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package com.sun.enterprise.jxtamgmt;

import net.jxta.id.ID;

import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.TreeMap;
import java.util.concurrent.locks.ReentrantLock;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Manages Cluster Views and notifies cluster view listeners when cluster view
 * changes
 */
public class ClusterViewManager {
    private static final Logger LOG = JxtaUtil.getLogger(ClusterViewManager.class.getName());
    private TreeMap<String, SystemAdvertisement> view = new TreeMap<String, SystemAdvertisement>();
    private SystemAdvertisement advertisement = null;
    private SystemAdvertisement masterAdvertisement = null;
    private List<ClusterViewEventListener> cvListeners = new ArrayList<ClusterViewEventListener>();
    private long viewId = 0;
    private long masterViewID = 0;
    private ClusterManager manager;
    private ReentrantLock viewLock = new ReentrantLock();

    /**
     * Constructor for the ClusterViewManager object
     *
     * @param advertisement the advertisement of the instance associated with
     *                      this object
     * @param manager       the cluster manager
     * @param listeners     <code>List</code> of <code>ClusterViewEventListener</code>
     */
    public ClusterViewManager(final SystemAdvertisement advertisement,
                              final ClusterManager manager,
                              final List<ClusterViewEventListener> listeners) {
        this.advertisement = advertisement;
        this.manager = manager;
        cvListeners.addAll(listeners);
    }

    public void start() {
        //Self appointed as master and then discover so that we resolve to the right one
        setMaster(advertisement, true);
    }

    public void addClusterViewEventListener(
            final ClusterViewEventListener listener) {
        cvListeners.add(listener);
    }

    public void removeClusterViewEventListener(final ClusterViewEventListener listener) {
        cvListeners.remove(listener);
    }

    /**
     * adds a system advertisement
     *
     * @param advertisement system adverisement to add
     */
    void add(final SystemAdvertisement advertisement) {
        lockLog("add()");
        viewLock.lock();
        try {
            if (!view.containsKey(advertisement.getID().toString())) {
                LOG.log(Level.FINER, new StringBuffer().append("Adding ")
                        .append(advertisement.getName())
                        .append("   ")
                        .append(advertisement.getID().toString())
                        .toString());

                view.put(advertisement.getID().toString(), advertisement);
                LOG.log(Level.FINER, MessageFormat.format("Cluster view now contains {0} entries", getViewSize()));
            }
        } finally {
            viewLock.unlock();
        }
    }

    /**
     * Set the master instance
     *
     * @param advertisement Master system adverisement
     * @param notify        if true, notifies registered listeners
     */
    void setMaster(final SystemAdvertisement advertisement, boolean notify) {
        if (!advertisement.equals(masterAdvertisement)) {
            masterAdvertisement = advertisement;
            lockLog("setMaster()");
            viewLock.lock();
            try {
                view.put(masterAdvertisement.getID().toString(), masterAdvertisement);
            } finally {
                viewLock.unlock();
            }
            if (notify) {
                notifyListeners(new ClusterViewEvent(
                        ClusterViewEvents.MASTER_CHANGE_EVENT,
                        advertisement));
            }
            if (advertisement.getID().equals(this.advertisement.getID())) {
                LOG.log(Level.FINER, "Setting MasterNode Role");
            } else {
                LOG.log(Level.FINER,
                        new StringBuffer().append("Setting Master Node :")
                                .append(advertisement.getName()).append(' ')
                                .append(advertisement.getID()).toString());
            }

        }
    }

    /**
     * Set the master instance with new view
     *
     * @param newView list of advertisements
     * @param advertisement Master system adverisement
     * @return true if there is master's change, false otherwise
     */
    boolean setMaster( final List<SystemAdvertisement> newView, final SystemAdvertisement advertisement ) {
        if( advertisement.equals( masterAdvertisement ) )
            return false;
        if ( newView != null )
            addToView( newView );
        setMaster( advertisement, true );
        return true;
    }

    /**
     * Gets the master advertisement
     *
     * @return SystemAdvertisement Master system adverisement
     */
    public SystemAdvertisement getMaster() {
        return masterAdvertisement;
    }

