package gov.hhs.fha.nhinc.gateway.aggregator.persistence;

import java.util.Date;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import gov.hhs.fha.nhinc.properties.PropertyAccessor;
import java.util.Calendar;

/**
 * This class is used to manage the garbage collection on the AGGREGATOR
 * database tables.  It will get run each time a startTransaction is called,
 * and it will use settings in the gateway.properties file to determine 
 * how often to kick off the garbage collection thread and how hold a
 * transaction must be to be considered stale.
 * 
 * @author Les Westberg
 */
public class GarbageCollectorMgr 
{
    private static Log log = LogFactory.getLog(GarbageCollectorMgr.class);
    private static Date dtLastRun = new Date();       // The date that the garbage collector was last run.
    private static final String GATEWAY_PROPERTY_FILE = "gateway";
    private static final String GARBAGE_COLLECT_TIME_DURATION = "aggregatorGarbageCollectionTimeDuration";
    private static final String GARBAGE_COLLECT_STALE_DURATION = "aggregatorGarbageCollectionStaleDuration";

    /**
     * Default constructor.
     */
    public GarbageCollectorMgr()
    {
    }
    
    /**
     * This method checks to see if we should run the collector based on the 
     * time settings in the gateway.properties file.  If we should run it, then
     * true is returnd.  Otherwise false is returned.
     * 
     * @return TRUE if we should run the garbage collector.
     */
    private static boolean bRunCollector()
    {
        String sTimeDuration = "";
        int iTimeDuration = 0;
        try
        {
            sTimeDuration = PropertyAccessor.getProperty(GATEWAY_PROPERTY_FILE, GARBAGE_COLLECT_TIME_DURATION);
            iTimeDuration = Integer.parseInt(sTimeDuration);
        }
        catch (Exception e)
        {
            String sErrorMessage = "Failed to read and parse property: " + GARBAGE_COLLECT_TIME_DURATION +
                                   " from PropertyFile: " + GATEWAY_PROPERTY_FILE + ".propertues.  No " +
                                   "garbage collection will be done on the aggregator tables.";
            log.error(sErrorMessage);
            return false;
        }
        
        if ((sTimeDuration == null) ||
            (sTimeDuration.length() <= 0))
        {
            String sErrorMessage = "Failed to read and parse property: " + GARBAGE_COLLECT_TIME_DURATION +
                                   " from PropertyFile: " + GATEWAY_PROPERTY_FILE + ".propertues.  No " +
                                   "garbage collection will be done on the aggregator tables.";
            log.error(sErrorMessage);
            return false;
        }
            
        Calendar oCal = Calendar.getInstance();
        oCal.add(Calendar.SECOND, (-1) * iTimeDuration);
        
        if (oCal.getTime().getTime() > dtLastRun.getTime())
        {
            return true;
        }
        
        return false;
    }
    
    /**
     * This method checks to see if it is time to run the garbage collection
     * thread based on the settings in the gateway.properties file.  If it is, then
     * it spins off a thread to do garbage collection of the aggregator tables.
     */
    public static void runGarbageCollection()
    {
        // see if we need to run the collector...
        //----------------------------------------
        if (bRunCollector())
        {
            String sStaleDuration = "";
            int iStaleDuration = 0;
            
            try
            {
                sStaleDuration = PropertyAccessor.getProperty(GATEWAY_PROPERTY_FILE, GARBAGE_COLLECT_STALE_DURATION);
                iStaleDuration = Integer.parseInt(sStaleDuration);
            } 
            catch (Exception e)
            {
                String sErrorMessage = "Failed to read and parse property: " + GARBAGE_COLLECT_STALE_DURATION +
                                       " from PropertyFile: " + GATEWAY_PROPERTY_FILE + ".propertues.  No " +
                                       "garbage collection will be done on the aggregator tables.";
                log.error(sErrorMessage);
                return;
            }
            
            if ((sStaleDuration == null) ||
                (sStaleDuration.length() <= 0))
            {
                String sErrorMessage = "Failed to read and parse property: " + GARBAGE_COLLECT_STALE_DURATION +
                                       " from PropertyFile: " + GATEWAY_PROPERTY_FILE + ".propertues.  No " +
                                       "garbage collection will be done on the aggregator tables.";
                log.error(sErrorMessage);
                return;
            }
            
            Calendar oCal = Calendar.getInstance();
            oCal.add(Calendar.SECOND, (-1) * iStaleDuration);
            
            log.debug("Running aggregator garbage collection thread now.");
            
            GarbageCollectorThread oCollectorThread = new GarbageCollectorThread(oCal.getTime());
            oCollectorThread.run();
            dtLastRun = new Date();
            
        }
    }
    
}