// ==UserScript==
// @name        Twitch - Mute ads
// @namespace   TWITCHADS
// @description Automatically mutes the Twitch player when an advertisement started and unmute it once finished.
// @include     https://www.twitch.tv/*
// @include     https://twitch.tv/*
// @version     1.0
// @license     MIT
// @author      Harest
// @grant       none
// @downloadURL none
// ==/UserScript==
var _tmuteVars = { "timerCheck": 1000, // Checking rate of ad in progress
                  "playerMuted": false, // Player muted or not
                  "adsDisplayed": 0 // Number of ads displayed;
                 };

// Check if there's an ad
function checkAd()
{
  var advert = document.getElementsByClassName('twitch-stitched-ad');
  //if (advert.length == 0) advert = document.getElementsByClassName('player-ad-notice'); // fallback test
  if ((advert.length >= 1 && _tmuteVars.playerMuted === false) || (_tmuteVars.playerMuted === true && advert.length === 0)) 
  {
    console.log(advert);
    mutePlayer();
  }
}

// (un)Mute Player
function mutePlayer()
{
  if (document.getElementsByClassName("player-button--volume").length >= 1)
  {
    document.getElementsByClassName("player-button--volume")[0].click();
    _tmuteVars.playerMuted = !(_tmuteVars.playerMuted);

    if (_tmuteVars.playerMuted === false)
    {
      _tmuteVars.adsDisplayed++;
      console.log("Ad #" + _tmuteVars.adsDisplayed + " detected. Player muted.");
    } else {
      console.log("Ad #" + _tmuteVars.adsDisplayed + " finished. Player unmuted.");
    }
  } else {
    console.log("No volume button found (class changed ?).");
  }
}

_tmuteVars.autoCheck = setInterval(checkAd, _tmuteVars.timerCheck);