// ==UserScript==
// @name        Duolingo - autoStart next Lesson
// @description Automatically starts next lesson when Duolingo loads.
// @version     1.2
// @namespace   minirock
// @match       https://www.duolingo.com/*
// @require  http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js
// @downloadURL none
// ==/UserScript==


var lURL0 = '';
var lURL1 = '';

function last_url() {
    lURL0 = lURL1;
    lURL1 = window.location.href;
}

function next_lesson_start() {
    let lessons = document.querySelectorAll("div[class='QmbDT']");
    if (lessons.length === 0) return;

    for (let i = 0; i < lessons.length; ++i) {
        var lesson = lessons[i].querySelector("div[data-test='level-crown']");
        if (lesson === null) {
            var last_finished = i;
            break;
        }
    }

    // go to next unfinished lesson
    lessons[last_finished].querySelector("div[class='_2albn']").click();

    var status = Array.prototype.filter.call(lessons[last_finished].querySelectorAll("div[class='_2yvEQ']"), function (element) {
        return RegExp('^0% Complete').test(element.textContent);
    });

    // status > 0 == lesson : tips
    if (status.length !== 0) {
        console.log('TIPS');
        lessons[last_finished].querySelectorAll("button")[1].click()
    } else {
        console.log('LESSON');
        lessons[last_finished].querySelector("button[data-test='start-button']").click();
    }
}

function next_lesson_start_from_tips() {
    let tips = document.querySelector("div[class='_2LApJ']");
    if (tips !== null) {
        tips.querySelectorAll("button")[0].click();
    }
}

$(document).ready(function () {
    last_url();
    next_lesson_start();
});

let keyEventListener = function (event) {
    if (event.keyCode === 13) {
        next_lesson_start_from_tips();
        next_lesson_start();
    }
}

document.addEventListener("keyup", keyEventListener);

// start automatically next after 2s
history.pushState = ( f => function pushState(){
    var ret = f.apply(this, arguments);
    window.dispatchEvent(new Event('pushstate'));
    window.dispatchEvent(new Event('locationchange'));
    
    last_url();

    if (lURL0.indexOf('/practice') == -1) setTimeout(next_lesson_start, 2000);
    else setTimeout(function () { window.location.href = '/practice'; }, 2000);

    return ret;
})(history.pushState);

window.addEventListener('popstate',()=>{
    window.dispatchEvent(new Event('locationchange'))
});