index.js

'use strict';
/**
 * index.js
 * Package main entry point
 */
const fetch = require('node-fetch');
const parseString = require('xml2js').parseString;
const stripNS = require('xml2js').processors.stripPrefix;
const DepartureBoardSoap = require('./soap');



/**
 * This is the main LiveDepartureBoardService class
 * It will allow access to both the user and staff versions of the Live Departureboard Services
 * This access depend on the type of token that you have and which service it is valid for.
 * 
 * For more details on each service see:
 * user service - https://lite.realtime.nationalrail.co.uk/OpenLDBWS/
 * staff service - https://lite.realtime.nationalrail.co.uk/OpenLDBSVWS/
 */
class LiveDepartureBoardService {

  /**
   * Create an instance of the service to allow access to the operations
   * @param {*} accessToken this MUST be a valid registered token
   * @param {*} staffVersion true to access the staff version (token should be a staff token) or false to access the user version. Defaults to the user version.
   */
  constructor(accessToken = "0000-0000-0000-0000", staffVersion = false) {
    this.staffVersion = staffVersion;
    this.refUrl = "https://lite.realtime.nationalrail.co.uk/OpenLDBSVWS/ldbsvref.asmx";
    this.refTargetNamespace = "http://thalesgroup.com/RTTI/2015-05-14/ldbsv_ref/";
    this.baseURL = (staffVersion) ? "https://lite.realtime.nationalrail.co.uk/OpenLDBSVWS/ldbsv12.asmx": "https://lite.realtime.nationalrail.co.uk/OpenLDBWS/ldb11.asmx";
    this.targetNamespace = (staffVersion) ? "http://thalesgroup.com/RTTI/2017-10-01/ldbsv/" : "http://thalesgroup.com/RTTI/2017-10-01/ldb/";
    this.accessToken = accessToken;
  }

  /**
   * Query the LiveDepartureBoardService for the requested data
   * @param {String} method - the LDBWS or LDBSVWS to perform 
   * @param {Object} options  - a JSON object consisting of the key/value pairs for the requested method
   * @param {Bool} useRef - only applies for the staff version of the API and allows access to those calls that use the reference data endpoint - default is false
   * @param {Bool} withAttributes - don't filter the attributes out from the result - default is false
   */
  async call(method, options, useRef = false, withAttributes = false, ) {

    try{
      const soapCall = new DepartureBoardSoap(this.accessToken, (useRef) ? this.refTargetNamespace : this.targetNamespace, method, options).generateCall();
      const response = await fetch((useRef) ? this.refUrl: this.baseURL, {
        method: 'post',
        body: soapCall,
        headers: {'content-type' : "text/xml"}
      });
      const body = await  response.text();
      if(response.status !== 200){
        throw Error(`API Error ${response.status}: ${response.statusText}`)
      }

      if(withAttributes) {
        return await this._parseResultWithAttributes(body, method);      
      }
      return await this._parseResult(body, method);
    
    } catch(error) {
      console.error(error);
      return false;
    }

  }

  // Private method to parse result to JSON
  _parseResult(body, method) {
    return new Promise((resolve, reject) => {
      parseString(body, {
        tagNameProcessors: [stripNS],
        explicitArray : false,
        ignoreAttrs : true
      }, function(err, result){
        if(!err){
          const data = result.Envelope.Body[`${method}Response`];
          resolve(data);
        } else {
          reject(err);
        }
      });        
    });
  }

  // Private method to parse result to JSON and return all data including attributes
  // this version will return the the content text as "_"  and all associated attribute in "$"
  // for more information see https://www.npmjs.com/package/xml2js
  _parseResultWithAttributes(body, method) {
    return new Promise((resolve, reject) => {
      parseString(body, {
        tagNameProcessors: [stripNS],
        explicitArray : false,
        ignoreAttrs : false
      }, function(err, result){
        if(!err){
          const data = result.Envelope.Body[`${method}Response`];
          resolve(data);
        } else {
          reject(err);
        }
      });        
    });
  }

}

module.exports = LiveDepartureBoardService;