// ==UserScript==
// @name        WaniKani Review Countdown Timer
// @namespace   ajpazder
// @description Adds a time limit to review questions.
// @version     1.0.0
// @author      Johnathon Pazder
// @copyright   2016+, Johnathon Pazder
// @license     MIT; http://opensource.org/licenses/MIT
// @include     http*://www.wanikani.com/review/session*
// @run-at      document-end
// @grant       none
// @downloadURL none
// ==/UserScript==

// Change this if you want to make things easier (or harder).
var timeLimitSeconds = 10;

onReviewItemChange(function () {
	startCountdown(timeLimitSeconds);
});

function onReviewItemChange(callback) {
	// questionType is always updated, even when switching between 
    // radicals (which only have one question type).
	$.jStorage.listenKeyChange('questionType', callback);
}

var countdown;
function startCountdown(seconds) {
	// This function could potentially be called multiple times on 
    // the same item so, just to be safe, we'll clear any existing 
    // counter interval before we start a new one.
	clearInterval(countdown);
	
    var timeRemaining = seconds * 1000;
	var updateInterval = 100; // ms
	countdown = setInterval(function () {
		if (answerAlreadySubmitted()) {
			clearInterval(countdown);
			return;
		}
		
		var displayTime = (timeRemaining / 1000).toFixed(1);
		updateCountdownDisplay(displayTime);
		
		if (timeRemaining === 0) {
			clearInterval(countdown);
			submitWrongAnswer();
			return;
		}
		
		timeRemaining -= updateInterval;
		
	}, updateInterval);
}

function answerAlreadySubmitted() {
	return $("#user-response").is(":disabled");
}

function submitWrongAnswer() {
	if (isReadingQuestion()) {
		setResponseTo('これをわからない');
	}
	else {
		setResponseTo('I don\'t know this');
	}
	
	submitAnswer();
}

function isReadingQuestion() {
	return $('#question-type').hasClass('reading');
}

function setResponseTo(value) {
	$('#answer-form input').val(value);
}

function submitAnswer() {
	$('#answer-form button').click();
}

function updateCountdownDisplay(time) {
	// If this is only called once per question change, the counter doesn't show
	// for some reason.  There's probably some other JS running that overwrites it.
	if ($('#countdown').length === 0) {
		$('#question-type h1').append(' (<span id="countdown"></span>s)');
	}
	
	$('#countdown').text(time);
}