// ==UserScript==
// @description Redirects Youtube URLs to Invidio.us
// @name Invidious Redirect
// @namespace Backend
// @include http://www.youtube.com/*
// @include https://www.youtube.com/*
// @version 1.3
// @run-at document-start
// @grant none
// ==/UserScript==

// prevent youtube content from loading; used to be a simple document.write, but greasemonkey complains
var newDoc = document.implementation.createHTMLDocument ("");
document.replaceChild (document.importNode(newDoc.documentElement, true), document.documentElement);
document.body.innerHTML = '<h1>Redirecting, please wait...</h1>';
document.close();

// pick a random instance with a good health record
fetch("https://api.invidious.io/instances.json?sort_by=type,health").then((response) => {
    response.json().then((instances) => {
        var filtered, domain, idx, a;

        filtered = instances.filter((i) => {
            var monitor = i[1].monitor;
            var type = i[1].type;
          
            if(type != "https") { 
              return false;
            }
          
            if (monitor) {
              return monitor.dailyRatios[0].ratio == "100.00";
            }
          
            // no monitoring data, let it through; might change later to filter in 2 steps and only 
            // let unknown status instances through if no health info has been found
            return true;
        }).map((i) => { return i[0] });

        idx = Math.floor(Math.random() * filtered.length);
        domain = filtered[idx];

        if (/watch\?|channel|embed/.test(window.location.href) && window.location.href.indexOf('list=WL') < 0) {
            a = window.location.href.replace(/www\.youtube\.com/, domain);
            window.location.replace(a);
        }
    });
});