window.Tabs = (function(Utils) {

  var addClass = Utils.addClass;
  var hasClass = Utils.hasClass;
  var removeClass = Utils.removeClass;
  var setOptions = Utils.setOptions;

  Tabs.prototype.defaults = {
    tabContainer: ".us-tabs",
    tabLinks: ".us-tabs-nav-mainlink",
    tabNav: ".us-tabs-nav",
    changeUrls: true,
    activeClass: "active",
    collapsible: false,
    autoScroll: true
  };

  function Tabs(options) {
    var ref = this.options = setOptions(options, this.defaults);
    var tabContainer = ref.tabContainer;
    var tabLinks = ref.tabLinks;

    this.activeTabEvent = new CustomEvent('ustyle.tab.active');
    this.tabs = document.querySelectorAll(tabContainer + ' ' + tabLinks);
    if(!this.tabs.length) return;
    this.filter = this.tabs.item(0).getAttribute("data-target") ? "data-target" : "href";
    this.init();

    var handleClick = (function (_this) {
      return function (e) {
        var target = e.currentTarget;
        if (_this.isAccordion() && _this.options.collapsible && _this.isActive(target)) {
          _this.collapse(target);
          _this.hashClear();
        } else {
          _this.navigateTo(target);
          _this.scrollToTab(target);
          _this.hashChange(target);
        }

        return e.preventDefault();
      }
    })(this);

    forEach(this.tabs, function (index, tab) {
      tab.addEventListener('click', handleClick);
    });
  }

  Tabs.prototype.init = function() {
    var activeTab = this.activeTab();
    var initialHash = this.tabFromHash();

    if (initialHash) {
      return this.navigateTo(initialHash);
    } else if (activeTab) {
      return this.navigateTo(activeTab);
    } else if (!this.options.collapsible || !this.isAccordion()) {
      return this.navigateTo(this.tabs.item(0));
    }
  };

  Tabs.prototype.hashChange = function(target) {
    if (!this.options.changeUrls) return;

    return window.location.replace("#!" + (getSelector(target).replace(/#/, "")));
  };

  Tabs.prototype.hashClear = function() {
    if (!this.options.changeUrls) return;

    var url = window.location.pathname + window.location.search;
    return typeof history.replaceState === "function" ? history.replaceState("", document.title, url) : void 0;
  };

  Tabs.prototype.navigateTo = function(target) {
    var selector = getSelector(target);
    var selected = document.querySelector(selector);
    var activeClass = this.options.activeClass;
    var filter = this.filter;

    forEach(this.tabs, function (index, tab) {
      removeClass(tab, activeClass);
    });

    forEach(this.tabs, function (index, tab) {
      if (tab.getAttribute(filter) === selector) {
        return addClass(tab, activeClass);
      }
    });

    forEach(selected.parentNode.children, function (index, child) {
      if (child !== selected) {
        removeClass(child, activeClass);
      }
    });

    addClass(selected, activeClass);
    return selected.dispatchEvent(this.activeTabEvent);
  };

  Tabs.prototype.collapse = function(target) {
    var selected = document.querySelector(getSelector(target));
    var activeClass = this.options.activeClass;

    forEach(this.tabs, function (index, tab) {
      removeClass(tab, activeClass);
    });

    return removeClass(selected, activeClass);
  };

  Tabs.prototype.scrollToTab = function(target) {
    if (!(this.isAccordion() && this.options.autoScroll)) {
      return;
    }

    var selected = document.querySelector(getSelector(target));
    return selected.scrollIntoView();
  };

  Tabs.prototype.activeTab = function() {
    var activeTab = null;
    var activeClass = this.options.activeClass;
    var matchingTab = null;

    forEach(this.tabs, function (index, tab) {
      if (hasClass(tab, activeClass)) {
        return matchingTab = tab;
      }
    });

    return matchingTab;
  };

  Tabs.prototype.tabFromHash = function() {
    var tabId = window.location.hash.replace("!", "");
    var filter = this.filter;
    var matchingTab = null;

    forEach(this.tabs, function (index, tab) {
      if (tab.getAttribute(filter) === tabId) {
        return matchingTab = tab;
      }
    });

    return matchingTab;
  };

  Tabs.prototype.isActive = function(target) {
    return getSelector(target) === getSelector(this.activeTab());
  };

  Tabs.prototype.isAccordion = function() {
    var tabNav = document.querySelector(this.options.tabNav);

    return !(tabNav.offsetWidth > 0 || tabNav.offsetHeight > 0);
  };

  var getSelector = function(clicked) {
    return clicked.getAttribute("data-target") || clicked.getAttribute("href");
  };

  var forEach = function (array, callback, scope) {
    for (var i = array.length - 1; i >= 0; i--) {
      callback.call(scope, i, array[i]);
    }
  };

  return Tabs;
})(this.Utils);