    /**
     * Retrieves a system advertisement from a the table
     *
     * @param id instance id
     * @return Returns the SystemAdvertisement associated with id
     */
    public SystemAdvertisement get(final ID id) {
        final SystemAdvertisement adv;
        lockLog("get()");
        viewLock.lock();
        try {
            adv = view.get(id.toString());
        } finally {
            viewLock.unlock();
        }
        return adv;
    }

    /**
     * removes an entry from the table. This is only called when a
     * failure occurs.
     *
     * @param advertisement Instance advertisement
     * @return SystemAdvertisement removed  or null if not in view.
     */
    SystemAdvertisement remove(final SystemAdvertisement advertisement) {
        ID id = advertisement.getID();
        if (containsKey(id)) {
            lockLog("remove()");
            viewLock.lock();
            try {
                view.remove(id.toString());
            } finally {
                viewLock.unlock();
            }

            LOG.log(Level.FINER, "Removed " + advertisement.getName() + "   "+ advertisement.getID().toString());
        } else {
            LOG.log(Level.FINEST, "Skipping removal of " + id+ " Not in view");
        }
        return advertisement;
    }

    public boolean containsKey(final ID id) {
        final boolean contains;
        viewLock.lock();
        try {
            contains = view.containsKey(id.toString());
        } finally {
            viewLock.unlock();
        }

        return contains;
    }

    /**
     * Resets the view
     */
    void reset() {
        LOG.log(Level.FINEST, "Resetting View");
        lockLog("reset()");
        viewLock.lock();
        try {
            view.clear();
            view.put(advertisement.getID().toString(), advertisement);
        } finally {
            viewLock.unlock();
        }
    }

    /**
     * Returns a sorted localView
     *
     * @return The localView List
     */
    public ClusterView getLocalView() {
        final TreeMap<String, SystemAdvertisement> temp;
        lockLog("getLocalView()");
        viewLock.lock();
        try {
            temp = (TreeMap<String, SystemAdvertisement>) view.clone();
        } finally {
            viewLock.unlock();
        }
        LOG.log(Level.FINEST, "returning new ClusterView with view size:" + view.size());
        return new ClusterView(temp, viewId++);
    }

    /**
     * Gets the viewSize attribute of the ClusterViewManager object
     *
     * @return The viewSize
     */
    public int getViewSize() {
        int size;
        lockLog("getViewSize()");
        viewLock.lock();
        try {
            size = view.size();
        } finally {
            viewLock.unlock();
        }
        return size;
    }

    /**
     * Returns the top node on the list
     *
     * @return the top node on the list
     */
    SystemAdvertisement getMasterCandidate() {
        final SystemAdvertisement adv;
        final String id = view.firstKey();
        lockLog("getMasterCandidate()");
        viewLock.lock();
        try {
            adv = view.get(id);
        } finally {
            viewLock.unlock();
        }
        LOG.log(Level.FINER,
                new StringBuffer().append("Returning Master Candidate Node :")
                        .append(adv.getName()).append(' ').append(adv.getID())
                        .toString());
        return adv;
    }

    /**
     * Determines whether this node is the Master
     *
     * @return true if this node is the master node
     */
    public boolean isMaster() {
        return masterAdvertisement != null && masterAdvertisement.getID().equals(advertisement.getID());
    }

    /**
     * Determines whether this node is at the top of the list
     *
     * @return true if this node is a the top of the list, false otherwise
     */
    public boolean isFirst() {
        final String id = view.firstKey();
        return advertisement.getID().toString().equals(id);
    }

