<?php
// $Id: subscriptions_mail.module,v 1.22 2009/04/14 02:26:21 salvis Exp $

/**
 * @file
 * Subscriptions module mail gateway.
 */

/**
 * Implementation of hook_cron().
 *
 * Takes items from {subscriptions_queue} and generates notification emails.
 */
function subscriptions_mail_cron() {

  // set_time_limit(3600);  drupal_set_message('DON\'T FORGET TO REMOVE THE TIME LIMIT EXTENSION!!!');

  global $user, $language;
  drupal_init_language();
  include_once drupal_get_path('module', 'subscriptions_mail') .'/subscriptions_mail.templates.inc';

  $mails_allowed = variable_get('subscriptions_number_of_mails', 0);
  $from = _subscriptions_mail_site_mail();
  $old_uid = 0;
  $single_count = 0;
  $digest_count = 0;
  $loaded_objects = array();
  $users = array();
  $fields = array();
  $mails = array();

  // Strategy for cron:
  // Use 50% of the remaining time to process queue items, send single messages, and assemble digest messages;
  // send the digest messages in the other half and hopefully leave some time for other modules.
  $total_seconds = ini_get('max_execution_time');
  $lost_seconds = timer_read('page')/1000;
  $available_seconds = $total_seconds - $lost_seconds;
  //TEST: watchdog('cron', "Subscriptions has $available_seconds of $total_seconds seconds available.");

  while (($mails_allowed <= 0 || $single_count + count($mails) < $mails_allowed)
          && $total_seconds - timer_read('page')/1000 > $available_seconds*variable_get('subscriptions_cron_percent', 50)/100) {
    $result = db_query_range('SELECT * FROM {subscriptions_queue} WHERE last_sent + send_interval < %d ORDER BY sqid', time(), 0, 1);
    if (!($s = db_fetch_array($result))) {
      break;  // No more subscriptions, terminate loop.
    }
    
    if (!isset($users[$s['uid']])) {
      $users[$s['uid']] = user_load(array('uid' => $s['uid']));
    }
    $saved_user = $user;
    $saved_language = $language;
    session_save_session(FALSE);
    $user = $users[$s['uid']];
    drupal_init_language();
    $langcode = $language->language;

