<?php

/**

 * @file

 * API functions for processing and sending e-mail.

 */

/**

 * Auto-detect appropriate line endings for e-mails.

 *

 * $conf['mail_line_endings'] will override this setting.

 */

define('MAIL_LINE_ENDINGS', isset($_SERVER['WINDIR']) || (isset($_SERVER['SERVER_SOFTWARE']) && strpos($_SERVER['SERVER_SOFTWARE'], 'Win32') !== FALSE) ? "\r\n" : "\n");

/**

 * Composes and optionally sends an e-mail message.

 *

 * Sending an e-mail works with defining an e-mail template (subject, text

 * and possibly e-mail headers) and the replacement values to use in the

 * appropriate places in the template. Processed e-mail templates are

 * requested from hook_mail() from the module sending the e-mail. Any module

 * can modify the composed e-mail message array using hook_mail_alter().

 * Finally drupal_mail_system()->mail() sends the e-mail, which can

 * be reused if the exact same composed e-mail is to be sent to multiple

 * recipients.

 *

 * Finding out what language to send the e-mail with needs some consideration.

 * If you send e-mail to a user, her preferred language should be fine, so

 * use user_preferred_language(). If you send email based on form values

 * filled on the page, there are two additional choices if you are not

 * sending the e-mail to a user on the site. You can either use the language

 * used to generate the page ($language global variable) or the site default

 * language. See language_default(). The former is good if sending e-mail to

 * the person filling the form, the later is good if you send e-mail to an

 * address previously set up (like contact addresses in a contact form).

 *

 * Taking care of always using the proper language is even more important

 * when sending e-mails in a row to multiple users. Hook_mail() abstracts

 * whether the mail text comes from an administrator setting or is

 * static in the source code. It should also deal with common mail tokens,

 * only receiving $params which are unique to the actual e-mail at hand.

 *

 * An example:

 *

 * @code

 *   function example_notify($accounts) {

 *     foreach ($accounts as $account) {

 *       $params['account'] = $account;

 *       // example_mail() will be called based on the first drupal_mail() parameter.

 *       drupal_mail('example', 'notice', $account->mail, user_preferred_language($account), $params);

 *     }

 *   }

 *

 *   function example_mail($key, &$message, $params) {

 *     $data['user'] = $params['account'];

 *     $options['language'] = $message['language'];

 *     user_mail_tokens($variables, $data, $options);

 *     switch($key) {

 *       case 'notice':

 *         // If the recipient can receive such notices by instant-message, do

 *         // not send by email.

 *         if (example_im_send($key, $message, $params)) {

 *           $message['send'] = FALSE;

 *           break;

 *         }

 *         $langcode = $message['language']->language;

 *         $message['subject'] = t('Notification from !site', $variables, array('langcode' => $langcode));

 *         $message['body'][] = t("Dear !username\n\nThere is new content available on the site.", $variables, array('langcode' => $langcode));

 *         break;

 *     }

 *   }

 * @endcode

 *

 * Another example, which uses drupal_mail() to format a message for sending

 * later:

 *

 * @code

 *   $params = array('current_conditions' => $data);

 *   $to = 'user@example.com';

 *   $message = drupal_mail('example', 'notice', $to, $language, $params, FALSE);

 *   // Only add to the spool if sending was not canceled.

 *   if ($message['send']) {

 *     example_spool_message($message);

 *   }

 * @endcode

 *

 * @param $module

 *   A module name to invoke hook_mail() on. The {$module}_mail() hook will be

 *   called to complete the $message structure which will already contain common

 *   defaults.

 * @param $key

 *   A key to identify the e-mail sent. The final e-mail id for e-mail altering

 *   will be {$module}_{$key}.

 * @param $to

 *   The e-mail address or addresses where the message will be sent to. The

 *   formatting of this string will be validated with the

 *   @link http://php.net/manual/filter.filters.validate.php PHP e-mail validation filter. @endlink

 *   Some examples are:

 *   - user@example.com

 *   - user@example.com, anotheruser@example.com

 *   - User <user@example.com>

 *   - User <user@example.com>, Another User <anotheruser@example.com>

 * @param $language

 *   Language object to use to compose the e-mail.

 * @param $params

 *   Optional parameters to build the e-mail.

 * @param $from

 *   Sets From to this value, if given.

 * @param $send

 *   If TRUE, drupal_mail() will call drupal_mail_system()->mail() to deliver

 *   the message, and store the result in $message['result']. Modules

 *   implementing hook_mail_alter() may cancel sending by setting

 *   $message['send'] to FALSE.

