// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
package com.cloud.ha;

import java.util.Date;
import java.util.Map;
import java.util.concurrent.TimeUnit;

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

import org.apache.cloudstack.framework.config.dao.ConfigurationDao;
import org.apache.cloudstack.managed.context.ManagedContextRunnable;

import com.cloud.alert.AlertManager;
import com.cloud.usage.dao.UsageJobDao;
import com.cloud.utils.db.Transaction;
import com.cloud.utils.db.TransactionLegacy;

@Local(value={HighAvailabilityManager.class})
public class HighAvailabilityManagerExtImpl extends HighAvailabilityManagerImpl {
	
    @Inject
	UsageJobDao _usageJobDao;
    
    @Inject ConfigurationDao configDao;
    
	@Override
	public boolean configure(final String name, final Map<String, Object> xmlParams) throws ConfigurationException {
		super.configure(name, xmlParams);
        return true;
	}

	@Override
    public boolean start() 
	{
		super.start();
		
	        
        boolean enableUsage = new Boolean(configDao.getValue("enable.usage.server"));
        
        //By default, usage is enabled for production
        //Devs might override this value to disable usage in their setup
        if(enableUsage)
        {
        	_executor.scheduleAtFixedRate(new UsageServerMonitorTask(), 60*60, 10*60, TimeUnit.SECONDS); // schedule starting in one hour to execute every 10 minutes
        }
        
        return true;
    }
	
	protected class UsageServerMonitorTask  extends ManagedContextRunnable{
        @Override
        protected void runInContext() {
            if (s_logger.isInfoEnabled()) {
                s_logger.info("checking health of usage server");
            }

            try {
                boolean isRunning = false;
                TransactionLegacy txn = TransactionLegacy.open(TransactionLegacy.USAGE_DB);
                try {
                    Date lastHeartbeat = _usageJobDao.getLastHeartbeat();
                    if (lastHeartbeat != null) {
                        long sinceLastHeartbeat = System.currentTimeMillis() - lastHeartbeat.getTime();
                        if (sinceLastHeartbeat <= (10 * 60 * 1000)) {
                            // if it's been less than 10 minutes since the last heartbeat, then it appears to be running, otherwise send an alert
                            isRunning = true;
                        }
                    }
                    if (s_logger.isDebugEnabled()) {
                        s_logger.debug("usage server running? " + isRunning + ", heartbeat: " + lastHeartbeat);
                    }
                } finally {
                    txn.close();

                    // switch back to VMOPS db
                    TransactionLegacy swap = TransactionLegacy.open(TransactionLegacy.CLOUD_DB);
                    swap.close();
                }

                if (!isRunning) {
                    _alertMgr.sendAlert(AlertManager.ALERT_TYPE_USAGE_SERVER, 0, new Long(0), "No usage server process running", "No usage server process has been detected, some attention is required");
                } else {
                    _alertMgr.clearAlert(AlertManager.ALERT_TYPE_USAGE_SERVER, 0, 0);
                }
            } catch (Exception ex) {
                s_logger.warn("Error while monitoring usage job", ex);
            }
        }
    }
}