<?php
/**
 * @file
 * This file contains conversion functions.
 */

define('SWIFTMAILER_DATE_PATTERN', '(Mon|Tue|Wed|Thu|Fri|Sat|Sun), [0-9]{2} (Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) [0-9]{4} (2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]) (\+|\-)([01][0-2])([0-5][0-9])');
define('SWIFTMAILER_MAILBOX_PATTERN', '(^.*\<.*@.*\>$|^.*@.*$)');

/**
 * Determines the header type based on the a header key and value.
 *
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 *
 * @return string
 *   The header type as determined based on the provided header key
 *   and value.
 */
function swiftmailer_get_headertype($key, $value) {

  if (swiftmailer_is_id_header($key, $value)) {
    return SWIFTMAILER_HEADER_ID;
  }

  if (swiftmailer_is_path_header($key, $value)) {
    return SWIFTMAILER_HEADER_PATH;
  }

  if (swiftmailer_is_mailbox_header($key, $value)) {
    return SWIFTMAILER_HEADER_MAILBOX;
  }

  if (swiftmailer_is_date_header($key, $value)) {
    return SWIFTMAILER_HEADER_DATE;
  }

  if (swiftmailer_is_parameterized_header($key, $value)) {
    return SWIFTMAILER_HEADER_PARAMETERIZED;
  }

  return SWIFTMAILER_HEADER_TEXT;

}

/**
 * Adds a text header to a message.
 *
 * @param Swift_Message $message
 *   The message which the text header is to be added to.
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 */
function swiftmailer_add_text_header(Swift_Message $message, $key, $value) {

  // Remove any already existing header identified by the provided key.
  swiftmailer_remove_header($message, $key);

  // Add the header.
  $message->getHeaders()->addTextHeader($key, $value);
}

/**
 * Checks whether a header is a parameterized header.
 *
 * @see http://swift_mailer.org/docs/header-parameterized
 *
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 *
 * @return boolean
 *   TRUE if the provided header is a parameterized header,
 *   and otherwise FALSE.
 */
function swiftmailer_is_parameterized_header($key, $value) {
  if (preg_match('/;/', $value)) {
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Adds a parameterized header to a message.
 *
 * @param Swift_Message $message
 *   The message which the parameterized header is to be added to.
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 */
function swiftmailer_add_parameterized_header(Swift_Message $message, $key, $value) {

  // Remove any already existing header identified by the provided key.
  swiftmailer_remove_header($message, $key);

  // Define variables to hold the header's value and parameters.
  $header_value = NULL;
  $header_parameters = array();

  // Split the provided value by ';' (semicolon), which we assume is the
  // character is used to separate the parameters.
  $parameter_pairs = explode(';', $value);

  // Iterate through the extracted parameters, and prepare each of them to be
  // added to a parameterized message header. There should be a single text
  // parameter and one or more key/value parameters in the provided header
  // value. We assume that a '=' (equals) character is used to separate the
  // key and value for each of the parameters.
  foreach ($parameter_pairs as $parameter_pair) {

    // Find out whether the current parameter pair really is a parameter
    // pair or just a single value.
    if (preg_match('/=/', $parameter_pair) > 0) {

      // Split the parameter so that we can access the parameter's key and
      // value separately.
      $parameter_pair = explode('=', $parameter_pair);

      // Validate that the parameter has been split in two, and that both
      // the parameter's key and value is accessible. If that is the case,
      // then add the current parameter's key and value to the array which
      // holds all parameters to be added to the current header.
      if (!empty($parameter_pair[0]) && !empty($parameter_pair[1])) {
        $header_parameters[trim($parameter_pair[0])] = trim($parameter_pair[1]);
      }

    }
    else {
      $header_value = trim($parameter_pair);
    }
  }

  // Add the parameterized header.
  $message->getHeaders()->addParameterizedHeader($key, $header_value, $header_parameters);

}

/**
 * Checks whether a header is a date header.
 *
 * @see http://swift_mailer.org/docs/header-date
 *
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 *
 * @return boolean
 *   TRUE if the provided header is a date header, and otherwise FALSE.
 */
function swiftmailer_is_date_header($key, $value) {
  if (preg_match('/' . SWIFTMAILER_DATE_PATTERN . '/', $value)) {
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Adds a date header to a message.
 *
 * @param Swift_Message $message
 *   The message which the date header is to be added to.
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 */
function swiftmailer_add_date_header(Swift_Message $message, $key, $value) {

  // Remove any already existing header identified by the provided key.
  swiftmailer_remove_header($message, $key);

  // Add the header.
  $message->getHeaders()->addDateHeader($key, $value);
}

/**
 * Checks whether a header is a mailbox header.
 *
 * It is difficult to distinguish id, mailbox and path headers from each other
 * as they all may very well contain the exact same value. This function simply
 * checks whether the header key equals to 'Message-ID' to determine if the
 * header is a path header.
 *
 * @see http://swift_mailer.org/docs/header-mailbox
 *
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 *
 * @return boolean
 *   TRUE if the provided header is a mailbox header, and otherwise FALSE.
 */
function swiftmailer_is_mailbox_header($key, $value) {
  if (preg_match('/' . SWIFTMAILER_MAILBOX_PATTERN . '/', $value)) {
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Adds a mailbox header to a message.
 *
 * @param Swift_Message $message
 *   The message which the mailbox header is to be added to.
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 */
function swiftmailer_add_mailbox_header(Swift_Message $message, $key, $value) {

