// To use this script:
// - For chrome, install https://chrome.google.com/webstore/detail/tampermonkey/dhdgffkkebhmkfjojejmpbldmpobfkfo?hl=en
// - For firefox, install https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/
// ==UserScript==
// @name        Facebook AdBlock
// @namespace   facebook_adblock
// @include     https://www.facebook.com/
// @version     1
// @grant       none
// ==/UserScript==

var rules = {
  ".uiStreamSponsoredLink!parentNode(elem, 16)": function(elem) {
    return elem.classList.contains("userContentWrapper");
  },
  ".uiStreamSponsoredLink!parentNode(elem, 15)": function(elem) {
    return elem.textContent.indexOf("Like Page") !== -1;
  },
  ".uiStreamSponsoredLink!parentNode(elem, 11)": function(elem) {
    return elem.classList.contains("userContentWrapper");
  },
};

function parentNode(element, n) {
  while(n-- && element) {
    element = element.parentNode;
  }

  return element;
}

window.killAdTimer = null;

function killAds() {
  observer.disconnect();
  for (var rule in rules) {
    var splittedSelector = rule.split("!");
    var elementSelector = splittedSelector[0];
    var should_hide = splittedSelector[1];
    var elements = document.querySelectorAll(elementSelector);

    for (var i=0; i<elements.length; i++) {
      var elem = elements[i];
      var selectedElement = eval(should_hide);
      if (rules[rule](selectedElement)) {
        selectedElement.parentNode.removeChild(selectedElement);
      }
    }
  }
  window.killAdTimer = null;
  
  observer.observe(document, {
    subtree: true,
    attributes: true
  });
};

MutationObserver = window.MutationObserver || window.WebKitMutationObserver;

var observer = new MutationObserver(function(mutations, observer) {
  if (window.killAdTimer != null) {
    return;
  }

  window.killAdTimer = window.setTimeout(killAds, 500);
});

observer.observe(document, {
  subtree: true,
  attributes: true
});