// ==UserScript==
// @name         YouTube Focus Mode
// @namespace    http://tampermonkey.net/
// @version      1.0.3
// @description  Put YouTube in focus mode! Hides all unasked for content (recommendations, subscriptions, related, etc.) on the home and watch pages.
// @author       EmeraldSlash
// @match        *://*.youtube.com/*
// @grant        none
// @downloadURL none
// ==/UserScript==

(function() {
    'use strict';

    // css selectors and enable states for various features of this script
    // delete home page feed
    const HOME_PAGE_FEED = ["[page-subtype='home']", true];
    // auto focus search bar when home page feed deleted
    const HOME_PAGE_SEARCH_BAR = ["input#search", true];
    // delete related feed on watch page
    const WATCH_PAGE_RELATED = ["ytd-compact-video-renderer.ytd-watch-next-secondary-results-renderer:not([expansion='collapsed']).ytd-watch-next-secondary-results-renderer", true];
    // delete the related feed's continuations element which is what handles infinite scroll
    const WATCH_PAGE_CONTINUATION = ["#continuations.style-scope.ytd-watch-next-secondary-results-renderer", true];
    // delete the video wall that shows within the player when a video finishes
    const WATCH_PAGE_VIDEOWALL = [".ytp-endscreen-content", true];

    // import library for detecting added elements
    // insertion-query v1.0.3 (2016-01-20)
    // license:MIT
    // Zbyszek Tenerowicz <naugtur@gmail.com> (http://naugtur.pl/)
    var insertionQ=function(){"use strict";function a(a,b){var d,e="insQ_"+g++,f=function(a){(a.animationName===e||a[i]===e)&&(c(a.target)||b(a.target))};d=document.createElement("style"),d.innerHTML="@"+j+"keyframes "+e+" {  from {  outline: 1px solid transparent  } to {  outline: 0px solid transparent }  }\n"+a+" { animation-duration: 0.001s; animation-name: "+e+"; "+j+"animation-duration: 0.001s; "+j+"animation-name: "+e+";  } ",document.head.appendChild(d);var h=setTimeout(function(){document.addEventListener("animationstart",f,!1),document.addEventListener("MSAnimationStart",f,!1),document.addEventListener("webkitAnimationStart",f,!1)},n.timeout);return{destroy:function(){clearTimeout(h),d&&(document.head.removeChild(d),d=null),document.removeEventListener("animationstart",f),document.removeEventListener("MSAnimationStart",f),document.removeEventListener("webkitAnimationStart",f)}}}function b(a){a.QinsQ=!0}function c(a){return n.strictlyNew&&a.QinsQ===!0}function d(a){return c(a.parentNode)?a:d(a.parentNode)}function e(a){for(b(a),a=a.firstChild;a;a=a.nextSibling)void 0!==a&&1===a.nodeType&&e(a)}function f(f,g){var h=[],i=function(){var a;return function(){clearTimeout(a),a=setTimeout(function(){h.forEach(e),g(h),h=[]},10)}}();return a(f,function(a){if(!c(a)){b(a);var e=d(a);h.indexOf(e)<0&&h.push(e),i()}})}var g=100,h=!1,i="animationName",j="",k="Webkit Moz O ms Khtml".split(" "),l="",m=document.createElement("div"),n={strictlyNew:!0,timeout:20};if(m.style.animationName&&(h=!0),h===!1)for(var o=0;o<k.length;o++)if(void 0!==m.style[k[o]+"AnimationName"]){l=k[o],i=l+"AnimationName",j="-"+l.toLowerCase()+"-",h=!0;break}var p=function(b){return h&&b.match(/[^{}]/)?(n.strictlyNew&&e(document.body),{every:function(c){return a(b,c)},summary:function(a){return f(b,a)}}):!1};return p.config=function(a){for(var b in a)a.hasOwnProperty(b)&&(n[b]=a[b])},p}();

    // update function that gets called everytime a new page loads
    // mostly redundant because of insertionQ? only relevant on fresh page loads & for search bar focusing
    function update() {
        // remove homepage feed
        if (HOME_PAGE_FEED[1]) {
            let result = document.querySelectorAll(HOME_PAGE_FEED[0]);
            if (result.length > 0) {
                result[0].remove();

                // focus search bar if homepage feed was removed
                if (HOME_PAGE_SEARCH_BAR[1]) {
                    let search = document.querySelector(HOME_PAGE_SEARCH_BAR[0]);
                    if (search) {
                        search.focus();
                    }
                }
            }
        }

        // remove related section on watch page
        if (WATCH_PAGE_RELATED[1]) {
            let result = document.querySelectorAll(WATCH_PAGE_RELATED[1]);
            if (WATCH_PAGE_CONTINUATION[1]) {
                result = [...result, ...document.querySelectorAll(WATCH_PAGE_CONTINUATION[0])];
            }
            if (WATCH_PAGE_VIDEOWALL[1]) {
                result = [...result, ...document.querySelectorAll(WATCH_PAGE_VIDEOWALL[0])];
            }
            if (result.length > 0) {
                for (let i = 0; i < result.length; i++) {
                    result[i].remove()
                }
            }
        }
    }

    // page change and element added listeners
    document.addEventListener('yt-navigate-finish', update);

    // remove related section on watch page and infinite scroll element
    if (WATCH_PAGE_RELATED[1]) {
        insertionQ(WATCH_PAGE_RELATED[0]).every(function(element) {
            element.remove()
        })
        if (WATCH_PAGE_CONTINUATION[1]) {
            insertionQ(WATCH_PAGE_CONTINUATION[0]).every(function(element) {
                element.remove()
            })
        }
        if (WATCH_PAGE_VIDEOWALL[1]) {
            insertionQ(WATCH_PAGE_VIDEOWALL[0]).every(function(element) {
                element.remove()
            })
        }
    }

    // call initial update
    update()
})();