLogger;
import tudelft.utilities.logging.Reporter;

/**
 * A websocket based {@link ProtocolToPartyConn}. it contains a websocket
 * connection to a party (that will be started using the partyserver
 * start-new-party protocol). Must be public so that it can be accessed as
 * ClientEndpoint by apache tomcat. This is internally used.
 * 
 * <p>
 * The @ClientEndpoint annotation is important, the runserver is creating these
 * sockets programatically, from a received ws: URL.
 */
@ClientEndpoint
public class WebSocketProtToPartyConn extends DefaultListenable<Action>
		implements ProtocolToPartyConn {
	// 20MB seems reasonable limit?
	private static final int MAX_MESSAGE_SIZE = 20 * 1024 * 1024;
	private final Reporter log;

	private final Reference reference;

	private WebSocketContainer container;
	private Session session = null;
	private URI partyuri;
	private Throwable error = null;

	/**
	 * Buffers incoming text.
	 */
	private StringBuffer buffer = new StringBuffer();

	/**
	 * Constructor that uses default {@link Reporter}
	 * 
	 * @param reference the address to to a http GET to get a websocket to a new
	 *                  running party.
	 */
	public WebSocketProtToPartyConn(Reference reference) {
		this(reference, new ReportToLogger("runserver"));
	}

	/**
	 * 
	 * @param reference the address to to a http GET to get a websocket to a new
	 *                  running party.
	 * @param reporter  the {@link Reporter} used for logging important
	 *                  events/issues
	 * @throws IOException if the party does not start properly.
	 */
	public WebSocketProtToPartyConn(Reference reference, Reporter reporter) {
		this.reference = reference;
		this.log = reporter;

	}

	public WebSocketProtToPartyConn init() throws IOException {
		log.log(Level.INFO, "Trying to start up party " + reference);
		URI partyuri = startParty(reference);

		container = ContainerProvider.getWebSocketContainer();
		// #50 disable: might cause large buffer. And why is this a good limit
		// anyway
		// container.setDefaultMaxTextMessageBufferSize(200000);

		log.log(Level.INFO,
				"Trying to make websocket connection to running party "
						+ partyuri);
		try {
			container.connectToServer(this, partyuri);
		} catch (DeploymentException e) {
			throw new IOException(
					"Failed to connect with running party at " + partyuri, e);
		}
		log.log(Level.INFO, "Created websocket connection at  " + partyuri);
		return this;
	}

	/**
	 * 
	 * @param reference the address to to a http GET to get a websocket to a new
	 *                  running party.
	 * @return URI of websocket behind which is a running party
	 * @throws IOException if party did not start correctly
	 */
	private URI startParty(Reference reference) throws IOException {
		HttpURLConnection conn = (HttpURLConnection) reference.getURI().toURL()
				.openConnection();
		// if this throws, the IOException seems to contain the "retry later"
		// message already
		conn.setRequestMethod("GET");
		conn.setReadTimeout(20000);
		conn.connect();
		BufferedReader rd;
		try {
			rd = new BufferedReader(
					new InputStreamReader(conn.getInputStream()));
		} catch (IOException e) {
			if (conn.getErrorStream() == null) {
				throw new IOException("Failed to connect " + reference
						+ ", no server error message", e);
			}
			// read the detail message from the error stream
			rd = new BufferedReader(
					new InputStreamReader(conn.getErrorStream()));
			throw new IOException(rd.readLine(), e);
		}
		String partysocketaddress = rd.readLine();
		log.log(Level.INFO, "startparty returned " + partysocketaddress);
		if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
			throw new IOException(
					"Something went wrong connecting to the party:"
							+ conn.getResponseCode());
		}
		try {
			this.partyuri = new URI(partysocketaddress);
		} catch (URISyntaxException e1) {
			throw new IOException("Failed to start party at " + reference, e1);
		}
		return partyuri;
	}

	/************* implements {@link ConnectionWithParty} ***************/
	@Override
	public void send(Inform info) throws IOException {
		if (session == null)
			return;
		session.getBasicRemote()
				.sendText(Jackson.instance().writeValueAsString(info));
	}

	@Override
	public Reference getReference() {
		return this.reference;
	}

	@Override
	public PartyId getParty() {
		String name = partyuri.getPath();
		return new PartyId(name.substring(name.lastIndexOf('/') + 1));
	}

	@Override
	public void close() {
		log.log(Level.INFO, "Party close called");
		// a close event is not necessarily a bug?
		// setError(new SocketException("socket is closed"));
		try {
			session.close();
			this.session = null;
		} catch (IOException e) {
			log.log(Level.SEVERE, "failed to close websocket", e);
		}
	}

	/************* implements ClientEndpoint ***************/

	@OnOpen
	public void onOpen(Session session) {
		log.log(Level.INFO, "Party is being connected: " + session);
// #50 we now buffer partial messages
//		session.setMaxTextMessageBufferSize(MAX_MESSAGE_SIZE);
//		session.setMaxBinaryMessageBufferSize(MAX_MESSAGE_SIZE);
		this.session = session;
	}

	@OnClose
	public void onClose(Session userSession, CloseReason reason) {
		log.log(Level.INFO, "closing websocket " + reference + ":" + reason);
		if (reason.getReasonPhrase() != null
				&& !reason.getReasonPhrase().isEmpty()) {
			setError(new RemoteException("Session " + reference
					+ " closed abnormally (see party server for more details) "
					+ reason.getReasonPhrase()));
		}
		// seems NOT an error. Unless the party deliberately and silently
		// closes its connection.
		// Setting error will cause a print of stacktrace that is disturbing.
		// It seems we can not check at this point if session was finished.
		// setError(new SocketException("socket has been closed"));
	}

	@OnMessage
	public void processMessage(String message, boolean islast) {
		// #50 avoid fixed (large) buffers
		buffer.append(message);
		if (islast) {
			String msg = buffer.toString();
			buffer = new StringBuffer();
			try {
				Action act = Jackson.instance().readValue(msg, Action.class);
				notifyListeners(act);
			} catch (IOException e) {
				log.log(Level.WARNING,
						"received bad message from client " + reference, e);
				setError(e);
				close();
			}
		}
	}

	@OnError
	public void processError(Throwable t) {
		log.log(Level.SEVERE, "Something went wrong internally!", t);
		setError(t);
	}

	@Override
	public URI getRemoteURI() {
		return partyuri;
	}

	@Override
	public Throwable getError() {
		return error;
	}

	/**
	 * Sets the connection to final error state and report null to listeners.
	 * Only the first error is reported, the rest is ignored.
	 * 
	 * @param err the error that occurred.
	 */
	private void setError(Throwable err) {
		boolean isSet = false;
		synchronized (this) {
			if (this.error == null) {
				this.error = err;
				isSet = true;
			}
		}
		if (isSet) {
			// special event that tells protocol that we're probably in error
			// state.
			notifyListeners(null);
		}
	}

}

/**
 * Indicates an exceeption occured on a remote machine. The remote machine did
 * not pass a stacktrace (because it does not fit into a websocket close call).
 *
 */
class RemoteException extends Exception {
	public RemoteException(String message) {
		super(message, null, false, false);

	}
}