package org.bitrepository.audittrails.store;
   
   import java.math.BigInteger;
   import java.sql.Connection;
   import java.sql.PreparedStatement;
   import java.sql.ResultSet;
   import java.sql.SQLException;
   
   import org.bitrepository.bitrepositoryelements.AuditTrailEvent;
  import org.bitrepository.bitrepositoryelements.FileAction;
  import org.bitrepository.common.utils.CalendarUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.bitrepository.audittrails.store.AuditDatabaseExtractor.*;
  
  /**
   * Class to iterate over the set of AuditTrailEvents produced by a resultset.  
   */
  public class AuditEventIterator {
  
      /** The log.*/
      private Logger log = LoggerFactory.getLogger(getClass());
      private ResultSet auditResultSet = null;
      private Connection conn = null;
      private final PreparedStatement ps;
      
      /**
       * @param ps The prepare statement to execute and iterate over.
       */
      public AuditEventIterator(PreparedStatement ps) {
          this.ps = ps;
      }
      
      /**
       * Method to explicitly close the ResultSet in the AuditEventIterator 
       * @throws SQLException in case of a sql error
       */
      public void close() throws SQLException {
          if(auditResultSet != null) {
              auditResultSet.close();
          }
          
          if(ps != null) {
              ps.close();
          }
          
          if(conn != null) {
              conn.setAutoCommit(true);
              conn.close();
              conn = null;
          }
      }
      
      /**
       * Method to return the next AuditTrailEvent in the ResultSet
       * When no more AuditTrailEvents are available, null is returned and the internal ResultSet closed. 
       * @return The next AuditTrailEvent available in the ResultSet, or null if no more events are available. 
       * @throws SQLException In case of a sql error. 
       */
      public AuditTrailEvent getNextAuditTrailEvent() {
          try {
              AuditTrailEvent event = null;
              if(auditResultSet == null) {
                  conn = ps.getConnection();
                  conn.setAutoCommit(false);
                  ps.setFetchSize(100);
                  long tStart = System.currentTimeMillis();
                  log.debug("Executing query to get AuditTrailEvents resultset");
                  auditResultSet = ps.executeQuery();
                  log.debug("Finished executing AuditTrailEvents query, it took: " + (System.currentTimeMillis() - tStart) + "ms");
              }
              if(auditResultSet.next()) {
                  event = new AuditTrailEvent();
                  event.setActionDateTime(CalendarUtils.getFromMillis(auditResultSet.getTimestamp(POSITION_OPERATION_DATE).getTime()));
                  event.setActionOnFile(FileAction.fromValue(auditResultSet.getString(POSITION_OPERATION)));
                  event.setAuditTrailInformation(auditResultSet.getString(POSITION_AUDIT_TRAIL));
                  event.setActorOnFile(auditResultSet.getString(POSITION_ACTOR_NAME));
                  event.setFileID(auditResultSet.getString(POSITION_FILE_ID));
                  event.setInfo(auditResultSet.getString(POSITION_INFORMATION));
                  event.setReportingComponent(auditResultSet.getString(POSITION_CONTRIBUTOR_ID));
                  event.setSequenceNumber(BigInteger.valueOf(auditResultSet.getLong(POSITION_SEQUENCE_NUMBER)));
                  event.setOperationID(auditResultSet.getString(POSITION_OPERATION_ID));
                  event.setCertificateID(auditResultSet.getString(POSITION_FINGERPRINT));
              } else {
                  close();
              }
      
              return event;
          } catch (Exception e) {
              try {
                  close();
              } catch (SQLException e1) {
                  throw new RuntimeException("Failed to close ResultSet or PreparedStatement", e1);
              }
              throw new IllegalStateException("Could not extract the wanted audittrails", e);
          } 
      }
  
 }