private void addOrRemoveSubscription()

in src/main/java/com/awslabs/aws/greengrass/provisioner/implementations/helpers/BasicGroupUpdateHelper.java [344:415]
51 lines of code
8 McCabe index (conditional complexity)

    private void addOrRemoveSubscription(UpdateArguments updateArguments, GroupInformation groupInformation) {
        List<Subscription> subscriptions = v2GreengrassHelper.getSubscriptions(groupInformation)
                .orElseThrow(() -> new RuntimeException("Group not found, can not continue"));

        String source = updateArguments.subscriptionSource;
        String target = updateArguments.subscriptionTarget;
        String subject = updateArguments.subscriptionSubject;
        GreengrassGroupId greengrassGroupId = ImmutableGreengrassGroupId.builder().groupId(groupInformation.id()).build();

        if (updateArguments.addSubscription) {
            List<Function> functions = v2GreengrassHelper.getFunctions(groupInformation)
                    .orElseThrow(() -> new RuntimeException("Group not found, can not continue"));
            List<Device> devices = v2GreengrassHelper.getDevices(groupInformation)
                    .orElseThrow(() -> new RuntimeException("Group not found, can not continue"));

            // Is the source valid?
            Optional<String> validatedSource = validateSubscriptionSourceOrTarget(source, functions, devices);

            if (!validatedSource.isPresent()) {
                // Source is invalid
                throw new RuntimeException(String.join("", "Source [", source, "] ", SUBSCRIPTION_ERROR));
            } else {
                source = validatedSource.get();
            }

            // Is the target valid?
            Optional<String> validatedTarget = validateSubscriptionSourceOrTarget(target, functions, devices);

            if (!validatedTarget.isPresent()) {
                // Target is invalid
                throw new RuntimeException(String.join("", "Target [", target, "] ", SUBSCRIPTION_ERROR));
            } else {
                target = validatedTarget.get();
            }

            Set<Subscription> existingSubscriptions = getMatchingSubscriptions(subscriptions, source, target, subject);

            if (existingSubscriptions.size() != 0) {
                throw new RuntimeException("Subscription already exists.  Nothing to do.");
            }

            Subscription subscription = subscriptionHelper.createSubscription(source, target, subject);
            subscriptions.add(subscription);

            log.info(String.join("", "Subscription added [", subscription.source(), ", ", subscription.target(), ", ", subscription.subject(), "]"));
        } else if (updateArguments.removeSubscription) {
            Set<Subscription> existingSubscriptions = getMatchingSubscriptions(subscriptions, source, target, subject);

            if (existingSubscriptions.size() == 0) {
                throw new RuntimeException("Subscription doesn't exist.  Nothing to do.");
            } else if (existingSubscriptions.size() > 1) {
                log.error(jsonHelper.toJson(existingSubscriptions));
                throw new RuntimeException("More than one matching subscription exists.  Specify a more specific match.");
            }

            // Exactly one, remove it
            Subscription subscriptionToRemove = existingSubscriptions.iterator().next();
            subscriptions.remove(subscriptionToRemove);
            log.info(String.join("", "Subscription removed [", subscriptionToRemove.source(), ", ", subscriptionToRemove.target(), ", ", subscriptionToRemove.subject(), "]"));
        } else {
            throw new RuntimeException("This should never happen.  This is a bug.");
        }

        String newSubscriptionDefinitionVersionArn = greengrassHelper.createSubscriptionDefinitionAndVersion(subscriptions);

        GroupVersion newGroupVersion = GroupVersion.builder()
                .subscriptionDefinitionVersionArn(newSubscriptionDefinitionVersionArn)
                .build();

        // Do nothing extra if successful
        createAndWaitForDeployment(greengrassGroupId, newGroupVersion);
    }