/**
 * Set the options for trackingOptout:
 * `doNotTrackRespected`: Set whether you have your installation respect the browser’s DoNotTrack option
 * `storageKey`: Set the name of the key where the current status get's saved
 * `enabledPerDefault`: Set this to true if you want the tracking enabled per default
 */
const OPTIONS = {
  doNotTrackRespected: true,
  storageKey: "trackingEnabled",
  enabledPerDefault: true
};

function isMSExternal(external) {
  return "msTrackingProtectionEnabled" in external;
}

/**
 * get the browser’s DoNotTrack setting
 * @var DO_NOT_TRACK boolean
 */
const DO_NOT_TRACK = (() => {
  const dnt =
    window.doNotTrack || navigator.doNotTrack || navigator.msDoNotTrack;
  if (dnt === "1" || dnt === "yes") {
    return true;
  }
  // All versions of IE
  if (window.external && isMSExternal(window.external)) {
    return window.external.msTrackingProtectionEnabled();
  }
  return false;
})();

/**
 * Return the string for select elements
 * @param {string} element
 * @param {string} modifier
 */
function selector(element, modifier) {
  return (
    ".tracking-optout" +
    (element ? `__${element}` : "") +
    (modifier ? `--${modifier}` : "")
  );
}

/**
 * Return an array from nodes
 * @param selector
 * @param context
 */
function nodeArray(selector) {
  return [].slice.call(document.querySelectorAll(selector));
}

/**
 * Save all checkboxes in an array
 */
const CHECKBOXES = nodeArray(selector("input"));

/**
 * Set visibility of elements
 * @param {string} selector
 * @param {boolean} show
 */
function visibility(selector, show) {
  nodeArray(selector).forEach((element) => {
    element.style.display = show ? null : "none";
  });
}

/**
 * Remove elements from the dom
 * @param {string} selector
 */
function remove(selector) {
  nodeArray(selector).forEach((element) => {
    element.parentNode.removeChild(element);
  });
}

/**
 * Hide elements
 * @param {string} selector
 */
function hide(selector) {
  visibility(selector, false);
}

/**
 * Show elements
 * @param {string} selector
 */
function show(selector) {
  visibility(selector, true);
}

/**
 * Display the current status of the tracking (enabled or not)
 * @param {bool} enable
 */
function displayStatus(enable) {
  CHECKBOXES.forEach((checkbox) => {
    checkbox.checked = enable;
  });
  trackingOptout.enabled = enable;
  hide(selector("status"));
  show(selector("status", enable ? "active" : "inactive"));
}

/**
 * Set Status
 * @param {bool} enable
 */
function setStatus(enable) {
  localStorage.setItem(OPTIONS.storageKey, enable ? "true" : "false");
  displayStatus(!!enable);
  return !!enable;
}

/**
 * Toggle the status
 */
function toggleStatus() {
  const status = !trackingOptout.enabled;
  setStatus(status);
  return status;
}

/**
 * Log if do not track is active and toggle or set is called
 */
function forbidden() {
  console.log("Do not track is enabled, so no tracking where enabled");
  return false;
}

const trackingOptout = {
  doNotTrack: DO_NOT_TRACK,
  enabled: null,
  toggle: toggleStatus,
  set: setStatus
};

(() => {
  const OLDIE = selector("oldie");
  const DNT = selector("dnt");
  const LABEL = selector("label");

  if (DO_NOT_TRACK && OPTIONS.doNotTrackRespected) {
    remove(OLDIE);
    show(DNT);
    trackingOptout.enabled = false;
    trackingOptout.set = forbidden;
    trackingOptout.toggle = forbidden;
    return;
  }
  remove(DNT);
  if (typeof Storage !== "undefined") {
    remove(OLDIE);
    const SAVED_STATUS = localStorage.getItem(OPTIONS.storageKey);
    if (SAVED_STATUS === null) {
      // Set default value
      setStatus(OPTIONS.enabledPerDefault);
    } else {
      displayStatus(SAVED_STATUS === "true");
    }
    CHECKBOXES.forEach((input) => {
      input.addEventListener("change", toggleStatus);
    });
    show(LABEL);
    return;
  }
  remove(LABEL);
  show(OLDIE);
})();

window.trackingOptout = trackingOptout;