/**
 * sendEmail
 * Function mapped to Laravel route. Defines variable arrays and calls Email Class executeEmail.
 *
 * @param   Request         $request            Request object passed via AJAX from client.
 */
public function sendEmail(Request $request) {
    $fromEmail = $request['fromEmail'];
    $fromPass = $request['fromPass'];
    $host = $request['hostName'];
    $port = $request['port'];
    $emailSettings = array($host,$port,$fromEmail,$fromPass);

    $emailTemplate = 'emails.' . $request['emailTemplate'];
    $emailTemplateType = substr($request['emailTemplate'],0,3);
    $emailTemplateTarget = substr($request['emailTemplate'],3,1);
    $template = array($emailTemplate,$emailTemplateType,$emailTemplateTarget);

    $period = 4;
    $subject = $request['subject'];
    $projectName = $request['projectName'];
    $projectId = intval($projectName,strpos($projectName,'_'));
    $projectName = substr($projectName,0,strpos($projectName,'_')-1);
    $companyName = $request['companyName'];
    $params = array($period,$projectName,$projectId,$companyName,$subject);

    try {
        Email::executeEmail($emailSettings,$template,$params);
    } catch(OutOfBoundsException $oobe) {
        //mail server settings not valid
    } catch(FailureException $fee) {
        //email failed to be sent to server
    } catch(PDOException $pdoe) {
        DBManager::logConnectError(__CLASS__,__FUNCTION__,$pdoe->getMessage(),$pdoe->getTrace());
    } catch(QueryException $qe) {
        DBManager::logQueryError(__CLASS__,__FUNCTION__,$qe);
    }
}

/**
 * executeEmail
 * Public-facing method to send an email to a database of users if they are a valid recipient.
 *
 * @param   array                   $emailSettings          Host, port, username, and password variables for the mail server
 * @param   array                   $template               Email Template, Template Type, Template Target Type for user validation
 *          string                  Email Template          Path to the blade.php template file from the views directory
 *          string                  Template Type           Specifies whether the email is an Advanced (adv) or Basic (bsc) scam
 *          string                  Template Target Type    Specifies whether the email is a Targeted (T) or Generic (G) scam
 * @param   array                   $params                 Period, Project Name, Project ID, From Email Address, Company Name, Subject
 *          int                     Period                  Number of weeks to check back for recipient validation
 *          string                  Project Name            Name of this project
 *          int                     Project Id              ID of this project
 *          string                  From Email Address      Email to be sent from
 *          string                  Company Name            Name of company sponsoring this awareness test
 *          string                  Subject                 Subject of email
 * @throws  OutOfBoundsException                            Thrown from setEmailEnvironmentSettings if a setting is not valid
 * @throws  FailureException                                Thrown from sendEmail() if mail fails to be given to mail server
 * @throws  PDOException                                   Thrown from DBManager->query()
 * @throws  QueryException                                  Thrown from DBManager->query()
 */
public static function executeEmail($emailSettings, $template, $params) {
    self::setEmailEnvironmentSettings($emailSettings);
    $db = new DBManager();
    $sql = "SELECT * FROM gaig_users.users;";
    $users = $db->query($sql,array(),array('PDO::ATTR_CURSOR'),array('PDO::CURSOR_SCROLL'));
    $userIterator = new PDOIterator($users);
    foreach($userIterator as $user) {
        if(self::validateUser($template[1],$template[2],$user,$params[0])) {
            $to = $user['USR_Email'];
            $urlId = self::getUrlId($user);
            $companyName = $params[3];
            $subject = $params[4];
            if(is_null($params[3])) {
                $companyName = 'your organization';
            }
            if(is_null($params[4])) {
                $subject = 'Corporate Communication';
            }
            $headers = array('companyName'=>$companyName,'projectName'=>$params[1],'projectId'=>$params[2],
                'lastName'=>$user['USR_LastName'],'username'=>$user['USR_Username'],'urlId'=>$urlId);
            self::sendEmail($template[0],$headers,$to,getenv('MAIL_USERNAME'),$subject);
            $project_new = $params[6] . '-' . $params[4];
            $projects = array($project_new,$user['USR_ProjectMostRecent'],$user['USR_ProjectPrevious']);
            self::updateUserProjects($projects,$user);
        }
    }
}

/**
 * setEmailEnvironmentSettings
 * Checks if the settings are valid settings, then sets or returns an exception.
 *
 * @param   array                   $emailSettings      Host, port, username, and password variables for the mail server
 * @throws  OutOfBoundsException
 */
private function setEmailEnvironmentSettings($emailSettings) {
    $pattern = ';(?:https?://)?(?:[a-zA-Z0-9.-]+?.(?:com|net|org|gov|edu|mil)|d+.d+.d+.d+);';
    if(!preg_match($pattern,$emailSettings[0]) || !filter_var($emailSettings[1],FILTER_VALIDATE_INT) ||
        !filter_var($emailSettings[2],FILTER_VALIDATE_EMAIL)) {
        $message = '';
        if(!preg_match($pattern,$emailSettings[0])) {
            $message .= 'Host is not a valid host name or IP address. host=' . $emailSettings[0] . 'n';
        }
        if(!filter_var($emailSettings[1],FILTER_VALIDATE_INT)) {
            $message .= 'Port is not a valid integer. port=' . $emailSettings[1] . 'n';
        }
        if(!filter_var($emailSettings[2],FILTER_VALIDATE_EMAIL)) {
            $message .= 'Username is not a valid email address. username=' . $emailSettings[2] . 'n';
        }
        throw new OutOfBoundsException($message);
    }
    putenv("MAIL_HOST=$emailSettings[0]");
    putenv("MAIL_PORT=$emailSettings[1]");
    putenv("MAIL_USERNAME=$emailSettings[2]");
    putenv("MAIL_PASSWORD=$emailSettings[3]");
}

