request-multi-streams/request-multi-streams.js

Make multiple http requests. Receive response progress indicators, pipe streams.

'use strict';

const request = require('request');
const progress = require('request-progress');
const eventEmitter = require('events').EventEmitter;

// defaults
const defaultNumberOfRequests = 1;

/**
 * Creates an iterable Array that is going to assist the async requests
 * @param {Int} n Number of iterations (Array size)
 * @return {Array} Iterable array filled with integers
 */
function createIterable(n) {
  var arr = Array.apply(null, Array(n));
  return arr.map((x, i) => i);
}

/**
 *
 * Get a streams for locations. Build an iterable in the process.
 * @param {Object} args
 *
 * @return {Object} EventEmitter
 */
function get(args) {
  const iterable = createIterable(
    args.numberOfRequests || defaultNumberOfRequests
  );
  const emitter = new eventEmitter();
  for (const i of iterable) {
    let reqNumber = i + 1;
    const stream = progress(request(args.options), args.progressOptions)
      .on('response', response => {
        emitter.emit('response', {
          reqNumber: reqNumber,
          args: args,
          response: response,
          stream: stream,
        });
      })
      .on('progress', progress => {
        emitter.emit('progress', {
          reqNumber: reqNumber,
          args: args,
          progress: progress,
        });
      })
      .on('end', () => {
        emitter.emit('end', { reqNumber: reqNumber, args: args });
      })
      .on('error', error => {
        emitter.emit('error', {
          reqNumber: reqNumber,
          args: args,
          error: error,
        });
      });
  }
  return emitter;
}

/**
 * Dispatches the requests.
 * @param {Array} requests
 * @return {Object} the key is the url for each request/response
 */
function streams(requests) {
  if (!requests || requests.length === 0) {
    return new Error('There is no requests to be made');
  }
  let emitters = {};
  for (const request of requests) {
    emitters[request.options.url] = get(request);
  }
  return emitters;
}

module.exports = {
  streams: streams,
};