/*-
 * ================================================================================
 * eCOMP Portal
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property
 * ================================================================================
 * Licensed 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 org.openecomp.portalapp.portal.listener;

import java.util.List;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.openecomp.portalapp.portal.logging.aop.EPMetricsLog;
import org.openecomp.portalapp.portal.logging.format.EPAppMessagesEnum;
import org.openecomp.portalapp.portal.logging.logic.EPLogUtil;
import org.openecomp.portalapp.portal.ueb.EPUebHelper;
import org.openecomp.portalapp.portal.utils.EPSystemProperties;
import org.openecomp.portalapp.portal.utils.EcompPortalUtils;
import org.openecomp.portalsdk.core.logging.logic.EELFLoggerDelegate;
import org.openecomp.portalsdk.core.util.SystemProperties;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.transaction.annotation.Transactional;

@Transactional
@org.springframework.context.annotation.Configuration
@EnableAspectJAutoProxy
@EPMetricsLog
public class HealthMonitor {
	
	@Autowired
	private SessionFactory sessionFactory;
	
	@Autowired
	private EPUebHelper epUebHelper;
	
	private static boolean databaseUp;
	private static boolean uebUp;
	private static boolean frontEndUp;
	private static boolean backEndUp;
	private static boolean dbClusterStatusOk;
	private static boolean dbPermissionsOk;
	public static boolean isSuspended = false;
			
	Thread healthMonitorThread;
	
	EELFLoggerDelegate logger = EELFLoggerDelegate.getLogger(HealthMonitor.class);
	
	public HealthMonitor() {
		
	}
	
	public static boolean isDatabaseUp() {
		return databaseUp;
	}
	
	public static boolean isClusterStatusOk() {
		return dbClusterStatusOk;
	}
	
	public static boolean isDatabasePermissionsOk() {
		return dbPermissionsOk;
	}

	public static boolean isUebUp() {
		return uebUp;
	}
	
	public static boolean isFrontEndUp() {
		return frontEndUp;
	}
	
	public static boolean isBackEndUp() {
		return backEndUp;
	}
				
	private void monitorEPHealth() throws InterruptedException{
		
		int numIntervalsDatabaseHasBeenDown = 0;
		int numIntervalsClusterNotHealthy = 0;
		int numIntervalsDatabasePermissionsIncorrect = 0;
		int numIntervalsUebHasBeenDown = 0;
				
		logger.debug(EELFLoggerDelegate.debugLogger, "==> Health Monitor thread started");
		
		long sleepInterval = (Long.valueOf(SystemProperties.getProperty(EPSystemProperties.HEALTH_POLL_INTERVAL_SECONDS)) * 1000);
		long numIntervalsBetweenAlerts = Long.valueOf(SystemProperties.getProperty(EPSystemProperties.HEALTHFAIL_ALERT_EVERY_X_INTERVALS));
		logger.debug(EELFLoggerDelegate.debugLogger, "Polling health every " + sleepInterval + " milliseconds. Alerting every " 
		                  + (sleepInterval * numIntervalsBetweenAlerts)/1000 + " seconds when component remains down.");
		
		while (true)
		{   					
   		    //
	    	//  Get DB status.  If down, signal alert once every X intervals.
	    	//
	    	databaseUp = this.checkIfDatabaseUp();
		    if (databaseUp == false) {
			
		    	if ((numIntervalsDatabaseHasBeenDown % numIntervalsBetweenAlerts) == 0){
				    // Write a Log entry that will generate an alert
		    		EPLogUtil.logEcompError(EPAppMessagesEnum.BeHealthCheckMySqlError);
		    		logger.debug(EELFLoggerDelegate.debugLogger, "Database down, logging to error log to trigger alert.");
 		            numIntervalsDatabaseHasBeenDown++;
		        }
		        else {
			        numIntervalsDatabaseHasBeenDown = 0;
		        }
		    }
		    
	    	dbClusterStatusOk = this.checkClusterStatus();
		    if (dbClusterStatusOk == false) {
			
		    	if ((numIntervalsClusterNotHealthy % numIntervalsBetweenAlerts) == 0){
		    		EPLogUtil.logEcompError(EPAppMessagesEnum.BeHealthCheckMySqlError);
		    		logger.debug(EELFLoggerDelegate.debugLogger, "Cluster nodes appear to be down, logging to error log to trigger alert.");
		    		numIntervalsClusterNotHealthy++;
		        }
		        else {
		        	numIntervalsClusterNotHealthy = 0;
		        }
		    }
		    
