CyTube Retard Filter

// @name         CyTube Retard Filter
// @namespace    http://neet.horse/
// @version      0.3.0
// @description  Filter fucking retarded chat messages (AKA messages I personally don't like) from CyTube
// @author       Floorb
// @match        https://cytu.be/r/mlpanniversary
// @icon         https://www.google.com/s2/favicons?sz=64&domain=cytu.be
// @grant        none
// ==/UserScript==

// Trying to make scripts that fuck with global functions like this is fucking annoying because of Greasemonkey's retarded
// sandboxing that you can just get around by injecting a <script> node anyways.
(function() {
  unsafeWindow.backupAddChatMessage = null;

  var backupAddChatMessage = unsafeWindow.addChatMessage;
  // If a message contains any of these strings, bypass filtering on it
  var whitelist = ['floorb'];
  // If a message contains any of these strings, kill it.
  var blacklist = ['i hate the antifim', 'haber', 'remove creatures', 'i hate the anti fim', ':writers.room:', ':moonman:', 'not canon', 'i hate this episode'];
  // If a message matches any of these regexes, kill it.
  var niggeregexes = [/:i.think.ponyville.sucks: [0-9]+ :i.think.ponyville.sucks:/];

  // Counter of number of messages we killed.
  var killedMessages = 0;

  // Moving average stuff for stats.
  var avgWindow = 30 * 1000;
  var alpha = 2 / (31); // Smoothing factor for 30-second window
  var filteredMessages = [];
  var ema = 0;

  function messagesFilteredLastSecond() {
    var now = Date.now();
    return filteredMessages.filter(timestamp => now - timestamp <= 1000).length;
  }

  function updateEMA() {
    const currentValue = messagesFilteredLastSecond();
    ema = alpha * currentValue + (1 - alpha) * ema;
    updateKilledMessages();
  }

  function updateKilledMessages() {
    var elem = document.getElementById('rf-killed');

    if (!elem) {
      var child = document.getElementById('ugh'); // Embiggen Emote List button
      if (!child) return;
      elem = document.createElement('span');
      elem.id = 'rf-killed';
      child.parentElement.insertBefore(elem, child.nextSibling);
    }

    elem.innerText = "Filtered: " + killedMessages + " (" + ema.toFixed(2) + "/sec)";
  }

  // Called whenever we kill a message
  function killedMessage(data) {
    var now = Date.now();

    console.log('[CyTube Retard Filter] Killed message (' + killedMessages + ' total)');
    console.log(data);

    filteredMessages.push(now);
    // Remove messages outside the 30-second window
    filteredMessages = filteredMessages.filter(timestamp => now - timestamp <= avgWindow);
    killedMessages++;
    updateKilledMessages();

    return null;
  }

  function hookAddChatMessage(data) {
    var msg = data.msg.toLowerCase();

    // Don't filter messages that mention us
    if (unsafeWindow.CLIENT && unsafeWindow.CLIENT.name && msg.indexOf(unsafeWindow.CLIENT.name.toLowerCase()) !== -1) {
      return unsafeWindow.backupAddChatMessage(data);
    }

    for (const wl of whitelist) {
      if (msg.indexOf(wl) !== -1) {
        return backupAddChatMessage(data);
      }
    }

    for (const bl of blacklist) {
      if (msg.indexOf(bl) !== -1) {
        killedMessage(data);
        return null;
      }
    }

    for (const nr of niggeregexes) {
      if (nr.test(msg)) {
        killedMessage(data);
        return null;
      }
    }

    return unsafeWindow.backupAddChatMessage(data);
  }

  exportFunction(hookAddChatMessage, unsafeWindow, {defineAs: "hookAddChatMessage"});

  // This is in a setTimeout() because we need to wait for all the Xae shit to finish loading.
  // This will have the effect of redefining the global addChatMessage() function to call our hook.
  setTimeout(() => {
    var script = document.createElement('script');
    script.textContent = `
      window.backupAddChatMessage = window.addChatMessage;
      window.addChatMessage = function(data) {
        return hookAddChatMessage(data);
      }
      console.log('[CyTube Chat Filter] Hooked addChatMessage()');
    `;
    document.body.appendChild(script);
  }, 10000);

  setInterval(updateEMA, 1000);
})();