  // Remove any already existing header identified by the provided key.
  swiftmailer_remove_header($message, $key);

  // Parse mailboxes.
  $mailboxes = swiftmailer_parse_mailboxes($value);

  // Add the header.
  $message->getHeaders()->addMailboxHeader($key, $mailboxes);
}

/**
 * Checks whether a header is an id header.
 *
 * It is difficult to distinguish id, mailbox and path headers from each other
 * as they all may very well contain the exact same value. This function simply
 * checks whether the header key equals to 'Message-ID' to determine if the
 * header is a path header.
 *
 * @see http://swift_mailer.org/docs/header-id
 *
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 *
 * @return boolean
 *   TRUE if the provided header is an id header, and otherwise FALSE.
 */
function swiftmailer_is_id_header($key, $value) {
  if (valid_email_address($value) && $key == 'Message-ID') {
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Adds an id header to a message.
 *
 * @param Swift_Message $message
 *   The message which the id header is to be added to.
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 */
function swiftmailer_add_id_header(Swift_Message $message, $key, $value) {

  // Remove any already existing header identified by the provided key.
  swiftmailer_remove_header($message, $key);

  // Add the header.
  $message->getHeaders()->addIdHeader($key, $value);
}

/**
 * Checks whether a header is a path header.
 *
 * It is difficult to distinguish id, mailbox and path headers from each other
 * as they all may very well contain the exact same value. This function simply
 * checks whether the header key equals to 'Message-ID' to determine if the
 * header is a path header.
 *
 * @see http://swift_mailer.org/docs/header-path
 *
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 *
 * @return boolean
 *   TRUE if the provided header is a path header, and otherwise FALSE.
 */
function swiftmailer_is_path_header($key, $value) {
  if (valid_email_address($value) && $key == 'Return-Path') {
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Adds a path header to a message.
 *
 * @param Swift_Message $message
 *   The message which the path header is to be added to.
 *
 * @param string $key
 *   The header key.
 * @param string $value
 *   The header value.
 */
function swiftmailer_add_path_header(Swift_Message $message, $key, $value) {

  // Remove any already existing header identified by the provided key.
  swiftmailer_remove_header($message, $key);

  // Add the header.
  $message->getHeaders()->addPathHeader($key, $value);
}

/**
 * Removes a header from a message.
 *
 * @param Swift_Message $message
 *   The message which the header is to be removed from.
 * @param string $key
 *   The header key.
 */
function swiftmailer_remove_header(Swift_Message $message, $key) {

  // Get message headers.
  $headers = $message->getHeaders();

  // Remove the header if it already exists.
  $headers->removeAll($key);

}

/**
 * Converts a string holding one or more mailboxes to an array.
 *
 *  @param $value
 *    A string holding one or more mailboxes.
 */
function swiftmailer_parse_mailboxes($value) {

  // Split mailboxes by ',' (comma) and ';' (semicolon).
  //$mailboxes_raw = preg_split('/(,|;)/', $value);
  $mailboxes_raw = array();
  preg_match_all("/((?:^|\s){0,}(?:(?:\".*?\"){0,1}.*?)(?:$|,|;))/", $value, $mailboxes_raw);

  // Define an array which will keep track of mailboxes.
  $mailboxes = array();

  // Iterate through each of the raw mailboxes and process them.
  foreach ($mailboxes_raw[0] as $mailbox_raw) {

    if (empty($mailbox_raw)) {
      continue;
    }

    // Remove leading and trailing whitespace.
    $mailbox_raw = trim($mailbox_raw);

    if (preg_match('/^.*<.*>.*$/', $mailbox_raw)) {
      $mailbox_components = explode('<', $mailbox_raw);
      $mailbox_name = trim(preg_replace("/\"/", "", $mailbox_components[0]));
      $mailbox_address = preg_replace('/>.*/', '', $mailbox_components[1]);
      if (valid_email_address($mailbox_address)) {
        $mailboxes[$mailbox_address] = $mailbox_name;
      }
    }
    else {
      $mailbox_address = preg_replace("/(,|;)/", "", $mailbox_raw);
      if (valid_email_address($mailbox_address)) {
        $mailboxes[] = $mailbox_address;
      }
    }
  }

  return $mailboxes;
}

/**
 * Filters out unwanted elements from a message.
 *
 * @param Swift_Message $message
 *   The message which unwanted elements is to be filtered out from.
 */
function swiftmailer_filter_message(Swift_Message $message) {
  $headers = $message->getHeaders();

  $senders = $headers->get('From')->getAddresses();
  if (!empty($senders)) {
    for ($i = 0; $i < count($senders); $i++) {
      if (!valid_email_address($senders[$i])) {
        $headers->remove('From', $i);
        watchdog('swiftmailer', 'The invalid "From" e-mail address "!mail" was skipped.', array('!mail' => $senders[$i]), WATCHDOG_WARNING);
      }
    }
  }

  $recipients = $headers->get('To')->getAddresses();
  if (!empty($recipients)) {
    for ($i = 0; $i < count($recipients); $i++) {
      if (!valid_email_address($recipients[$i])) {
        $headers->remove('To', $i);
        watchdog('swiftmailer', 'The invalid "To" e-mail address "!mail" was skipped.', array('!mail' => $recipients[$i]), WATCHDOG_WARNING);
      }
    }
  }
}