package ca.uhn.hl7v2.hoh.raw.client;
   
   import java.io.IOException;
   import java.net.Socket;
   import java.net.URL;
   import java.text.SimpleDateFormat;
   import java.util.ArrayList;
   import java.util.Date;
   import java.util.IdentityHashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.concurrent.Executors;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.TimeUnit;
  
  import ca.uhn.hl7v2.hoh.api.IClientMultithreaded;
  import ca.uhn.hl7v2.hoh.util.Validate;
  
  /**
   * <p>
   * Raw message sender using the HL7 over HTTP specification which uses a
   * {@link ScheduledExecutorService} to provide advanced functionality such as
   * persistent connections which time out and close automatically.
   * </p>
   * <p>
   * This connector uses an executor service which can start worker threads, so
   * use caution if embedding within a J2EE container.
   * </p>
   */
  public class HohRawClientMultithreaded extends AbstractRawClient implements IClientMultithreaded {
  
  	/**
  	 * Default {@link #setSocketTimeout(long) Socket Timeout}, 10000ms
  	 */
  	public static final long DEFAULT_SOCKET_TIMEOUT = 10000;
  
  	private static final org.slf4j.Logger ourLog = org.slf4j.LoggerFactory.getLogger(HohRawClientMultithreaded.class);
  
  	private final ScheduledExecutorService myExecutorService;
  	private final Map<Socket, Long> myIdleSocketsToTimeBecameIdle = new IdentityHashMap<>();
  	private final SimpleDateFormat myLogTimeFormat = new SimpleDateFormat("HH:mm:ss,SSS");
  	private boolean myReapingScheduled;
  	private long mySocketTimeout = DEFAULT_SOCKET_TIMEOUT;
  
  	/**
  	 * Constructor
  	 */
  	public HohRawClientMultithreaded() {
  		myExecutorService = Executors.newScheduledThreadPool(1);
  	}
  
  	/**
  	 * Constructor
  	 * 
  	 * @param theHost
  	 *            The HOST (name/address). E.g. "192.168.1.1"
  	 * @param thePort
  	 *            The PORT. E.g. "8080"
  	 * @param thePath
  	 *            The path being requested (must either be blank or start with
  	 *            '/' and contain a path). E.g. "/Apps/Receiver.jsp"
  	 */
  	public HohRawClientMultithreaded(String theHost, int thePort, String thePath) {
  		this();
  
  		setHost(theHost);
  		setPort(thePort);
  		setUriPath(thePath);
  	}
  
  	/**
  	 * Constructor
  	 * 
  	 * @param theHost
  	 *            The HOST (name/address). E.g. "192.168.1.1"
  	 * @param thePort
  	 *            The PORT. E.g. "8080"
  	 * @param theUriPath
  	 *            The URI path being requested (must either be blank or start with
  	 *            '/' and contain a path). E.g. "/Apps/Receiver.jsp"
  	 * @param theExecutorService
  	 *            The executor service to use for detecting stale sockets
  	 */
  	public HohRawClientMultithreaded(String theHost, int thePort, String theUriPath, ScheduledExecutorService theExecutorService) {
  		super(theHost, thePort, theUriPath);
  		Validate.notNull(theExecutorService, "executorService");
  
  		myExecutorService = theExecutorService;
  	}
  
  	/**
  	 * Constructor
  	 * 
  	 * @param theUrl
  	 *            The URL to connect to
  	 */
  	public HohRawClientMultithreaded(URL theUrl) {
 		this();
 		setUrl(theUrl);
 	}
 
 	/**
 	 * Constructor
 	 * 
 	 * @param theUrl
 	 *            The URL to connect to
 	 * @param theExecutorService
 	 *            The executor service to use for detecting stale sockets
 	 */
 	public HohRawClientMultithreaded(URL theUrl, ScheduledExecutorService theExecutorService) {
 		super(theUrl);
 		Validate.notNull(theExecutorService, "executorService");
 
 		myExecutorService = theExecutorService;
 	}
 
 	@Override
 	protected synchronized Socket provideSocket() throws IOException {
 		Socket retVal;
 		if (myIdleSocketsToTimeBecameIdle.size() == 0) {
 			ourLog.info("Creating new remote connection to {}:{}", getHost(), getPort());
 			retVal = connect();
 		} else {
 			retVal = myIdleSocketsToTimeBecameIdle.keySet().iterator().next();
 			myIdleSocketsToTimeBecameIdle.remove(retVal);
 			if (retVal.isClosed()) {
 				ourLog.trace("Found existing remote connection to {}:{} but it was closed, to going to open a new one", getHost(), getPort());
 				retVal = connect();
 			} else {
 				ourLog.trace("Returning existing remote connection to {}:{}", getHost(), getPort());
 			}
 		}
 		return retVal;
 	}
 
