twitter-stream-channels/lib/MockDataRetriever.js

Manage multiple filters on the same Twitter stream

/**
 * @module twitter-stream-channels
 */

var twit = require('twit');
var fs = require('fs');

/**
 * This contructor is private, you should access it via {{#crossLink "TwitterStreamChannels/launchMockDataRetriever"}}TwitterStreamChannels.launchMockDataRetriever(credentials,options){{/crossLink}}
 * 
 * This will allow you to create your own json data mocks
 * 
 * Keep in mind this class is not designed to retrieve lots of tweets on long duration.
 * 
 * It was only designed to ease the creation of your data mocks to use after with `TwitterStreamChannels.getMockedClass()`
 * 
 * More infos in the [README on the github repo](https://github.com/topheman/twitter-stream-channels#api)
 * @class MockDataRetriever
 * @constructor
 * @private
 * @param {Object} credentials
 * @param {String} credentials.consumer_key
 * @param {String} credentials.consumer_secret
 * @param {String} credentials.access_token
 * @param {String} credentials.access_token_secret
 * @param {Object} options
 * @param {Array} options.track array of keywords to track
 * @param {String} options.output filepath of the json file where to put the retrieved tweets
 * @param {String} [options.maxNumber=200] maximum number of tweets that will be retrieved (default 200 / max 500)
 * @param {String} [options.timeout=100000] maximum delay after the stream will close whatever number of tweets are captured (default 100 000ms)
 * @return {MockDataRetriever}
 */
var MockDataRetriever = function(credentials,options){
  if(typeof options === 'undefined'){
    throw new Error("options parameter is mandatory");
  }
  if(typeof options.track === 'undefined'){
    throw new Error("options.track parameter is mandatory");
  }
  if(options.track instanceof Array !== true){
    throw new Error("options.track parameter must be an array of keywords");
  }
  if(options.output === 'undefined'){
    throw new Error("options.output parameter is mandatory");
  }
  if(typeof options.maxNumber === 'undefined'){
    options.maxNumber = 200;
  }
  if(options.maxNumber > 500){
    options.maxNumber = 500;
  }
  if(typeof options.timeout === 'undefined' || options.timeout > 100000){
    options.timeout = 100000;
  }
  
  var date = new Date();
  
  var client = new twit(credentials);
  
  var tweets = [];
  
  var stream = client.stream('statuses/filter', {track: options.track});
  
  var onEnd = function() {
    stream.stop();
    console.log('');
    console.log('> stopped stream after '+( (new Date()).getTime() - date.getTime() )+'ms - '+tweets.length+' tweets retrieved');
    if(tweets.length > 0){
    tweets = JSON.stringify(tweets);
      fs.writeFile(options.output,tweets,function(err,data){
        console.log('> writing retrieved tweets into file : '+options.output);
        if(err){
          console.log('> ! an error occured while writing tweets to file');
        }
        process.exit();
      });
    }
    else{
      console.log('> ! no tweets retrieved, not writing into file : '+options.output);
      process.exit();
    }
  };
  
  stream.on('connect', function() {
    console.log('> connecting to twitter');
  });
  
  stream.on('connected', function() {
    console.log('> connected to twitter - will disconnect in '+options.timeout+'ms or when '+options.maxNumber+' tweets are retrieved');
  });

  stream.on('disconnect', function() {
    console.log('> disconnected from twitter - please retry');
  });
  
  stream.on('tweet', function(tweet) {
    tweets.push(tweet);
    process.stdout.clearLine();  // clear current text
    process.stdout.cursorTo(0);  // move cursor to beginning of line
    process.stdout.write(tweets.length+' tweets retrieved');  // write text
    if(tweets.length >= options.maxNumber){
      onEnd();
    }
  });

  setTimeout(function() {
    onEnd();
  }, options.timeout);
  
};

module.exports = MockDataRetriever;