	    	dbPermissionsOk = this.checkDatabaseAndPermissions();
		    if (dbPermissionsOk == false) {
			
		    	if ((numIntervalsDatabasePermissionsIncorrect % numIntervalsBetweenAlerts) == 0){
		    		EPLogUtil.logEcompError(EPAppMessagesEnum.BeHealthCheckMySqlError);
		    		logger.debug(EELFLoggerDelegate.debugLogger, "Database permissions don't seem correct, logging to error log to trigger alert.");
		    		numIntervalsDatabasePermissionsIncorrect++;
		        }
		        else {
		        	numIntervalsDatabasePermissionsIncorrect = 0;
		        }
		    }
		    		
		    //
		    //  Get UEB status.  Publish a bogus message to EP inbox, if 200 OK returned, status is Up.
		    //  If down, signal alert once every X intervals.
		    //  EP will ignore this bogus message.
		    //
		    uebUp = this.checkIfUebUp();
            if (uebUp == false) {
				
    	    	if ((numIntervalsUebHasBeenDown % numIntervalsBetweenAlerts) == 0){
				    // Write a Log entry that will generate an alert
    	    		EPLogUtil.logEcompError(EPAppMessagesEnum.BeHealthCheckUebClusterError);
			    	logger.debug(EELFLoggerDelegate.debugLogger, "UEB down, logging to error log to trigger alert");
 		            numIntervalsUebHasBeenDown++;
		        }
		        else {
			        numIntervalsUebHasBeenDown = 0;
		        }
		    }
		
            //The front end should be up because the API is called through proxy front end server.
            frontEndUp = true; 
		    
		    
		    //If the rest API called, the backend  is always up
		    backEndUp = true;
		    
		    //
		    //  future nice to have...get Partner status
  		    //
		    //  For all apps exposing a rest url, query one of the rest urls(/roles?) and manage a list
		    //  of app name/status.  We might not return back a non 200 OK in health check, but we
            //  could return information in the json content of a health check.
 		    //
            
            //
	    	//  Get DB status.  If down, signal alert once every X intervals.
	    	//
		    Thread.sleep(sleepInterval);
		}
	}
	
	@PostConstruct
	public void initHealthMonitor() {
		
		healthMonitorThread = new Thread("EP HealthMonitor thread") {
		    public void run(){
	  	        try {
					monitorEPHealth();
				} catch (InterruptedException e) {
					logger.debug(EELFLoggerDelegate.debugLogger, "<== Health Monitor thread exiting..." + EcompPortalUtils.getStackTrace(e));
				} catch(Exception e) {
					logger.error(EELFLoggerDelegate.errorLogger, "Exception occurred in Healthcheck monitor thread." + EcompPortalUtils.getStackTrace(e));
				}
		    }
		};
		if (healthMonitorThread != null) {
		    healthMonitorThread.start();
		}
	}
	
	@PreDestroy
	public void closeHealthMonitor()
	{
		this.healthMonitorThread.interrupt();
	}
    
	
    private boolean checkIfDatabaseUp() {
		
		boolean isUp = false;
		
		Session localSession = null;
		
		try {
			localSession = sessionFactory.openSession();
			
			if (localSession != null) {
				
				String sql = "select app_name from fn_app where app_id=1";
		        Query query = localSession.createSQLQuery(sql);
		        @SuppressWarnings("unchecked")
			    List <String>queryList = query.list();
		        if (queryList != null) {
		            isUp = true;
		        }
		        localSession.close();
		    }
		}
		catch (Exception e) {
			logger.error(EELFLoggerDelegate.errorLogger, EcompPortalUtils.getStackTrace(e));
			isUp = false;
		}
		
		return isUp;	
	}

	
    private boolean checkClusterStatus() {
		
		boolean isUp = false;
		
