<?php

/*
 * This file is part of the symfony package.
 * (c) 2004-2006 Fabien Potencier <fabien.potencier@symfony-project.com>
 * (c) 2004-2006 Sean Kerr.
 * 
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

/**
 * Provides support for session storage using a MySQL brand database.
 *
 * <b>Required parameters:</b>
 *
 * # <b>db_table</b> - [none] - The database table in which session data will be
 *                              stored.
 *
 * <b>Optional parameters:</b>
 *
 * # <b>db_id_col</b>    - [sess_id]   - The database column in which the
 *                                       session id will be stored.
 * # <b>db_data_col</b>  - [sess_data] - The database column in which the
 *                                       session data will be stored.
 * # <b>db_time_col</b>  - [sess_time] - The database column in which the
 *                                       session timestamp will be stored.
 * # <b>session_name</b> - [symfony]   - The name of the session.
 *
 * @package    symfony
 * @subpackage storage
 * @author     Fabien Potencier <fabien.potencier@symfony-project.com>
 * @author     Sean Kerr <skerr@mojavi.org>
 * @version    SVN: $Id: sfMySQLSessionStorage.class.php 3329 2007-01-23 08:29:34Z fabien $
 */
class sfMySQLSessionStorage extends sfSessionStorage
{
  protected
    $resource = null;

  /**
   * Initializes this Storage instance.
   *
   * @param sfContext A sfContext instance
   * @param array   An associative array of initialization parameters
   *
   * @return boolean true, if initialization completes successfully, otherwise false
   *
   * @throws <b>sfInitializationException</b> If an error occurs while initializing this Storage
   */
  public function initialize($context, $parameters = null)
  {
    // disable auto_start
    $parameters['auto_start'] = false;

    // initialize the parent
    parent::initialize($context, $parameters);

    if (!$this->getParameterHolder()->has('db_table'))
    {
        // missing required 'db_table' parameter
        $error = 'Factory configuration file is missing required "db_table" parameter for the Storage category';

        throw new sfInitializationException($error);
    }

    // use this object as the session handler
    session_set_save_handler(array($this, 'sessionOpen'),
                             array($this, 'sessionClose'),
                             array($this, 'sessionRead'),
                             array($this, 'sessionWrite'),
                             array($this, 'sessionDestroy'),
                             array($this, 'sessionGC'));

    // start our session
    session_start();
  }

  /**
   * Closes a session.
   *
   * @return boolean true, if the session was closed, otherwise false
   */
  public function sessionClose()
  {
    // do nothing
    return true;
  }

  /**
   * Destroys a session.
   *
   * @param string A session ID
   *
   * @return boolean true, if the session was destroyed, otherwise an exception is thrown
   *
   * @throws <b>sfDatabaseException</b> If the session cannot be destroyed.
   */
  public function sessionDestroy($id)
  {
    // get table/column
    $db_table  = $this->getParameterHolder()->get('db_table');
    $db_id_col = $this->getParameterHolder()->get('db_id_col', 'sess_id');

    // cleanup the session id, just in case
    $id = mysql_escape_string($id);

    // delete the record associated with this id
    $sql = 'DELETE FROM '.$db_table.' WHERE '.$db_id_col.' = \''.$id.'\'';

    if (@mysql_query($sql, $this->resource))
    {
      return true;
    }

    // failed to destroy session
    $error = 'MySQLSessionStorage cannot destroy session id "%s"';
    $error = sprintf($error, $id);

    throw new sfDatabaseException($error);
  }

  /**
   * Cleans up old sessions.
   *
   * @param int The lifetime of a session
   *
   * @return boolean true, if old sessions have been cleaned, otherwise an exception is thrown
   *
   * @throws <b>sfDatabaseException</b> If any old sessions cannot be cleaned
   */
  public function sessionGC($lifetime)
  {
    // determine deletable session time
    $time = time() - $lifetime;

    // get table/column
    $db_table    = $this->getParameterHolder()->get('db_table');
    $db_time_col = $this->getParameterHolder()->get('db_time_col', 'sess_time');