 *

 * @return

 *   The $message array structure containing all details of the

 *   message. If already sent ($send = TRUE), then the 'result' element

 *   will contain the success indicator of the e-mail, failure being already

 *   written to the watchdog. (Success means nothing more than the message being

 *   accepted at php-level, which still doesn't guarantee it to be delivered.)

 */

function drupal_mail($module, $key, $to, $language, $params = array(), $from = NULL, $send = TRUE) {

  $default_from = variable_get('site_mail', ini_get('sendmail_from'));

  // Bundle up the variables into a structured array for altering.

  $message = array(

    'id'       => $module . '_' . $key,

    'module'   => $module,

    'key'      => $key,

    'to'       => $to,

    'from'     => isset($from) ? $from : $default_from,

    'language' => $language,

    'params'   => $params,

    'send'     => TRUE,

    'subject'  => '',

    'body'     => array()

  );

  // Build the default headers

  $headers = array(

    'MIME-Version'              => '1.0',

    'Content-Type'              => 'text/plain; charset=UTF-8; format=flowed; delsp=yes',

    'Content-Transfer-Encoding' => '8Bit',

    'X-Mailer'                  => 'Drupal'

  );

  if ($default_from) {

    // To prevent e-mail from looking like spam, the addresses in the Sender and

    // Return-Path headers should have a domain authorized to use the originating

    // SMTP server.

    $headers['From'] = $headers['Sender'] = $headers['Return-Path'] = $default_from;

  }

  if ($from) {

    $headers['From'] = $from;

  }

  $message['headers'] = $headers;

  // Build the e-mail (get subject and body, allow additional headers) by

  // invoking hook_mail() on this module. We cannot use module_invoke() as

  // we need to have $message by reference in hook_mail().

  if (function_exists($function = $module . '_mail')) {

    $function($key, $message, $params);

  }

  // Invoke hook_mail_alter() to allow all modules to alter the resulting e-mail.

  drupal_alter('mail', $message);

  // Retrieve the responsible implementation for this message.

  $system = drupal_mail_system($module, $key);

  // Format the message body.

  $message = $system->format($message);

  // Optionally send e-mail.

  if ($send) {

    // The original caller requested sending. Sending was canceled by one or

    // more hook_mail_alter() implementations. We set 'result' to NULL, because

    // FALSE indicates an error in sending.

    if (empty($message['send'])) {

      $message['result'] = NULL;

    }

    // Sending was originally requested and was not canceled.

    else {

      $message['result'] = $system->mail($message);

      // Log errors.

      if (!$message['result']) {

        watchdog('mail', 'Error sending e-mail (from %from to %to).', array('%from' => $message['from'], '%to' => $message['to']), WATCHDOG_ERROR);

        drupal_set_message(t('Unable to send e-mail. Contact the site administrator if the problem persists.'), 'error');

      }

    }

  }

  return $message;

}

/**

 * Returns an object that implements the MailSystemInterface interface.

 *

 * Allows for one or more custom mail backends to format and send mail messages

 * composed using drupal_mail().

 *

 * An implementation needs to implement the following methods:

 * - format: Allows to preprocess, format, and postprocess a mail

 *   message before it is passed to the sending system. By default, all messages

 *   may contain HTML and are converted to plain-text by the DefaultMailSystem

 *   implementation. For example, an alternative implementation could override

 *   the default implementation and additionally sanitize the HTML for usage in

 *   a MIME-encoded e-mail, but still invoking the DefaultMailSystem

 *   implementation to generate an alternate plain-text version for sending.

 * - mail: Sends a message through a custom mail sending engine.

 *   By default, all messages are sent via PHP's mail() function by the

 *   DefaultMailSystem implementation.

 *

 * The selection of a particular implementation is controlled via the variable

 * 'mail_system', which is a keyed array.  The default implementation

 * is the class whose name is the value of 'default-system' key. A more specific

 * match first to key and then to module will be used in preference to the

 * default. To specify a different class for all mail sent by one module, set

 * the class name as the value for the key corresponding to the module name. To

 * specify a class for a particular message sent by one module, set the class

 * name as the value for the array key that is the message id, which is

 * "${module}_${key}".