/**
 * validateUser
 * Function checks if the specified user has not received a test within the specified duration,
 *      if the template type is the same for the last two project participants, if the template target
 *      is the same for last three project participants, or if the last project is identical to the new project.
 *
 * @param   string                  $templateType       Specifies whether the email is an Advanced (adv) or Basic (bsc) scam
 * @param   string                  $templateTarget     Specifies whether the email is a Targeted (T) or Generic (G) scam
 * @param   array                   $user               Associative Array containing the fields associated to the user
 * @param   int                     $period             Number of weeks to check back for recipient validation
 * @return  bool
 */
private function validateUser($templateType,$templateTarget,$user,$period) {
    $db = new DBManager();
    $date = date('Y-m-d',strtotime('-' . $period . 'weeks')) . '00:00:00';
    $sql = "SELECT max(SML_AccessTimestamp) as 'timestamp_check' from gaig_users.sent_email where SML_UserId = ? and SML_ProjectName = ?;";
    $bindings = array($user['USR_UserId'],$user['USR_ProjectMostRecent']);
    $timestampData = $db->query($sql,$bindings);
    $result = $timestampData->fetch(PDO::FETCH_ASSOC);
    if(!filter_var($user['USR_Email'],FILTER_VALIDATE_EMAIL)) {
        $this->badEmailAddressWarning(['USR_Username'] . ' has a bad email address. email=' . $user['USR_Email']);
        return false;
    }
    if($result['timestamp_check'] <= $date) {
        return true;
    } else if($templateType == substr($user['USR_ProjectMostRecent'],-5,3) &&
        $templateType == substr($user['USR_ProjectPrevious'],-5,3)) {
        return false;
    } else if($templateTarget == substr($user['USR_ProjectMostRecent'],-2,1) &&
        $templateTarget == substr($user['USR_ProjectPrevious'],-2,1) &&
        $templateTarget == substr($user['USR_ProjectLast'],-2,1)) {
        return false;
    } else if($templateType.$templateTarget ==
        substr($user['USR_ProjectMostRecent'],strpos($user['USR_ProjectMostRecent'],'-')+1,4)) {
        return false;
    }
    return true;
}

/**
 * getUrlId
 * Generates or retrieves the UniqueURLId of the passed user.
 *
 * @param   array           $user           User array extracted from PDOStatement
 * @return  string
 */
private function getUrlId($user) {
    $db = new DBManager();
    if(!is_null($user['USR_UniqueURLId'])) {
        $urlId = $user['USR_UniqueURLId'];
    } else {
        $urlId = $this->random_str(15);
        $sql = "UPDATE gaig_users.users SET USR_UniqueURLId=?;";
        $bindings = array($urlId);
        $db->query($sql,$bindings);
    }
    return $urlId;
}

/**
 * updateUserProjects
 * Updates the user with the newest project and rotates the old projects down one.
 *
 * @param   array           $projects       Most Recent Project, Previous Project, Oldest Project
 * @param   array           $user           User array extracted from PDOStatement
 */
private function updateUserProjects($projects,$user) {
    $db = new DBManager();
    $sql = "UPDATE gaig_users.users SET USR_ProjectMostRecent=?, USR_ProjectPrevious=?,
                USR_ProjectLast=? WHERE USR_Username=?;";
    $bindings = array($projects[0],$projects[1],$projects[2],$user['USR_Username']);
    $db->query($sql,$bindings);
}

/**
 * sendEmail
 * Iterates through the PDO Result Set of users. Calls validRecipientAlgo to validate user. Sends email if
 *      valid and updates user if valid.
 * @param   array                   $params             Required parameters to pass to the email template
 * @param   string                  $from               Email to be sent from
 * @param   string                  $subject            Subject of email
 * @throws  FatalErrorException
 */
private function sendEmail($template, $headers, $to, $from, $subject) {
    if(!Mail::send(['html' => $template],$headers, function($m) use ($from, $to, $subject) {
        $m->from($from);
        $m->to($to)->subject($subject);
    })) {
        throw new FailureException('Email failed to send to ' . $to . ' from ' . $from);
    }
}

/**
 * random_str
 * Generates a random string.
 *
 * @param   int         $length         Length of string to be returned
 * @param   string      $keyspace       Allowed characters to be used in string
 * @return  string
 */
private function random_str($length, $keyspace = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ')
{
    $str = '';
    $max = mb_strlen($keyspace, '8bit') - 1;
    for ($i = 0; $i < $length; ++$i) {
        $str .= $keyspace[random_int(0, $max)];
    }
    return $str;
}

/**
 * badEmailAddressWarning
 * Logs error when a bad email address is found associated with a user
 *
 * @param   string          $message        Error message to be logged
 */
private function badEmailAddressWarning($message) {
    $path = '../storage/logs/badEmailAddress' . date('m-d-Y') . '.log';
    if(!file_exists($path)) {
        $file = fopen($path,'w');
        fclose($file);
    }
    error_log($message,3,$path);
}