// ==UserScript==
// @name        Invidious Instance Changer
// @namespace   InvidiousChanger
// @author      Cyberdevil
// @license     GPL version 3 or any later version::: https://www.gnu.org/licenses/gpl-3.0.html
// @description Menu UI Invidious instances changer
// @homepageURL https://libregit.spks.xyz/heckyel/book/src/branch/master/scripts-greasemonkey
// @include     https://*
// @version     0.0.3
// @grant       GM.setValue
// @grant       GM.getValue
// @grant       GM.xmlhttpRequest
// ==/UserScript==

// Console Style - Debug
let consoleCSS = 'background: #000; color: #00FF00; padding: 0px 7px; border: 1px solid #00FF00; line-height: 16px;';

// BETWEEN HERE and ..
if (GM_getValue('invidious.instances.isUpdating') === true) { return; }

const instancesStr = GM_getValue('invidious.instances');
if (!instancesStr){ // First time fetching instances list.
  updateInstances();
  return;
}

let instances = instancesStr.split(';');
if (instances.indexOf(window.location.host) < 0) { return; }
// .. BETWEEN HERE is run on every request, so keep it minimal.


let lastUpdated = GM_getValue('invidious.instances.lastUpdate');
let diffHours = (Date.now() - lastUpdated) / (1000 * 60 * 60);
//let diffMins = (Date.now() - lastUpdated) / (1000 * 60);

// Update instances
if (diffHours > 24) {
  updateInstances();
}

function updateInstances() {
  GM_setValue('invidious.instances.isUpdating', true);
  GM_xmlhttpRequest ({
    method: 'GET',
    url   : 'https://instances.invidio.us/instances.json',
    onload: function (request) {
      if(request.readyState == 4) {
	if(request.status == 200) {
	  processJson(JSON.parse(request.responseText));
	  saveInstances();
	}
	GM_setValue('invidious.instances.isUpdating', false);
      }
    }
  });
}

function processJson(json) {
  let newList = [];
  for (i in json) {
    if (json[i][1]['type'] != 'https') {
      continue;
    }
    if (!json[i][1]['monitor']) {
      continue;
    }
    if( json[i][1]['monitor']['statusClass'] != 'success') {
      continue;
    }

    newList.push(json[i][1]['uri']);
    console.log(json[i][0]);
  }
  instances = newList;
}

function saveInstances() {
  let str = '';
  for (i in instances) {
    let url = new URL(instances[i]);
    str = str.concat(url.host).concat(";");
    console.log(url.host);
  }
  str = str.substr(0,str.length-1)
  console.log(str);
  GM_setValue('invidious.instances.lastUpdate', Date.now());
  GM_setValue('invidious.instances', str);
}

function getRandomInstance() {
  let newInstances = instances
  newInstances.splice (newInstances.indexOf(parsedUrl.host), 1); // remove current instance.
  let random = Math.floor(Math.random() * newInstances.length)
  return newInstances[Math.floor(Math.random() * newInstances.length)];
}

function generateRandomUrl(args) {
  return generateUrl(getRandomInstance(), args);
}

function generateUrl(host, args) {
  let url = "https://".concat(host.concat("/"));
  url = url.concat(args);
  return url;
}

// --- UI stuff
const parsedUrl = new URL(window.location);
// -- UI methods
function go() {
  // Change instance
  const args = parsedUrl.pathname.substr(1, parsedUrl.pathname.length).concat(parsedUrl.search);
  const url = generateUrl(instanceSelect.item(instanceSelect.selectedIndex).text, args);
  replaceUrl(url);
}

function random() {
  // Change to random instance
  const args = parsedUrl.pathname.substr(1, parsedUrl.pathname.length).concat(parsedUrl.search);
  const url = generateRandomUrl(args);
  replaceUrl(url);
}

function replaceUrl(url) {
  window.location.replace(url);
}

// -- UI elements
// - Main div
let mainDiv = document.createElement("div");
mainDiv.style.width = "200px";
mainDiv.style.position = "fixed";
mainDiv.style.top = 0;

// - Combobox
let instanceSelect = document.createElement("select");
instanceSelect.style.color = "#fff";
instanceSelect.style.background = "#232323";
instanceSelect.style.border = "1px solid #a0a0a0";
for (i in instances) {
  if (instances[i] == parsedUrl.host) {
    // Skip current instance
    continue;
  }
  let option = document.createElement("option");
  option.text = instances[i];
  instanceSelect.add(option);
}

// - Go button
let goButton = document.createElement("input");
goButton.style.color = "#fff";
goButton.style.background = " #232323";
goButton.style.border = "1px solid #a0a0a0";
goButton.setAttribute("type", "button");
goButton.setAttribute("value", "Go");
goButton.addEventListener("click", go, false);

// - Random button
let randomButton = document.createElement("input");
randomButton.style.color = "#fff";
randomButton.style.background = " #232323";
randomButton.style.border = "1px solid #a0a0a0";
randomButton.setAttribute("type", "button");
randomButton.setAttribute("value", "Random");
randomButton.addEventListener("click", random, false);

// - Add stuff
mainDiv.appendChild(instanceSelect);
mainDiv.appendChild(goButton);
mainDiv.appendChild(randomButton);
document.body.appendChild(mainDiv);

function statuscheck(){
  // Console Feedback
  console.log("%cUSERSCRIPT | " + GM_info.script.name + " " + GM_info.script.version + " | successfully initialized", consoleCSS);
}

statuscheck();