 *

 * For example to debug all mail sent by the user module by logging it to a

 * file, you might set the variable as something like:

 *

 * @code

 * array(

 *   'default-system' => 'DefaultMailSystem',

 *   'user' => 'DevelMailLog',

 * );

 * @endcode

 *

 * Finally, a different system can be specified for a specific e-mail ID (see

 * the $key param), such as one of the keys used by the contact module:

 *

 * @code

 * array(

 *   'default-system' => 'DefaultMailSystem',

 *   'user' => 'DevelMailLog',

 *   'contact_page_autoreply' => 'DrupalDevNullMailSend',

 * );

 * @endcode

 *

 * Other possible uses for system include a mail-sending class that actually

 * sends (or duplicates) each message to SMS, Twitter, instant message, etc, or

 * a class that queues up a large number of messages for more efficient bulk

 * sending or for sending via a remote gateway so as to reduce the load

 * on the local server.

 *

 * @param $module

 *   The module name which was used by drupal_mail() to invoke hook_mail().

 * @param $key

 *   A key to identify the e-mail sent. The final e-mail ID for the e-mail

 *   alter hook in drupal_mail() would have been {$module}_{$key}.

 *

 * @return MailSystemInterface

 */

function drupal_mail_system($module, $key) {

  $instances = &drupal_static(__FUNCTION__, array());

  $id = $module . '_' . $key;

  $configuration = variable_get('mail_system', array('default-system' => 'DefaultMailSystem'));

  // Look for overrides for the default class, starting from the most specific

  // id, and falling back to the module name.

  if (isset($configuration[$id])) {

    $class = $configuration[$id];

  }

  elseif (isset($configuration[$module])) {

    $class = $configuration[$module];

  }

  else {

    $class = $configuration['default-system'];

  }

  if (empty($instances[$class])) {

    $interfaces = class_implements($class);

    if (isset($interfaces['MailSystemInterface'])) {

      $instances[$class] = new $class();

    }

    else {

      throw new Exception(t('Class %class does not implement interface %interface', array('%class' => $class, '%interface' => 'MailSystemInterface')));

    }

  }

  return $instances[$class];

}

/**

 * An interface for pluggable mail back-ends.

 */

interface MailSystemInterface {

  /**

   * Format a message composed by drupal_mail() prior sending.

   *

   * @param $message

   *   A message array, as described in hook_mail_alter().

   *

   * @return

   *   The formatted $message.

   */

   public function format(array $message);

  /**

   * Send a message composed by drupal_mail().

   *

   * @param $message

   *   Message array with at least the following elements:

   *   - id: A unique identifier of the e-mail type. Examples: 'contact_user_copy',

   *     'user_password_reset'.

   *   - to: The mail address or addresses where the message will be sent to.

   *     The formatting of this string will be validated with the

   *     @link http://php.net/manual/filter.filters.validate.php PHP e-mail validation filter. @endlink

   *     Some examples are:

   *     - user@example.com

   *     - user@example.com, anotheruser@example.com

   *     - User <user@example.com>

   *     - User <user@example.com>, Another User <anotheruser@example.com>

   *   - subject: Subject of the e-mail to be sent. This must not contain any

   *     newline characters, or the mail may not be sent properly.

   *   - body: Message to be sent. Accepts both CRLF and LF line-endings.

   *     E-mail bodies must be wrapped. You can use drupal_wrap_mail() for

   *     smart plain text wrapping.

   *   - headers: Associative array containing all additional mail headers not

   *     defined by one of the other parameters.  PHP's mail() looks for Cc and

   *     Bcc headers and sends the mail to addresses in these headers too.

   *

   * @return

   *   TRUE if the mail was successfully accepted for delivery, otherwise FALSE.

   */

   public function mail(array $message);

}

/**

 * Performs format=flowed soft wrapping for mail (RFC 3676).

 *

 * We use delsp=yes wrapping, but only break non-spaced languages when

 * absolutely necessary to avoid compatibility issues.

 *

 * We deliberately use LF rather than CRLF, see drupal_mail().

 *

 * @param string $text

 *   The plain text to process.

 * @param string $indent (optional)

 *   A string to indent the text with. Only '>' characters are repeated on

 *   subsequent wrapped lines. Others are replaced by spaces.

 *

 * @return string

 *   The content of the email as a string with formatting applied.

 */

function drupal_wrap_mail($text, $indent = '') {

  // Convert CRLF into LF.

  $text = str_replace("\r", '', $text);

  // See if soft-wrapping is allowed.