    /**
     * the index of id this view, or -1 if this view does not contain this
     * element.
     *
     * @param id id
     * @return the index of id this view, or -1 if this view does not
     *         contain this element.
     */
    public int indexOf(final ID id) {
        if (id == null) {
            return -1;
        }
        final String idStr = id.toString();
        int index = 0;
        String key;
        for (String s : view.keySet()) {
            key = s;
            if (key.equals(idStr)) {
                return index;
            }
            index++;
        }
        return -1;
    }

    public ID getID(final String name) {
        return manager.getID(name);
    }

    /**
     * Adds a list of advertisements to the view
     *
     * @param newView       list of advertisements
     * @param cvEvent       the cluster event
     * @param authoritative whether the view is authoritative or not
     */
    void addToView(final List<SystemAdvertisement> newView,
                   final boolean authoritative,
                   final ClusterViewEvent cvEvent) {
        //TODO: need to review the use cases of the callers of method
        if (cvEvent == null) {
            return;
        }

        if (authoritative) {
            boolean changed = addToView( newView );
            if (changed) {
                //only if there are changes that we notify
                notifyListeners(cvEvent);
            }
        }
    }

    /**
     * Adds a list of advertisements to the view
     *
     * @param newView       list of advertisements
     * @return true if there are changes, false otherwise
     */
    private boolean addToView( final List<SystemAdvertisement> newView ) {
        boolean changed = false;
        LOG.log( Level.FINER, "Resetting View" );
        reset();
        lockLog( "addToView()" );
        viewLock.lock();
        try {
            if( !newView.contains( manager.getSystemAdvertisement() ) ) {
                view.put( manager.getSystemAdvertisement().getID().toString(),
                          manager.getSystemAdvertisement() );
            }
            for( SystemAdvertisement elem : newView ) {
                LOG.log( Level.FINER,
                         new StringBuffer().append( "Adding " )
                                 .append( elem.getID() ).append( " to view" )
                                 .toString() );
                if( !changed && !view.containsKey( elem.getID().toString() ) ) {
                    changed = true;
                }
                // Always add the wire version of the adv
                view.put( elem.getID().toString(), elem );
            }
        } finally {
            viewLock.unlock();
        }
        return changed;
    }

    void notifyListeners(final ClusterViewEvent event) {
        LOG.log(Level.FINER, MessageFormat.format("Notifying the {0} to listeners, peer in event is {1}",
                    event.getEvent().toString(), event.getAdvertisement().getName()));
        for (ClusterViewEventListener elem : cvListeners) {
            elem.clusterViewEvent(event, getLocalView());
        }
    }

    public void setInDoubtPeerState(final SystemAdvertisement adv) {
        if (adv == null) {
            throw new IllegalArgumentException("SystemAdvertisment may not be null");
        }
        notifyListeners(new ClusterViewEvent(ClusterViewEvents.IN_DOUBT_EVENT, adv));
    }

    public void setPeerStoppingState(final SystemAdvertisement adv) {
        if (adv == null) {
            throw new IllegalArgumentException("SystemAdvertisment may not be null");
        }
        notifyListeners(new ClusterViewEvent(ClusterViewEvents.PEER_STOP_EVENT, adv));
    }

    public void setClusterStoppingState(final SystemAdvertisement adv) {
        if (adv == null) {
            throw new IllegalArgumentException("SystemAdvertisment may not be null");
        }
        notifyListeners(new ClusterViewEvent(ClusterViewEvents.CLUSTER_STOP_EVENT, adv));
    }

    public void setPeerNoLongerInDoubtState(final SystemAdvertisement adv) {
        if (adv == null) {
            throw new IllegalArgumentException("SystemAdvertisment may not be null");
        }
        notifyListeners(new ClusterViewEvent(ClusterViewEvents.NO_LONGER_INDOUBT_EVENT, adv));
    }

    public long getMasterViewID() {
        return masterViewID;
    }

    public void setMasterViewID(long masterViewID) {
        this.masterViewID = masterViewID;
    }
    private void lockLog(String method) {
        LOG.log(Level.FINE, MessageFormat.format("{0} viewLock Hold count :{1}, lock queue count:{2}", method, viewLock.getHoldCount(), viewLock.getQueueLength()));
    }

    public void setPeerReadyState(SystemAdvertisement adv) {
        if (adv == null) {
            throw new IllegalArgumentException("SystemAdvertisment may not be null");
        }
        notifyListeners(new ClusterViewEvent(ClusterViewEvents.JOINED_AND_READY_EVENT, adv));

    }
}