Youtube Fullscreen Mode

Automatically switch YouTube screens to 100 height and 100 width screens.

// ==UserScript==
// @name:ko           유튜브 풀스크린
// @name              Youtube Fullscreen Mode
// @name:ru           Youtube Полный режим
// @name:ja           Youtubeフルスクリーンモードの
// @name:zh-CN        优酷全屏模式
// @name:zh-TW        優酷全屏模式

// @description:ko    유튜브 화면을 자동으로 꽉 찬 화면으로 바꿉니다.
// @description       Automatically switch YouTube screens to 100 height and 100 width screens.
// @description:ru    Автоматическое переключение экрана на YouTube на экран высотой 100 и шириной 100.
// @description:ja    ユーチューブ画面を高さ100、広さ100画面に自動転換。
// @description:zh-CN YouTube画面自动转换成100高、100宽的画面。
// @description:zh-TW YouTube畫面自動轉換成100高、100寬的畫面。

// @namespace         https://ndaesik.tistory.com/
// @version           2023.08.23.1003
// @author            ndaesik
// @icon              https://lh3.googleusercontent.com/iLZyxGK7l1343U4E7eAfgKbRWW6qhzCJq-Z92M60JzCMntFyaFF2GUQVRxPhfGcy6qRISLjHv4fX1vtq0TZkZMAzBjM
// @match             *://*.youtube.com/*
// ==/UserScript==

const suggestBoxToDarkCSS = document.createElement('style');
suggestBoxToDarkCSS.innerText = `
[dark] {color-scheme: dark;}`.replaceAll(';','!important;')

const fullscreenVideoCSS = document.createElement('style');
fullscreenVideoCSS.innerText = `
ytd-app:not([guide-persistent-and-visible]) [theater] #player video,
:is(ytd-watch-flexy[theater],ytd-watch-flexy[fullscreen]) #full-bleed-container {
height: 100vh; max-height: 100vh; min-height: 100vh;}`.replaceAll(';','!important;')

const autoHideTopCSS = document.createElement('style');
autoHideTopCSS.innerText = `
#masthead-container.ytd-app:hover, #masthead-container.ytd-app:focus-within {width:100%;}
#masthead-container.ytd-app,
#masthead-container.ytd-app:not(:hover):not(:focus-within) {width:calc(50% - 150px);}
#masthead-container.ytd-app:not(:hover):not(:focus-within) {transition:width 0.4s ease-out 0.4s;}
ytd-app:not([guide-persistent-and-visible]) :is(#masthead-container ytd-masthead, #masthead-container.ytd-app::after) {transform: translateY(-56px); transition: transform .1s .3s ease-out;}
ytd-app:not([guide-persistent-and-visible]) :is(#masthead-container:hover ytd-masthead, #masthead-container:hover.ytd-app::after, #masthead-container:focus-within ytd-masthead) {transform: translateY(0px);}
ytd-app:not([guide-persistent-and-visible]) ytd-page-manager {margin-top: 0;}`.replaceAll(';','!important;')
autoHideTopCSS.className = "autoHideTopCSS";

function isWatchPage() {
    return !(document.URL.indexOf('watch') == -1)
};

function isTheaterMode() {
    let scrollbarWidth = window.innerWidth - document.querySelector('ytd-app').offsetWidth;
    let playerWidth = document.querySelector('#ytd-player')?.offsetWidth;
    let isWidePlayer = scrollbarWidth + playerWidth == window.innerWidth;
    return ( isWatchPage() && isWidePlayer )
};

function alwaysTheaterMode() {
    let clickModeButtonRepeatly = setInterval( _ => {
        if ( isTheaterMode() ) {
            clearInterval( clickModeButtonRepeatly );
        } else {
            document.querySelectorAll('.ytp-size-button')?.forEach( e => e.click());
            clearInterval( clickModeButtonRepeatly );
        }
    }, 100);
    setTimeout( _ => {
        clearInterval( clickModeButtonRepeatly );
    }, 10000);
};

['yt-navigate-finish', 'load', 'unload', 'locationchange'].forEach( e => {
    window.addEventListener( e, _ => {
        isWatchPage() ? document.head.appendChild(autoHideTopCSS) : false;
        document.head.appendChild(suggestBoxToDarkCSS);
        document.head.appendChild(fullscreenVideoCSS);
        alwaysTheaterMode();
        window.scrollTo(0, 0);
    });
});

window.addEventListener('click', _ => {
    setTimeout( _ => {
        if ( !isWatchPage() || !isTheaterMode() ) {
            document.querySelector('.autoHideTopCSS')?.remove()
        } else if ( isTheaterMode() ) {
            document.head.appendChild(autoHideTopCSS)
        }
    }, 100);
});