// ==UserScript==
// @name         YTB字幕自动翻译－>中文简体
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  translate to Chinese automatically. 自动点击翻译字幕到中文简体
// @author       qwertyuiop6
// @match        https://www.youtube.com/watch*
// @grant        none
// ==/UserScript==

(function(){
    const $=document.querySelector.bind(document);
    const $$=document.querySelectorAll.bind(document);

    let video=$('video');
    let subtitlesButton=$('.ytp-subtitles-button[aria-pressed="false"]')
    let settingsButton=$('.ytp-settings-button');

    function checkAndClick(){

        let sub=findElem($$('[role="menuitem"]'),"字幕");
        if (!sub) return false;
        sub.click();

        let subc = findElem($$('[role="menuitemradio"]'),"中文");
        if (subc) {
            subc.click();
            settingsButton.click();
        } else {
            let autoTrans = findElem($$('[role="menuitemradio"]'),"自动翻译");
            if (!autoTrans) return false;
            autoTrans.click();
            let autoTransC = findElem($$('[role="menuitemradio"]'),"中文（简体）");
            if (!autoTransC) return false;
            autoTransC.click();
        }
        return true;
    }

    function findElem(elems,text) {
        for (let node of elems) {
            if (node.textContent.startsWith(text)) {
                return node
            }
        }
        return null
    }

    function clickToTranslate(){
        if (subtitlesButton) subtitlesButton.click();
        settingsButton.click();
        if(!checkAndClick()) settingsButton.click();
    }

    video.addEventListener('loadstart',clickToTranslate)

    window.addEventListener('load', ()=>{
        video.dispatchEvent(new Event('loadstart'))
    })

})();