SC.getDonwloadLinks.js

/********************
Name          : SC.getDonwloadLinks
Version       : 0.1.0
Last-Modified : 13.05.19
Description   : Snippets extracts track's urls from the page and inserts direct download link 
**********************/

console.clear();
// The clientId may be gotten from http request uri
// 		Usage: urlInstance.searchParams.set(`client_id`, clientId)
var clientId = `98bwvJm1CyzjAZCeNbMb7RZKWoS3zvEe`;


// Helpers 
HTMLElement.prototype.$ = HTMLElement.prototype.querySelector
HTMLElement.prototype.$$= HTMLElement.prototype.querySelectorAll
NodeList.prototype.map  = Array.prototype.map;
String.prototype.contains = function(str){ return new RegExp(str).test(this) }


/*
* Makes clipboard (temporary buffer) managment easier
* Usage: new Clipspace().copy('foo') // copies 'foo' string to the clipboard
**/
var Clipspace = class {
      static version = '1.0.0';
      constructor (container) {
        this.container = container || document.body;
        this.id    = 'clipboard-area';
        this.el    =  this.container.querySelector('#'+this.id);
        if (!this.el) {
           this.el =  document.createElement('textarea');
           this.container.appendChild(this.el);
        }

        this.el.style.position  = 'absolute'
        this.el.style.top       = '-9999px';
        this.el.contentEditable = true;
        this.el.id              = this.id;

      }
      copy(text) {
        this.el.value = text
        this.el.select();
        var result = document.execCommand('copy');
        this.el.blur();
        return result
      }
}

/*
*
* @return {Array.<Object>} -- where TrackInstance is following (the item's type's isn't complete):
**/
var SCTracksFromJsonP = async function(){
	const scripts = Array.from(document.body.querySelectorAll(`script`));
	const dataSource = scripts.pop();
	const data = [];
	const wbpckjsp = new Function(`webpackJsonp`,dataSource.textContent.replace(`n(e.id)`,`n(e.data[0])`))
	wbpckjsp(function(_, localDataStore){
		localDataStore[0](null, null, (e) => {
			data.push(e)
		});
	});

	let tracks = data.reduce(function(arr, e){

		if (e.kind === "playlist") {
		   return arr.concat(e.tracks)
		};

		if (e.kind === "track") {
			arr.push(e)
			return arr
		};
		return arr
	}, []);

	// Fetch direct urls to the file sound resources
	// Make sure that argument of the all(...) here is array of promises
	return await Promise.all(tracks.map(async function(track){
		if (track.download_url) {
			return track
		}
		if (!(track.media && track.media.transcodings)) { return track }

		var transcodings = track.media.transcodings.map(async function (trans) {
				trans.url = new URL(trans.url);
				trans.url.searchParams.set(`client_id`, clientId);

			var response = await fetch(trans.url);
				if (!response.ok) { throw new Error(`track fetching transcoding url failed: ${response.status} ${response.statusText }`) }
				if (response.status === 200) { 
					// if fetched successfully then return parsed url 
					var mp3Url = await response.text();
					var urlObj = JSON.parse(mp3Url);
						trans.directUrl = urlObj.url;
				}
			return trans
		});
		track.media.transcodings = await Promise.all(transcodings)		

		return track
	}))
};

// Creates link element
var Link = function({ textDisplay, url, downloadFileName }) {
	console.log('Inserting link!')
	if (!url) { throw new Error('Url required!') }
	var link = document.createElement('a');
	link.href = url;
	link.download = downloadFileName || 'New File';
	link.textContent = textDisplay;
	link.title = 'Song download link';
	link.target = '_blank';
	return link
}


var clipspace = new Clipspace();
// Scraps tracks ulrs from the current page
var  initDownloadFileButton = function (tracks) {

	var track = tracks[0];
	var trans = track.media.transcodings;
		url   = trans[1].directUrl || trans[0].directUrl || trans[2].directUrl || track.download_url;
	var fileName = `${track.user.username} - ${track.title}`;

		// Initialize link
		window._previous_dnload_button && window._previous_dnload_button.remove();
	let link = Link({
			textDisplay: 'Steal song!', 
			url : url,
			downloadFileName: fileName,

		});
		link.addEventListener('contextmenu', function(){
			clipspace.copy(fileName);
		})
		window._previous_dnload_button = link;
		link.className = 'soundActions__purchaseLink sc-truncate sc-buylink sc-buylink-responsive sc-buylink-medium sc-buylink-default';

	let actionpanel = document.body.$('.listenEngagement__actions .sc-button-group') // SoundCloud
	  || document.body.$('.playlist-actions') 
	  || document.body.$('.collectionSection__top') // 
	  || document.body.$('#watch7-user-header') // YouTube
	  if (actionpanel) {
		  actionpanel.appendChild(link);
	  }


};
;(async function () {
	var tracks;
	try {

		tracks = await SCTracksFromJsonP();
		if (tracks.length === 1) {
			initDownloadFileButton(tracks);
		} else {
		};

		console.log(tracks)

	} catch (e) {
		console.log('Total failure!')
		console.error(e)
	}
	console.log(tracks.map(t => t.id).join(','))
	console.log(tracks)
})()
// 	donwloadCb();