		Session localSession = null;
		
		try {
			localSession = sessionFactory.openSession();
			if (localSession != null) {
			    /////////////////////////////////////////////////////////////////////////
  			    // If all nodes are unhealthy in a cluster, this will throw an exception 
			    /////////////////////////////////////////////////////////////////////////
		        String sql = "select * from mysql.user";
		        Query query = localSession.createSQLQuery(sql);
		        @SuppressWarnings("unchecked")
			    List <String>queryList = query.list();
		        if (queryList != null) {
		            isUp = true;
		        }
			}
		}
		catch (Exception e) {
			logger.error(EELFLoggerDelegate.errorLogger, "checkClusterStatus() exception msg = " + e.getMessage());
			if ((e.getCause() != null) && (e.getCause().getMessage() != null)) {
			    logger.error(EELFLoggerDelegate.errorLogger, "checkClusterStatus() exception msg = " + e.getCause().getMessage());
			}
			logger.error(EELFLoggerDelegate.errorLogger, "Exception inside checkClusterStatus() exception = " + EcompPortalUtils.getStackTrace(e));
			isUp = false;
		}
		finally {
			if (localSession != null) {
				localSession.close();
			}
		}
		
		return isUp;
			
	}

	
    private boolean checkDatabaseAndPermissions() {
		
		boolean isUp = false;
		
		Session localSession = null;
		
		try {
			localSession = sessionFactory.openSession();
			if (localSession != null) {
		        String sql = "SHOW GRANTS FOR CURRENT_USER";
		        Query query = localSession.createSQLQuery(sql);
		        @SuppressWarnings("unchecked")
		        List<String> grantsList = query.list();
		        for (String str : grantsList) {
  		    	    if ((str.toUpperCase().contains("ALL")) 
		    			|| 
		    		(str.toUpperCase().contains("DELETE") && 
		    		 str.toUpperCase().contains("SELECT") && 
		    		 str.toUpperCase().contains("UPDATE") && 
		    		 str.toUpperCase().contains("INSERT"))) {
		    		    isUp = true;
		    		    break;
		    	    }
		        }
		        if (isUp == false) {
		    	    logger.error(EELFLoggerDelegate.errorLogger, "checkDatabaseAndPermissions() returning false.  SHOW GRANTS FOR CURRENT_USER being dumped:");
		    	    for (String str : grantsList) {
		    		    logger.error(EELFLoggerDelegate.errorLogger, "grants output item = [" + str + "]");
			        }
		        }
			}
		}
		catch (Exception e) {
			logger.error(EELFLoggerDelegate.errorLogger, "checkDatabaseAndPermissions() exception msg = " + e.getMessage());
			if ((e.getCause() != null) && (e.getCause().getMessage() != null)) {
			    logger.error(EELFLoggerDelegate.errorLogger, "checkDatabaseAndPermissions() exception msg = " + e.getCause().getMessage());
			}
			logger.error(EELFLoggerDelegate.errorLogger, "Exception inside checkDatabaseAndPermissions() exception = " + EcompPortalUtils.getStackTrace(e));
			isUp = false;
		}
		finally {
			if (localSession != null) {
				localSession.close();
			}
		}
		
		return isUp;
			
	}

    
	private boolean checkIfUebUp() {
		boolean uebUp = false;
		try {
		    boolean isAvailable = epUebHelper.checkAvailability();
		    boolean messageCanBeSent = epUebHelper.MessageCanBeSentToTopic();
		    uebUp = (isAvailable && messageCanBeSent);
		}
		catch (Exception e) {
			logger.error(EELFLoggerDelegate.errorLogger, "Exception inside CheckIfUebUp exception = " + EcompPortalUtils.getStackTrace(e));
		}
		
		return uebUp;
		
		
	}

	/*
	private boolean checkIfFeUp() {
		boolean frontenndUp = false;
		try {
		     	String url = SystemProperties.getProperty(EPSystemProperties.FE_URL);	            
	            if(StringUtils.isEmpty(url))
	            {	            	
	        		logger.debug(EELFLoggerDelegate.debugLogger, "The front end URL is empty. Cannot check the status");
	            	return frontenndUp;
	            }
	            
	            url = url.replace("index.html", "app/healthCheck.json");
	            	            
	            URL frontEndURL = new URL(url);
	            
	            HttpURLConnection con = (HttpURLConnection) frontEndURL.openConnection();

	            // optional default is GET
	            con.setRequestMethod("GET");
	            
	            int responseCode = con.getResponseCode();
	            logger.debug(EELFLoggerDelegate.debugLogger, "Fronend response code : " + responseCode);
	            	            
	            if(responseCode == 200)
	            {
	            	frontenndUp = true;
	            }	            
	    	  
		}
		catch(Exception e){
			logger.error(EELFLoggerDelegate.errorLogger, "Exception occurred while trying to access font end" + EcompPortalUtils.getStackTrace(e));
	    }
		
		return frontenndUp;				
	}
	*/
}