/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.core.db;
  
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.sql.Connection;
  import java.sql.PreparedStatement;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;
  
  import ch.qos.logback.core.UnsynchronizedAppenderBase;
  import ch.qos.logback.core.db.dialect.DBUtil;
  import ch.qos.logback.core.db.dialect.SQLDialect;
  import ch.qos.logback.core.db.dialect.SQLDialectCode;
  
  /**
   * @author Ceki Gülcü
   * @author Ray DeCampo
   * @author Sébastien Pennec
   */
  public abstract class DBAppenderBase<E> extends UnsynchronizedAppenderBase<E> {
  
    protected ConnectionSource connectionSource;
    protected boolean cnxSupportsGetGeneratedKeys = false;
    protected boolean cnxSupportsBatchUpdates = false;
    protected SQLDialect sqlDialect;
  
    protected abstract Method getGeneratedKeysMethod();
  
    protected abstract String getInsertSQL();
  
    @Override
    public void start() {
  
      if (connectionSource == null) {
        throw new IllegalStateException(
            "DBAppender cannot function without a connection source");
      }
  
      sqlDialect = DBUtil
          .getDialectFromCode(connectionSource.getSQLDialectCode());
      if (getGeneratedKeysMethod() != null) {
        cnxSupportsGetGeneratedKeys = connectionSource.supportsGetGeneratedKeys();
      } else {
        cnxSupportsGetGeneratedKeys = false;
      }
      cnxSupportsBatchUpdates = connectionSource.supportsBatchUpdates();
      if (!cnxSupportsGetGeneratedKeys && (sqlDialect == null)) {
        throw new IllegalStateException(
            "DBAppender cannot function if the JDBC driver does not support getGeneratedKeys method *and* without a specific SQL dialect");
      }
  
      // all nice and dandy on the eastern front
      super.start();
    }
  
    /**
     * @return Returns the connectionSource.
     */
    public ConnectionSource getConnectionSource() {
      return connectionSource;
    }
  
    /**
     * @param connectionSource
     *          The connectionSource to set.
     */
    public void setConnectionSource(ConnectionSource connectionSource) {
      this.connectionSource = connectionSource;
    }
  
    @Override
    public void append(E eventObject) {
      Connection connection = null;
      try {
        connection = connectionSource.getConnection();
        connection.setAutoCommit(false);
        PreparedStatement insertStatement;
  
        if (cnxSupportsGetGeneratedKeys) {
          String EVENT_ID_COL_NAME = "EVENT_ID";
          // see
          if (connectionSource.getSQLDialectCode() == SQLDialectCode.POSTGRES_DIALECT) {
            EVENT_ID_COL_NAME = EVENT_ID_COL_NAME.toLowerCase();
          }
          insertStatement = connection.prepareStatement(getInsertSQL(),
             new String[] { EVENT_ID_COL_NAME });
       } else {
         insertStatement = connection.prepareStatement(getInsertSQL());
       }
 
       long eventId;
       // inserting an event and getting the result must be exclusive
       synchronized (this) {
         subAppend(eventObject, connection, insertStatement);
         eventId = selectEventId(insertStatement, connection);
       }
       secondarySubAppend(eventObject, connection, eventId);
 
       // we no longer need the insertStatement
       close(insertStatement);
       insertStatement = null;
 
       connection.commit();
     } catch (Throwable sqle) {
       addError("problem appending event", sqle);
     } finally {
       DBHelper.closeConnection(connection);
     }
   }
 
   protected abstract void subAppend(E eventObject, Connection connection,
       PreparedStatement statement) throws Throwable;
 
   protected abstract void secondarySubAppend(E eventObject, Connection connection,
       long eventId) throws Throwable;
 
   protected long selectEventId(PreparedStatement insertStatement,
       Connection connection) throws SQLException, InvocationTargetException {
     ResultSet rs = null;
     Statement idStatement = null;
     boolean gotGeneratedKeys = false;
     if (cnxSupportsGetGeneratedKeys) {
       try {
         rs = (ResultSet) getGeneratedKeysMethod().invoke(insertStatement,
             (Object[]) null);
         gotGeneratedKeys = true;
       } catch (InvocationTargetException ex) {
         Throwable target = ex.getTargetException();
         if (target instanceof SQLException) {
           throw (SQLException) target;
         }
         throw ex;
       } catch (IllegalAccessException ex) {
         addWarn(
             "IllegalAccessException invoking PreparedStatement.getGeneratedKeys",
             ex);
       }
     }
 
     if (!gotGeneratedKeys) {
       idStatement = connection.createStatement();
       idStatement.setMaxRows(1);
       String selectInsertIdStr = sqlDialect.getSelectInsertId();
       rs = idStatement.executeQuery(selectInsertIdStr);
     }
 
     // A ResultSet cursor is initially positioned before the first row;
     // the first call to the method next makes the first row the current row
     rs.next();
     long eventId = rs.getLong(1);
 
     rs.close();
 
     close(idStatement);
     idStatement = null;
 
     return eventId;
   }
 
   void close(Statement statement) throws SQLException {
     if (statement != null) {
       statement.close();
     }
   }
 
   @Override
   public void stop() {
     super.stop();
   }
 }