Implementation of @FeelBetterBot

feelbetter.js

var Twit = require("twit");
var config = require('./oauthconfig'); 

console.log("config:");
console.log(config);

var T = new Twit({
    consumer_key:  config.consumer_key,
    consumer_secret: config.consumer_secret,
    access_token: config.access_token,
    access_token_secret: config.access_token_secret
});

var cb = function(err, reply) {
    if(err){
  console.log(err);
    }
}

/** Actual message logic **/
// TODO : think of more things to put here, possibly balance out all the "Feel better!"
var feelBetter = "Feel better!";
var worthwhile = "You are a valuable, worthwhile human being!";
var mmap = { "i need a hug" : "*hug*",
	         "i hate myself" : "You deserve to love yourself!",
	         "makes me feel worthless" : worthwhile,	     
	         "i'm worthless" : worthwhile,
	         "i'm so worthless" : worthwhile,
	         "i feel worthless" : worthwhile,	     
	         "i feel like crap" : feelBetter,
	         "i feel like shit" : feelBetter,
	         "i feel crappy" : feelBetter,
	         "i feel shitty" : feelBetter,
	         "i feel terrible" : feelBetter,
	         "i feel horrible" : feelBetter };
	     
function streamFilterTrack() {
    var trackparts = [];
    for(var key in mmap){
        trackparts.push(key);
    }
    return trackparts.join(",");
}

function millis() {
  return (new Date()).valueOf();
}

var minTimeNextTweet = millis();
var mean = 45 * 60 * 1000; // 45 minutes in millis 

function gammaDraw(shape, scale){
    // parameterized such that shape * scale = mean
    // shape must be an integer ( TODO : allow shape to be double > 0)
    var x = 0;
    // sum k draws from gamma(1,1) = exp(1)
    for(var i=0;i<shape;i++){
        x = x - Math.log(Math.random());
    }
    // scale to beta
    return scale * x;
}

function waitTime() {
    var shape = 15; // peaky curve, not like an exponential
    var minWait = 5 * 60 * 1000; // always wait at least 5 minutes
    return minWait + gammaDraw(shape, (mean - minWait)/ shape);
}

var isGood = function(tweet) {
    return ( // should not be retweet
	     ! tweet.retweeted_status &&     
	     // should not be directed at other specific users
	     ! tweet.entities.user_mentions.length > 0);	    	    
}

var maybeResponse = function(tweettext) {
    var lower = tweettext.toLowerCase();
    for(var key in mmap) {
	// if our phrase is in text, return associated response
	if(lower.indexOf(key) >= 0) {
	    return mmap[key];
	}
    }
    return false;
}


function log(prefix){
    return function(msg){
        console.log(prefix);
    };
}


var stream;

function setupStream(){
    stream = T.stream("statuses/filter", {track : streamFilterTrack()});
    stream.on('warning', log("warning"));
    stream.on('reconnect', log("reconnect"));
    stream.on('disconnect', function(msg){
        stream = setupStream();
        stream.start();
    });
    stream.on("tweet", function (tweet) {
        if( isGood(tweet) ) {
	    var response = maybeResponse(tweet.text);
	    var now = millis();
	    if( response && (now > minTimeNextTweet)) {
	        var wait = waitTime();
	        console.log( "next tweet in " + wait / (60 * 1000) + " minutes");
	        minTimeNextTweet = millis() + wait;
	    
	        var replyToId = tweet.id_str;
	        var userName = tweet.user.screen_name;
	        var reply = { status : "@"+ userName+ " "+response,
			      in_reply_to_status_id : replyToId};
	        console.log(reply);
	        T.post("statuses/update", reply, cb);
	    }
        }
    });
    return stream;
}

stream = setupStream();