    do {  // once and repeat while adding to a digest
      if ($user->status && $user->access) {
        $cids = array();
        $load_function = $s['load_function'];
        $index = $load_args = $s['load_args'];
        if (!isset($loaded_objects[$user->uid][$load_function][$load_args])) {
          if (is_numeric($load_args)) {
            $object = $load_function($load_args, $s['sqid'], $s['is_new']);
          }
          else {
            $load_args = unserialize($load_args);
            $load_args[] = $s['is_new'];
            $object = call_user_func_array($load_function, $load_args);
          }
          if (!empty($object)) {
            $access = module_invoke_all('subscriptions', 'access', $load_function, $load_args, $object);
            // One FALSE vote is enough to deny. Also, we need a non-empty array.
            $allow = !empty($access) && array_search(FALSE, $access) === FALSE;
            $loaded_objects[$user->uid][$load_function][$index] = $allow ? $object : FALSE;
          }
        }
        if ($object = $loaded_objects[$user->uid][$load_function][$index]) {
          if (!isset($users[$object->uid])) {
            $users[$object->uid] = user_load(array('uid' => $object->uid));
          }
          $sender = $users[$object->uid];
          $module = $s['module'];
          $ori_field = $field = $s['field'];
          $ori_value = $value = $s['value'];
          if (!isset($fields[$langcode][$module])) {
            $fields[$langcode][$module] = module_invoke_all('subscriptions', 'fields', $module);
          }
          if ($module == 'node' && $field == 'nid' && (!empty($object->_subscriptions_is_updated) || !empty($object->_subscriptions_is_new)) && user_access('subscribe to content types', $user)) {
            $unlisteds = variable_get('subscriptions_unlisted_content_types', array());
            if (isset($object->type) && !in_array($object->type, $unlisteds)) {
              $field = 'type';
              $value = $object->type;
            }
          }
          $mailvars_function = $fields[$langcode][$module][$field]['mailvars_function'];
          $mailkey = $fields[$langcode][$module][$field]['mailkey'];
          if (!is_numeric($value)) {
            $mailkey .= '-'. $value;
          }
          $digest = $s['digest'] > 0 || $s['digest'] == -1 && _subscriptions_get_setting('digest', 0) > 0;
          if ($digest) {
            $body_template = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY .'+item', $langcode, 'body', 'DITEM');
          }
          else {
            $body_template = subscriptions_mail_template_load($mailkey, $langcode, 'body', 'BODY');
            $subject_template = subscriptions_mail_template_load($mailkey, $langcode, 'subject', 'SUBJ');
          }
          init_theme();
          $show_node_info = (isset($object->type) ? theme_get_setting('toggle_node_info_'. $object->type) : TRUE);
          $base = 'user/'. $s['uid'];
          $mailvars = array(
            '!site' => variable_get('site_name', 'drupal'),
            '!recipient_name' => $s['name'],
            '!recipient_page' => url($base, array('absolute' => TRUE)),
            '!sender_name' => ($show_node_info ? ($sender->uid ? $sender->name : variable_get('anonymous', '!sender_name')) : '!sender_name'),
            '!sender_page' => ($show_node_info && $sender->uid ? url("user/$sender->uid", array('absolute' => TRUE)) : '!sender_page'),
            '!sender_contact_page' => ($show_node_info ? (empty($sender->contact) ? t('(disabled)') : url("user/$sender->uid/contact", array('absolute' => TRUE))) : '!sender_contact_page'),
            '!sender_has_contact_page' => ($show_node_info ? (empty($sender->contact) ? 0 : 1) : 0),
            '!manage_url' => url($base .'/subscriptions', array('absolute' => TRUE)),
            '!name' => $s['name'],
            '!subs_type' => $fields[$langcode][$module][$field]['!subs_type'],
            '!unsubscribe_url' => url("s/del/$module/$ori_field/$ori_value/". $s['author_uid'] .'/'. $s['uid'] .'/'. md5(drupal_get_private_key() . $module . $ori_field . $ori_value . $s['author_uid'] . $s['uid']), array('absolute' => TRUE)),
          );
          $mailvars_function($mailvars, $object, $field, $s);
          $mailvars += module_invoke_all('subscriptions_get_mailvars', $object);
          if ($digest && !empty($object->_subscriptions_comments) && module_exists('subscriptions_content')) {
            $digest_comment_template = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY .'+comment', $langcode, 'body', 'DITEMCMT');
            $mailvars['!comments'] = _subscriptions_content_format_comments($object, $digest_comment_template, '');
          }
          $body = strtr(subscriptions_mail_template_preprocess($body_template, $mailvars), $mailvars);
          if ($digest) {
            $mails[$s['uid']]['bodies'][] = $body;
            $mails[$s['uid']]['send'] = array(
              'name' => $s['name'],
              'mail' => $s['mail'],
              'from' => $from,
              '!name' => $mailvars['!name'],
              '!manage_url' => $mailvars['!manage_url'],
            );
          }
          else {
            $subject = strtr(subscriptions_mail_template_preprocess($subject_template, $mailvars), $mailvars);
            _subscriptions_mail_send('passthru', $s['name'], $s['mail'], $subject, $body, $from, $s['uid']);
            ++$single_count;
          }
        }
      }
      db_query("DELETE FROM {subscriptions_queue} WHERE load_function = '%s' AND load_args = '%s' AND uid = %d", $s['load_function'], $s['load_args'], $s['uid']);

      if ($digest) {
        // TODO: Get the next queue item for this user and finish off this user's digest
        // before moving on to the next user. All messages in one digest together count
        // as one mail, and if the number of mails is limited (per cron run), we must
        // not let this cause a split up of the digest.
        // Issue: We must know which notifications to send according to their send_interval.
      }
    } while ( FALSE );  // TODO: while adding to a digest

