/**
  * Perform the necessary actions to send a password reset mail
  *
  * @param $user_name_or_email string Username or user's email
  *
  * @return bool success status
  */
 public static function requestPasswordReset($user_name_or_email)
 {
     if (empty($user_name_or_email)) {
         Session::add('feedback_negative', Text::get('FEEDBACK_USERNAME_EMAIL_FIELD_EMPTY'));
         return false;
     }
     // check if that username exists
     $result = UserModel::getUserDataByUserNameOrEmail($user_name_or_email);
     if (!$result) {
         Session::add('feedback_negative', Text::get('FEEDBACK_USER_DOES_NOT_EXIST'));
         return false;
     }
     // generate integer-timestamp (to see when exactly the user (or an attacker) requested the password reset mail)
     // generate random hash for email password reset verification (40 char string)
     $temporary_timestamp = time();
     $user_password_reset_hash = sha1(uniqid(mt_rand(), true));
     // set token (= a random hash string and a timestamp) into database ...
     $token_set = self::setPasswordResetDatabaseToken($result->user_name, $user_password_reset_hash, $temporary_timestamp);
     if (!$token_set) {
         return false;
     }
     // ... and send a mail to the user, containing a link with username and token hash string
     $mail_sent = self::sendPasswordResetMail($result->user_name, $user_password_reset_hash, $result->user_email);
     if ($mail_sent) {
         return true;
     }
     // default return
     return false;
 }