    // delete the record associated with this id
    $sql = 'DELETE FROM '.$db_table.' '.
           'WHERE '.$db_time_col.' < '.$time;

    if (@mysql_query($sql, $this->resource))
    {
      return true;
    }

    // failed to cleanup old sessions
    $error = 'MySQLSessionStorage cannot delete old sessions';

    throw new sfDatabaseException($error);
  }

  /**
   * Opens a session.
   *
   * @param string
   * @param string
   *
   * @return boolean true, if the session was opened, otherwise an exception is thrown
   *
   * @throws <b>sfDatabaseException</b> If a connection with the database does not exist or cannot be created
   */
  public function sessionOpen($path, $name)
  {
    // what database are we using?
    $database = $this->getParameterHolder()->get('database', 'default');

    // get the database resource
    $this->resource = $this->getContext()
                           ->getDatabaseManager()
                           ->getDatabase($database)
                           ->getResource();

    return true;
  }

  /**
   * Reads a session.
   *
   * @param string A session ID
   *
   * @return boolean true, if the session was read, otherwise an exception is thrown
   *
   * @throws <b>sfDatabaseException</b> If the session cannot be read
   */
  public function sessionRead($id)
  {
    // get table/column
    $db_table    = $this->getParameterHolder()->get('db_table');
    $db_data_col = $this->getParameterHolder()->get('db_data_col', 'sess_data');
    $db_id_col   = $this->getParameterHolder()->get('db_id_col', 'sess_id');
    $db_time_col = $this->getParameterHolder()->get('db_time_col', 'sess_time');

    // cleanup the session id, just in case
    $id = mysql_escape_string($id);

    // delete the record associated with this id
    $sql = 'SELECT '.$db_data_col.' ' .
           'FROM '.$db_table.' ' .
           'WHERE '.$db_id_col.' = \''.$id.'\'';

    $result = @mysql_query($sql, $this->resource);

    if ($result != false && @mysql_num_rows($result) == 1)
    {
      // found the session
      $data = mysql_fetch_row($result);

      return $data[0];
    }
    else
    {
      // session does not exist, create it
      $sql = 'INSERT INTO '.$db_table.' ('.$db_id_col.', ' .
             $db_data_col.', '.$db_time_col.') VALUES (' .
             '\''.$id.'\', \'\', '.time().')';

      if (@mysql_query($sql, $this->resource))
      {
        return '';
      }

      // can't create record
      $error = 'MySQLSessionStorage cannot create new record for id "%s"';
      $error = sprintf($error, $id);

      throw new sfDatabaseException($error);
    }
  }

  /**
   * Writes session data.
   *
   * @param string A session ID
   * @param string A serialized chunk of session data
   *
   * @return boolean true, if the session was written, otherwise an exception is thrown
   *
   * @throws <b>sfDatabaseException</b> If the session data cannot be written
   */
  public function sessionWrite($id, &$data)
  {
    // get table/column
    $db_table    = $this->getParameterHolder()->get('db_table');
    $db_data_col = $this->getParameterHolder()->get('db_data_col', 'sess_data');
    $db_id_col   = $this->getParameterHolder()->get('db_id_col', 'sess_id');
    $db_time_col = $this->getParameterHolder()->get('db_time_col', 'sess_time');

    // cleanup the session id and data, just in case
    $id   = mysql_escape_string($id);
    $data = mysql_escape_string($data);

    // delete the record associated with this id
    $sql = 'UPDATE '.$db_table.' ' .
           'SET '.$db_data_col.' = \''.$data.'\', ' .
           $db_time_col.' = '.time().' ' .
           'WHERE '.$db_id_col.' = \''.$id.'\'';

    if (@mysql_query($sql, $this->resource))
    {
      return true;
    }

    // failed to write session data
    $error = 'MySQLSessionStorage cannot write session data for id "%s"';
    $error = sprintf($error, $id);

    throw new sfDatabaseException($error);
  }

  /**
   * Executes the shutdown procedure.
   *
   */
  public function shutdown()
  {
  }
}
