use node and twit to look at relationships between twitterers

mutual.js

#!/usr/bin/env node

var Twit = require('twit');
var async = require('async');

var T = new Twit({
  consumer_key: '😈',
  consumer_secret: '😈',
  access_token: '😈',
  access_token_secret: '😈'
});

var args = process.argv;
if (args.length < 4) {
  console.error('Error [mutual]: Bad # of arguments');
  console.log("Usage: `mutual darth '<>' duckthecat [--simple]`");
}
else {
  var simple = !!args[5];

  // "darth '<<' duckthecat" — darth's followers that duck follows
  // "darth '<>' duckthecat" — darth's followers that follow duck
  // "darth '>>' duckthecat" — duck's followers that darth follows
  // "darth '><' duckthecat" — people that darth follows that duck follows
  var user1 = (args[3].charAt(0) === '>' ? 'friends' : 'followers');
  var user2 = (args[3].charAt(1) === '<' ? 'friends' : 'followers');

  async.parallel([
    function(callback){
      var user1opts = { screen_name: args[2], count: 5000 };

      T.get(user1 + '/ids', user1opts, function(err,data,response) {
        if (err) return callback(err);
        if (!simple){
          console.log('remaining ' +
                      user1 + ' requests: ' +
                      response.headers['x-rate-limit-remaining']);
        }
        var user1Ids = data.ids;
        var cursor = data.next_cursor_str;
        async.whilst(
          function(){ return cursor !== '0'; },
          function(callback){
            var getUser1Opts = {
              cursor: cursor,
              screen_name: args[2],
              count: 5000
            };
            T.get(user1 + '/ids', getUser1Opts, function(err, data, response) {
              if (err) return callback(err);

              user1Ids = user1Ids.concat(data.ids);
              cursor = data.next_cursor_str;
              return callback(null);
            });
          },
          function(err) {
            if (err) { return callback(err); }
            return callback(null, user1Ids);
          });
      });
    },
    function(callback){
      var user2opts = { screen_name: args[4], count: 5000 };
      T.get(user2 + '/ids', user2opts, function(err,data,response) {
        if (err) return callback(err);

        if (!simple){
          console.log('remaining ' +
                      user2 + ' requests: ' +
                      response.headers['x-rate-limit-remaining']);
        }
        var user2Ids = data.ids;
        var cursor = data.next_cursor_str;
        async.whilst(
          function(){ return cursor !== '0'; },
          function(callback){
            var getUser2Opts = {
              cursor: cursor,
              screen_name: args[4],
              count: 5000
            };
            T.get(user2 + '/ids', getUser2Opts, function(err,data,response) {
              if (err) return callback(err);

              user2Ids = user2Ids.concat(data.ids);
              cursor = data.next_cursor_str;
              return callback(null);
            });
          },
          function(err) {
            if (err) return callback(err);
            return callback(null, user2Ids);
          });
      });
    }
  ],function(err, results){
    if (err) {
      return console.error(err);
    }
    var all = results[0].concat(results[1]);
    // http://stackoverflow.com/questions/840781/easiest-way-to-find-duplicate-values-in-a-javascript-array
    var sorted = all.sort();
    var i = all.length;
    var mutuals = [];
    while (i--) {
      if (sorted[i + 1] === sorted[i]) {
        mutuals.push(sorted[i]);
      }
    }

    if (!simple){
      var n = mutuals.length;
      var output1 = '@' + args[2];
      output1 += (user1 === 'friends' ?
                  ' is following' : ' is followed by');
      var output2 = '@' + args[4];
      output2 += (user2 === 'friends' ?
                  ' is following' : ' is followed by');
      console.log(output1 + ' ' + n + ' people that ' + output2);
    }

    async.whilst(
      function(){ return mutuals.length; },
      function(callback){
        var lookups = '';
        var lookupLimit = (mutuals.length < 100 ?
                           mutuals.length : 100 );
        while (lookupLimit--) {
          lookups += ',' + mutuals.pop();
        }
        lookups = lookups.slice(1);

        T.post('users/lookup',{ user_id: lookups }, function(err,data,res) {
          if(err) {
            console.error('users/lookup error:');
            return callback(err);
          }
          var k = data.length;
          while (k--) {
            if (simple){
              console.log(data[k].screen_name);
            }
            else {
              console.log(data[k].name +
                          ' (@' + data[k].screen_name + ')');
            }
          }
          return callback(null);
        });
      },
      function(err){
        if (err) return console.error(err);
        return true;
      }
    );
  });
}