    $user = $saved_user;
    $language = $saved_language;
    session_save_session(TRUE);
  }

  if ($mails) {
    session_save_session(FALSE);
    foreach ($mails as $uid => $user_mails) {
      $user = $users[$uid];
      drupal_init_language();
      $langcode = $language->language;
      $s = $user_mails['send'];
      $subject_template = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY, $langcode, 'subject', 'DSUBJ');
      $body_template = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY, $langcode, 'body', 'DBODY');
      $separator = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY .'+item', $langcode, 'subject', 'SEP');
      $mailvars['!bodies'] = implode($separator, $user_mails['bodies']);
      $mailvars['!name'] = $s['!name'];
      $mailvars['!manage_url'] = $s['!manage_url'];
      $subject = strtr(subscriptions_mail_template_preprocess($subject_template, $mailvars), $mailvars);
      $body = strtr(subscriptions_mail_template_preprocess($body_template, $mailvars), $mailvars);
      _subscriptions_mail_send(SUBSCRIPTIONS_DIGEST_MAILKEY, $s['name'], $s['mail'], $subject, $body, $s['from'], $uid);
      ++$digest_count;
    }
    $user = $saved_user;
    $language = $saved_language;
    session_save_session(TRUE);
  }
  if ($single_count + $digest_count > 0) {
    $watchdog = 'watchdog';  // keep potx from translating 'cron'
    $watchdog('cron', '!module sent !single_count single and !digest_count digest notifications in !used_seconds of !available_seconds available seconds; !remaining_items queue items left.', array(
      '!module'            => 'Subscriptions',
      '!single_count'      => $single_count,
      '!digest_count'      => $digest_count,
      '!used_seconds'      => (integer) (timer_read('page')/1000 - $lost_seconds),
      '!available_seconds' => (integer) $available_seconds . ($lost_seconds > 5*$total_seconds/100 ? " ($total_seconds)" : ''),
      '!remaining_items'   => db_result(db_query("SELECT COUNT(*) FROM {subscriptions_queue} WHERE last_sent + send_interval < %d", time())),
    ));
  }
}

/**
 * Implementation of hook_mail().
 */
function subscriptions_mail_mail($key, &$message, $params) {
  global $base_url;
  
  $url = parse_url($base_url);
  $list_id = variable_get('site_name', '') .' '. t('Subscriptions') .' <subscriptions.'. $url['host'] .'>'; 
  
  $message['subject'] = $params['context']['subject'];
  $message['body'] = $params['context']['message'];
  $message['headers']['List-Id'] = $list_id;
}


/**
 * Send the notification by mail.
 */
function _subscriptions_mail_send($mailkey, $name, $to, $subject, $body, $from, $uid) {
  global $user;

  $mail_success = drupal_mail('subscriptions_mail', $mailkey, $to, user_preferred_language($user), array(
    'account' => $user,
    'object' => NULL,
    'context' => array(
      'recipient' => $to,
      'subject' => $subject,
      'message' => $body,
    ),
  ), $from, TRUE);

  $watchdog_params = array('@name' => $name, '@to' => "<$to>");
  if (!empty($mail_success['result'])) {
    if (variable_get('subscriptions_watchgood', 1)) {
      watchdog('subscriptions', 'notification for @name at @to', $watchdog_params);
    }
    db_query("UPDATE {subscriptions_user} SET last_sent = %d WHERE uid = %d", time(), $uid);
    if (!db_affected_rows()) {
      @db_query("INSERT INTO {subscriptions_user} (uid, last_sent) VALUES(%d, %d)", $uid, time());
    }
  }
  else {
    watchdog('subscriptions', 'error mailing notification for @name at @to', $watchdog_params, WATCHDOG_ERROR);
  }
}

/**
 * Return the 'From:' address to use for sending e-mail.
 */
function _subscriptions_mail_site_mail($address_only = FALSE) {
  $email = variable_get('subscriptions_site_mail', '');
  if (empty($email)) {
    $email = variable_get('site_mail', ini_get('sendmail_from'));
  }
  if (!$address_only && ($name = variable_get('subscriptions_site_mail_name', FALSE))) {
    $email = '"'. $name .'" <'. $email .'>';
  }
  return $email;
}

/**
 * Implementation of hook_form_alter().
 *
 * Adds to the Mail templates form at admin/build/mail-edit if old D5 tables are found.
 */
function subscriptions_mail_form_mail_edit_list_form_alter(&$form, $form_state) {
  if (db_table_exists('subscriptions_mail_edit') || 
      db_table_exists('mail_edit_d5') && db_result(db_query("SELECT COUNT(*) FROM {mail_edit_d5} WHERE mailkey LIKE 'subscriptions-%'")) > 0) {
    include_once drupal_get_path('module', 'subscriptions_mail') .'/subscriptions_mail.mail_edit_D5.inc';
    _subscriptions_mail_form_mail_edit_list_form_alter($form, $form_state);
  }
}

