death-notifier/src/main/php/com/fwdekker/deathnotifier/mailer/Mailer.php

<?php

namespace com\fwdekker\deathnotifier\mailer;

use com\fwdekker\deathnotifier\Response;
use Exception;
use Monolog\Logger;
use PDO;
use PHPMailer\PHPMailer\Exception as MailerException;
use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\SMTP;


/**
 * Queues up mails and sends them when appropriate.
 */
class Mailer
{
    /**
     * @var Logger The logger to use for logging.
     */
    private Logger $logger;
    /**
     * @var array<string, array<string, mixed>> The configuration to use for mailing.
     */
    private array $config;
    /**
     * @var PDO The database connection to interact with.
     */
    private PDO $conn;


    /**
     * Constructs a new mailer.
     *
     * @param array<string, array<string, mixed>> $config the configuration to use for mailing
     * @param Logger $logger the logger to use for logging
     * @param PDO $conn the connection to the email database
     */
    public function __construct(array $config, Logger $logger, PDO $conn)
    {
        $this->logger = $logger;
        $this->config = $config;
        $this->conn = $conn;
    }


    /**
     * Populates the database with the necessary structures for emails.
     *
     * @return void
     */
    public function install(): void
    {
        $this->conn->exec("CREATE TABLE email_tasks(type TEXT NOT NULL,
                                                    recipient TEXT NOT NULL,
                                                    arg1 TEXT NOT NULL DEFAULT(''),
                                                    arg2 TEXT NOT NULL DEFAULT(''),
                                                    PRIMARY KEY (type, recipient, arg1, arg2));");
    }


    /**
     * Queues an email to be sent.
     *
     * @param Email $email the email to queue
     * @return Response a satisfied `Response` if the email was queued, or an unsatisfied `Response` otherwise
     */
    public function queue_email(Email $email): Response
    {
        $stmt = $this->conn->prepare("INSERT OR IGNORE INTO email_tasks (type, recipient, arg1, arg2)
                                      VALUES (:type, :recipient, :arg1, :arg2);");
        $stmt->bindValue(":type", $email->type);
        $stmt->bindValue(":recipient", $email->recipient);
        $stmt->bindValue(":arg1", $email->arg1);
        $stmt->bindValue(":arg2", $email->arg2);

        return $stmt->execute() ? Response::satisfied() : Response::unsatisfied(null);
    }

    /**
     * Sends all emails in the queue.
     *
     * @return void
     */
    public function process_queue(): void
    {
        // Open mailer
        $mailer = new PHPMailer();
        $mailer->IsSMTP();
        $mailer->CharSet = "UTF-8";

        $mailer->SMTPAuth = true;
        $mailer->SMTPDebug = SMTP::DEBUG_OFF;
        $mailer->SMTPKeepAlive = true;
        $mailer->SMTPSecure = PHPMailer::ENCRYPTION_SMTPS;
        $mailer->Host = $this->config["mail"]["host"];
        $mailer->Port = $this->config["mail"]["port"];
        $mailer->Username = $this->config["mail"]["username"];
        $mailer->Password = $this->config["mail"]["password"];
        try {
            $mailer->setFrom($this->config["mail"]["username"], $this->config["mail"]["from_name"]);
        } catch (MailerException $exception) {
            $this->logger->error("Failed to set 'from' address while processing queue.", ["cause" => $exception]);
            $mailer->smtpClose();
        }

        // Get queue
        $stmt = $this->conn->prepare("SELECT type, recipient, arg1, arg2 FROM email_tasks;");
        $stmt->execute();
        $email_tasks = $stmt->fetchAll(PDO::FETCH_ASSOC);

        // Process queue
        $stmt = $this->conn->prepare("DELETE FROM email_tasks
                                      WHERE type=:type AND recipient=:recipient AND arg1=:arg1 AND arg2=:arg2;");
        $stmt->bindParam(":type", $type);
        $stmt->bindParam(":recipient", $recipient);
        $stmt->bindParam(":arg1", $arg1);
        $stmt->bindParam(":arg2", $arg2);
        foreach ($email_tasks as ["type" => $type, "recipient" => $recipient, "arg1" => $arg1, "arg2" => $arg2]) {
            try {
                $email = Email::deserialize($type, $recipient, $arg1, $arg2);
                $mailer->Subject = $email->getSubject();
                $mailer->Body = $email->getBody($this->config);

                try {
                    $mailer->addAddress($recipient);
                    $mailer->send();
                } catch (MailerException $exception) {
                    $this->logger->error(
                        "Failed to send mail.",
                        ["cause" => $exception, "email" => $email]
                    );
                    $mailer->getSMTPInstance()->reset();
                }

                $mailer->clearAddresses();
            } catch (Exception $exception) {
                $this->logger->error(
                    "Failed to send mail.",
                    ["cause" => $exception]
                );
                $mailer->getSMTPInstance()->reset();
            }

            $stmt->execute();
        }
    }
}