// ==UserScript==
// @name         Nico dl
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  下载N站视频 | Download video from nicovideo.jp
// @author       ctrn43062
// @include        *//www.nicovideo.jp/watch/sm*
// @icon         https://www.google.com/s2/favicons?domain=nicovideo.jp
// @grant        none
// @license MIT
// @downloadURL none
// ==/UserScript==

const ITEM_KEY = 'DMCSource.isHLSDisabled';
const DOWNLOAD_SVG = `<svg version="1.1"id="Capa_1"xmlns="http://www.w3.org/2000/svg"xmlns:xlink="http://www.w3.org/1999/xlink"x="0px"y="0px"viewBox="0 0 330 330"style="enable-background:new 0 0 330 330;"xml:space="preserve"><g><path d="M165,0C74.019,0,0,74.018,0,165c0,90.98,74.019,165,165,165s165-74.02,165-165C330,74.018,255.981,0,165,0z M165,300c-74.439,0-135-60.561-135-135S90.561,30,165,30s135,60.561,135,135S239.439,300,165,300z"/><path d="M211.667,127.121l-31.669,31.666V75c0-8.285-6.716-15-15-15c-8.284,0-15,6.715-15,15v83.787l-31.665-31.666c-5.857-5.857-15.355-5.857-21.213,0c-5.858,5.859-5.858,15.355,0,21.213l57.271,57.271c2.929,2.93,6.768,4.395,10.606,4.395c3.838,0,7.678-1.465,10.607-4.393l57.275-57.271c5.857-5.857,5.858-15.355,0.001-21.215C227.021,121.264,217.524,121.264,211.667,127.121z"/><path d="M195,240h-60c-8.284,0-15,6.715-15,15c0,8.283,6.716,15,15,15h60c8.284,0,15-6.717,15-15C210,246.715,203.284,240,195,240z"/></svg>`


function createDownloadButton() {
    const playbackRateButton = document.querySelector('.ActionButton.PlaybackRateButton');
    const wrapper = playbackRateButton.parentElement;
    const downloadButton = document.createElement('button');
    downloadButton.innerHTML = DOWNLOAD_SVG;
    downloadButton.className = 'ActionButton ControllerButton PlayerRepeatOnButton';
    downloadButton.setAttribute('disabled', true);
    downloadButton.setAttribute('data-title', '下载视频');

    wrapper.insertBefore(downloadButton, playbackRateButton);

    return {
        setSrc: function(src) {
            downloadButton.removeAttribute('disabled');
            downloadButton.onclick = function() {
                window.open(src)
            };
        },
        disable: function() {
            downloadButton.setAttribute('disabled', true);
        }
    }
}


(function() {
    'use strict';
    const isHttp = localStorage.getItem(ITEM_KEY);

    if (isHttp === null || isHttp === 'false') {
        localStorage.setItem(ITEM_KEY, 'true');
        location.reload();
    }

    const downloadButton = createDownloadButton();

    const observer = new MutationObserver(mutationsList => {
        for (let mutation of mutationsList) {
            const target = mutation.target;
            if (mutation.attributeName === 'src') {
                if (target.src) {
                    downloadButton.setSrc(target.src);
                } else {
                    downloadButton.disable();
                }
            }
        }
    });

    const video = document.querySelector('#MainVideoPlayer > video');

    observer.observe(video, {
        attributes: true
    });
})();