mastermind.js

var app;
function main() {
	app = new Vue({
		el: '#app',
		data: {
			dictionary: [],
			words: [],
			guess: "?????",
			n_best: 0,
			history: [],
			score: { exact: 0, misplaced: 0 },
			won: false,
		},
		computed: {
			best_score: function() { return this.words.length ? this.words[0].score : 0; },
			dictionary_loaded: function() { return this.dictionary.length > 0; },
			welcome: function() { return this.words.length == 0; },
		},
		watch: {
			'score.exact': watch('exact'),
			'score.misplaced': watch('misplaced'),
		},
		methods: {
			start: start,
			keepGuessing: function() { this.n_best = 2; },
			win: win,
		}
	});

	var xhr = new XMLHttpRequest();
	xhr.open('GET', 'words.json', true);
	xhr.onload = function (e) {
		if (this.status == 200) {
			app.dictionary = JSON.parse(this.response);
		}
	}
	xhr.send();
}

function watch(type) {
	return function(to, from) {
		document.querySelector(`label[for='${type}-${from}']`).classList.toggle('is-checked', false);
		document.querySelector(`label[for='${type}-${to}']`).classList.toggle('is-checked', true);
	};
}

function start() {
	app.score.exact = 0;
	app.score.misplaced = 0;
	app.words = app.dictionary.map(word => { return { word: word, score: 0 }; });
	app.history = [];
	app.won = false;
	makeGuess();
}

function makeGuess() {
	const s0 = app.words[0].score;
	bests = app.words.filter(w => w.score == s0);
	app.n_best = bests.length;
	if (bests.length > 1) { // filter last guessed word to avoid repetitions
		bests = bests.filter(w => w.word != app.guess);
	}
	app.guess = bests[Math.floor(Math.random() * bests.length)].word;
}

function submit() {
	evaluate(app.guess, app.score.exact, app.score.misplaced);
	if (!app.won) {
		app.score.exact = 0;
		app.score.misplaced = 0;
		makeGuess();
	}
}

function evaluate(guess, exact, misplaced) {
	app.history.push({ guess:guess, exact:exact, misplaced:misplaced });
	if (exact == 5) {
		win();
	} else {
		app.words = app.words.filter(w => w.word != guess);
		for (var w of app.words) {
			const s = score(guess, w.word);
			w.score += (Math.abs(exact - s.exact) + Math.abs(misplaced - s.misplaced) +
				Math.abs(exact + misplaced - s.exact - s.misplaced)) / 2;
		}
		app.words.sort((a, b) => a.score - b.score);
	}
}

function score(w1, w2) {
	var e = 0;
	var m = 0;
	var r1 = [];
	var r2 = [];

	// count exact matches
	for (var i = 0; i < w1.length; i++) {
		if (w1[i] == w2[i]) {
			e++;
		} else {
			r1.push(w1[i]);
			r2.push(w2[i]);
		}
	}

	// count misplaced matches
	r1.sort();
	r2.sort();
	var i = 0;
	var j = 0;
	while (i < r1.length && j < r2.length) {
		if (r1[i] == r2[j]) {
			m++;
			i++;
			j++;
		} else if (r1[i] < r2[j]) {
			i++;
		} else {
			j++;
		}
	}
	return { exact: e, misplaced: m };
}

function win() {
	app.won = true;
	checkHistory();
}

function checkHistory() {
	for (var i = 0; i < app.history.length; i++) {
		const h = app.history[i];
		var s = score(app.guess, h.guess);
		for (var t of ['exact', 'misplaced']) {
			if (s[t] != h[t]) {
				s['bad-' + t] = h[t];
			}
		}
		if (Object.keys(s).length > 2) {
			s.guess = h.guess;
			s.bad = true;
			Vue.set(app.history, i, s);
		}
	}
}

function replay(log) {
	start();
	// convert log if it's a string
	if (typeof("log") == "string") {
		var tokens = log.split(/\s+/);
		var guesses = [];
		while (tokens.length) {
			guesses.push(tokens.splice(0, 3));
		}
		log = [];
		for (g of guesses) {
			log.push({
				guess: g[0],
				exact: parseInt(g[1]) || 0,
				misplaced: parseInt(g[2]) || 0,
			});
		}
	}
	// replay log
	while (log.length) {
		const entry = log.shift();
		evaluate(entry.guess, entry.exact, entry.misplaced);
	}
	makeGuess();
}

// execute main
main();