package cz.cuni.amis.pogamut.ut2004.communication.worldview;
   
   import java.util.ArrayList;
   import java.util.LinkedList;
   import java.util.List;
   import java.util.Queue;
   
   import com.google.inject.Inject;
   import com.google.inject.name.Named;
  
  import cz.cuni.amis.pogamut.base.communication.mediator.IMediator;
  import cz.cuni.amis.pogamut.base.communication.translator.event.IWorldChangeEvent;
  import cz.cuni.amis.pogamut.base.component.bus.IComponentBus;
  import cz.cuni.amis.pogamut.base.component.bus.event.BusAwareCountDownLatch;
  import cz.cuni.amis.pogamut.base.component.bus.exception.ComponentNotRunningException;
  import cz.cuni.amis.pogamut.base.component.bus.exception.ComponentPausedException;
  import cz.cuni.amis.pogamut.base.component.controller.ComponentDependencies;
  import cz.cuni.amis.pogamut.base.utils.guice.AgentScoped;
  import cz.cuni.amis.pogamut.base.utils.logging.IAgentLogger;
  import cz.cuni.amis.pogamut.base3d.ILockableVisionWorldView;
  import cz.cuni.amis.pogamut.ut2004.communication.messages.gbinfomessages.BeginMessage;
  import cz.cuni.amis.pogamut.ut2004.communication.messages.gbinfomessages.EndMessage;
  import cz.cuni.amis.pogamut.ut2004.communication.messages.gbinfomessages.Player;
  import cz.cuni.amis.utils.exception.PogamutInterruptedException;
  import java.util.logging.Level;
  
  /**
   * Lockable word view.
   * <p>
   * <p>
   * Contains GameBots2004 correct locking of the worldview.
   * <p>
   * <p>
   * All messages are processed always in batches (all messages between
   * EndMessages are one batch) meaning that the world view is always correct!
   * <p>
   * <p>
   * When worldview is lock()ed it postpones the events until unlock()ed, which is
   * triggering raising all events that came from the lock().
   * <p>
   * <p>
   * <b>lock() method here blocks</b> until the END message of the batch is hit,
   * then the world view is considered to be fully locked and let the lock()
   * continue. You may use it to create correct sync bot. (just lock() the world
   * view before your logic and unlock() the world view after the logic finishes)
   * <p>
   * <p>
   * The world view is unlocked from the beginning.
   * <p>
   * <p>
   * The locking mechanism starts to work with the first BeginMessage. (To let all
   * other events to be processed automatically during the handshake.)
   * 
   * @author Jimmy
   *         <p>
   *         <p>
   * 
   * 
   * @author Jimmy
   * @see UT2004LockableWorldView
   */
  @AgentScoped
  public class UT2004SyncLockableWorldView extends UT2004WorldView
  		implements ILockableVisionWorldView {
  
  	public static final String WORLDVIEW_DEPENDENCY = "UT2004SyncLockableWorldViewDependency";
  
  	/**
  	 * Here we store batches that are complete (ends with the EndMessage).
  	 */
  	private Queue<List<IWorldChangeEvent>> batches = new LinkedList<List<IWorldChangeEvent>>();
  
  	/**
  	 * Here we store new events that are coming from the Mediator.
  	 */
  	private List<IWorldChangeEvent> currentBatch = new ArrayList<IWorldChangeEvent>();
  
  	/**
  	 * Whether the world view is locked.
  	 */
  	private boolean locked = false;
  
  	/**
  	 * First the world view will become locked, when the next END message is
  	 * received, it will raise this flag meaning the lock() succeeded (the
  	 * lockLatch has been raised) and we have to buffer all new messages.
  	 */
  	private boolean inLock = false;
  
  	/**
  	 * First BEG message
  	 */
  	private boolean beginCame = false;
  
  	/**
  	 * Synchronization mutex for this class.
  	 */
  	private final Object objectMutex = new Object();
  
 	/**
 	 * lock() waits on this latch to continue...
 	 */
 	private BusAwareCountDownLatch lockLatch;
 
 	/**
 	 * Whether the stop() method has been called.
 	 */
 	private boolean stopRequested = false;
 	
 	/**
 	 * Whether the pause() method has been called.
 	 */
 	private boolean pauseRequested = false;
 
 	@Inject
 	public UT2004SyncLockableWorldView(
 			@Named(WORLDVIEW_DEPENDENCY) ComponentDependencies dependencies,
 			IMediator mediator,
 			IComponentBus bus, IAgentLogger log) {
 		super(dependencies, mediator, bus, log);		
 	}
 