/**
 * Implementation of hook_form_alter().
 *
 * Adds to the General Settings part at admin/settings/subscriptions.
 */
function subscriptions_mail_form_subscriptions_settings_form_alter(&$form, &$form_state) {
  global $user;
  $tr = 't';

  // check the $base_url (#199039, #226335)
  $url = url('', array('absolute' => TRUE));
  if (empty($_POST) && preg_match('!//($|/|localhost/|([0-9]{1,3}\.){3}[0-9]{1,3}/)!', $url)) {
    drupal_set_message(t('Your installation returns %url as the base URL of the site. This is probably not what you want, and it can usually be fixed by setting the %variable variable in your %file file.', array('%url' => $url, '%variable' => '$base_url', '%file' => 'settings.php')), 'error');
  }

  $form['mail_settings'] = array(
      '#type' => 'fieldset',
      '#title' => t('Mail settings'),
      '#weight' => -3,
  );
  $form['mail_settings']['subscriptions_site_mail'] = array(
    '#type'          => 'textfield',
    '#title'         => t('E-mail address'),
    '#default_value' => _subscriptions_mail_site_mail(TRUE),
    '#description'   => t('A valid e-mail address to be used as the %From and %Reply_To address by the auto-mailer for !module notifications.  To lessen the likelihood of e-mail being marked as spam, this e-mail address should use the same domain as the website.', array('%From' => 'From', '%Reply_To' => 'Reply-To', '!module' => 'Subscriptions')) .'<br />'. t('Clear this field to use the default site e-mail address.'),
  );
  $form['mail_settings']['subscriptions_site_mail_name'] = array(
    '#type'          => 'textfield',
    '#title'         => t('E-mail name'),
    '#default_value' => variable_get('subscriptions_site_mail_name', ''),
    '#description'   => t('An optional name to go with the e-mail address above, no "double-quotes".') .'<br />'. t('Clear this field to use the e-mail address only &mdash; some e-mail clients will display only the portion of the address to the left of the @ sign.'),
  );
  $form['mail_settings']['subscriptions_number_of_mails'] = array(
    '#type'          => 'textfield',
    '#title'         => t('Maximum number of notifications to send per cron job'),
    '#default_value' => variable_get('subscriptions_number_of_mails', 0),
    '#description'   => t("!module tries to use a good part of the remaining time during each cron run. If it's using too much time or you need to limit the number of outgoing e-mails for some other reason, then set the number here. The default is 0, which means unlimited.", array('!module' => 'Subscriptions')),
  );
  $form['mail_settings']['subscriptions_watchgood'] = array(
    '#type'          => 'checkbox',
    '#title'         => t('Display watchdog entries for successful mailings'),
    '#default_value' => variable_get('subscriptions_watchgood', 1),
    '#description'   => t('Logs successful mailings to the watchdog log.  Default is ON, but with many subscribers this will generate a huge number of log entries.'),
  );
  $form['mail_settings']['subscriptions_watchstats'] = array(
    '#type'          => 'checkbox',
    '#title'         => t('Display summary watchdog entries per cron job'),
    '#default_value' => variable_get('subscriptions_watchstats', 1),
    '#description'   => t('Logs the mailing counts, time spent, and size of the remaining queue to the watchdog log.  This is valuable information for estimating the load on the cron job and on your mail server.  Default is ON.'),
  );
}

/**
 * Implementation of hook_mailkeys().
 *
 * Provide mailkeys for mail_edit.
 *
 * @ingroup hooks
 */
function subscriptions_mail_mailkeys() {
  $mailkeys['digest'] = t('Digest subscriptions notifications');
  return $mailkeys;
}

/**
 * Implementation of hook_mail_edit_tokens_list().
 *
 * Provide replacable tokens for mail_edit.
 *
 * @ingroup hooks
 */
function subscriptions_mail_mail_edit_tokens_list($mailkey, $options = array()) {
  //$tokens = module_invoke('subscriptions_content', 'mail_edit_tokens_list', $mailkey, $options);
  $tokens = subscriptions_mail_subscriptions_tokens_list($mailkey, $options);
  $tokens += array(
    '!bodies' => t('The digested items (separated by a separator), as defined below:'),
  );
  return $tokens;
}

