MQTT trigger script template

/**

 * General Trigger Preprocessor

 * 

 * ⚠️ This function runs BEFORE the main function.

 * 

 * It processes raw trigger data (e.g., MQTT, HTTP, SQS) before passing it to `main()`.

 * Common tasks:

 * - Convert binary payloads to string/JSON

 * - Extract metadata

 * - Filter messages

 * - Add timestamps/context

 * 

 * The returned object determines `main()` parameters:

 * - `{a: 1, b: 2}` → `main(a, b)`

 * - `{payload}` → `main(payload)`

 * 

 * @param wm_trigger - Trigger details (e.g., MQTT, HTTP)

 * @param payload - Raw trigger data (format varies by trigger type)

 * @returns Processed data for `main()`

 */

export async function preprocessor(

  wm_trigger: {

    kind: 'http' | 'email' | 'webhook' | 'websocket' | 'kafka' | 'nats' | 'postgres' | 'sqs' | 'mqtt',

    mqtt?: {

      topic: string,

      retain: boolean,

      pkid: number,

      qos: number,

      v5?: {

        payload_format_indicator?: number,

        topic_alias?: number,

        response_topic?: string,

        correlation_data?: Array<number>,

        user_properties?: Array<[string, string]>,

        subscription_identifiers?: Array<number>,

        content_type?: string

      }

    }

  },

  payload: Array<number>,

) {

  if (wm_trigger.kind === 'mqtt' && wm_trigger.mqtt) {

    const uint8Payload = new Uint8Array(payload);

    const payloadAsString = new TextDecoder().decode(uint8Payload);

    return {

      contentType: wm_trigger.mqtt.v5?.content_type,

      payload: uint8Payload,

      payloadAsString

    };

  }

  return { kind: wm_trigger.kind };

}

/**

 * Main Function - Handles processed trigger events

 * 

 * ⚠️ Called AFTER `preprocessor()`, with its return values.

 * 

 * @param payload - Raw binary payload

 * @param payloadAsString - Decoded string payload

 * @param contentType - MQTT v5 content type (if available)

 */

export async function main(payload: Uint8Array, payloadAsString: string, contentType?: string) {

}