Simplify adding EventBus rules to SST

directory_structure.txt

src/functions
├── events
│   ├── emailSubscriptionCreated
│   │   ├── emailSubscriptionCreated.html
│   │   └── handler.ts
│   ├── invitationCreated
│   ├── outbox
│   ├── teamUpdated
│   └── userUpdated
├── utils

EventStack.ts

import {Config, EventBus, EventBusRuleProps, Queue, Stack, StackContext, Table} from "@serverless-stack/resources";

const snakeToCamel = (s: string) => s.replace(/(_\w)/g, k => k[1].toUpperCase());

const addBusinessRule = (stack: Stack, bus: EventBus, dlq: Queue, eventType: string) => {
  const ruleKey = eventType.replace(".", "_");
  const queueName = `${ruleKey}_queue`;
  const handlerLambda = `functions/events/${snakeToCamel(ruleKey)}/handler.main`;

  const rules: Record<string, EventBusRuleProps> = {};
  rules[ruleKey] = {
    pattern: {
      detailType: [eventType]
    },
    targets: {
      function: new Queue(
        stack,
        queueName,
        {
          consumer: {
            function: {
              handler: handlerLambda,
              deadLetterQueueEnabled: true,
              deadLetterQueue: dlq.cdk.queue,
            }
          }
        }
      ),
    }
  };

  bus.addRules(stack, rules);
};

export function EventStack({stack}: StackContext) {
  const bus = new EventBus(stack, "StudiousEventsBus", {});
  const dlq = new Queue(stack, "StudiousEventsDLQ");

  addBusinessRule(stack, bus, dlq, "emailSubscription.created");
  addBusinessRule(stack, bus, dlq, "user.updated");
  addBusinessRule(stack, bus, dlq, "team.updated");
  addBusinessRule(stack, bus, dlq, "invitation.created");

  const EVENT_BUS = new Config.Parameter(
    stack,
    "EVENT_BUS",
    {
      value: bus.eventBusName
    }
  );

  const table = new Table(stack, "StudiousEventsTable",
    {
      fields: {
        sourceKey: "string",
        createdAt: "string"
      },
      primaryIndex: {
        partitionKey: "sourceKey",
        sortKey: "createdAt"
      },
      stream: true,
      consumers: {
        outbox: {
          function: {
            handler: "functions/events/outbox/handler.main",
            permissions: [bus],
            config: [EVENT_BUS],
          },
        }
      }
    }
  );

  const EVENT_OUTBOX_TABLE_NAME = new Config.Parameter(
    stack,
    "EVENT_OUTBOX_TABLE_NAME",
    {
      value: table.tableName
    }
  );

  return {
    EVENT_OUTBOX_TABLE_NAME,
    EVENT_BUS
  };
}