main.js

// Import built-in Node.js package path.
const path = require('path');

/**
 * Import the ServiceNowConnector class from local Node.js module connector.js
 *   and assign it to constant ServiceNowConnector.
 * When importing local modules, IAP requires an absolute file reference.
 * Built-in module path's join method constructs the absolute filename.
 */
const ServiceNowConnector = require(path.join(__dirname, '/connector.js'));

/**
 * Import built-in Node.js package events' EventEmitter class and
 * assign it to constant EventEmitter. We will create a child class
 * from this class.
 */
const EventEmitter = require('events').EventEmitter;

/**
 * The ServiceNowAdapter class.
 *
 * @summary ServiceNow Change Request Adapter
 * @description This class contains IAP adapter properties and methods that IAP
 *   brokers and products can execute. This class inherits the EventEmitter
 *   class.
 */
class ServiceNowAdapter extends EventEmitter {

  /**
   * Here we document the ServiceNowAdapter class' callback. It must follow IAP's
   *   data-first convention.
   * @callback ServiceNowAdapter~requestCallback
   * @param {(object|string)} responseData - The entire REST API response.
   * @param {error} [errorMessage] - An error thrown by REST API call.
   */

  /**
   * Here we document the adapter properties.
   * @typedef {object} ServiceNowAdapter~adapterProperties - Adapter
   *   instance's properties object.
   * @property {string} url - ServiceNow instance URL.
   * @property {object} auth - ServiceNow instance credentials.
   * @property {string} auth.username - Login username.
   * @property {string} auth.password - Login password.
   * @property {string} serviceNowTable - The change request table name.
   */

  /**
   * @memberof ServiceNowAdapter
   * @constructs
   *
   * @description Instantiates a new instance of the Itential ServiceNow Adapter.
   * @param {string} id - Adapter instance's ID.
   * @param {ServiceNowAdapter~adapterProperties} adapterProperties - Adapter instance's properties object.
   */
  constructor(id, adapterProperties) {
    // Call super or parent class' constructor.
    super();
    // Copy arguments' values to object properties.
    this.id = id;
    this.props = adapterProperties;
    // Instantiate an object from the connector.js module and assign it to an object property.
    this.connector = new ServiceNowConnector({
      url: this.props.url,
      username: this.props.auth.username,
      password: this.props.auth.password,
      serviceNowTable: this.props.serviceNowTable
    });
  }

  /**
   * @memberof ServiceNowAdapter
   * @method connect
   * @summary Connect to ServiceNow
   * @description Complete a single healthcheck and emit ONLINE or OFFLINE.
   *   IAP calls this method after instantiating an object from the class.
   *   There is no need for parameters because all connection details
   *   were passed to the object's constructor and assigned to object property this.props.
   */
  connect() {
    // As a best practice, Itential recommends isolating the health check action
    // in its own method.
    this.healthcheck();
  }

  /**
  * @memberof ServiceNowAdapter
  * @method healthcheck
  * @summary Check ServiceNow Health
  * @description Verifies external system is available and healthy.
  *   Calls method emitOnline if external system is available.
  *
  * @param {ServiceNowAdapter~requestCallback} [callback] - The optional callback
  *   that handles the response.
  */
  healthcheck(callback) {

  let callbackData = null;
  let callbackError = null;

  this.getRecord((result, error) => {
        /**
        * For this lab, complete the if else conditional
        * statements that check if an error exists
        * or the instance was hibernating. You must write
        * the blocks for each branch.
        */
    if (error) {
        /**
        * Write this block.
        * If an error was returned, we need to emit OFFLINE.
        * Log the returned error using IAP's global log object
        * at an error severity. In the log message, record
        * this.id so an administrator will know which ServiceNow
        * adapter instance wrote the log message in case more
        * than one instance is configured.
        * If an optional IAP callback function was passed to
        * healthcheck(), execute it passing the error seen as an argument
        * for the callback's errorMessage parameter.
        */
        this.emitOffline();
        log.error('{this.id} : offline');
        callbackData = error;
    } else {
        /**
        * Write this block.
        * If no runtime problems were detected, emit ONLINE.
        * Log an appropriate message using IAP's global log object
        * at a debug severity.
        * If an optional IAP callback function was passed to
        * healthcheck(), execute it passing this function's result
        * parameter as an argument for the callback function's
        * responseData parameter.
        */
        this.emitOnline();
        log.debug('{this.id} : online');
        callbackData = result;
      }
    });
  }

  /**
   * @memberof ServiceNowAdapter
   * @method emitOffline
   * @summary Emit OFFLINE
   * @description Emits an OFFLINE event to IAP indicating the external
   *   system is not available.
   */
  emitOffline() {
    this.emitStatus('OFFLINE');
    log.warn('ServiceNow: Instance is unavailable.');
  }

  /**
   * @memberof ServiceNowAdapter
   * @method emitOnline
   * @summary Emit ONLINE
   * @description Emits an ONLINE event to IAP indicating external
   *   system is available.
   */
  emitOnline() {
    this.emitStatus('ONLINE');
    log.info('ServiceNow: Instance is available.');
  }

  /**
   * @memberof ServiceNowAdapter
   * @method emitStatus
   * @summary Emit an Event
   * @description Calls inherited emit method. IAP requires the event
   *   and an object identifying the adapter instance.
   *
   * @param {string} status - The event to emit.
   */
  emitStatus(status) {
    this.emit(status, { id: this.id });
  }

  
  getRecord(callback) {
    /**
     * Write the body for this function.
     * The function is a wrapper for this.connector's get() method.
     * Note how the object was instantiated in the constructor().
     * get() takes a callback function.
     */
     this.connector.get((data, error) => { 
         if (error) {
             console.error(`\nGET error:\n${JSON.stringify(error)}`);
             callback([], error);
         }
         if (data) {
             if (data.body) {
                 let result = JSON.parse(data.body);
                 let tickets = [];
                 console.debug(`\nGET request:\n${JSON.stringify(data.body)}`);
                 result.result.forEach((change) => {
                     let newChange = {
                         change_ticket_number: change.number,
                         change_ticket_key: change.sys_id,
                         active: change.active,
                         priority: change.priority,
                         description: change.description,
                         work_start: change.work_start,
                         work_end: change.work_end
                     };
                     tickets.push(newChange);
                 })
                 callback(tickets);
             }
         }
     })
  }

  /**
   * @memberof ServiceNowAdapter
   * @method postRecord
   * @summary Create ServiceNow Record
   * @description Creates a record in ServiceNow.
   *
   * @param {ServiceNowAdapter~requestCallback} callback - The callback that
   *   handles the response.
   */
  postRecord(callback) {
    /**
     * Write the body for this function.
     * The function is a wrapper for this.connector's post() method.
     * Note how the object was instantiated in the constructor().
     * post() takes a callback function.
     */
     this.connector.post({}, (data, error) => {
         if (error) {
             console.error(`\nPOST request:\n${JSON.stringify(error)}`);
             callback(data, error);
         }
         if (data) {
             if (data.body) {
                 console.debug(`\nPOST request:\n${JSON.stringify(data.body
                 )}`);
                 const result = JSON.parse(data.body);
                 const ticket = result.result;
                 const newTicket = { change_ticket_number: ticket.number,
                    change_ticket_key: ticket.sys_id,
                    active: ticket.active,
                    priority: ticket.priority,
                    description: ticket.description,
                    work_start: ticket.work_start,
                    work_end: ticket.work_end
                 };
                 callback(newTicket, error);
             }
         }
     })
  }

}

module.exports = ServiceNowAdapter;