3. Генерация email из шаблонов

<action id="notifyEmail"
        type="list_itemTracking"
        icon="ENVELOPE"
        text="msg://notifyEmail.text"/>

<hbox id="buttonsPanel" classNames="buttons-panel">
    <!--...-->
    <button id="notifyEmailButton" action="bookingsDataGrid.notifyEmail"/>
</hbox>

@ViewComponent
private DataGrid<Booking> bookingsDataGrid;
@Autowired
private MessageTemplateProperties messageTemplateProperties; (1)
@Autowired
private MessageTemplatesGenerator messageTemplatesGenerator; (2)
@Autowired
private Emailer emailer; (3)
@Autowired
private Notifications notifications; (4)

@Subscribe("bookingsDataGrid.notifyEmail")
public void onBookingsDataGridNotifyEmail(final ActionPerformedEvent event) {
    Booking booking = bookingsDataGrid.getSingleSelectedItem();
    User creator = booking.getCreator(); (5)

    String email = creator.getEmail();
    if (email == null) {
        showNoEmailNotification(creator); (6)
        return;
    }

    List<String> messages = messageTemplatesGenerator.generateMultiTemplate()
            .withTemplateCodes("booking-email-subject", "booking-email-body") (7)
            .withParams(
                    Map.of(
                            "booking", booking,
                            "today", new Date(),
                            "penalty", 5000
                    )) (8)
            .generate();

    EmailInfo emailInfo = EmailInfoBuilder.create()
            .setAddresses(email)
            .setSubject(messages.get(0))
            .setBody(messages.get(1))
            .setBodyContentType("text/html; charset=UTF-8")
            .build(); (9)

    try {
        emailer.sendEmail(emailInfo); (10)
    } catch (EmailException e) {
        showSendingErrorNotification(email);
    }

    showSendingSuccessNotification(email); (11)
}

private void showSendingErrorNotification(String email) {
    notifications.create("Failed to send email to %s".formatted(email))
            .withThemeVariant(NotificationVariant.LUMO_ERROR)
            .show();
}

private void showNoEmailNotification(User creator) {
    notifications.create("%s did not specify an email".formatted(creator.getDisplayName()))
            .withThemeVariant(NotificationVariant.LUMO_ERROR)
            .show();
}

private void showSendingSuccessNotification(String email) {
    notifications.create("The message has been successfully sent to %s".formatted(email))
            .withThemeVariant(NotificationVariant.LUMO_SUCCESS)
            .show();
}