/**
 *  Copyright (C) 2010 Cloud.com, Inc.  All rights reserved.
 * 
 * This software is licensed under the GNU General Public License v3 or later.
 * 
 * It is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * 
 */

package com.cloud.alert;

import java.util.Map;

import javax.ejb.Local;
import javax.naming.ConfigurationException;

import org.apache.log4j.Logger;

import com.cloud.cluster.ClusterManager;
import com.cloud.cluster.ClusterNodeJoinEventArgs;
import com.cloud.cluster.ClusterNodeLeftEventArgs;
import com.cloud.cluster.ManagementServerHostVO;
import com.cloud.cluster.dao.ManagementServerHostDao;
import com.cloud.utils.component.ComponentLocator;
import com.cloud.utils.db.GlobalLock;
import com.cloud.utils.events.EventArgs;
import com.cloud.utils.events.SubscriptionMgr;

@Local(value=AlertAdapter.class)
public class ClusterAlertAdapter implements AlertAdapter {
	
	private static final Logger s_logger = Logger.getLogger(ClusterAlertAdapter.class);
	
	private AlertManager _alertMgr;
    private String _name;

    private ManagementServerHostDao _mshostDao;
    
    public void onClusterAlert(Object sender, EventArgs args) {
		if(s_logger.isDebugEnabled()) {
            s_logger.debug("Receive cluster alert, EventArgs: " + args.getClass().getName());
        }
    	
    	if(args instanceof ClusterNodeJoinEventArgs) {
    		onClusterNodeJoined(sender, (ClusterNodeJoinEventArgs)args);
    	} else if(args instanceof ClusterNodeLeftEventArgs) {
    	    onClusterNodeLeft(sender, (ClusterNodeLeftEventArgs)args);
    	} else {
    		s_logger.error("Unrecognized cluster alert event");
    	}
    }
    
    private void onClusterNodeJoined(Object sender, ClusterNodeJoinEventArgs args) {
		if(s_logger.isDebugEnabled()) {
            s_logger.debug("Handle cluster node join alert, self node: " + args.getSelf());
        }
    	
    	for(ManagementServerHostVO mshost : args.getJoinedNodes()) {
    		if(mshost.getId() == args.getSelf().longValue()) {
				if(s_logger.isDebugEnabled()) {
                    s_logger.debug("Management server node " + mshost.getServiceIP() + " is up, send alert");
                }
				
			    _alertMgr.sendAlert(AlertManager.ALERT_TYPE_MANAGMENT_NODE, 0, new Long(0),
		    		"Management server node " + mshost.getServiceIP() + " is up", "");
			    break;
    		}
    	}
    }
    
    private void onClusterNodeLeft(Object sender, ClusterNodeLeftEventArgs args) {
    	
		if(s_logger.isDebugEnabled()) {
            s_logger.debug("Handle cluster node left alert, self node: " + args.getSelf());
        }
    	
    	for(ManagementServerHostVO mshost : args.getLeftNodes()) {
    		if(mshost.getId() != args.getSelf().longValue()) {
    			GlobalLock lock = GlobalLock.getInternLock("ManagementAlert." + mshost.getId());
    			try {
    				if(lock.lock(180)) {
    					try {
    						ManagementServerHostVO alertHost = _mshostDao.findById(mshost.getId());
    						if(alertHost.getAlertCount() == 0) {
    							_mshostDao.increaseAlertCount(mshost.getId());

    							if(s_logger.isDebugEnabled()) {
                                    s_logger.debug("Detected management server node " + mshost.getServiceIP() + " is down, send alert");
                                }
    							
    						    _alertMgr.sendAlert(AlertManager.ALERT_TYPE_MANAGMENT_NODE, 0, new Long(0),
						    		"Management server node " + mshost.getServiceIP() + " is down", "");
    						} else {
    							if(s_logger.isDebugEnabled()) {
                                    s_logger.debug("Detected management server node " + mshost.getServiceIP() + " is down, but alert has already been set");
                                }
    						}
    					} finally {
    						lock.unlock();
    					}
    				}
    			} finally {
    				lock.releaseRef();
    			}
    		}
    	}
    }

	@Override
	public boolean configure(String name, Map<String, Object> params)
		throws ConfigurationException {
		
		if (s_logger.isInfoEnabled()) {
            s_logger.info("Start configuring cluster alert manager : " + name);
        }

		ComponentLocator locator = ComponentLocator.getCurrentLocator();

        _mshostDao = locator.getDao(ManagementServerHostDao.class);
        if(_mshostDao == null) {
            throw new ConfigurationException("Unable to get " + ManagementServerHostDao.class.getName());
        }
		
		_alertMgr = locator.getManager(AlertManager.class);
		if (_alertMgr == null) {
			throw new ConfigurationException("Unable to get " + AlertManager.class.getName());
		}
		
		try {
			SubscriptionMgr.getInstance().subscribe(ClusterManager.ALERT_SUBJECT, this, "onClusterAlert");
		} catch (SecurityException e) {
			throw new ConfigurationException("Unable to register cluster event subscription");
		} catch (NoSuchMethodException e) {
			throw new ConfigurationException("Unable to register cluster event subscription");
		}
		
		return true;
	}

	@Override
	public String getName() {
		return _name;
	}

	@Override
	public boolean start() {
		return true;
	}

	@Override
	public boolean stop() {
		return true;
	}
}