/**
 * Implementation of hook_subscriptions_tokens_list().
 *
 * Provide replacable tokens for mail_edit.
 * mail_edit calls only the hook in the module that registered the mailkey,
 * but we call this hook function from there to add some common tokens.
 *
 * @ingroup hooks
 */
function subscriptions_mail_subscriptions_tokens_list($mailkey, $options = array()) {
  $tokens = array();
  switch ($mailkey) {
    case 'digest':
      break;
    default:
      $tokens += array(
        '!site'           => t('The name of the site.'),
        '!recipient_name' => t('Name of the recipient.'),
        '!recipient_page' => t('The user page of the recipient.'),
        '!manage_url'     => t('The URL where the user can manage her subscriptions.'),
      );
  }
  if (isset($options['tokens'])) {
    $tokens += $options['tokens'];
  }
  return $tokens;
}

/**
 * Implementation of hook_mail_edit_text().
 *
 * Provide default templates for mail_edit.
 *
 * @ingroup hooks
 */
function subscriptions_mail_mail_edit_text($mailkey, $language) {
  include_once drupal_get_path('module', 'subscriptions_mail') .'/subscriptions_mail.templates.inc';
  $return = array();
  $return['subject'] = subscriptions_mail_template('DSUBJ', $language->language);
  $return['body'] = subscriptions_mail_template('DBODY', $language->language);
  return $return;
}

/**
 * Implementation of hook_subscriptions_mail_text().
 *
 * Provide default templates for mail_edit.
 *
 * @ingroup hooks
 */
function subscriptions_mail_subscriptions_mail_text($mailkey, $language) {
  include_once drupal_get_path('module', 'subscriptions_mail') .'/subscriptions_mail.templates.inc';
  $return = array();
  $return['subject'] = subscriptions_mail_template('SUBJ', $language->language);
  $return['body'] = subscriptions_mail_template('BODY', $language->language);
  return $return;
}

/**
 * Implementation of hook_form_alter().
 *
 * Add the digest parts to the subscriptions_mail_digest mail_edit page.
 *
 * @ingroup hooks
 * @ingroup form
 */
function subscriptions_mail_form_mail_edit_trans_alter(&$form, &$form_state) {
  $mailkey = 'subscriptions_mail_digest';
  if ($form['id']['#value'] == $mailkey) {
    $tr = 't';
    $langcode = $form['language']['#value'];

    $form['mail']['subject']['#title'] = t('Digest subject');
    $form['mail']['body']['#title'] = t('Digest body');
    $form['mail']['body']['#rows'] = 8;
    
    $digest_item = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY .'+item', $langcode, 'body', 'DITEM');
    $digest_item_separator = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY .'+item', $langcode, 'subject', 'SEP');
    $digest_item_comment = subscriptions_mail_template_load(SUBSCRIPTIONS_DIGEST_MAILKEY .'+comment', $langcode, 'body', 'DITEMCMT');

    $form['mail']['digest_item'] = array(
      '#title'      => t('Digest item'),
      '#type'       => 'textarea',
      '#default_value'  => $digest_item,
      '#rows' => 15,
    );
    if ($placeholders = module_invoke('subscriptions_content', 'mail_edit_tokens_list', 'digest')) {
      $doc = "<dl>\n";
      foreach ($placeholders as $name => $description) {
        $doc .= '<dt>'. $name .'</dt>';
        $doc .= '<dd>'. $description .'</dd>';
      }
      $doc .= "</dl>\n";
      $form['mail']['digest_item_help'] = array(
        '#title' => $tr('Replacement patterns'),
        '#type' => 'fieldset',
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
      );
      $form['mail']['digest_item_help']['help'] = array(
        '#value' => $doc,
      );
    }
    $form['mail']['digest_item_comment'] = array(
      '#title'      => t('Digest item comment'),
      '#type'       => 'textarea',
      '#default_value'  => $digest_item_comment,
      '#rows' => 4,
      '#description' => t('The comments inside a digest item body.'),
    );
    if ($placeholders = module_invoke('subscriptions_content', 'mail_edit_tokens_list', 'comments')) {
      $doc = "<dl>\n";
      foreach ($placeholders as $name => $description) {
        $doc .= '<dt>'. $name .'</dt>';
        $doc .= '<dd>'. $description .'</dd>';
      }
      $doc .= "</dl>\n";
      $form['mail']['comment_token_help'] = array(
        '#title' => t('Replacement patterns'),
        '#type' => 'fieldset',
        '#collapsible' => TRUE,
        '#collapsed' => TRUE,
      );
      $form['mail']['comment_token_help']['help'] = array(
        '#value' => $doc,
      );
    }
    $form['mail']['digest_item_separator'] = array(
      '#title'      => t('Digest item separator'),
      '#type'       => 'textarea',
      '#default_value' => $digest_item_separator,
      '#rows' => 2,
      '#description' => t('The separator between digest items (if needed).'),
    );
    
