private _getEventTopicFromMessage()

in device/transport/mqtt/src/mqtt.ts [969:1019]
27 lines of code
18 McCabe index (conditional complexity)

  private _getEventTopicFromMessage(message: Message, extraSystemProperties?: { [key: string]: string }): string {

    const DT_SUBJECT = 'dt-subject';
    /*Codes_SRS_NODE_COMMON_MQTT_BASE_16_008: [The `sendEvent` method shall use a topic formatted using the following convention: `devices/<deviceId>/messages/events/`.]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_036: [ If a `moduleId` was not specified in the transport connection, the `sendOutputEvent` method shall use a topic formatted using the following convention: `devices/<deviceId>/messages/events/`. ]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_037: [ If a `moduleId` was specified in the transport connection, the `sendOutputEvent` method shall use a topic formatted using the following convention: `devices/<deviceId>/<moduleId>/messages/events/`. ]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_034: [ If the connection string specifies a `moduleId` value, the `sendEvent` method shall use a topic formatted using the following convention: `devices/<deviceId>/<moduleId>/messages/events/` ]*/
    let topic = this._topicTelemetryPublish;
    const systemProperties: { [key: string]: string } = extraSystemProperties || {};

    /*Codes_SRS_NODE_COMMON_MQTT_BASE_16_011: [The `sendEvent` method shall serialize the `messageId` property of the message as a key-value pair on the topic with the key `$.mid`.]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_040: [ The `sendOutputEvent` method shall serialize the `messageId` property of the message as a key-value pair on the topic with the key `$.mid`. ]*/
    if (message.messageId) systemProperties['$.mid'] = message.messageId;
    /*Codes_SRS_NODE_COMMON_MQTT_BASE_16_012: [The `sendEvent` method shall serialize the `correlationId` property of the message as a key-value pair on the topic with the key `$.cid`.]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_041: [ The `sendOutputEvent` method shall serialize the `correlationId` property of the message as a key-value pair on the topic with the key `$.cid`. ]*/
    if (message.correlationId) systemProperties['$.cid'] = message.correlationId;
    /*Codes_SRS_NODE_COMMON_MQTT_BASE_16_013: [The `sendEvent` method shall serialize the `userId` property of the message as a key-value pair on the topic with the key `$.uid`.]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_042: [ The `sendOutputEvent` method shall serialize the `userId` property of the message as a key-value pair on the topic with the key `$.uid`. ]*/
    if (message.userId) systemProperties['$.uid'] = message.userId;
    /*Codes_SRS_NODE_COMMON_MQTT_BASE_16_014: [The `sendEvent` method shall serialize the `to` property of the message as a key-value pair on the topic with the key `$.to`.]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_043: [ The `sendOutputEvent` method shall serialize the `to` property of the message as a key-value pair on the topic with the key `$.to`. ]*/
    if (message.to) systemProperties['$.to'] = message.to;
    /*Codes_SRS_NODE_COMMON_MQTT_BASE_16_015: [The `sendEvent` method shall serialize the `expiryTimeUtc` property of the message as a key-value pair on the topic with the key `$.exp`.]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_044: [ The `sendOutputEvent` method shall serialize the `expiryTimeUtc` property of the message as a key-value pair on the topic with the key `$.exp`. ]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_16_084: [The `sendEvent` method shall serialize the `contentType` property of the message as a key-value pair on the topic with the key `$.ct`.]*/
    if (message.contentType) systemProperties['$.ct'] = <string>message.contentType;
    /*Codes_SRS_NODE_DEVICE_MQTT_16_083: [The `sendEvent` method shall serialize the `contentEncoding` property of the message as a key-value pair on the topic with the key `$.ce`.]*/
    if (message.contentEncoding) systemProperties['$.ce'] = <string>message.contentEncoding;
    if (message.interfaceId) systemProperties['$.ifid'] = message.interfaceId;

    if (message.expiryTimeUtc) {
      const expiryString = message.expiryTimeUtc instanceof Date ? message.expiryTimeUtc.toISOString() : message.expiryTimeUtc;
      systemProperties['$.exp'] = (expiryString || undefined);
    }

    const sysPropString = querystring.stringify(systemProperties);
    topic += sysPropString;

    /*Codes_SRS_NODE_COMMON_MQTT_BASE_16_009: [If the message has properties, the property keys and values shall be uri-encoded, then serialized and appended at the end of the topic with the following convention: `<key>=<value>&<key2>=<value2>&<key3>=<value3>(...)`.]*/
    /*Codes_SRS_NODE_DEVICE_MQTT_18_038: [ If the outputEvent message has properties, the property keys and values shall be uri-encoded, then serialized and appended at the end of the topic with the following convention: `<key>=<value>&<key2>=<value2>&<key3>=<value3>(...)`. ]*/
    if (message.properties && message.properties.count() > 0) {
      for (let i = 0; i < message.properties.count(); i++) {
        if (i > 0 || sysPropString) topic += '&';
        const keyName = message.properties.propertyList[i].key;
        topic += encodeURIComponent(((keyName === DT_SUBJECT) ? ('$.sub') : (keyName)))
                   + '=' + encodeURIComponent(message.properties.propertyList[i].value);
      }
    }

    return topic;
  }