 	/**
 	 * When the world view is locked - no batches are processes until unlocked.
 	 * 
 	 * @throws PogamutInterruptedException
 	 */
 	public void lock() throws PogamutInterruptedException, ComponentNotRunningException {
 		if (isPaused()) throw new ComponentPausedException(controller.getState().getFlag(), this);
 		if (!isRunning()) throw new ComponentNotRunningException(controller.getState().getFlag(), this);
 		synchronized (objectMutex) {
 			if (isLocked())
 				return;
 			locked = true;
 			if (log.isLoggable(Level.FINER)) log.finer("World view is being locked.");
 		}
 		if (isPaused()) {
 			if (log.isLoggable(Level.FINER)) log.finer("World view paused, unlocking.");
 			locked = false;
 			throw new ComponentPausedException(controller.getState().getFlag(), this);
 		}
 		if (!isRunning()) {
 			if (log.isLoggable(Level.FINER)) log.finer("World view not running, unlocking.");
 			locked = false;
 			throw new ComponentNotRunningException(controller.getState().getFlag(), this);
 		}
 		lockLatch.await();
 		if (log.isLoggable(Level.FINER)) log.finer("World view locked.");
 		if (pauseRequested) { 
 			throw new ComponentPausedException("Component pause requested.", this);
 		}
 		if (stopRequested) {
 			throw new ComponentNotRunningException("Component stop requested.", this);
 		}
 	}
 
 	/**
 	 * Unlocks the world view - triggers processing of all events till the last
 	 * EndMessage that came between lock() / unlock() calls.
 	 */
 	public void unlock() throws ComponentNotRunningException {
 		synchronized (objectMutex) {
 			if (!isLocked())
 				return;
 			locked = false;
 			if (log.isLoggable(Level.FINER)) log.finer("World view is being unlocked.");
 			inLock = false;
 			processBatches();
 			if (log.isLoggable(Level.FINER)) log.finer("World view unlocked.");
 			// reinitialize the lock latch so the next lock() blocks as well
 			lockLatch = new BusAwareCountDownLatch(1, eventBus, this);
 		}
 	}
 
 	public boolean isLocked() {
 		return locked;
 	}
 
 	public boolean isInLock() {
 		return inLock;
 	}
 
 	/**
 	 * Process all messages that are stored inside the batches and clears them.
 	 * <p><p>
 	 * <b>Unsync!</b>
 	 */
 	private void processBatches() {
 		// process old batches
 		for (List<IWorldChangeEvent> batch : batches) {
 			processBatch(batch);
 		}
 		batches.clear();
 		// process current opened batch
 		processBatch(currentBatch);
 	}
 
 	/**
 	 * Does super.notifyEvent(event) for each event in the batch.
 	 * <p>
 	 * <p>
 	 * <b>Unsync!</b>
 	 * 
 	 * @param batch
 	 */
 	private void processBatch(List<IWorldChangeEvent> batch) {
 		for (IWorldChangeEvent event : batch) {
 			super.notify(event);
 		}
 		batch.clear();
 	}
 
 	/**
 	 * Implements locking logic.
 	 */
 	@Override
 	public void notify(IWorldChangeEvent event) {
 
   		synchronized (objectMutex) {
 			if (!beginCame) {
 				if (event instanceof BeginMessage) {
 					beginCame = true;
 				} else {
 					super.notify(event);
 					return;
 				}
 			}			
 			if (isLocked()) {
 				if (isInLock()) {
 					// we're IN LOCK - logic is running, do not process any new
 					// message
 					if (event instanceof EndMessage) {
 						currentBatch.add(event);
 						batches.add(currentBatch);
 						currentBatch = new ArrayList<IWorldChangeEvent>(
 								currentBatch.size() + 10);
 					} else {
 						currentBatch.add(event);
 					}
 				} else {
 					// we're waiting for the next EndMessage
 					if (event instanceof EndMessage) {
 						// EndMessage came! Notify...
 						super.notify(event);
 						// ... raise the latch and let the logic continue!
 						if (log.isLoggable(Level.FINER)) log.finer("World view in-locked state, raising the lock() latch.");
 						lockLatch.countDown();
 						inLock = true;
 					} else {
 						// not an EndMessage, process as usual
 						super.notify(event);
 					}
 				}
 			} else {
 				super.notify(event);
 			}
 		}
 	}
 	
 	@Override
 	protected void start(boolean startPaused) {
 		super.start(startPaused);
 		lockLatch = new BusAwareCountDownLatch(1, eventBus, this);
 		stopRequested = false;
 		pauseRequested = false;
 	}
 
 	@Override
 	protected void preStop() {
 		super.preStop();
 		synchronized (objectMutex) {
 			stopRequested = true;
 			lockLatch.countDown();
 		}
 	}
 	
 	@Override
 	protected void prePause() {
 		super.preStop();
 		synchronized (objectMutex) {
 			pauseRequested = true;
 			lockLatch.countDown();
 		}
 	}
 	
 	@Override
 	protected void resume() {
 		super.resume();
 		synchronized(objectMutex) {
 			lockLatch.countDown();
 			lockLatch = new BusAwareCountDownLatch(1, eventBus, this);
 			pauseRequested = false;
 		}
 	}
 	
 	@Override
 	protected void stop() {
 		super.stop();
 		synchronized (objectMutex) {
 			stopRequested = true;
 			lockLatch.countDown();
 		}
 	}
 
 }