  $clean_indent = _drupal_html_to_text_clean($indent);

  $soft = strpos($clean_indent, ' ') === FALSE;

  // Check if the string has line breaks.

  if (strpos($text, "\n") !== FALSE) {

    // Remove trailing spaces to make existing breaks hard, but leave signature

    // marker untouched (RFC 3676, Section 4.3).

    $text = preg_replace('/(?(?<!^--) +\n|  +\n)/m', "\n", $text);

    // Wrap each line at the needed width.

    $lines = explode("\n", $text);

    array_walk($lines, '_drupal_wrap_mail_line', array('soft' => $soft, 'length' => strlen($indent)));

    $text = implode("\n", $lines);

  }

  else {

    // Wrap this line.

    _drupal_wrap_mail_line($text, 0, array('soft' => $soft, 'length' => strlen($indent)));

  }

  // Empty lines with nothing but spaces.

  $text = preg_replace('/^ +\n/m', "\n", $text);

  // Space-stuff special lines.

  $text = preg_replace('/^(>| |From)/m', ' $1', $text);

  // Apply indentation. We only include non-'>' indentation on the first line.

  $text = $indent . substr(preg_replace('/^/m', $clean_indent, $text), strlen($indent));

  return $text;

}

/**

 * Transforms an HTML string into plain text, preserving its structure.

 *

 * The output will be suitable for use as 'format=flowed; delsp=yes' text

 * (RFC 3676) and can be passed directly to drupal_mail() for sending.

 *

 * We deliberately use LF rather than CRLF, see drupal_mail().

 *

 * This function provides suitable alternatives for the following tags:

 * <a> <em> <i> <strong> <b> <br> <p> <blockquote> <ul> <ol> <li> <dl> <dt>

 * <dd> <h1> <h2> <h3> <h4> <h5> <h6> <hr>

 *

 * @param $string

 *   The string to be transformed.

 * @param $allowed_tags (optional)

 *   If supplied, a list of tags that will be transformed. If omitted, all

 *   all supported tags are transformed.

 *

 * @return

 *   The transformed string.

 */

function drupal_html_to_text($string, $allowed_tags = NULL) {

  // Cache list of supported tags.

  static $supported_tags;

  if (empty($supported_tags)) {

    $supported_tags = array('a', 'em', 'i', 'strong', 'b', 'br', 'p', 'blockquote', 'ul', 'ol', 'li', 'dl', 'dt', 'dd', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'hr');

  }

  // Make sure only supported tags are kept.

  $allowed_tags = isset($allowed_tags) ? array_intersect($supported_tags, $allowed_tags) : $supported_tags;

  // Make sure tags, entities and attributes are well-formed and properly nested.

  $string = _filter_htmlcorrector(filter_xss($string, $allowed_tags));

  // Apply inline styles.

  $string = preg_replace('!</?(em|i)((?> +)[^>]*)?>!i', '/', $string);

  $string = preg_replace('!</?(strong|b)((?> +)[^>]*)?>!i', '*', $string);

  // Replace inline <a> tags with the text of link and a footnote.

  // 'See <a href="http://drupal.org">the Drupal site</a>' becomes

  // 'See the Drupal site [1]' with the URL included as a footnote.

  _drupal_html_to_mail_urls(NULL, TRUE);

  $pattern = '@(<a[^>]+?href="([^"]*)"[^>]*?>(.+?)</a>)@i';

  $string = preg_replace_callback($pattern, '_drupal_html_to_mail_urls', $string);

  $urls = _drupal_html_to_mail_urls();

  $footnotes = '';

  if (count($urls)) {

    $footnotes .= "\n";

    for ($i = 0, $max = count($urls); $i < $max; $i++) {

      $footnotes .= '[' . ($i + 1) . '] ' . $urls[$i] . "\n";

    }

  }

  // Split tags from text.

  $split = preg_split('/<([^>]+?)>/', $string, -1, PREG_SPLIT_DELIM_CAPTURE);

  // Note: PHP ensures the array consists of alternating delimiters and literals

  // and begins and ends with a literal (inserting $null as required).

  $tag = FALSE; // Odd/even counter (tag or no tag)

  $casing = NULL; // Case conversion function

  $output = '';

  $indent = array(); // All current indentation string chunks

  $lists = array(); // Array of counters for opened lists

  foreach ($split as $value) {

    $chunk = NULL; // Holds a string ready to be formatted and output.

    // Process HTML tags (but don't output any literally).

    if ($tag) {

      list($tagname) = explode(' ', strtolower($value), 2);