// ==UserScript==
// @name         Universal encrypted video downloader
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Bypass the encrypted video download protection via js hook
// @author       Evan
// @match        https://www.bilibili.com/video/*
// @match        https://www.bilibili.com/bangumi/play/*
// @match        https://www.youtube.com/watch*
// @match        https://www.huya.com/*
// @match        https://live.bilibili.com/*
// @grant        none
// ==/UserScript==

evanEnv = new Object();
evanEnv.mediaSources = [];
evanEnv.enableAutoForward = true;
evanEnv.enableAutoDownload = true;

(function () {
    evanEnv.videos = document.getElementsByTagName('video');
    evanEnv.buildArrayBuffer = function (bufferList) {
        var totalLength = 0;
        for (var i = 0; i < bufferList.length; i++) {
            totalLength += bufferList[i].byteLength;
        }
        var tmp = new Uint8Array(totalLength);
        var lastLength = 0;
        for (var ix = 0; ix < bufferList.length; ix++) {
            tmp.set(new Uint8Array(bufferList[ix]), lastLength);
            lastLength += bufferList[ix].byteLength;
        }
        return tmp.buffer;
    };
    evanEnv.downloadRawData = function (bufferList, fileName = 'out.mp4') {
        var buff = evanEnv.buildArrayBuffer(bufferList);
        let url = window.URL.createObjectURL(new Blob([buff], {type: "arraybuffer"}))
        const link = document.createElement('a');
        link.style.display = 'none';
        link.href = url;
        link.setAttribute('download', fileName);
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
    };

    evanEnv.download = function () {
        for (var i = 0; i < evanEnv.mediaSources.length; i++) {
            var currentItem = evanEnv.mediaSources[i];
            if (currentItem.downloaded == undefined || currentItem.downloaded == false) {
                for (var x = 0; x < currentItem.rawSources.length; x++) {
                    evanEnv.downloadRawData(currentItem.rawSources[x], 'mediasource_' + i + '_' + x + '.mp4');
                }
            }
            currentItem.downloaded = true;
        }
    };
    evanEnv.downloadMediaSource = function (mediaSource) {
        for (var x = 0; x < mediaSource.rawSources.length; x++) {
            evanEnv.downloadRawData(mediaSource.rawSources[x], 'mediasource_' + x + '.mp4');
            mediaSource.downloaded = true;
        }
    };

    var proxy_addSourceBuffer = MediaSource.prototype.addSourceBuffer;
    MediaSource.prototype.addSourceBuffer = function (mimeType) {
        var mediaSourceThis = this;

        evanEnv.mediaSources.push(this);
        this.lastPos = 0;
        if (evanEnv.enableAutoDownload) {
            this.onsourceended = function () {
                evanEnv.download();
            };
            this.onsourceclose = function () {
                evanEnv.downloadMediaSource(this);
            };
        }


        var retSourceBuffer = proxy_addSourceBuffer.apply(this, [].slice.call(arguments));
        if (this.rawSources == undefined) {
            this.rawSources = [];
        }
        var buffList = [];
        this.rawSources.push(buffList);
        retSourceBuffer.rawData = buffList;
        if (evanEnv.enableAutoForward) {
            retSourceBuffer.onupdate = function () {
                if (this.buffered != this.buffered.length > 0) {
                    var endPos = this.buffered.end(0);
                    if (endPos > 5 && endPos - mediaSourceThis.lastPos > 25) {
                        evanEnv.videos[0].currentTime = endPos - 3;
                        mediaSourceThis.lastPos = evanEnv.videos[0].currentTime;
                    }
                }
            };
        }
        return retSourceBuffer;
    };
    var proxy_appendBuffer = SourceBuffer.prototype.appendBuffer;
    SourceBuffer.prototype.appendBuffer = function (buf) {
        this.rawData.push(buf);
        return proxy_appendBuffer.apply(this, [].slice.call(arguments));
    };
})();