package gov.bnl.gums.configuration;
   
   import java.io.BufferedWriter;
   import java.io.ByteArrayInputStream;
   import java.io.IOException;
   import java.io.StringWriter;
   import java.net.URL;
   import java.text.DateFormat;
   import java.text.ParseException;
  import java.text.SimpleDateFormat;
  import java.util.Collection;
  import java.util.Date;
  import java.util.Iterator;
  
  import javax.xml.parsers.ParserConfigurationException;
  
  import org.apache.log4j.Logger;
  import org.xml.sax.SAXException;
  
  import gov.bnl.gums.GUMS;
  import gov.bnl.gums.configuration.Configuration;
  import gov.bnl.gums.db.ConfigurationDB;
  import gov.bnl.gums.persistence.HibernatePersistenceFactory;
  import gov.bnl.gums.persistence.LocalPersistenceFactory;
  import gov.bnl.gums.persistence.PersistenceFactory;
  
  /** Implements the logic to store the configuration in a database except for the bare
   * configuration to specify the persistence factory at which to store the configuration.
   *
   * @author Jay Packard
   */
  public class DBConfigurationStore extends ConfigurationStore {
  	private Logger log = Logger.getLogger(FileConfigurationStore.class);
  	private ConfigurationDB configDB;
  	private Configuration conf;
  	private Date mostRecentModification = null;
  
  	public DBConfigurationStore(ConfigurationDB configDB) {
  		this.configDB = configDB;
  	}
  
  	public void deleteBackupConfiguration(String name) {
  		if (!configDB.deleteBackupConfiguration(name))
  			throw new RuntimeException("Could not delete backup configuration '"+name+"' from database");
  	}
  
  	public boolean isActive() {
  		return configDB.isActive();
  	}
  
  	public Collection getBackupNames() {
  		return configDB.getBackupNames(format);
  	}
  
  	public Date getLastModification() {
  		Date date = configDB.getLastModification();
  		if (log.isTraceEnabled())
  			log.trace("Last modification from database: "+date.toString());
  		return date;
  	}
  
  	public synchronized Configuration retrieveConfiguration() throws Exception {
  		ByteArrayInputStream stream = null;
  		try {
  			Date lastModification = getLastModification(); 
  			if (mostRecentModification==null || mostRecentModification.before(lastModification)) {
  				String configText = configDB.retrieveCurrentConfiguration();
  				this.conf = ConfigurationToolkit.parseConfiguration(configText, false);
  				log.debug("Configuration "+conf+" reloaded from database");
  				mostRecentModification = lastModification;
  				return conf;
  			}
  		} catch (Exception e) {
  			throw new RuntimeException(e.getMessage());
  		} finally {
  			if (stream != null)
  				stream.close();
  		}
  		return conf;
  	}
  
  	public synchronized Configuration restoreConfiguration(String name) throws Exception {
  		ByteArrayInputStream stream = null;
  		try {
  			String configText = configDB.restoreConfiguration(name);
  			this.conf = ConfigurationToolkit.parseConfiguration(configText, false);
  			log.debug("Configuration '" + name + "', "+conf+" restored from database");
  			mostRecentModification = getLastModification();
  			return conf;
  		} catch (Exception e) {
  			throw new RuntimeException(e.getMessage());
  		} finally {
  			if (stream != null)
  				stream.close();
  		}
  	}
  
  	public synchronized void setConfiguration(Configuration conf, boolean backupCopy, String name, Date date) throws Exception {
                  if (date==null)
                         date = new Date();
 
 		if (backupCopy && (name==null || name.length()==0))
 			name = format.format(date); 
 		
 		configDB.setConfiguration(conf.toXml(), backupCopy, name, date);
 		log.debug("Configuration "+conf+" saved to database");
 		this.conf = conf;
 		mostRecentModification = date;
 	}
 
 }