    $form['op']['#submit'][] = 'subscriptions_mail_form_mail_edit_trans_save';
    if (isset($form['delete'])) {
      $form['delete']['#submit'][] = 'subscriptions_mail_form_mail_edit_trans_delete';
    }
  } 
}

/**
 * Save handler for enhanced mail_edit page.
 */
function subscriptions_mail_form_mail_edit_trans_save($form, &$form_state) {
  $id = $form_state['values']['id'];
  $form_state['values']['description'] = '';
  $form_state['values']['subject'] = $form_state['values']['digest_item_separator'];
  $form_state['values']['body'] = $form_state['values']['digest_item'];
  $form_state['values']['id'] = $id .'+item';
  mail_edit_trans_save($form, $form_state);
  $form_state['values']['subject'] = '';
  $form_state['values']['body'] = $form_state['values']['digest_item_comment'];
  $form_state['values']['id'] = $id .'+comment';
  mail_edit_trans_save($form, $form_state);
}

/**
 * Delete handler for enhanced mail_edit page.
 */
function subscriptions_mail_form_mail_edit_trans_delete($form, &$form_state) {
  foreach (array('item', 'comment') as $key) {
    db_query("DELETE FROM {mail_edit} WHERE id = '%s' AND language = '%s'", $form_state['values']['id'] ."+$key", $form_state['values']['language']);
  }
}

/**
 * Preprocess a mail template (subject or body), detecting conditional clauses
 * that conform to a prescribed syntax
 *
 * @param string $template
 *  the template for preprocessing
 * @param array $mailvars
 *  an associatvie array of currently existing variables that are to be
 *  interpolated into the template later , and which can be used by this
 *  function for preprocessing
 *
 * This function allows the administrator to specify ternary-type conditions
 * to determine what text is used in a mail in a particular situation, using
 * the variables that are currently available for that mail for reference.
 * The syntax is standard PHP/C-style ternary syntax, but only allows the
 * "==" and "!=":
 * {{!variable_name==sometext?text for true condition:text for false condition}}
 *
 * sometext must not contain a question mark, and the true text no colon.
 */
function subscriptions_mail_template_preprocess($template, $mailvars) {
  preg_match_all('/{{(?P<condition>[^?]+?)\?(?P<true>[^:]*?):(?P<false>[^\]]*?)}}/', $template, $conditions);

  // locate the actual operators/operand for each
  $replacement = '';
  foreach ($conditions[0] as $k => $v) {
    preg_match('/(?P<operand_1>!.+)\s*(?P<operator>==|!=)\s*(?P<operand_2>.+)/', $conditions['condition'][$k], $matches);
    $operand1 = (isset($mailvars[$matches['operand_1']]) ? $mailvars[$matches['operand_1']] : $matches['operand_1']);
    if ($matches['operator'] == '==') {
      $replacement = ($operand1 == $matches['operand_2']) ? $conditions['true'][$k] : $conditions['false'][$k];
    }
    elseif ($matches['operator'] == '!=') {
      $replacement = ($operand1 != $matches['operand_2']) ? $conditions['true'][$k] : $conditions['false'][$k];
    }
    else {
      continue;
    }
    // replace the condition with the result of its evalutation
    $template = str_replace($v, $replacement, $template);
  }
  return $template;
}

/**
 * Implementation of hook_mail_alter().
 *
 * Remove any trailing spaces (must run after mail_edit_mail_alter()!).
 */
function subscriptions_mail_mail_alter(&$message) {
  $message['body'] = preg_replace('/ +(\r?\n)/', '\\1', $message['body']);
}