 	/**
 	 * Returns a socket to the pool. If the socket is closed, it will
 	 * not be returned.
 	 */
 	@Override
 	protected synchronized void returnSocket(Socket theSocket) {
 		if (theSocket.isClosed()) {
 			return;
 		}
 		
 		long now = System.currentTimeMillis();
 
 		// TODO: reap immediately if timeout is 0
 		
 		if (ourLog.isDebugEnabled()) {
 			if (mySocketTimeout == -1) {
 				ourLog.debug("Returning socket, will not attempt to reap");
 			} else {
 				ourLog.debug("Returning socket, will be eligible for reaping at " + myLogTimeFormat.format(new Date(now + mySocketTimeout)));
 			}
 		}
 
 		myIdleSocketsToTimeBecameIdle.put(theSocket, now);
 		scheduleReaping();
 	}
 
 	private void scheduleReaping() {
 		long now = System.currentTimeMillis();
 		if (myReapingScheduled) {
 			ourLog.debug("Reaping already scheduled");
 			return;
 		}
 
 		if (myIdleSocketsToTimeBecameIdle.size() < 1) {
 			return;
 		}
 
 		if (mySocketTimeout == -1) {
 			return;
 		}
 		
 		long earliestReapingTime = Long.MAX_VALUE;
 		for (Long next : myIdleSocketsToTimeBecameIdle.values()) {
 			long nextReapingTime = next + mySocketTimeout;
 			if (nextReapingTime < earliestReapingTime) {
 				earliestReapingTime = nextReapingTime;
 			}
 		}
 
 		long delay = earliestReapingTime - now;
 		if (ourLog.isDebugEnabled()) {
 			ourLog.debug("Scheduling socket reaping in {} ms at {}", delay, myLogTimeFormat.format(new Date(earliestReapingTime)));
 		}
 
 		myExecutorService.schedule(new TimeoutTask(), delay, TimeUnit.MILLISECONDS);
 		myReapingScheduled = true;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public long getSocketTimeout() {
 		return mySocketTimeout;
 	}
 
 	/**
 	 * {@inheritDoc}
 	 */
 	public synchronized void setSocketTimeout(long theSocketTimeout) {
 		if (mySocketTimeout < -1) {
 			throw new IllegalArgumentException("Socket timeout must be -1, 0, or a positive integer");
 		}
 		mySocketTimeout = theSocketTimeout;
 		myReapingScheduled = false;
 		scheduleReaping();
 	}
 
 	private class TimeoutTask implements Runnable {
 		public void run() {
 
 			if (mySocketTimeout == -1) {
 				return;
 			}
 			
 			ourLog.debug("Beginning socket reaping pass");
 			try {
 
 				List<Socket> socketsToClose = new ArrayList<>();
 				long closeIfActiveBefore = System.currentTimeMillis() - mySocketTimeout;
 				synchronized (HohRawClientMultithreaded.this) {
 
 					for (Iterator<Map.Entry<Socket, Long>> iter = myIdleSocketsToTimeBecameIdle.entrySet().iterator(); iter.hasNext();) {
 						Entry<Socket, Long> nextEntry = iter.next();
 						if (nextEntry.getValue() <= closeIfActiveBefore) {
 							Socket key = nextEntry.getKey();
 							socketsToClose.add(key);
 							ourLog.info("Closing idle socket with local port {} because it has been idle since {}", key.getLocalPort(), new Date(nextEntry.getValue()));
 							iter.remove();
 						} else {
 							if (ourLog.isDebugEnabled()) {
 								ourLog.debug("Next socket has " + (nextEntry.getValue() - closeIfActiveBefore) + "ms remaining");
 							}
 						}
 					}
 
 					myReapingScheduled = false;
 					scheduleReaping();
 				}
 
 				for (Socket next : socketsToClose) {
 					closeSocket(next);
 				}
 			} catch (Throwable e) {
 				ourLog.error("Failure during reaper pass", e);
 			}
 		}
 	}
 
 }