markov.js

module.exports = {

MarkovBot : 
	function (text) {
		this.txt = text.replace(/[,-\/#!$%\^&\*;:{}=\-_`~()]/g,"");
		this.words = this.txt.toLowerCase().split(" ");


		this.triples = function () {
			var w = 0;
			var words = this.words;

			if (this.words.length < 3) {
				return;
			} 
			else {
				return {
					next : function () {
						return w < words.length - 2 ?
								{triple: [words[w], words[w+1], words[w+2]], ind: w++, done: false} :
								{done: true}
					}
				}
			}
		}

		this.database = function () {
			this.cache = {};
			var iter = this.triples();
			var currTrip = iter.next();
			while (!currTrip.done) {
				triple = currTrip.triple;
				w1 = triple[0];
				w2 = triple[1];
				w3 = triple[2];
				if (w1+"_"+w2 in this.cache) {
					this.cache[w1+"_"+w2].push(w3);
				} else {
					this.cache[w1+"_"+w2] = [w3];
				}
				currTrip = iter.next();
			}
			return this.cache;
		}

		this.getRandomInt = function (min, max) {
		    return Math.floor(Math.random() * (max - min + 1)) + min;
		}

		this.textGen = function (maxlen) {
			var genWords = [];
			if (this.words.length <= 1) {
				return "Get on the chat more you fuckwit. Jesus christ. I've had it up to here with your shit. Stupid dicknugget.";
			}
			var seedIndex = this.getRandomInt(0, this.words.length-2);
			var firstWord = this.words[seedIndex];
			var secondWord = this.words[seedIndex+1];
			for (var i = 0; i < Math.min(maxlen, this.words.length); i++) {
				if (firstWord+"_"+secondWord in this.cache) {
					var resList = this.cache[firstWord+"_"+secondWord];
					var resultant = resList[Math.floor(Math.random()*resList.length)];
					genWords.push(resultant);
					tmp = this.cache[firstWord+"_"+secondWord];
					firstWord = secondWord;
					secondWord = tmp[Math.floor(Math.random()*tmp.length)];
				} else {
					seedIndex = this.getRandomInt(0, this.words.length-2);
					firstWord = this.words[seedIndex];
					secondWord = this.words[seedIndex+1];
					var resList = this.cache[firstWord+"_"+secondWord];
					var resultant = resList[Math.floor(Math.random()*resList.length)];
					genWords.push(resultant);
					tmp = this.cache[firstWord+"_"+secondWord];
					firstWord = secondWord;
					secondWord = tmp[Math.floor(Math.random()*tmp.length)];
				}
			}
			// console.log(genWords.join(" ").equals(genWords.toLowerCase().join(" ")));
			//console.log(genWords);
			genWords[0] = genWords[0].charAt(0).toUpperCase() + genWords[0].slice(1);
			genWords[genWords.length - 1] += "."; 
			return genWords.join(" ");

		}

		this.cache = this.database();

		return this;

	}

}