package geniusweb.partiesserver;

import java.io.IOException;
import java.net.UnknownHostException;
import java.util.logging.Level;

import javax.management.MalformedObjectNameException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import geniusweb.partiesserver.repository.AvailablePartiesRepo;
import geniusweb.partiesserver.repository.AvailableParty;
import geniusweb.partiesserver.repository.RunningPartiesRepo;
import geniusweb.partiesserver.repository.RunningParty;
import tudelft.utilities.logging.ReportToLogger;
import tudelft.utilities.logging.Reporter;
import tudelft.utilities.repository.NoResourcesNowException;

/**
 * Servlet implementation class RunParty. It's behind the url
 * partiesserver/run/NAME where NAME is the name of the party that needs to be
 * run.
 */
public class RunParty extends HttpServlet {
	private static final int DEFAULT_TIMEOUT = 3000; // ms
	private static final long serialVersionUID = 1L;
	private final Reporter log;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public RunParty() {
		this(new ReportToLogger("partiesserver"));
	}

	/**
	 * 
	 * @param reporter the reporter where we log issues to.
	 */
	public RunParty(Reporter reporter) {
		this.log = reporter;
	}

	/**
	 * See
	 * {@link HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)}.
	 * Returns
	 * <ul>
	 * <li>URL with websocket address to contact the now running agent.
	 * <li>SC_NOT_FOUND (404) if attempt is made to access non-running party.
	 * <li>SC_SERVICE_UNAVAILABLE (503) if there are no free slots to run the
	 * party.
	 * <li>SC_EXPECTATION_FAILED (417) if something else goes wrong during
	 * instantiating the party (then see logs for more details)
	 * </ul>
	 */
	@Override
	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		String name = request.getPathInfo().substring(1);
		log.log(Level.INFO, "request to run " + name);
		System.setSecurityManager(new SimpleSecurityManager());
		AvailableParty party = AvailablePartiesRepo.instance().get(name);
		if (party == null) {
			log.log(Level.INFO, "party " + name + " does not exist");
			response.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		}
		// try to avoid needless creation of the party.
		if (RunningPartiesRepo.instance().availableSlots() <= 0) {
			tryLater(response, name);
			return;
		}

		RunningParty running;
		try {
			running = RunningParty.create(party, DEFAULT_TIMEOUT);
		} catch (Throwable e1) {
			log.log(Level.WARNING, "Failed to instantiate party " + name, e1);
			response.sendError(HttpServletResponse.SC_EXPECTATION_FAILED,
					"Failed to instantiate party " + name + ":"
							+ e1.getMessage()
							+ ". See partiesserver log for stack trace");
			return;
		}

		// in the mean time, another party may have taken the slot anyway...
		// the chances that this happens is small though.
		try {
			RunningPartiesRepo.instance().put(running);
		} catch (NoResourcesNowException e) {
			running.getParty().terminate();
			tryLater(response, name);
			return;
		}
		log.log(Level.INFO, "started " + name);
		String url;
		try {
			url = "ws://" + Constants.getIpAddressAndPort()
					+ request.getContextPath() + "/party/" + running.getID();
		} catch (MalformedObjectNameException | UnknownHostException e) {
			throw new IOException("Failure creating websocket address", e);
		}
		response.getWriter().append(url);

	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	@Override
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

	/**
	 * Reply with 503 plus message that the caller should try later
	 * 
	 * @param response the response container
	 * @param name     the name of the party that was attempted to launch
	 * @throws IOException
	 */
	private void tryLater(HttpServletResponse response, String name)
			throws IOException {
		long time = RunningPartiesRepo.instance().estimateCleanupTime()
				.getTime();
		log.log(Level.INFO, "There are no free slots to run the party " + name
				+ ". suggesting " + time);
		// sendError does not always work as expected, avoid it.
		response.setStatus(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
		response.getWriter().append("retry later at " + time);
	}

}