Download-button generating userscript for CR@TU-Delft

crtud-downloader.user.js

// ==UserScript==
// @name         TUDelft collegerama downloader
// @namespace    http://your.homepage/
// @version      0.1
// @description  enter something useful
// @author       You
// @match        https://collegerama.tudelft.nl/Mediasite/Play/*
// @require      http://code.jquery.com/jquery-latest.js
// @grant        none
// ==/UserScript==

$(document).ready(function() {    
    main(generateMessage(document.location.href));
});

function make_button(href){
  $('body').append('<a href="' + href + '"><input type="button" value="Download as WMV!" id="CP"></a>');
  $("#CP").css("position", "fixed").css("top", 0).css("left", 0);
}

// Helper functions to generate the correct POST-api link
var extractResourceId, extractQueryString;
(function(){
    var parser = document.createElement('a');
    extractResourceId = function(url){
        parser.href = url;
        ph = parser.pathname.split('/');
        return ph.slice(-1)[0];
    }

    extractQueryString = function(url){
        parser.href = url;
        return parser.search;
    }
})();

// Generate the correct PlayerOptions request message
function generateMessage(url){
    rid = extractResourceId(url);
    qs = extractQueryString(url);
    var msg = {
        getPlayerOptionsRequest: {
            ResourceId: rid,
            QueryString: qs
        }
    };
    return JSON.stringify(msg);
}

// Extract the video location from the PlayerOptions Response
function parseRequest(json_data){
	var vid_location = json_data.d.Presentation.Streams[0].VideoUrls[1].Location;
    return vid_location;
}

// Place request and place button with parsed response
function main (message) {
    var client = new XMLHttpRequest();
    client.open("POST", "https://collegerama.tudelft.nl/Mediasite/PlayerService/PlayerService.svc/json/GetPlayerOptions");
    client.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
    client.onload = function () {
        var response = JSON.parse(this.responseText);
        var vid_location = parseRequest(response);
        make_button(vid_location);
    };
    client.send(message);
}