<?php

/*

 * This file is part of SwiftMailer.

 * (c) 2004-2009 Chris Corbyn

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

/**

 * Throttles the rate at which emails are sent.

 * @package Swift

 * @subpackage Plugins

 * @author Chris Corbyn

 */

class Swift_Plugins_ThrottlerPlugin

  extends Swift_Plugins_BandwidthMonitorPlugin

  implements Swift_Plugins_Sleeper, Swift_Plugins_Timer

{

  /** Flag for throttling in bytes per minute */

  const BYTES_PER_MINUTE = 0x01;

  /** Flag for throttling in emails per minute */

  const MESSAGES_PER_MINUTE = 0x10;

  /**

   * The Sleeper instance for sleeping.

   * @var Swift_Plugins_Sleeper

   * @access private

   */

  private $_sleeper;

  /**

   * The Timer instance which provides the timestamp.

   * @var Swift_Plugins_Timer

   * @access private

   */

  private $_timer;

  /**

   * The time at which the first email was sent.

   * @var int

   * @access private

   */

  private $_start;

  /**

   * The rate at which messages should be sent.

   * @var int

   * @access private

   */

  private $_rate;

  /**

   * The mode for throttling.

   * This is {@link BYTES_PER_MINUTE} or {@link MESSAGES_PER_MINUTE}

   * @var int

   * @access private

   */

  private $_mode;

  /**

   * An internal counter of the number of messages sent.

   * @var int

   * @access private

   */

  private $_messages = 0;

  /**

   * Create a new ThrottlerPlugin.

   * @param int $rate

   * @param int $mode, defaults to {@link BYTES_PER_MINUTE}

   * @param Swift_Plugins_Sleeper $sleeper (only needed in testing)

   * @param Swift_Plugins_Timer $timer (only needed in testing)

   */

  public function __construct($rate, $mode = self::BYTES_PER_MINUTE,

    Swift_Plugins_Sleeper $sleeper = null, Swift_Plugins_Timer $timer = null)

  {

    $this->_rate = $rate;

    $this->_mode = $mode;

    $this->_sleeper = $sleeper;

    $this->_timer = $timer;

  }

  /**

   * Invoked immediately before the Message is sent.

   * @param Swift_Events_SendEvent $evt

   */

  public function beforeSendPerformed(Swift_Events_SendEvent $evt)

  {

    $time = $this->getTimestamp();

    if (!isset($this->_start))

    {

      $this->_start = $time;

    }

    $duration = $time - $this->_start;

    if (self::BYTES_PER_MINUTE == $this->_mode)

    {

      $sleep = $this->_throttleBytesPerMinute($duration);

    }

    else

    {

      $sleep = $this->_throttleMessagesPerMinute($duration);

    }

    if ($sleep > 0)

    {

      $this->sleep($sleep);

    }

  }

  /**

   * Invoked when a Message is sent.

   * @param Swift_Events_SendEvent $evt

   */

  public function sendPerformed(Swift_Events_SendEvent $evt)

  {

    parent::sendPerformed($evt);

    ++$this->_messages;

  }

  /**

   * Sleep for $seconds.

   * @param int $seconds

   */

  public function sleep($seconds)

  {

    if (isset($this->_sleeper))

    {

      $this->_sleeper->sleep($seconds);

    }

    else

    {

      sleep($seconds);

    }

  }

  /**

   * Get the current UNIX timestamp

   * @return int

   */

  public function getTimestamp()

  {

    if (isset($this->_timer))

    {

      return $this->_timer->getTimestamp();

    }

    else

    {

      return time();

    }

  }

  // -- Private methods

  /**

   * Get a number of seconds to sleep for.

   * @param int $timePassed

   * @return int

   * @access private

   */

  private function _throttleBytesPerMinute($timePassed)

  {

    $expectedDuration = $this->getBytesOut() / ($this->_rate / 60);

    return (int) ceil($expectedDuration - $timePassed);

  }

  /**

   * Get a number of seconds to sleep for.

   * @param int $timePassed

   * @return int

   * @access private

   */

  private function _throttleMessagesPerMinute($timePassed)

  {

    $expectedDuration = $this->_messages / ($this->_rate / 60);

    return (int) ceil($expectedDuration - $timePassed);

  }

}